Evaluation of antimicrobial activities of the ethanolic extracts of the leaf of senna alata and bark of piliostigma thonningii and the effect of their combination against skin infections

Afosi, A.B. ; Shittu, A.O. ; Adekunle, R.B. ; Bello, R.H. ; Attah, F.A. ; Eniayewu, O.I. (2020-06-04)


The skin is the largest, multi-layered organ with a protective function. However, a breach as a result of damage to the epidermis causes micro-organisms to penetrate and cause infections. This study evaluated the antimicrobial activities of the extracts of leaf of Senna alata and bark of Piliostigma thonningii as well as possible effect of the extracts combination in varying ratios. Ethanolic extracts of leaf of S. alata and bark of P. thonningii were evaluated for antimicrobial activities against selected Gram-positive - Staphylococcus aureus, Gram-negative - Escherichia coli, Pseudomonas aeruginosa Citrobacter freundii, Yersinia enterocolitica; and fungal strain - Candida albican using agar well diffusion method at 100, 200 and 300 mg/mL and in combination at 75:25, 25:75 and 50:50 ratios against selected microorganisms. Gentamicin and Nystatin were used as positive controls. Triplicate zones of inhibition were measured after 24 and 72 hours for bacterial and fungal isolates respectively. The extracts of S. alata and P. thonningii had means of zones of inhibition ranging from 24.00±1.06 to 13.00±0.00 and 30.00±0.43 to 15.00±1.00 against S. aureus and 21.50±0.25 to 18.00±0.00 and 19.00±0.43 to 17.00±0.81 against E. coli respectively. Only the extract of S. alata showed antifungal activity with mean of zones of inhibition ranging from 30.00±0.53 to 12.00±0.82 against C. albicans. The synergistic activity S. alata and P. thonningii at ratio 50:50 produced the highest activity against S. aureus and E. coli. Considering these antimicrobial activities observed, the two extracts have shown interesting potentials in the treatment of skin infections.