Antistaphylococcal Activity of N-Butanol and Aqueous Sub-Fractions of Alchornea cordifolia Leaves

Aims: To carry out the antistaphylococcal activity of n-butanol and aqueous sub-fractions of Alchornea cordifolia (Schumach. And Thonn.) Müll. Arg. leaf extract against multidrug resistant Staphylococcus aureus.
Study Design: Characterization and antibiotic susceptibility determination of the test S. aureus isolates, extraction of A. cordifolia leaf, partitioning of the extract, Zones of inhibition and Minimum Inhibitory and Bactericidal Concentrations determination.
Place and Duration of Study: Department of Pharmaceutics and Pharmaceutical Microbiology, Ahmadu Bello University, Zaria, Nigeria. February 2010 to October 2011.
Methodology: A. cordifolia leaves were collected from Abuja, Nigeria. The activity of the ethanol extract, N-butanol (NSF) and aqueous (ASF) sub-fractions of the plant leaf against five clinical staphylococcal isolates and the standard Methicillin Resistant S. aureus (MRSA) ATCC 33591 were determined using agar-well diffusion and broth dilution methods. The antibiotic susceptibility pattern of the isolates was determined by the Kirby-Bauer-CLSI modified disc agar diffusion technique (DAD).
Results: The diameter zones of inhibition showed by ethanol extract against the test staphylococcal isolates ranged between 12 mm - 26 mm, while the diameter zones of inhibition observed from N-butanol sub-fraction and aqueous sub-fraction against the isolates were between 11 mm - 36.5 mm and 11 mm - 35 mm respectively. The diameter zones of inhibition of the sub-fractions against the standard MRSA ATCC 33591 ranged from 11 mm – 27.5 mm. The diameter zones of inhibition of the test antibiotics ranged from 10 mm to 23 mm. The Minimum Inhibitory Concentration (M. I. C.) and Minimum Bactericidal Concentration (M. B. C.) values produced by ethanol extract were higher than those of the sub-fractions. N-butanol sub-fraction produced the lowest M. I. C and M. B. C. values of 0.625 mg/ml – 1.25 mg/ml and 1.25 mg/ml – 2.5 mg/ml respectively. The M. I. C. and M. B. C. values of the N-butanol sub-fraction against the standard strain ATCC 33591 were 1.25 mg/ml and 2.5 mg/ml respectively.
Conclusion: The tested N-butanol and aqueous sub-fractions of A. cordifolia leaf were active against the S. aureus strains at low concentrations. The plant can be a possible candidate in the search for alternative antistaphylococcal agents.