Filamentous Fungi-Derived Orsellinic Acid-Sesquiterpene Meroterpenoids: Fungal Sources, Chemical Structures, Bioactivities, and Biosynthesis

Abstract

Fungi-derived polyketide-terpenoid hybrids are important meroterpenoid natural products that possess diverse structure scaffolds with a broad spectrum of bioactivities. Herein, we focus on an ever-increasing group of meroterpenoids, orsellinic acid-sesquiterpene hybrids comprised of biosynthetic start unit orsellinic acid coupling to a farnesyl group or/and its modified cyclic products. The review entails the search of China National Knowledge Infrastructure (CNKI), Web of Science, Science Direct, Google Scholar, and PubMed databases up to June 2022. The key terms include “orsellinic acid”, “sesquiterpene”, “ascochlorin”, “ascofuranone”, and “Ascochyta viciae”, which are combined with the structures of “ascochlorin” and “ascofuranone” drawn by the Reaxys and Scifinder databases. In our search, these orsellinic acid-sesquiterpene hybrids are mainly produced by filamentous fungi. Ascochlorin was the first compound reported in 1968 and isolated from filamentous fungus Ascochyta viciae (synonym: Acremonium egyptiacum; Acremonium sclerotigenum); to date, 71 molecules are discovered from various filamentous fungi inhabiting in a variety of ecological niches. As typical representatives of the hybrid molecules, the biosynthetic pathway of ascofuranone and ascochlorin are discussed. The group of meroterpenoid hybrids exhibits a broad arrange of bioactivities, as highlighted by targeting hDHODH (human dihydroorotate dehydrogenase) inhibition, antitrypanosomal, and antimicrobial activities. This review summarizes the findings related to the structures, fungal sources, bioactivities, and their biosynthesis from 1968 to June 2022.

Key words

filamentous fungi - orsellinic acid - ascochlorin - antitumor - hDHODH - biosynthesis

Introduction

Polyketide-terpenoid hybrids are well-known to be meroterpenoid natural products. They are widely distributed in the fungal kingdom, which displays potent activities and remarkable structures, exemplified by mycophenolic acids, yanuthones, and aspernidines, as well as those that are derived from 3,5-demethylorsellinic acid, etc. [1], [2], [3].

Orsellinic acid-sesquiterpene meroterpenoids are a small group of polyketide-terpenoids. The hybrids are featured by the composition of orsellinic acid moiety and farnesyl group or/and its folded products with diverse scaffolds mainly transformed by terpene synthases. Without exception, the farnesyl part of all hybrids is attached to orsellinic acid moiety at the C-3 position (red bond). Mainly filamentous fungi are dominant producers that can inhabit a variety of ecological niches.

Due to their unique structures, as well as promising bioactivities, the small group of meroterpenoids has attracted considerable attention from chemists and biologists. Ascochlorin was the first example isolated from filamentous fungus Ascochyta viciae (A. viciae) in 1968, which has been later identified as Acremonium egyptiacum (synonym: Acremonium sclerotigenum) [4], [5]. Structurally, the structures of this group are reminiscent of vitamin E (γ-tocotrienol), the essential substance of mammalian health, and coenzyme Q10, as well as ubiquinone derivatives [6], [7]. Bedside-formed farnesyl variants, including monocyclic and bicyclic products, mediated by terpene cyclase and tailoring enzymes are responsible for further enlarging the chemical space. The sesquiterpene moiety is mainly decorated with etherification, acylation, oxidation, addition, rearrangement reaction, etc. Particularly, rearrangement reactions result in a change in carbon frameworks. In addition, various enzyme catalysts have been formed in nature to act on halogens in the skeleton through oxidation, reduction, and other strategies, playing an important role in the structural diversity and functional enrichment of natural products. Halogenation is a common modification reaction and usually occurs in biosynthetic start unit orsellinic acid at C-5. This halogenation process is catalyzed by the halogenase AscD, which performs or does not perform its function, resulting in different products obtained, such as compound 12 with chlorine and compound 13 without chlorine.

The diverse chemical space confers a broad range of biological activities, including antivirus, antitumor, anti-inflammatory, hypolipidemic, and anti-trypanosome. Because of structural similarity with ubiquinone derivatives, such as decylubiquinone, the group of meroterpenoids is highlighted by hDHODH (human dihydroorotate dehydrogenase) inhibiting activity. hDHODH is a key enzyme involved in the de novo pyrimidine biosynthesis, which is frequently overexpressed to support their growth of cancer cells. Inhibition of hDHODH activity has been proven to validate to suppress proliferation of cancer cells and represents a promising target for chemotherapeutic drugs [7], [8], [9]. The literature search strategy involved the search of the Web of Science, Science Direct, Google Scholar, PubMed, Reaxys, and Scifinder databases up to June 2022. The significant bioactivities of some compounds such as ascofuranone and ascochlorin have been intensively studied, and the reviews relating to bioactivities have been summarized [7], [10], [11].

In this review, we focus on the structure isolation, purification, filamentous fungi sources, and biological activities of orsellinic acid-sesquiterpene hybrids from 1968 to June 2022 (Table 1S, Supporting Information).

Overview

Orsellinic acid-sesquiterpene hybrids are almost produced by filamentous fungi. These producing fungi can widely inhabit various ecological niches, such as marine sponge, coral, terrestrial soil, etc. The original study of the hybrids can be traced back to 1968, and ascochlorin represent the first compound isolated from filamentous fungus A. viciae. This review summarizes that 71 orsellinic acid-sesquiterpene hybrids (1 – 71) have been isolated and identified from filamentous fungi over the past half century (until June 2022).

Based on the biosynthesis of the hybrids, these compounds are classified into three groups based on cyclization of the sesquiterpenoid part, namely, linear type, monocyclic type, and bicyclic type.

Biosynthesis

Since 1968, orsellinic acid-sesquiterpene hybrids were continually isolated; however, its biosynthetic pathway was not completely analyzed until 2019.

In 2016, the biosynthetic gene cluster for LL-Z1272β (2) from Stachybotrys bisbyi PYH05 – 7 was identified by Li et al. The heterologous expression in Aspergillus oryzae NSAR1 unveiled the basic biosynthetic route of LL-Z1272β, supported by the production of orsellinic acid and ilicicolinic acid B (5, also named as grifolic acid) [12].

Araki et al. reported the detailed biosynthetic pathway of ascofuranone (22) and ascochlorin (33) in A. egyptiacum in 2019 ([Fig. 1]) [13]. Briefly, it turns out that orsellinic acid is synthesized from PKS (polyketide synthase) and serves as the starting unit of the hybrids. Then, the prenyltransferase AscA attaches a farnesyl diphosphate (FPP) group to the orsellinic acid skeleton at the C-3 position to form a linear meroterpenoid product, ilicicolinic acid B (5). For this class of orsellinic acid-sesquiterpene hybrids, post-biosynthetic decoration included chlorination, etherification, acylation, oxidation, and glycosylation, which increased structural and functional diversity of the polyketide-terpenoid hybrids. The post-modifications also sometimes played ecological roles, such as plant defense and inhibition of pathogen growth. The Acremonium sp. LG0808, a producer of polyketide-terpenoid hybrids, is a plant endophytic fungus that may interact between plants and microbes, thereby playing a role in plant defense. The carboxylic acid group of 5 was reduced to the aldehyde group by AscB to produce ilicicolin B (2). Subsequent chlorination occurs at C-5 under the catalysis of AscD and resulted in the production of ilicicolin A (1). AscE is responsible for the epoxidation reaction between C-10′ and C-11′, thereby forming the common intermediate LL-Z 1272α epoxide (3). Compound 3 is the common precursor, as the branching point of the biosynthetic pathways of 22 and 33. 3 was first modified by terpene cyclase AscF to generate monocyclic six-membered ring product ilicicolin C (35), and then oxidized by AscG to give 33. In ascofuranone biosynthesis branches, compound 3 comes through the hydroxylation at C-8′ by P450 monooxygenase to generate 23, followed by cyclization by AscF to finally produce 22 [7].

Fig. 1 The biosynthesis of ascofuranone (22) and ascochlorin (33). Enzymes are abbreviated as follows: PKS, polyketide synthase; PT, prenyltransferase; Red, reductase; Hal, halogenase; TPC, terpene cyclase; Dh, dehydrogenase; MO, monooxygenase; Epo, epoxidase [13].

Linear Type

The linear type contains 21 molecules (1 – 21) in which the farnesyl group is formed to the linear sesquiterpene attached to orsellinic acid at C-3. Compounds 1 and 2 are the first reported cases belonging to this type. The linear ones are always co-isolated with other structure types and are usually considered as the biosynthetic precursors.

LL-Z 1272α (1) and LL-Z 1272β (2) ([Fig. 2]), as anti-Tetrahymena pyriformis compounds, were originally isolated from filamentous fungi Fusarium sp. LL-Z 1272 in 1969. At the same time, orsellinic acid was co-isolated from fermentation extracts [14]. Subsequently, both compounds were isolated from Cylindrocladium ilicicola strain MFC-870 and named ilicicolin A and ilicicolin B, respectively [15], [16]. Both compounds were also discovered in several filamentous fungi of different genus, such as Acremonium, Cylindrocarpon, Nectria, and Neonectria [17], [18], [19], [20], [21], [22], [23], [24].

Fig. 2 Structures of compounds 1 – 4. The red bond is to easily draw a distinction between PKS unit and terpene unit and to highlight the coupling position of two precursor units (the same below).

Compound 1 can inhibit the proliferation of lymphocytic leukemia Jurkat cells at 10 µM with an inhibition rate of 71.43% [25]. Guo et al. reported that 1 showed an antitumor effect by inhibiting the signal pathway of enhancer of zeste homolog 2 [26]. Compound 2 showed testosterone-5α-reductase (T-5α-reductase) inhibitory activity on rat prostate with an IC₅₀ value of 0.36 mM [20] and antitrypanosomal activity toward Trypanosoma brucei brucei strain GUTat 3.1 and Trypanosoma brucei rhodesiense strain STIB900 with IC₅₀ values of 49 and 59 nM, respectively [27]. T-5α-reductase is one of the important drug targets for benign prostatic hyperplasia by inhibiting the transformation of testosterone to dihydrotestosterone [28], [29], [30], [31]. Compound 2 also exhibited antibacterial activity against Bacillus subtilis and methicillin-resistant Staphylococcus aureus (MRSA) with IC₅₀ values of 1.06 and 0.74 µM, respectively [23], and moderate antifungal activity against Ustilago violacea and Fusarium oxysporum with inhibition zones of 4 and 5 mm [32].

LL-Z 1272α epoxide (3) ([Fig. 2]) was isolated as a precursor of ascochlorin from A. viciae J-29 in 2009 [33]. Compound 3 was the epoxidation product of 1. Both Microcera sp. BCC 17 074 and A. sclerotigenum GXIMD 02 501 produced 3 [18], [34]. It showed weak cytotoxic activity and potent hDHODH inhibition with an IC₅₀ value of 1.6 µM [18].

Ilicicolinic acid A (4) ([Fig. 2]) and ilicicolinic acid B (5) ([Fig. 3]) were first isolated from Cylindrocarpon sp. in 1993 [35]. Afterward, chemical studies were performed on Neonectria discophora SNB-CN63, which led to the isolation of ilicicolinic acids A, C – G (6−10), and ilicicolinol (11) ([Fig. 3]) [19], [36]. According to the Markovnikov orientation, compound 6 might be an H₂O addition product of 4. However, C-7′ configurations of 8 and 9 were unassigned.

Fig. 3 Structures of compounds 5 – 11.

Antimicrobial activities of compounds 4 – 11 were evaluated. Compound 4 was found to be selective activity with a minimum inhibitory concentration (MIC) value of 1 µg/mL against Escherichia coli. (ATCC 25 922). Compounds 8 and 9 were found to be selective in activity against microbial pathogen Trichophyton rubrum SNB-TR1 with MIC values of 8 and 8 µg/mL. Compounds 6, 7, and 11 showed weak antimicrobial activity against T. rubrum SNB-TR1, S. aureus ATCC29213, and MRSA ATCC33591, while compound 10 exhibited no antimicrobial activity (MIC>128 µg/mL) [19], [36]. Comprehensive analysis of the structure-activity relationships suggested that the presence of the chlorine atom was important to exert antimicrobial activities.

Chlorocylindrocarpol (12) ([Fig. 4]) was discovered from marine sponge-derived Acremonium sp. in 2009 [37], [38]. Cylindrocarpol (13) ([Fig. 4]) was isolated from Cylindrocarpon lucidum (MF 5710) in 1996 [39]. Subsequently, 12 and 13 were also found in Acremonium sp., Microcera sp. BCC 17 074, and A. sclerotigenum GXIMD 02 501 [18], [34], [37]. Compound 12 exhibited stronger antitumor activity against the MCF-7 cell line (breast cancer) with an IC₅₀ value of 6.2 µg/mL, comparable to doxorubicin (IC₅₀=8.6 µg/mL) [34]. It also displayed weak anti-inflammatory activity to inhibit the production of NO and IL-6 [37]. Compound 13 showed weak inhibitory activity (MIC=77 µM) against farnesyl-protein transferase (FPTase), which is a potential target for anticancer drugs [39]. Recently, 12 and 13 are reported to show hDHODH inhibitory activity with IC₅₀ values of 3.7 and 5.0 µM, respectively [18]. Nectchlorin B (14) ([Fig. 4]) was a methoxy adduct from compound 12. It was isolated from Microcera sp. BCC 17 074 and showed weak cytotoxicity [34].

Fig. 4 Structures of compounds 12 – 15.

Acremochlorins I – M (15 – 19) ([Fig. 4] and [5]) were identified as hDHODH inhibitors from coral-derived fungus A. sclerotigenum GXIMD 02 501. They showed hDHODH inhibition with the IC₅₀ values of 9.3, 7.9, 0.39, 0.50, and 0.52 µM, respectively. They also exhibited potent antiproliferative activity against MDA-MB-231 and MDA-MB-468 cell lines, with the IC₅₀ values ranging from 1.7 to 12 µM, except 15 and 16 (IC₅₀>60 µM) [18].

Fig. 5 Structures of compounds 16 – 19.

10′-hydroxyilicicolinic acid D (20) ([Fig. 6]) was initially isolated from Cylindrocarpon sp. SY-39 in 2018 and displayed antimicrobial activity against S. aureus (MIC=5.0 µg/mL) [40]. Cylindrocarpol dimer (21) ([Fig. 7]) was reported as a fungal metabolite, but its origin had not been identified; 21 showed hDHODH enzyme inhibition with an IC₅₀ value of 2.03 µM and anti-proliferation effects toward T lymphocyte cells with an IC₅₀ value of 9.32 µM [41].

Fig. 6 Structures of compounds 20 and 21.

Fig. 7 Structures of compounds 22 – 28.

Monocyclic Type

Most of these groups are distributed in monocyclic type, in which the farnesyl group was formed to the monocyclic sesquiterpene scaffold. In the group, a variety of cyclization patterns and post-modifications increased greatly the structure diversity. A total of 46 molecules (22 – 67) are included in the group, and 33 represents the first case of the group. Abundant cyclization patterns are endowed with significant activities.

Ascofuranone (22) ([Fig. 7]) was initially isolated from A. viciae in 1972 [38], [42]. Afterward, compound 22 appeared again in Acremonium sp., Paecilomyces variotii INA-199, Verticillium hemipterigenum BCC 2370, and Nectria sp (HIL Y 90 3333) [37], [43], [44], [45], [46], [47]. The detailed and impressive bioactivities will be discussed below.

Ascofuranol (23) ([Fig. 7]) was discovered from A. viciae Libert in 1973 [48] and coexisted with its derivatives in several filamentous fungi such as Acremonium sp. (J05B-1-F-3), A. sclerotigenum GXIMD 02 501, and V. hemipterigenum BCC 2370 [18], [37], [44]. Compound 23 exhibited weak anti-inflammatory activity [37] and hDHODH inhibition with an IC₅₀ value of 0.72 µM, as well as moderate cytotoxic activity against MDA-MB-231 and MDA-MB-468 cell lines with IC₅₀ values of 12 and 11 µM, respectively [18].

Ilicicolinal derivatives, ilicicolinal (24), and ilicicolinals B – I (25 – 32) ([Fig. 7] and [8]), together with compounds 4 – 11, were obtained from N. discophora SNB-CN63 [19]. Structurally, 24 and 25 are isomers; the furan ring in 24 is formed by the ether bond between C-3 and C-4, while that of 25 is due to etherification between C-2 and C-3. Compounds 26 – 28 possess a five-membered ring-containing sesquiterpene scaffold. Compounds 29 – 30 have a pyranoid ring formed between C-3 and C-4, while the formation of the pyranoid ring in 31 and 32 occurs between C-2 and C-3. Antimicrobial activities studies showed that 25 – 27 and 32 were selectively active with MIC values ranging from 8 to 16 µg/mL on two pathogens, S. aureus ATCC29213 and MRSA ATCC33591, while 24 and 28 – 31 were inactive (MIC≥128 µg/mL) [19]. Comparison of 24 and 25 suggests a formation pattern of ether was crucial for the antimicrobial activity.

Fig. 8 Structures of compounds 29 – 36.

Ascochlorin (33) ([Fig. 8]) was originally purified from A. viciae in 1968, and the partial structure was determined [4]. Its structure was finally elucidated by a combination of X-ray crystallography and physicochemical methods in 1969 [49]. Subsequent metabolite ilicicolin D (C. ilicicola MFC-870) and LL-Z 1272γ (Fusarium sp. LL-Z 1272) were confirmed to be identical to ascochlorin by comparisons of NMR, IR, TLC, and mixed melting point determination [14], [15], [16], [21].

Compounds 22 and 33 are representative molecules of the hybrids and exhibited impressive and diverse bioactivities, which have been well-documented in previous reviews [5], [7], [10], [37], [48], [50], [51], [52], [53], [54], [55], [56], [57], [58], [59], [60], [61], [62], [63], [64], [65], [66], [67], [68], [69], [70], [71], [72], [73], [74], [75], [76], [77], [78], [79], [80], [81], [82], [83], [84], [85], [86], [87]. Gao et al. reviewed antitumor activity, mechanisms, and antitumor drug targets of compounds 22 and 33 in 2020 [7]. As reviewed, 22 is a unique target for the treatment of African trypanosomiasis [10], [85], [88], [89], [90], [91], [92], [93], [94]. Briefly, compound 22 was found to be an inhibitor of TAO ubiquinol oxidase [54], recombinant Trypanosoma vivax alternative oxidase with a K_i value of 0.40 nM, and rTAO inhibitor with an IC₅₀ value of 1.3 nM [66], [69], [95], [96], [97], [98], [99], [100], [101], [102], [103], [104]. Potent inhibitory activity of trypanosomal glycerol kinase and TAO of T. b. brucei for 22 were described in 2019 [105]. In addition, 22 and 33 showed inhibitory activity against Cryptosporidium parvum AOX (alternative oxidase) with IC₅₀ values of 0.3 and 500 nM, respectively [68], potent sensitivity of recombinant Sauromatum guttatum AOX with IC₅₀ values of 0.06 and 7 nM and native Arum maculatum AOX with IC₅₀ values of 0.16 and 70 nM [106], [107], [108]; 33 was also reported to show specific inhibitory effect toward mitochondrial cytochrome bc1 complex [109] and a recombinant AOX inhibitor expressed in E. coli membranes 7.4 ± 3 nM [110].

Compounds 22 and 33 also showed antimicrobial activities. Both compounds exhibited moderate fungicidal activity against plant pathogenic fungus Phytophthora infestans [43], as well as significant antimicrobial activity against S. aureus, MRSA, S. epidermidis, B. subtilis, and the human pathogenic fungus Candida albicans with MIC values of 0.25 – 32 µg/mL [22], [47], [111]; 33 was active against Pseudomonas syringae with an IC₅₀ value of 28.5 µM [112] and against Aspergillus fumigatus with MIC values of 1.25 to 2.5 µg/mL [113], [114]. Furthermore, 22 and 33 displayed anti-inflammatory activity [37], [115], [116], [117], [118], [119], [120], [121], as well as a potent agonist of peroxisome proliferator-activated receptor with IC₅₀ values of 3.2 and 1 µM, respectively [122].

LL-Z 1272ζ (34), LL-Z 1272δ (35), and LL-Z 1272ε (36), together with 1, 2, and 33, were isolated from Fusarium sp. LL-Z 1272 in 1969 ([Fig. 8]) [14], [38]. Verticillium SP FO-2787, Fusarium sp. (internal strain 3042), Acremonium sp., Cylindrocarpon sp. FKI-4602, etc. are additional producers of these hybrids [21], [22], [34], [37], [43], [44]. It was noted that LL-Z 1272ζ (34) was proven to be the same as ilicicolin F.; 35 was known as ilicicolin C and 4,5-dihydroascochlorin, while 36 was identical to 4,5-dihydrodechloroascochlorin [15], [16], [21], [32]. Cyclohexanone-containing sesquiterpene moiety is the most common scaffold in the family, which is usually cyclized by the relevant terpene cyclase.

The bioactivities of 34 – 36 were evaluated. All exhibited moderate T 5α-reductase inhibitory activity with IC₅₀ values of 0.37 mM, 0.34 mM, and 0.37 mM, respectively [20]. Furthermore, 34 showed potent fungicidal activity against plant pathogenic fungi P. infestans at 500 mg/L [43] and good cytotoxic activities toward three cancer cell lines, KB, BC-1, and NCI-H187, as well as Vero cells with IC₅₀ values ranging from 0.69 to 1.9 µg/mL [44]; 34 was also active with IC₅₀ values of 28.5 µM against P. syringae [112]. Compound 35 could selectively inhibit the production of NO at 100 µM [37] and potent antibacterial activity toward B. megaterium with a zone of 10 mm [32]. Compound 36 showed strong antifungal activity toward Eurotium repens with a zone of 15 mm [32].

Another two derivatives, LL-Z 1272ε acid (37) and dechlorodeacetyloronctrin (38), were first separated and purified from Nectria sp. B-13 ([Fig. 9]). Compound 37 can completely inhibit the spore germination of Magnaporthe grisea with an MIC value of 15.6 µg/mL. Compound 38 had a weak inhibitory effect on the activity of Pyricularia oryzae [123].

Fig. 9 Structures of compounds 37 – 40.

Cylindrochlorin (39) ([Fig. 9]), also named 8′,9′-dehydroascochlorin [43] and ilicicolin E [15], [16], was first discovered from the methanol extract of the mycelium of Cylindrocladium sp. in 1970 and showed antiviral activity against Newcastle disease virus [124]. Meanwhile, compound 39 was found to be active on herpes simplex virus type 1 (HSV-1) with an IC₅₀ value of 0.19 µg/mL [44]. It showed potent fungicidal activity against A. fumigatus with an MIC value of 4.1 µM [43], [114]. It also exhibited cytotoxic activities in KB, BC-1, NCI-H187, and Vero cells with IC₅₀ values of 2.4, 0.53, 1.3, and 0.69 µg/mL, respectively [44]. Compound 39 was subsequently found from Cylindrocarpon sp. FKI-4602, Nectria sp (HIL Y 90 3333), Stilbella fimetaria (IBT 28 361), and Verticillium SP FO-2787 [20], [22], [43], [114].

Bioactivity-guided fractionation led to the discovery of hypolipidemic 4′-hydroxy-5′-hydroascochlorin (40) from A. viciae Libert in 1974 ([Fig. 9]) [125], while 4′,5′-dihydro-4′-hydroxyascochlorin, deacetylchloronectrin, and 4′,5′-dihydro-4′β-hydroxyascochlorin are considered to have the same structure with 4′-hydroxy-5′-hydroascochlorin [37], [44], [45], [47], [114]. Compound 40 was usually co-isolated with 10′-deoxy-10′α-hydroxyascochlorin (41), ascofuranone (22), ascochlorin (33), and other derivatives from different fungal genus, such as Acremonium sp. LG0808, V. hemipterigenum BCC 2370, Stilbella fimetaria (IBT 28 361), etc. [37], [44], [45], [47], [113]. Compounds 40 and 41 showed potent cytotoxic activities against the A549 (lung cancer) with IC₅₀ values of 4.1 and 0.9 µM, and the HepG2 (hepatocellular carcinoma) cancer cell line with IC₅₀ values of 44.7 and 5.8 µM, respectively [47]. Moreover, 40 can selectively inhibit NO and IL-6 production to display anti-inflammatory activity [37] and showed strong antibacterial activities against Ralstonia solanacearum with an MIC value of 3.13 µg/mL [126]; 41 exhibited metastatic prostate cancer cell migration inhibitory activity at 6 µM [45] and weak antimicrobial activity [47].

Ascochlorin N-acetylglucosamine (42), 4′-ketoascochlorin (43), and 4′5′-dihydro-4′-formylascochlorin (44) were isolated from marine-derived fungus S. fimetaria IBT 28 361 by the targeted dereplication of fungal extracts via UHPLC-DAD-QTOF-MS ([Fig. 10]). The additional amino sugar unit at the C-4′ position of 42 was identified as N-acetyl-α-D-glucosamine. At present, only compound 42 and vertihemipterin A (46) have α-D-glucosamine unit. Antifungal and antibacterial activities were assessed; 43 was found to have weak antibacterial activities against MRSA, while others were inactive [114].

Fig. 10 Structures of compounds 41 – 44.

8′-hydroxyascochlorin (45) ([Fig. 11]), vertihemipterin A (46), 4′,5′-dihydro-4′-hydroxyascochlorin, and 8′,9′-dehydroascochlorin were separated from the extracts of V. hemipterigenum BCC 2370 [44]. Meanwhile, compound 45 possessed more potent cytotoxicity than 46 [44].

Fig. 11 Structures of compounds 45 – 52.

In 1996, Singh et al. reported that cylindrol A (47), cylindrols A₁-A₄ (48 – 51), and cylindrols B and B₁ (53 – 54) were obtained from C. lucidum (MF 5710, ATCC 74 261) ([Fig. 11] and [12]) [38], [39], [127]. A soil-derived fungus, Cylindrocarpon sp. FKI-4602, was also reported to produce cylindrol A₅ (52), cylindrol A₄ (51), and cylindrol B (53) [22]. Compounds 47, 48, 50 – 51, and 53 showed broad FPTase inhibitory activity with IC₅₀ values of 0.7 µM to 13 µM [39]. In addition, 52 exhibited moderate antimicrobial activities toward B. subtilis ATCC 6633, Acholeplasma laidlawii KB174, M. smegmatis ATCC 607, and Kocuria rhizophila ATCC 9341 [22]; 53 could inhibit the production of NO, TNF-R, and IL-6 at 100 µM [37].

Fig. 12 Structures of compounds 53 – 58.

Chloronectrin (55) ([Fig. 12]) was initially discovered from Nectria coccinea in 1972 [21]. Nectchlorin A (56) ([Fig. 12]), together with 55 and 14, were isolated from Microcera sp. BCC 17 074 [34]. The five carbon linkers in 55 and 56 are further oxidized in contrast to analogs, and they displayed weak cytotoxic activity [34]. When bromide was added to chloride-free medium, Fusarium sp. could produce the bromo-analogue of ascochlorin, 3-bromoascochlorin (57) [21]. Supplementation of KBr to the Fusarium sp. culture medium led to the production of 3-bromoascochlorin (57) and 3-bromo-12,13-dihydroascochlorin (58) ([Fig. 12]). Compound 58 (IC₅₀=17.8 µM) showed slightly stronger cytotoxicity than compound 57 (IC₅₀=21.3 µM) [128]. Zhang et al. studied the antitumor mechanism of compound 57 by suppressing the MAPK pathway [129].

Acremochlorin A – F (59 – 64) ([Fig. 13]), together with compounds 15 – 19, were isolated from coral-derived fungus A. sclerotigenum GXIMD 02 501. Among them, 59 showed potent hDHODH inhibition with the IC₅₀ values of 74 nM and cytotoxic activity against MDA-MB-231 and MDA-MB-468 cell lines, with IC₅₀ values of 0.65 and 0.48 µM. Other metabolites (60 – 64) showed moderate hDHODH inhibition with IC₅₀ values ranging from 3.9 to 34 µM and weak cytotoxic activities (IC₅₀>60 µM) [18].

Fig. 13 Structures of compounds 59 – 67.

DimethoxyilicicolinC (65) ([Fig. 13]) was initially derived from Nectria sp. B-13 by silica gel column, gel chromatography, reverse phase silica gel chromatography, preparation thin-layer chromatography (PTLC), and HPLC [25]. It can be regarded as the methoxy substituent of ilicicolin C. Another difference is that compound 65 has an additional methyl group at C-8. However, compared with other analogs, it has no biological activity. In 1997, TAN-2355A (66) and TAN-2355B (67) ([Fig. 13]) with glycosides were found from Acremonium sp. FL-65227. For the binding of [3H]-TRH to CHO cells, compound 66 showed inhibitory activity with an IC₅₀ value of 52 µM [38], [130].

Bicyclic Type

This class contains four molecules (68 – 71) that are featured by the farnesyl group formed to a bicyclic sesquiterpene scaffold. In detail, compound 68 has a furan ring and a cyclohexanone moiety; 69 possesses a decalin unit and both metabolites 70 and 71 are involved in a fused 13 – 5 bicyclic ring system ([Fig. 14]).

Fig. 14 Structures of compounds 68 – 71.

Acremochlorin G (68) and acremochlorin H (69) were co-isolated with compounds 59 – 64 from the coral-derived fungus A. sclerotigenum GXIMD 02 501 and showed weak cytotoxic activity against MDA-MB-231 and MDA-MB-468 cells and hDHODH inhibitory activity. Interestingly, compound 69 is the first case of the ASC-type meroterpenoids with a drimane unit [18].

Acremofuranone A (70) and acremofuranone B (71) were isolated from Acremonium sp. (J05B-1-F-3) [37], [38], with the unprecedented cyclic skeleton. Compound 71 was defined as a dehydrated derivative of 70.

Conclusion

Orsellinic acid-sesquiterpene meroterpenoids aroused the great interest and attention of scientists because of their diverse bioactivities, particularly antitrypanosomal activity and antitumor activity inhibiting the hDHODH target protein. This review summarizes structures, filamentous fungi sources, activities, and biosynthesis of these types of compounds from 1968 to June 2022.

The statistical data revealed most orsellinic acid-sesquiterpenoid hybrids are produced by filamentous fungi. Of all the compounds reviewed, Acremonium/Ascochyta (25%), Neonectria (14%), Cylindrocarpon (14%), Fusarium (11%), Verticillium (7%), and Stachybotrys (7%) are predominant producers of increased structural diversity ([Fig. 15]). The remaining 22% of these compounds are scattered across another four genera including Stilbella, Microcera, Nectria, and Cylindrocladium. Furthermore, considering the structure frameworks, nearly 48% of the linear type, 39% of the monocyclic, and 100% of the bicyclic type are derived from Acremonium spp., indicating the potential differences of gene constitution in gene cluster or/and transcriptional regulation between different genera. Maybe it results from secondary metabolism regulated by environmental factors such as pH, medium nutrition, culture temperature, etc. In terms of inhabiting ecological niches, 34% of the investigated hybrids are produced by marine-derived fungi that are isolated from coral, sponge, and driftwood; 22 percent, 14 percent, and 7 percent of these compounds are coming from terrestrial soil- or arctic soil-derived fungi, pathogenic fungi, and endophytic fungi, respectively. In addition, dried cow dung, the dead leaf of beech, and a Nasutitermes corniger termite aerial nest-derived fungi are also the potential producers for production of the hybrids (19%), as shown in [Fig. 16]. It is noted that the hybrids produced by pathogenic fungi may play an important role in infecting the host or chemical arsenals for defense and even in the area of biological control.

Fig. 15 Fungal genus distribution of isolated compounds.

Fig. 16 Diverse ecological environments of producing fungi.

The related bioactivities for the meroterpenoids were also discussed in this review. To sum up, they showed a wide range of biological activities ([Fig. 17]). Approximately 28% of the meroterpenoids possessed cytotoxic activity including antitumor and antiproliferative activities. About 21%, 15%, and 10% of the meroterpenoids exhibited antimicrobial activity, testosterone-5α-reductase or farnesyl-protein transferase inhibitory activity, and anti-inflammatory activity, respectively ([Fig. 17]). The remaining 9% showed other activities including antiviral, hypolipidemic, and antitrypanosomal activities. Specifically, compound 2 showed more potent anti-African-trypanosomiasis activity (IC₅₀= 0.049 – 0.059 µM) than fexinidazole (IC₅₀=0.7 – 3.3 µM). The fexinidazole is the only oral preparation for the treatment of human African trypanosomiasis approved by the FDA; thus, compound 2 could be a potential anti-African-trypanosomiasis drug candidate or lead structure. Compound 59 showed stronger DHODH inhibitory activity (IC₅₀=74 nM) than teriflunomide which was approved by FDA for treating multiple sclerosis and rheumatoid arthritis. Furthermore, compound 59 has higher safety and fewer side effects than the commonly used DHODH inhibitor brequinar, suggesting the meroterpenoids are promising molecules for discovering the new class of DHODH inhibitors. Considering the lack of a systematic bioactive evaluation of these compounds in unified conditions, we failed to summarize the structure-activity relationships of the meroterpenoids among the linear, mono-, and bicyclic types. However, we take DHODH inhibition as an example; the bicyclic sesquiterpenes are less effective than that of linear and monocyclic sesquiterpenes. Most linear sesquiterpenes have better DHODH inhibitory activity than monocyclic sesquiterpene. Obviously, rich cyclization patterns about farnesyl moiety may have an impact on hDHODH inhibition.

Fig. 17 Bioactivity distribution of isolated compounds (1 – 71).

Given the aforementioned potential pharmaceutical values of the meroterpenoid hybrids, accurate mining of these resources is sought after. In the post-genome era, bioinformatics and omics analysis will facilitate the location of related biosynthetic gene clusters in the fungi kingdom. While using genome mining technologies, complemented by the global natural products, molecular networks (GNPs) can accelerate the discovery of the resource of the unknown natural hybrids. Considering silent biosynthetic gene clusters, low expression in the host strains, and the need for structure derivatization, the synthetic biology method and combinatorial biosynthesis, which are based on a platform of heterologous expression, will provide the opportunities to rationally access unidentified natural products and natural-product-like molecules.

Contributorsʼ Statement

Literature collection: H. Gao, L. Zhou, Y. Wang, X. Qian, Y. Liu; manuscript framework construction: H. Gao, P. Zhang, G. Wu; structural painting and proofreading: X. Qian, Y. Liu, Y. Wang; original draft writing: H. Gao, G. Wu; critical revision, language polishing, optimization of the manuscript: H. Gao, L. Zhou, P. Zhang, Y. Wang, G. Wu.

Conflict of Interest

The authors declare that they have no conflict of interest.

Acknowledgements

The authors acknowledge Prof. Dehai Li for his support in responding to the review comments, and also greatly appreciate the constructive comments from René Prétôt, Alessandra Braca and anonymous reviewers, which have made our review more comprehensive.

• References

• 1 Geris R, Simpson TJ. Meroterpenoids produced by fungi. Nat Prod Rep 2009; 26: 1063-1094
• 2 Matsuda Y, Abe I. Biosynthesis of fungal meroterpenoids. Nat Prod Rep 2016; 33: 26-53
• 3 Zhang X, Wang TT, Xu QL, Xiong Y, Zhang L, Han H, Xu K, Guo WJ, Xu Q, Tan RX, Ge HM. Genome mining and comparative biosynthesis of meroterpenoids from two phylogenetically distinct fungi. Angew Chem Int Ed Engl 2018; 57: 8184-8188
• 4 Tamura G, Suzuki S, Takatsuki A, Ando K, Arima K. Ascochlorin, a new antibiotic, found by the paper-disc agar-diffusion method. I. Isolation, biological and chemical properties of ascochlorin. (Studies on antiviral and antitumor antibiotics. I). J Antibiot 1968; 21: 539-544
• 5 Hijikawa Y, Matsuzaki M, Suzuki S, Inaoka DK, Tatsumi R, Kido Y, Kita K. Re-identification of the ascofuranone-producing fungus Ascochyta viciae as Acremonium sclerotigenum . J Antibiot 2016; 70: 304-307
• 6 Chai EZP, Shanmugam MK, Arfuso F, Dharmarajan A, Wang C, Kumar AP, Samy RP, Lim LH, Wang L, Goh BC, Ahn KS, Hui KM, Sethi G. Targeting transcription factor STAT3 for cancer prevention and therapy. Pharmacol Ther 2016; 162: 86-97
• 7 Yuan S, Gopal JV, Ren S, Chen L, Liu L, Gao Z. Anticancer fungal natural products: Mechanisms of action and biosynthesis. Eur J Med Chem 2020; 202: 112502
• 8 Petrovic MM, Roschger C, Chaudary S, Zierer A, Mladenovic M, Jakovljevic K, Markovic V, Botta B, Joksovic MD. Potent human dihydroorotate dehydrogenase inhibitory activity of new quinoline-4-carboxylic acids derived from phenolic aldehydes: Synthesis, cytotoxicity, lipophilicity and molecular docking studies. Bioorg Chem 2020; 105: 104373
• 9 Petrovic MM, Roschger C, Chaudary S, Zierer A, Mladenovic M, Markovic V, Trifunovic S, Joksovic MD. Low cytotoxic quinoline-4-carboxylic acids derived from vanillin precursors as potential human dihydroorotate dehydrogenase inhibitors. Bioorg Med Chem Lett 2021; 46: 128194
• 10 Barra L, Abe I. Chemistry of fungal meroterpenoid cyclases. Nat Prod Rep 2021; 38: 566-585
• 11 Shiomi K. Antiparasitic antibiotics from Japan. Parasitol Int 2021; 82: 102298
• 12 Li C, Matsuda Y, Gao H, Hu D, Yao XS, Abe I. Biosynthesis of LL-Z1272β: Discovery of a new member of NRPS-like enzymes for aryl-aldehyde formation. Chembiochem 2016; 17: 904-907
• 13 Araki Y, Awakawa T, Matsuzaki M, Cho R, Matsuda Y, Hoshino S, Shinohara Y, Yamamoto M, Kido Y, Inaoka DK, Nagamune K, Ito K, Abe I, Kita K. Complete biosynthetic pathways of ascofuranone and ascochlorin in Acremonium egyptiacum . Proc Natl Acad Sci U S A 2019; 116: 8269-8274
• 14 Ellestad GA, Evans jr. RH, Kunstmann MP. Some new terpenoid metabolites from an unidentified Fusarium species. Tetrahedron 1969; 25: 1323-1334
• 15 Hayakawa S, Minato H, Katagiri K. The ilicicolins from cylindrocladium ilicicola . J Antibiot 1971; 24: 653-654
• 16 Minato H, Katayama T, Hayakawa S, Katagiri K. Identification of ilicicolins with ascochlorin and LL-Z 1272. J Antibiot 1972; 25: 315-316
• 17 Liu X, Chen X, Qian F, Zhu T, Xu J, Li Y, Zhang L, Jiao B. Chlorinated phenolic sesquiterpenoids from the Arctic fungus Nectria sp. B-13. Biochem Syst Ecol 2015; 59: 22-25
• 18 Luo X, Cai G, Guo Y, Gao C, Huang W, Zhang Z, Lu H, Liu K, Chen J, Xiong X, Lei J, Zhou X, Wang J, Liu Y. Exploring marine-derived ascochlorins as novel human dihydroorotate dehydrogenase inhibitors for treatment of triple-negative breast cancer. J Med Chem 2021; 64: 13918-13932
• 19 Sorres J, Sabri A, Brel O, Stien D, Eparvier V. Ilicicolinic acids and ilicicolinal derivatives from the fungus Neonectria discophora SNB-CN63 isolated from the nest of the termite Nasutitermes corniger found in French Guiana show antimicrobial activity. Phytochemistry 2018; 151: 69-77
• 20 Takamatsu K, Rho MC, Masuma R, Hayashi M, Komiyama K, Tanaka H, Omura S. A novel testostone 5α-reductase inhibitor, 8′,9′-dehydroascochlorin produced by verticillium sp FO-2787. Chem Pharm Bull 1994; 42: 953-956
• 21 Aldridge DC, Borrow A, Foster RG, Large MS, Spencer H, Turner WB. Metabolites of Nectria coccinea . J Chem Soc Perkin 1 1972; 17: 2136-2141
• 22 Kawaguchi M, Fukuda T, Uchida R, Nonaka K, Masuma R, Tomoda H. A new ascochlorin derivative from Cylindrocarpon sp. FKI-4602. J Antibiot 2013; 66: 23-29
• 23 Wu B, Oesker V, Wiese J, Malien S, Schmaljohann R, Imhoff JF. Spirocyclic drimanes from the marine fungus Stachybotrys sp. strain MF347. Mar Drugs 2014; 12: 1924-1938
• 24 Guo R, Zhang Y, Duan D, Fu Q, Zhang X, Yu X, Wang S, Bao B, Wu W. Fibrinolytic evaluation of compounds isolated from a marine fungus Stachybotrys longispora FG216. Chin J Chem 2016; 34: 1194-1198
• 25 Liu X. Researches on structure elucidation and biological activities investigation of secondary metabolites of two polar fungi [PhD Thesis]. Shanghai: The Second Military Medical University; 2016
• 26 Guo L, Luo X, Yang P, Zhang Y, Huang J, Wang H, Guo YF, Huang W, Chen Z, Wang S, Wang J, Lei JP, Xiang S, Liu Y. Ilicicolin A exerts antitumor effect in castration-resistant prostate cancer via suppressing EZH2 signaling pathway. Front Pharmacol 2021; 12: 723729
• 27 Otoguro K, Ishiyama A, Namatame M, Nishihara A, Furusawa T, Masuma R, Shiomi K, Takahashi Y, Yamada H, Omura S. Selective and potent in vitro antitrypanosomal activities of ten microbial metabolites. J Antibiot 2008; 61: 372-378
• 28 Aggarwal S, Thareja S, Verma A, Bhardwaj TR, Kumar M. An overview on 5α-reductase inhibitors. Steroids 2010; 75: 109-153
• 29 Wilson FS, Busato J. Use of 5α-reductase inhibitor and delay in prostate cancer diagnosis and treatment. Int Braz J Urol 2020; 46: 456-458
• 30 Kim DG, Kwon HJ, Lim JH, Kim JH, Lee KP. Quisqualis indica extract ameliorates low urinary tract symptoms in testosterone propionate-induced benign prostatic hyperplasia rats. Lab Anim Res 2020; 36: 26
• 31 Traish AM. Health risks associated with long-term finasteride and dutasteride use: Itʼs time to sound the alarm. World J Mens Health 2020; 38: 323-337
• 32 Hussain H, Drogies KH, Al-Harrasi A, Hassan Z, Shah A, Rana UA, Green IR, Draeger S, Schulz B, Krohn K. Antimicrobial constituents from endophytic fungus Fusarium sp. Asian Pac J Trop Dis 2015; 5: 186-189
• 33 Hosono K, Ogihara J, Ohdake T, Masuda S. LL-Z1272α epoxide, a precursor of ascochlorin produced by a mutant of Ascochyta viciae . J Antibiot 2009; 62: 571-574
• 34 Isaka M, Yangchum A, Supothina S, Laksanacharoen P, Luangsa-Ard J, Hywel-Jones NL. Ascochlorin derivatives from the leafhopper pathogenic fungus Microcera sp. BCC 17074. J Antibiot 2015; 68: 47-51
• 35 Kuroda M, Takatsu T, Takahashi H, Hosoya T, Furuya K. New compound ilicicolinic acid A or B. Japanese Patent 05255184, 1993
• 36 Nirma C, Eparvier V, Stien D. Antibacterial ilicicolinic acids C and D and ilicicolinal from Neonectria discophora SNB-CN63 isolated from a termite nest. J Nat Prod 2015; 78: 159-162
• 37 Zhang P, Bao B, Dang HT, Hong J, Lee HJ, Yoo ES, Bae KS, Jung JH. Anti-inflammatory sesquiterpenoids from a sponge-derived fungus Acremonium sp. J Nat Prod 2009; 72: 270-275
• 38 Tian J, Lai D, Zhou L. Secondary metabolites from Acremonium fungi: Diverse structures and bioactivities. Mini-Rev. Med Chem 2017; 17: 603-632
• 39 Singh SB, Ball RG, Bills GF, Cascales C, Gibbs JB, Goetz MA, Hoogsteen K, Jenkins RG, Liesch JM, Lingham RB, Silverman KC, Zink DL. Chemistry and biology of cylindrols: Novel inhibitors of ras farnesyl-protein transferase from Cylindrocarpon lucidum . J Org Chem 1996; 61: 7727-7737
• 40 Suzuki T, Yoshida S, Koseki T, Aboshi T, Murayama T, Supratman U, Shiono Y. New metabolites produced by Cylindrocarpon sp. SY-39 from a driftwood. Chem Biodivers 2018; 15: e1700493
• 41 Shen W, Ren X, Zhu J, Xu Y, Lin J, Li Y, Zhao F, Zheng H, Li R, Cui X, Zhang X, Lu X, Zheng Z. Discovery of a new structural class of competitive hDHODH inhibitors with in vitro and in vivo anti-inflammatory, immunosuppressive effects. Eur J Pharmacol 2016; 791: 205-212
• 42 Sasaki H, Okutol T, Bosokau T, Nawata Y, Ando K. Ascofuranone, a new antibiotic from Ascochyta viciae . Tetrahedron Lett 1972; 13: 2541-2544
• 43 Bal-Tembe S, Kundu S, Roy K, Hiremath CP, Gole G, de Souza EP, Vijaya Kumar EKS, Gates DA, Pillmoor JB. Activity of the ilicicolins against plant pathogenic fungi. Pestic Sci 1999; 55: 645-647
• 44 Seephonkai P, Isaka M, Kittakoop P, Boonudomlap U, Thebtaranonth Y. A novel ascochlorin glycoside from the insect pathogenic fungus Verticillium hemipterigenum BCC 2370. J Antibiot 2004; 57: 10-16
• 45 Wanigesekaraa WMAP, Wijeratne EMK, Arnold AE, Gunatilaka AAL. 10′-deoxy-10α-hydroxyascochlorin, a new cell migration inhibitor and other metabolites from Acremonium sp., a fungal endophyte in Ephedra trifurca . Nat Prod Commun 2013; 5: 601-604
• 46 Mioso R, Marante FJT, de Laguna IHB. The chemical diversity of the ascomycete fungus Paecilomyces variotii . Appl Biochem Biotechnol 2015; 177: 781-791
• 47 Hao X, Li S, Ni J, Wang G, Li F, Li Q, Chen S, Shu J, Gan M. Acremopeptaibols A–F, 16-residue peptaibols from the sponge-derived Acremonium sp. IMB18-086 cultivated with heat-killed Pseudomonas aeruginosa . J Nat Prod 2021; 84: 2990-3000
• 48 Sasaki H, Hosokawa T, Sawada M, Ando K. Isolation and structure of ascofuranone and ascofranol, antibiotics with hypolipidemic activity. J Antibiot 1973; 26: 676-680
• 49 Nawata Y, Ando K, Tamura G, Arima K, Iitaka Y. The molecular structure of ascochlorin. J Antibiot 1969; 22: 511-512
• 50 Magae J, Nagai K, Nado K, Tamura G. Differentiation of mouse and human myeloid leukemia cells induced by an antitumor antibiotic, ascofuranone. Agric Biol Chem 1988; 12: 3143-3147
• 51 Hosokawa T, Suzuki K, Okutomi T, Sawada M, Ando K. Effect of ascofuranone on serum lipids of rats fed a cholesterol rich diet. Jpn J Pharmacol 1975; 25: 35-39
• 52 Magae J, Nagai K, Ando K, Yamasaki M, Tamura G. Effects of an antitumor agent, ascofuranone, on the macromolecular syntheses of intact cells. J Antibiot 1983; 36: 892-899
• 53 Minagawa N, Yabu Y, Kita K, Nagai K, Ohta N, Meguro K, Sakajo S, Yoshimoto A. An antibiotic, ascofuranone, specifically inhibits respiration and in vitro growth of long slender bloodstream forms of Trypanosoma brucei brucei . Mol Biochem Parasitol 1997; 84: 271-280
• 54 Fukai Y, Amino H, Hirawake H, Yabu Y, Ohta N, Minagawa N, Sakajo S, Yoshimoto A, Nagai K, Takamiya S, Kojima S, Kita K. Functional expression of the ascofuranone-sensitive Trypanosoma brucei brucei alternative oxidase in the cytoplasmic membrane of Escherichia coli . Comp Biochem Physiol Part C Pharmacol Toxicol Endocrinol 1999; 124: 141-148
• 55 Sawada M, Hosokawa T, Okutomi T, Ando K. Hypolipidemic property of ascofuranone. J Antibiot 1973; 26: 681-686
• 56 Magae J, Nagai K, Suzuki S, Yamasaki M, Ando K, Tamura G. Macrophage-specific effect on lipid metabolism by an antibiotic, ascofuranone. J Antibiot 1987; 40: 202-208
• 57 Yabu Y, Minagawa N, Kita K, Nagai K, Honma M, Sakajo S, Koide T, Ohta N, Yoshimoto A. Oral and intraperitoneal treatment of Trypanosoma brucei brucei with a combination of ascofuranone and glycerol in mice. Parasitol Int 1998; 47: 131-137
• 58 Saimoto H, Kido Y, Haga Y, Sakamoto K, Kita K. Pharmacophore identification of ascofuranone, potent inhibitor of cyanide-insensitive alternative oxidase of Trypanosoma brucei . J Biochem 2013; 153: 267-273
• 59 Kang JH, Park KK, Lee IS, Magae JJ, Ando K, Kim CH, Chang YC. Proteome analysis of responses to ascochlorin in a human osteosarcoma cell Line by 2-D gel electrophoresis and MALDI-TOF MS. J Proteome Res 2006; 5: 2620-2631
• 60 Magae J, Hotta M, Nagai K, Suzuli S, Ando K, Yamasaki M, Tamura G. Activation of natural cytotoxic activity and concomitant reduction of triglyceride content of murine spleen, treated with an antitumor antibiotic, ascofuranone. J Antibiot 1986; 39: 676-681
• 61 Magae J, Hayasaki J, Matsuda Y, Hotta M, Hosokawa T, Suzuki S, Nagai K, Ando K, Tamura G. Antitumor and antimetastatic activity of an antibiotic, ascofuranone, and activation of phagocytes. J Antibiot 1988; 41: 959-965
• 62 Magae J, Hosokawa T, Ando K, Nagai K, Tamura G. Antitumor protective property of an isoprenoid antibiotic, ascofuranone. J Antibiot 1982; 35: 1547-1552
• 63 Nihei C, Fukai Y, Kita K. Trypanosome alternative oxidase as a target of chemotherapy. Biochim Biophys Acta 2002; 1587: 234-239
• 64 Hosokawa T, Okutomi T, Sawada M, Ando K, Tamura G. Unusual concentration of urine and prevention of polydipsia by fungal prenylphenols in DOCA hypertensive rats. Eur. J Pharmacol 1981; 69: 429-438
• 65 Fukai Y, Nihei C, Kawai K, Yabu Y, Suzuki T, Ohta N, Minagawa N, Nagai K, Kita K. Overproduction of highly active trypanosome alternative oxidase in Escherichia coli heme-deficient mutant. Parasitol Int 2003; 52: 237-241
• 66 Nihei C, Fukai Y, Kawai K, Osanai A, Yabu Y, Suzuki T, Ohta N, Minagawa N, Nagai K, Kita K. Purification of active recombinant trypanosome alternative oxidase. FEBS Lett 2003; 538: 35-40
• 67 Yabu Y, Yoshida A, Suzuki T, Nihei C, Kawai K, Minagawa N, Hosokawa T, Nagai K, Kita K, Ohta N. The efficacy of ascofuranone in a consecutive treatment on Trypanosoma brucei brucei in mice. Parasitol Int 2003; 52: 155-164
• 68 Suzuki T, Hashimoto T, Yabu Y, Kido Y, Sakamoto K, Nihei C, Hato M, Suzuki S, Amano Y, Nagai K, Hosokawa T, Minagawa N, Ohta N, Kita K. Direct evidence for cyanide-insensitive quinol oxidase (alternative oxidase) in apicomplexan parasite Cryptosporidium parvum: Phylogenetic and therapeutic implications. Biochem Biophys Res Commun 2004; 313: 1044-1052
• 69 Suzuki T, Nihei C, Yabu Y, Hashimoto T, Suzuki M, Yoshida A, Nagai K, Hosokawa T, Minagawa N, Suzuki S, Kita K, Ohta N. Molecular cloning and characterization of Trypanosoma vivax alternative oxidase (AOX) gene, a target of the trypanocide ascofuranone. Parasitol Int 2004; 53: 235-245
• 70 Yabu Y, Suzuki T, Nihei C, Minagawa N, Hosokawa T, Nagai K, Kita K, Ohta N. Chemotherapeutic efficacy of ascofuranone in Trypanosoma vivax-infected mice without glycerol. Parasitol Int 2006; 55: 39-43
• 71 Cho HJ, Kang JH, Kwak JY, Lee TS, Lee IS, Park NG, Nakajima H, Magae J, Chang YC. Ascofuranone suppresses PMA-mediated matrix metalloproteinase-9 gene activation through the Ras/Raf/MEK/ERK- and Ap1-dependent mechanisms. Carcinogenesis 2007; 28: 1104-1110
• 72 Cho HJ, Kang JH, Kim T, Park KK, Kim CH, Lee IS, Min KS, Magae J, Nakajima H, Bae YS, Chang YC. Suppression of PAI-1 expression through inhibition of the EGFR-mediated signaling cascade in rat kidney fibroblast by ascofuranone. J Cell Biochem 2009; 107: 335-344
• 73 Kang JH, Cho HJ, Lee IS, Kim M, Lee IK, Chang YC. Comparative proteome analysis of TGF-beta1-induced fibrosis processes in normal rat kidney interstitial fibroblast cells in response to ascofuranone. Proteomics 2009; 9: 4445-4456
• 74 Hwang SL, Chang HW, Lee IK, Yang BK, Magae J, Chang YC. Ascofuranone prevents ER stress-induced insulin resistance via activation of AMP-activated protein kinase in L6 myotube cells. Biochem Biophys Res Commun 2010; 396: 967-972
• 75 Jeong JH, Kang SS, Park KK, Chang HW, Magae J, Chang YC. p 53-independent induction of G1 arrest and p 21WAF1/CIP1 expression by ascofuranone, an isoprenoid antibiotic, through downregulation of c-Myc. Mol Cancer Ther 2010; 9: 2102-2113
• 76 Chang YC, Cho HJ. Ascofuranone stimulates expression of adiponectin and peroxisome proliferator activated receptor through the modulation of mitogen activated protein kinase family members in 3T3-L1, murine pre-adipocyte cell line. Biochem Biophys Res Commun 2012; 422: 423-428
• 77 Jeong YJ, Cho HJ, Magae J, Lee IK, Park KG, Chang YC. Ascofuranone suppresses EGF-induced HIF-1alpha protein synthesis by inhibition of the Akt/mTOR/p 70S6K pathway in MDA-MB-231 breast cancer cells. Toxicol Appl Pharmacol 2013; 273: 542-550
• 78 Shiba T, Kido Y, Sakamoto K, Inaoka DK, Tsuge C, Tatsumi R, Takahashi G, Balogun EO, Nara T, Aoki T, Honma T, Tanaka A, Inoue M, Matsuoka S, Saimoto H, Moore AL, Harada S, Kita K. Structure of the trypanosome cyanide-insensitive alternative oxidase. Proc Natl Acad Sci U S A 2013; 110: 4580-4585
• 79 Minagawa N, Meguro K, Sakajo S, Yoshimoto A. Effects of ascofuranone on the mitochondria isolated from Hansenula anomala . Biosci Biotechnol Biochem 2014; 58: 1334-1335
• 80 Safdari Y, Khalili M, Ebrahimzadeh MA, Yazdani Y, Farajnia S. Natural inhibitors of PI3K/AKT signaling in breast cancer: emphasis on newly-discovered molecular mechanisms of action. Pharmacol Res 2015; 93: 1-10
• 81 Jager SN, Porta EOJ, Labadie GR. Tuning the Lewis acid phenol ortho-prenylation as a molecular diversity tool. Mol Divers (Basel) 2016; 20: 407-419
• 82 Matsuzaki M, Tatsumi R, Kita K. Protoplast generation from the ascofuranone-producing fungus Acremonium sclerotigenum . Cytologia (Tokyo) 2017; 82: 317-320
• 83 Park JY, Chung TW, Jeong YJ, Kwak CH, Ha SH, Kwon KM, Abekura F, Cho SH, Lee YC, Ha KT, Magae J, Chang YC, Kim CH. Ascofuranone inhibits lipopolysaccharide-induced inflammatory response via NF-kappaB and AP-1, p-ERK, TNF-alpha, IL-6 and IL-1beta in RAW 264.7 macrophages. PLoS One 2017; 12: e0171322
• 84 Miyazaki Y, Inaoka DK, Shiba T, Saimoto H, Sakura T, Amalia E, Kido Y, Sakai C, Nakamura M, Moore AL, Harada S, Kita K. Selective cytotoxicity of dihydroorotate dehydrogenase inhibitors to human cancer cells under hypoxia and nutrient-deprived conditions. Front Pharmacol 2018; 9: 997
• 85 West R, Cunningham T, Pennicott LE, Rao SPS, Ward SE. Toward more drug like inhibitors of trypanosome alternative oxidase. ACS Infect Dis 2018; 4: 592-604
• 86 Kim W, Chen W. Phytotoxic metabolites produced by legume-associated Ascochyta and its related genera in the dothideomycetes. Toxins (Basel) 2019; 11: 627
• 87 Qi Q, Lu X, Zheng Z, Li Y, Fan Y, Zhu J, Ren X, Cui X, Shi Y, Li S, Zhang H, Zhao B. F01WB-1315A and B, two dihydroorotate dehydrogenase inhibitors from microbial metabolites. Acta Microbiol Sin 2009; 49: 485-491
• 88 Kita K, Nihei C, Tomitsuka E. Parasite mitochondria as drug target: diversity and dynamic changes during the life cycle. Curr Med Chem 2003; 10: 2535-2548
• 89 Tsuda A, Witola WH, Ohashi K, Onuma M. Expression of alternative oxidase inhibits programmed cell death-like phenomenon in bloodstream form of Trypanosoma brucei rhodesiense . Parasitol Int 2005; 54: 243-251
• 90 de Souza W, Attias M, Rodrigues JC. Particularities of mitochondrial structure in parasitic protists (Apicomplexa and Kinetoplastida). Int J Biochem Cell Biol 2009; 41: 2069-2080
• 91 Kido Y, Shiba T, Inaoka DK, Sakamoto K, Nara T, Aoki T, Honma T, Tanaka A, Inoue M, Matsuoka S, Moore A, Harada S, Kita K. Crystallization and preliminary crystallographic analysis of cyanide-insensitive alternative oxidase from Trypanosoma brucei brucei . Acta Crystallogr Sect F Struct Biol Cryst Commun 2010; 66: 275-278
• 92 Fidalgo LM, Gille L. Mitochondria and trypanosomatids: targets and drugs. Pharm Res 2011; 28: 2758-2770
• 93 Young L, Rosell-Hidalgo A, Inaoka DK, Xu F, Albury M, May B, Kita K, Moore AL. Kinetic and structural characterisation of the ubiquinol-binding site and oxygen reduction by the trypanosomal alternative oxidase. Biochim Biophys Acta 2020; 1861: 148247
• 94 Awakawa T, Abe I. Reconstitution of polyketide-derived meroterpenoid biosynthetic pathway in Aspergillus oryzae . J Fungi (Basel) 2021; 7: 486-496
• 95 Kido Y, Sakamoto K, Nakamura K, Harada M, Suzuki T, Yabu Y, Saimoto H, Yamakura F, Ohmori D, Moore A, Harada S, Kita K. Purification and kinetic characterization of recombinant alternative oxidase from Trypanosoma brucei brucei . Biochim Biophys Acta 2010; 1797: 443-450
• 96 Xu F, Copsey AC, Young L, Barsottini MRO, Albury MS, Moore AL. Comparison of the kinetic parameters of alternative oxidases from Trypanosoma brucei and Arabidopsis thaliana-A tale of two cavities. Front Plant Sci 2021; 12: 744218
• 97 Fukai Y, Nihei C, Yabu Y, Suzuki T, Ohta N, Minagawa N, Nagai K, Kita K. Strain-specific difference in amino acid sequences of trypanosome alternative oxidase. Parasitol Int 2002; 51: 195-199
• 98 Shiomi K, Omura S. Antiparasitic agents produced by microorganisms. Proc Jpn Acad Ser B 2004; 80: 245-258
• 99 Kita K, Shiomi K, Omura S. Advances in drug discovery and biochemical studies. Trends Parasitol 2007; 23: 223-229
• 100 Ohashi-Suzuki M, Yabu Y, Ohshima S, Nakamura K, Kido Y, Sakamoto K, Kita K, Ohta N, Suzuki T. Differential kinetic activities of glycerol kinase among African trypanosome species phylogenetic and therapeutic implications. J Vet Med Sci 2011; 73: 615-621
• 101 Jeacock L, Baker N, Wiedemar N, Maser P, Horn D. Aquaglyceroporin-null trypanosomes display glycerol transport defects and respiratory-inhibitor sensitivity. PLoS Pathog 2017; 13: e1006307
• 102 Menzies SK, Tulloch LB, Florence GJ, Smith TK. The trypanosome alternative oxidase: a potential drug target?. Parasitology 2018; 145: 175-183
• 103 Ebiloma GU, Balogun EO, Cueto-Diaz EJ, de Koning HP, Dardonville C. Alternative oxidase inhibitors: mitochondrion-targeting as a strategy for new drugs against pathogenic parasites and fungi. Med Res Rev 2019; 39: 1-50
• 104 Shiba T, Inaoka DK, Takahashi G, Tsuge C, Kido Y, Young L, Ueda S, Balogun EO, Nara T, Honma T, Tanaka A, Inoue M, Saimoto H, Harada S, Moore AL, Kita K. Insights into the ubiquinol/dioxygen binding and proton relay pathways of the alternative oxidase. Biochim Biophys Acta 2019; 1860: 375-382
• 105 Balogun EO, Inaoka DK, Shiba T, Tsuge C, May B, Sato T, Kido Y, Nara T, Aoki T, Honma T, Tanaka A, Inoue M, Matsuoka S, Michels PAM, Watanabe YI, Moore AL, Harada S, Kita K. Discovery of trypanocidal coumarins with dual inhibition of both the glycerol kinase and alternative oxidase of Trypanosoma brucei brucei . FASEB J 2019; 33: 13002-13013
• 106 Williams BAP, Elliot C, Burri L, Kido Y, Kita K, Moore AL, Keeling PJ. A broad distribution of the alternative oxidase in microsporidian parasites. PLoS Pathog 2010; 6: e1000761
• 107 Elliott C, Young L, May B, Shearman J, Albury MS, Kido Y, Kita K, Moore AL. Purification and characterisation of recombinant DNA encoding the alternative oxidase from Sauromatum guttatum . Mitochondrion 2014; 19 Pt B: 261-268
• 108 Young L, May B, Pendlebury-Watt A, Shearman J, Elliott C, Albury MS, Shiba T, Inaoka DK, Harada S, Kita K, Moore AL. Probing the ubiquinol-binding site of recombinant Sauromatum guttatum alternative oxidase expressed in E. coli membranes through site-directed mutagenesis. Biochim Biophys Acta 2014; 1837: 1219-1225
• 109 Berry EA, Huang LS, Lee DW, Daldal F, Nagai K, Minagawa N. Ascochlorin is a novel, specific inhibitor of the mitochondrial cytochrome bc ₁ complex. Biochim Biophys Acta 2010; 1797: 360-370
• 110 Rosell-Hidalgo A, Young L, Moore AL, Ghafourian T. QSAR and molecular docking for the search of AOX inhibitors: A rational drug discovery approach. J Comput Aided Mol Des 2021; 35: 245-260
• 111 Minagawa N, Sakai S, Katsuragi R, Ando M. Effects of ascochlorin on the yeast Candida albicans . Biochim Biophys Acta 2012; 1817: S91
• 112 Gutiérrez M, Theoduloz C, Rodríguez J, Lolas M, Schmeda-Hirschmann G. Bioactive metabolites from the fungus Nectria galligena, the main apple canker agent in Chile. J Agric Food Chem 2005; 53: 7701-7708
• 113 Coleman JJ, Ghosh S, Okoli I, Mylonakis E. Antifungal activity of microbial secondary metabolites. PLoS One 2011; 6: e25321
• 114 Subko K, Kildgaard S, Vicente F, Reyes F, Genilloud O, Larsen TO. Bioactive ascochlorin analogues from the marine-derived fungus Stilbella fimetaria . Mar Drugs 2021; 19: 46
• 115 Padmalayam I, Suto M. Role of adiponectin in the metabolic syndrome: Current perspectives on its modulation as a treatment strategy. Curr Pharm Des 2013; 19: 5755-5763
• 116 Kang JH, Kim JK, Park WH, Park KK, Lee TS, Magae J, Nakajima H, Kim CH, Chang YC. Ascochlorin suppresses oxLDL-induced MMP-9 expression by inhibiting the MEK/ERK signaling pathway in human THP-1 macrophages. J Cell Biochem 2007; 102: 506-514
• 117 Magae J, Tsuruga M, Maruyama A, Furukawa C, Kojima S, Shimizu H, Ando K. Relationship between peroxisome proliferator-activated receptor-gamma activation and the ameliorative effects of ascochlorin derivatives on type II diabetes. J Antibiot 2009; 62: 365-369
• 118 Cho HJ, Kang JH, Jeong JH, Jeong YJ, Park KK, Park YY, Moon YS, Kim HT, Chung IK, Kim CH, Chang HW, Chang YC. Ascochlorin suppresses TGF-beta1-induced PAI-1 expression through the inhibition of phospho-EGFR in rat kidney fibroblast cells. Mol Biol Rep 2012; 39: 4597-4603
• 119 Lee SH, Kwak CH, Lee SK, Ha SH, Park J, Chung TW, Ha KT, Suh SJ, Chang YC, Chang HW, Lee YC, Kang BS, Magae J, Kim CH. Anti-inflammatory effect of ascochlorin in LPS-stimulated RAW 264.7 macrophage cells is accompanied with the down-regulation of iNOS, COX-2 and proinflammatory cytokines through NF-kappaB, ERK1/2, and p 38 signaling pathway. J Cell Biochem 2016; 117: 978-987
• 120 Park J, Kim HD, Lee SH, Kwak CH, Chang YC, Lee YC, Chung TW, Magae J, Kim CH. Ascochlorin induces caspase-independent necroptosis in LPS-stimulated RAW 264.7 macrophages. J Ethnopharmacol 2019; 239: 111898
• 121 Alexander MS, Hightower RM, Reid AL, Bennett AH, Iyer L, Slonim DK, Saha M, Kawahara G, Kunkel LM, Kopin AS, Gupta VA, Kang PB, Draper I. hnRNP L is essential for myogenic differentiation and modulates myotonic dystrophy pathologies. Muscle Nerve 2021; 63: 928-940
• 122 Togashi M, Ozawa S, Abe S, Nishimura T, Tsuruga M, Ando K, Tamura G, Kuwahara S, Ubukata M, Magae J. Ascochlorin derivatives as ligands for nuclear hormone receptors. J Med Chem 2003; 46: 4113-4123
• 123 Tang C. Studies on the secondary metabolites of Arctic-derived fungi Nectria sp. B-13 [Master Thesis]. Shanghai: Shanghai Ocean University; 2016
• 124 Kato A, Ando K, Tamura G, Arima K. Cylindrochlorin, a new antibiotic produced by cylindrocladium . J Antibiot 1970; 23: 168-169
• 125 Sasaki H, Hosakawa T, Nawata Y, Ando K. Isolation and structure of ascochlorin and its analogs. Agric Biol Chem 1974; 38: 1463-1466
• 126 Wei S, Ji Z. Isolation and antimicrobial activities of ascochlorin and its analogues from the metabolites of Cylindrocarpon olidum W1. Chin J Pestic Sci 2017; 19: 457-464
• 127 Singh SB, Zink DL, Bills GF, Jenkins RG, Silverman KC, Lingham RB. Cylindrol A: A novel inhibitor of ras farnesyl-protein transferase from Cylindrocarpon lucidum . Tetrahedron Lett 1995; 36: 4935-4938
• 128 Quan Z, Awakawa T, Wang D, Hu Y, Abe I. Multidomain P450 epoxidase and a terpene cyclase from the ascochlorin biosynthetic pathway in Fusarium sp. Org Lett 2019; 21: 2330-2334
• 129 Zhang Z, Zhang Y, Yang C, Wang Q, Wang H, Zhang Y, Deng W, Nie Y, Liu Y, Luo X, Huang J, Wang J. Antitumor effects of 3-bromoascochlorin on small cell lung cancer via inhibiting MAPK pathway. Cell Biol Int 2021; 45: 1-11
• 130 Tsuboya S, Shirasaki M, Ishimaru T. Terpene glycosides TAN-2355A and B of Acremonium and preparation of their derivatives as agonists of thyrotropin releasing hormone receptor. Japanese Patent 09157286, 1997

Publication History

Received: 10 February 2023

Accepted after revision: 24 May 2023

Accepted Manuscript online:
24 May 2023

Article published online:
23 June 2023