Evaluation of the antibacterial and wound healing activity of the crude and solvent fractions of leaves of Acanthus polystachus Delile

Abstract

Abstract Background: Medicinal plants play indispensible roles to treat various ailments. Acanthus polystachus (“Kosheshile” in Amharic) is one of the medicinal plants used traditionally for treatment of wound and bacterial infections. However, to date, no scientific report could be found concerning the wound healing & antibacterial activities. Thus, the present study provides a scientific evaluation for the antibacterial and wound healing potential of the crude and solvent fractions of Acanthus polystachus leaves. Methods: The crude extraction was carried out using 80% methanol and fractionated by chloroform, ethyl acetate followed by distilled water in increasing polarity. The antibacterial activity was evaluated using agar well diffusion &broth dilution techniques. The crude extract was prepared in 5% (w/w) and 10% (w/w) ointment & evaluated for wound healing activity using excision, infected & incision model in mice. The data was analyzed using Statistical Package for Social Sciences (SPSS version 20). One way analysis of variance (ANOVA) followed by Tukey test was employed & P-value <0.05 considered statistically significant. Results: The crude extract, ethyl acetate & aqueous fractions showed significant dose dependent antibacterial activities against against S. aureus, S. pyogen and P. aeruginosa at 250 & 500mg/ml concentrations (P <0.001). The most susceptible bacterium to crude extract was S. aureus with mean zone of inhibition 16.33 & 15.00 mm at 500 & 250mg/ml respectively. Similarly, in ethyl acetate & aqueous fractions S. pyogen & P. aeruginosa were more susceptible (at 500 mg/ml) with mean zone of inhibition 14 & 11.67 mm respectively. Furthermore, only the crude extract & chloroform fraction revealed antibacterial activity against K .pneumonia. However, E. coli was not susceptible to the crude extract & all solvent fractions. Both 5% & 10% (w/w) ointments exhibited significantly reduced period of epithelialization, increased wound contraction rate & tensile strength compared to the negative control group (P<0.05). Better wound healing activity was observed in 10% (w/w) than 5% (w/w) & nitrofurazone ointment treated groups however the difference was failed to reach statistical significance. Conclusion: These results collectively demonstrate that the crude extract & solvent fractions of A. polystachus leaves possesses antibacterial activities. Besides, the crude extract facilitated wound healing probably via its antibacterial activity; this justifies the traditional claimed use of the plant for treating wound and bacterial infections.