EVALUATION OF ANTIFUNGAL ACTIVITIES OF SOME MEDICINAL PLANT EXTRACTS AND FRACTIONS AGAINST CLINICAL ISOLATES OF CANDIDA ALBICANS

Abstract

The development of drug resistance by pathogenic yeast especially Candida albicans, has resulted in waste of financial resources globally. This study was aimed at evaluating the antifungal activities of some medicinal plant extracts and fractions against clinical isolates of Candida albicans. Four medicinal plants namely: Vernonia amygdalina, Azardirachta indica, Moringa oleifera, and Vitellaria paradoxa were used in this study. The leaves, stembark and root of each medicinal plants were successively extracted using reflux method to obtain crude extracts, the fractions were obtained by column and thin layer chromatography. Clinical samples used were obtained from high vaginal swab (25) and urine(5). All samples were cultured in Sabouraud Dextrose broth (SDB) and then on Sabouraud Dextrose Agar (SDA). Isolates were identified using standard microbiological and molecular techniques. Antifungal activities of the crude extracts and fractions were done by Agar Well Diffusion Method. The minimum inhibitory concentration (MIC) and minimum fungicidal concentration (MFC) of the extracts and fractions were also determined. Gas chromatography and mass spectrophotometer analysis (GCMS) were used to determine bioactive compounds in fractions. Acute and sub-acute toxicity studies were done using the method of Lorkes and Organization for Economic Corporation and Development (OECD) respectively. Antifungal activities of the crude extracts were assayed at varying concentrations of 40, 60, 80 and 100 mg/mL against eight strains of Candida albicans. The highest mean zone of inhibition (MZI) 21.00± 0.30 mm was observed for methanol leaf extract of Vernonia amygdalina against strain SC5314 (isolate B7). The lowest results for the MIC and MFC of the crude extracts were 6.25 and 25.0 mg/mL, respectively. The n-hexane, ethyl acetate and methanol crude extract of Vernonia amygdalina yielded 4, 6 and 6 fractions respectively while the n-hexane, ethylacetate and methanol crude extracts of Azardirachta indica gave 7 fractions each. Antifungal activity of the fractions against the strains were determined at a concentration of 5 and 10 mg/mL. The highest mean zone of inhibition (MZI) for the fractions was 16.00±0.80 mm which was recorded for fraction (F4) of Vernonia amygdalina leaf of n- hexane extract against strain P37005. The lowest value for MIC and MFC results for the active fractions were 1.25 and 3.125 mg/mL, respectively. The standard drug (fluconazole 1mg/mL) used had a higher inhibitory activity that ranged from 33.66±1.00 - 42.00±0.49 mm compared to the activity of the crude extracts and the fractions. Results of the GCMS revealed probable compounds that may have enhanced the activity of the extracts and fractions. Acute toxicity profile of the crude extracts of Vernonia amygdalina and Azardirachta indica on experimental rats showed no mortality for all groups exposed to the ,extract and as well no group had signs of toxicity. The sub-acute toxicity results on haematological and kidney parameters showed for both extracts were within the control value. Although, liver parameters and lipid profile showed significant increase (P<0.05) especially at doses of 600 mg/kgbw. Haematological and biochemical parameters for the active fractions were all within the control. The crude extracts of Vernonia amygdalina and Azardirachta indica leaf were the two active plants parts that showed significant activity.