The effect of flavonols in Anacardium occidentale L. leaf extracts on skin pathogenic microorganisms

Cashew (Anacardium occidentale L.) leaf is traditionally used to treat skin infections. Although many flavonols have been identified from its leaf extract, their inhibitory effects on skin pathogens are not yet determined. The aims of this study were to determine the antimicrobial (against skin pathogenic microbes) and antioxidant activities of four flavonol glycosides from the crude extract and three flavonol aglycones from the hydrolyzed extract. The hydrolyzed extract was found to show higher activities than the crude extract. Myricetin showed the highest activity against all the tested bacteria and yeast with the lowest Minimum Inhibition Concentration (MIC) of 7.81 μg/mL on Corynebacterium minutissimum ATCC23348. Myricetin also exhibited good primary antioxidant activities with the effective concentration with 50% of activity (EC₅₀) values ranged between 2.23 μg/mL and 6.40 μg/mL. The highest secondary antioxidant activity was indicated by myricetin-3-O-rhamnoside. Thus, myricetin can be considered as a bioactive compound of the hydrolyzed extract.