Antimicrobial effects of components of the bark extract of neem (Azadirachta indica A. J uss)
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Federal Univ. of Technology, Yola
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Preliminary phytochemical analysis showed that the leaves and bark of A. indica possess saponins,
tannins and phenolic compounds. The antimicrobial spectrum of the aqueous, methanol and acetone
extracts of leaves and bark of the plant was determined by agar diffusion method. The methanol and
acetone extracts of the bark at 1 Omg/ml concentration showed significant antimicrobial activities against
Staphylococcus aureus, Streptococcus pyogenes, Escherichia coli, Pseudomonas aeruginosa, Candida
albicans and Trichophyton mentagrophytes. The minimtim inhibitory concentration (MIC) values ofthe
methanol extract of the bark (0.3-0.4 mg/ml) were same or lower than those of ampicillin, erythromycin
and griseofulvin (0.2-0.5 mg/ml). The minimum bactericidal concentration (MBC) values (0.3-0.9
mg/ml) and the minimum fungicidal concentration 'values (MFC) (0.3-2.0 mg/ml) of the methanol
extract were comparable to those of ampicillin, erythromycin (0.2-0.6 mg/ml) and griseofulvin(0.8-l.O
mg/ml). Isolation of antimicrobial substances from the methanol extract of the bark was studied by thin
layer chromatography (TLC) developed by using benzene and methanol mixture (4:6). Two fractions
(A, B) were obtained. Fraction A (the upper band in TLC plate) showed significant activity (diameter of
zone 4.0-5.0 mm at 2.0 mg/ml concentration) against C. albicans and T mentagrophytes when
compared to crude extract (diameter of zone 3.0-5.0 mm at I 0 mg/ml concentration). So it may be
concluded that there is a scientific basis for traditional use of extracts of bark and leaves of A. indica in
skin infection and the active principles in the extracts may be purified by using TLC method.
Keywords
QH301 Biology