Planta Med 2007; 73(15): 1568-1573
DOI: 10.1055/s-2007-993744
Pharmacology
Original Paper
© Georg Thieme Verlag KG Stuttgart · New York

Mycological and Electron Microscopic Study of Solanum chrysotrichum Saponin SC-2 Antifungal Activity on Candida Species of Medical Significance

Armando Herrera-Arellano1 , María de los Angeles Martínez-Rivera2 , Maribel Hernández-Cruz2 , Edgar Oliver López-Villegas2 , Aída Verónica Rodríguez-Tovar2 , Laura Alvarez3 , Silvia Marquina-Bahena3 , Víctor Manuel Navarro-García1 , Jaime Tortoriello1
  • 1Centro de Investigación Biomédica del Sur, Instituto Mexicano del Seguro Social (IMSS), Xochitepec, Morelos, México
  • 2Escuela Nacional de Ciencias Biológicas, Instituto Politécnico Nacional, Cd. de México, México
  • 3Centro de Investigaciones Químicas, Universidad Autónoma del Estado de Morelos, Morelos, México
Further Information

Publication History

Received: March 29, 2007 Revised: October 1, 2007

Accepted: October 19, 2007

Publication Date:
03 December 2007 (online)

Abstract

Solanum chrysotrichum is utilized in traditional Mexican medicine for the treatment of mycotic skin infections. Several microbiological studies have provided evidence of its antifungal activity against dermatophytes and yeasts. S. chrysotrichum saponins have been identified as a group of compounds with antifungal activity and saponin SC-2 has demonstrated to be the most active. Previous clinical studies have shown the therapeutic effectiveness of S. chrysotrichum-derived saponin-standardized herbal products in the treatment of Tinea pedis and Pityriasis capitis. There is no previous evidence of the activity of these saponins against Candida non-albicans species, or fluconazole- and ketoconazole-resistant Candida strains. The present study reports the biological activity of the SC-2 saponin (inhibitory concentration [IC50] and minimum fungicide concentration [MFC]), against 12 Candida strains of clinical significance (C. albicans, five strains; C. glabrata and C. parapsilosis, two; C. krusei, C. lusitaniae and C. tropicalis, one), including some fluconazole (Fluco)- and ketoconazole (Keto)-resistant clinical isolates. In addition, SC-2-associated microstructural alterations were reported in four of the above-mentioned Candida species. Seven strains had IC50 of 200 μg/mL for SC-2, 400 μg/mL was found in four strains, and 800 μg/mL for a sole C. glabrata strain. Susceptibility to SC-2 saponin was as follows: C. albicans = C. lusitaniae > C. krusei > C. glabrata. The MFC was 800 μg/mL for the majority of strains (nine), 400 μg/mL for C. albicans (two strains) and C. lusitaniae. The ultrastructural Candida changes originated by SC-2 included the following: 1) damage on cytoplasmic membrane and organelles; 2) changes in cell wall morphology and density, with separation of cytoplasmatic membrane from cell wall and disintegration of the latter; and 3) total degradation of cellular components and death. Changes were manifested from 6 h of incubation, reaching their maximum effect at 48 h. In conclusion, the saponin SC-2 possesses fungicide and fungistatic activity on different Candida albicans and non-albicans species (including some azole-resistant strains) with IC50 values of 200 μg/mL (in Fluco-susceptible strains) and of 400 - 800 μg/mL (in Fluco-resistant strains). Additionally, we observed by transmission electron microscopy (TEM) that saponin SC-2 causes severe changes in all fungal cell membranes, and to a lesser degree on the cell wall.

Abbreviations

IC50:inhibitory concentration 50 %

MFC:minimal fungicidal concentration

CLSI:Clinical and Laboratory Standards Institute

CFU:colony forming units

Fluco:fluconazole

Itra:itraconazole

Keto:ketoconazole

AmB:amphotericin B

TEM:transmission electron microscopy

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Dr. Armando Herrera Arellano

Centro de Investigación Biomédica del Sur

IMSS

Argentina 1

62790 Xochitepec

Morelos

México

Phone: +52-777-361-2155

Fax: +52-777-361-2155

Email: armandoha_mx@yahoo.com.mx