Isolation of anti-Candida albicans compounds from Markhamia obtusifolia (Baker) Sprague (Bignoniaceae)

Abstract

An increase in clinical cases of Candidiosis globally as well as fungal resistance to drugs prompted the search for novel anti-Candida albicans agents fromplant sources. Leaf extracts of Markhamia obtusifolia were screened for activity against C. albicans in vitro. An acetone extract obtained following serial exhaustive extraction contained mainly the active components with at least four active zones on the bioautogram. Bioassay guided fractionation of this extract led to the isolation of three compounds which inhibited the growth of three C. albicans strains. Based on spectroscopy studies (NMR and MS), the compounds were identified as 3β-hydroxyurs-12-en-28-oic acid, ursolic acid (1) 3β, 19α-dihydroxyurs-12-en-28-oic acid, pomolic acid (2) and 2β, 3β, 19α -trihydroxy-urs-12-en-28-oic acid, 2-epi-tormentic acid (3). The most active compound was 3β, 19α-dihydroxy-12-ursen-28-oic acid (2) with a minimuminhibitory concentration (MIC) value of 12.5 μg/mL for C. albicans isolated from dog and 25.0 μg/mL for C. albicans fromcat and ATCC 90028 at 24 h following incubation. However, at 48 h of incubation MICs were N400 μg/mL for all the three compounds isolated. This study indicated that M. obtusifolia could be a potential source of active principles against C. albicans.