Antimicrobial activity of compounds from Acanthospermum hispidum DC and Caesalpinia bonduc (L.) ROXB: Beninese plants used by healers against HIV-associated microbial infections.

ABSTRACT

In this study, we have tested alcoholic extracts (60%) from four Beninese plants Ocimum gratissimum L., Acanthospermum hispidum DC, Caesalpinia bonduc (L) Roxb and Calotropis procera W. T. Aiton. They are used by the healers to prevent opportunistic diseases associated to HIV-AIDS; on six strains such as Escherichia coli O 157H7, Staphylococcus aureus ATCC 25923 which resist to methicillin (MRSA), Salmonella typhi, Klebsiella pneumonia, Candida albicans ATCC 10231, and Mycobacterium bovis BCG 040812 which cause microbial infections associated with HIV-AIDS. The results show that all the extracts are bacteriostatic and fungistatic but only the hydro-ethanolic extracts of Acanthospermum hispidum (HE2) and of Caesalpinia bonduc (HE3) presented antibiotic power (respectively ap = 2 and ap = 4) on Candida albicans ATCC 10231. The Mycobacterium bovis BCG shown resistance to tested extracts (CMI > 250 μg/mL). The two fungicidal extracts HE2 and HE3 did not show harmful effects on the cells WI–38 with an IC50 > 100 μg/mL for HE2 and IC50 = 50 μg/mL for HE3. The successive bio-guided purifications of extracts HE2 and HE3 permitted isolation of three antibacterial compounds Flavanone (M1); stigmasterol (M2); and quercetin (M3). The three isolated compounds possess antibiotic power (ap 3±1) on tested strains and are not toxic on shrimp larvae (LC50 0.30 ± 0.17 mg/mL).