Screening for antibacterial, antioxidant activity and toxicity of some medicinal plants used in Benin folkloric medicine

Abstract

Ten extracts from 10 medicinal plants, Acanthospermum hispidium, Argemone mexicana,Byrsocarpus coccineus, Canthium setosum, Croton lobatus, Dichapetalum guineense,Nauclea latifolia, Schrankia leptocarpa, Secamone afzelii, Pterocarpus erinaceus,traditionally used in Benin to treat infectious diseases and were screened for in vitroantibacterial activity towards Staphylococcus aureus, Enteroccocus feacalis, Escherichia coli and Pseudomonas aeruginosa. The 2, 2-diphenylpicrylhydrazyl radical scavenging activity and toxicity assay using Artemia salina were also performed. All extracts were effective against tested microorganisms at different level with MIC ranking from 0.31 to 10 mg/ml. The best inhibition on the growth of tested bacteria was observed with four extracts obtained from D. guineense, N. latifolia, and P. erinaceus (MIC = 0.313 mg/ml). The species S. aureus and E. faecalis were more sensitive than the other test bacteria. All extracts showed good radical scavenging activity range from 1.35 to 3.47 µg/ml. The most effective extract was the methanolic extract of S. leptocarpa, with an EC50 value of 1.35 µg/ml. The lethality test showed that all tested extracts have low toxicity against the shrimps with LC50 values ranging from 3.8 to 8.17 mg/ml. The results provide an evidence of the traditional use of same collected plants in the treatment of infective diseases. Key words: Antibacterial, antioxidant, toxicity, traditional medicine, Benin.