Planta Med 2015; 81 - SL4C_02
DOI: 10.1055/s-0035-1565337

Antifungal activity of quinoline alkaloids from Waltheria indica

S Cretton 1, S Dorsaz 2, Q Favre-Godal 1, A Azzollini 1, L Marcourt 1, JL Wolfender 1, M Cuendet 1, P Christen 1
  • 1School of Pharmaceutical Sciences, University of Geneva, University of Lausanne, Quai Ernest-Ansermet 30, CH-1211 Geneva 4, Geneva, Switzerland
  • 2Institute of Microbiology, University of Lausanne and University Hospital Center, Lausanne, Switzerland

The incidence of infections caused by Candida species (candidasis) has increased considerably over the past three decades, mainly due to a high number of immunocompromised patients (AIDS), an increasingly aged population, and the more widespread use of indwelling medical devices [1]. The increasing number of clinical isolates resistant to azole drugs and the limited number of alternative options (polyenes and echinocandins) have driven the search for new antifungal agents. As part of our project focused on the discovery of new natural antiparasitic compounds from Waltheria indica [2], extracts from this plant were screened against Candida albicans (CA). From the active alkaloid extract, sixteen 4-quinolone derivatives, i.e. antidesmone (1), 8-deoxoantidesmone (2), vanessine (3) and waltheriones E-Q (4-16) were isolated and characterized by NMR including 1 H-, 13C-NMR, HSQC, HMBC, COSY and NOESY experiments, ECD, UV, IR, and MS. Among these, five compounds 12-16 have not yet been described in the literature and vanessine (3) is reported for the first time in W. indica.

All these compounds showed significant in vitro inhibition of CA biofilm metabolic activity (MIC between 8 and 32 µg/mL), except waltherione O (14) with a MIC superior to 64 µg/mL. Moreover, alkaloids 1, 2, 4-6, 9, 13 and 16 inhibited CA planktonic cell growth at pH 4.6 with MIC values between 4 and 32 µg/mL. These promising results encourage further investigations to determine the range of activity towards other Candida species.

References: [1] Silva S, Negri M, Henriques M, Oliveira R, Williams DW, Azeredo J. Candida glabrata, Candida parapsilosis and Candida tropicalis: biology, epidemiology, pathogenicity and antifungal resistance. FEMS Microbiol Rev 2012; 36: 288 – 305. [2] Cretton S, Bréant L, Ambuehl C, Perozzo R, Marcourt L, Ebrahimi S, Hamburger M, Kaiser M, Cuendet M, Christen P. Antitrypanosomal quinoline alkaloids from the roots of Waltheria indica. J Nat Prod 2014; 77: 2304 – 2311.