Antifungal activity of a flavonoid-rich fraction from Costus spicatus leaves against dermatophytes
The leaves of Costus spicatus Swartz (Costaceae) are used for inflammatory diseases in folk medicine. Inhibitory activity on nitric oxide already was verified, in vitro, for flavonol diglycosides of this plant . In the present study, the inhibitory activity was assessed against dermatophytes from a rich-flavonoid fraction.
C. spicatus leaves of Amapá, Brazil (voucher n° 009585, herbarium Amapaense) were macerated with 40% aqueous ethanol for fifteen days. After concentration, the aqueous extract was stirred with Amberlite XAD-2®, Supelco (1:20, on the basis of extract dry weight), for 1h and packed in a column. The resin was washed with water and the adsorbed compounds were eluted with methanol. HPLC-DAD analysis was performed on an ODS-2 column (5µm, 250×4.6mm id) by using a discontinuous gradient of 5% aqueous HCOOH and MeOH, 5–80% for 0–50min followed by isocratic elution, at 1ml/min. Antifungal activity was evaluated against 5 dermatophytes. A macrodilution broth method was employed to determine the minimal inhibitory concentration (MIC) and the minimal lethal concentration (MLC), according to NCCLS . Three independent experiments were performed, in duplicate.
HPLC analysis showed that a flavonoid-rich fraction was obtained from XAD-2, which exhibited activity for all dermatophytes assayed. MIC and MLC were 140µg/ml for Trichophyton mentagrophytes, T. rubrum, Microsporum gypseum and Epidermophyton floccosum, the higher activity being against M. canis, which presented MIC and MLC values of 70µg/ml. These results suggest, for the first time, the antifungal effectiveness of C. spicatus leaves, namely of a flavonoid-rich fraction, for dermatophytoses which are referred to as „tinea“ infections.
Acknowledgements: FCT and POCTI/FEDER for financial support and Dra. Rosângela Sarkis, for the provision and classification of the plant.
References: 1. Silva B. et al. (2000) Phytochemistry, 53: 87–92. 2. National Committee for Clinical Laboratory Standards, M38P (2002) Wayne