The methanolic crude and methanol-aqueous extract of Alstonia macrophylla l
eaves and n-butanol part of the crude extract showed antimicrobial activity
against various strains of Staphylococcus aureus, Staphylococcus saprophyt
icus, Streptococcus faecalis, Escherichia coli, Proteus mirabilis, Trichoph
yton rubrum, Trichophyton mentagrophytes var. mentagrophytes and Microsporu
m gypseum. The minimum inhibitory concentration (MIC) values ranges from 64
to 1000 mug/ml for bacteria and 32- 128 mg/ml for dermatophytes. However,
the strains of Pseudomonas aeruginosa, Klebsiella sp. and Vibrio cholerae s
howed resistance against in vitro treatment of the extracts up to 2000 mug/
ml concentration, while the two yeast species were resistant even at 128 mg
/ml concentration. The stem bark extract prepared similarly was found to be
less active compared to the leaves. Phytochemical study indicates that the
crude extract contains tannins, flavonoids, saponins, sterols, triterpene
and reducing sugars. Further fractionation and purification of n-butanol pa
rt of the extract showed the presence of beta -sitosterol, ursolic acid, be
ta -sitosterol glucoside and a mixture of minor compounds only detected in
TLC. (C) 2001 Elsevier Science Ireland Ltd. All rights reserved.