Phytochemical screening, antioxidant and antimicrobial potential of stem barks of Coula edulis Baill. Pseudospondias longifolia Engl. and Carapa klaineana Pierre. from Gabon

Objective To evaluate the phytochemical constituents, antioxidant and antimicrobial potential of water-acetone, water-ethanol and water extracts of Coula edulis (C. edulis), Pseudospondia longifolia (P. longifolia) and Carapa klaineana (C. klaineana). Methods Presence of total phenols, flavonoids, tannins and proanthocyanidins was evaluated to estimate the effects of plants on microbial diseases. Water-acetone, water-ethanol and water extracts were examined for antioxidant activities. All plant extracts were evaluated against six reference strains, eleven clinical isolates and two fungal strains. Results The contents of total phenols [(12 857.56 ± 1.00) mg gallic acid equivalent/100 g], flavonoids [(1 634.13 ± 1.88) mg quercetin equivalent/100 g], tannins [(2 672.00 ± 1.59) mg tannic acid equivalent/100 g] and proanthocyanidins [(395.11 ± 0.83) mg apple procyanidin equivalent/100 g] were highest in the water-acetone and water-ethanol extracts from C. edulis in comparison with P. longifolia and C. klaineana. The water-acetone, water-ethanol and water extracts from C. edulis presented the highest antimicrobial activities against Neisseria gonorrhoeae, Enterococcus faecalis CIP 103907, Pseudomonas aeruginosa and Salmonella sp. The tested microorganisms showed sensitivity to all extracts of P. longifolia and C. klaineana with the exception of Shigella dysenteriae CIP 5451, Pseudomonas aeruginosa and Salmonella typhi. Conclusions Our results suggest that C. edulis extracts contain greater antioxidant and antimicrobial properties than P. longifolia and C. klaineana extracts.