Abstract

Methanolic extracts of the leaves of Cajanus cajan (pigeon pea), Ricinus communis (castor bean) and Thymus vulgaris (thyme) were investigated for their medicinal, antimicrobial and toxicological properties. Phytochemical screening of the leaves revealed the presence of tannins, phlobatannins, flavonoids, steroids, terpenoids, saponins and cardiac glycosides which are the most important bioactive constituents of medicinal plants. Antimicrobial testing against eight pathogenic bacteria showed that all the extracts possess antimicrobial properties with Thymus vulgaris being the most effective as it inhibited seven out of the eight bacteria tested. Rats were given daily oral administration of methanolic extracts of the leaves at two different concentrations (100 mg and 200 mg/kg body weight) for a period of 14 days. Analysis of kidney and liver function parameters in the serum and tissues of the rats show no significant difference (P < 0.05) between treated and untreated rats. Measurement of organ: body weight ratio did not show any indication of kidney or liver enlargement. These results showed that the extracts are not toxic and also possess medicinal components which are inhibitory to bacteria.

Key words:  Cajanus cajan, Ricinus communis, Thymus vulgaris, antimicrobial, toxicity.