Screening for anti-microbial activity and phytochemical constituents of some Nigerian medicinal plants

Abstract

Anti-microbial activity and phytochemical constituents of methanol extract ofPlumeria rubra (flower and leaf) and Eucalyptus globules (leaf) was investigated. Phytochemical screening of the crude extract revealed the presence of tannins, phlobatannins, saponins, flavonoids, steroids, terpenoids, cardiac glycosides and reducing sugar in the plants investigated. Phlobatanins were found to be absent in the methanol extract of Plumeria rubra (flower) and Eucalyptus globulus (leaf) except the methanol extracts of Plumeria rubra (leaf). All the crude extract displayed higher inhibitory effects at the tested concentration (20 mg/ml) except on Corynebacterium pyogenese and Bacilhis anthracis ofPlumeria rubra leaf and Streptococcus faecalis of Eucalyptus globules leaf. The infra-red (IR) spectra of the crude extract revealed the presence of different functional group ranging from hydroxyl group (OH) (3406 - 3338.6 cm-1), C-Hstr., alkyl group (2926.6 cm-1), C=O stretching for carbonyls (2162.1 cm-1), C-O bending for alcohols, ethers, esters, carboxylic acid and anhydrides (1310.6 - 1059.6 cm-1), C – H bending alkyl (1453.4 – 1376.2 cm-1) and C – H bending for methyl group (864.1 – 668.4 cm-1). Key words: Anti-microbial activity, phytochemical constituents, phytochemical screening, functional groups, infrared spectra, inhibitory effects.