Antibacterial properties and preliminary phytochemical analysis of methanolic extract of Ocimum gratissium (Scent Leaves)

Methanolic extract of the leaves of Ocimum gratissium (scent leaves) was screened for its phytochemical and antibacterial properties on some clinical bacterial isolates, visa vie as Staphylococcus aureus, Escherichia coli, Proteus mirabilis and Pseudomonas aeruginosa. The agar diffusion technique was used to assay the growth inhibition against the four bacterial isolates. The antibacterial effect of the methanolic extract of Ocimum gratissium was compared to that of some selected commercially available antibiotics. The inhibitory effect of the methanolic extract was comparable at all concentrations tested to the commercially available antibiotics indicating the high potency of the methanolic extract O. gratissium. Results obtained showed, the extract inhibits the growth of the test isolates with diameter of zones of inhibition of 5mm to 10mm for P. aeruginosa, P. mirabilis, E. coli and S. aureus respectively. The Broth microdilution assay gave minimal inhibitory concentration values ranging from 13.5μg/ml to 15.0μg/ml. The result of the phytochemical analysis of the dried leaves extracts revealed the presence of alkaloids, carbohydrate and saponins. Keywords: Herbalism, Phytochemicals, Scent, Beni

Bioaccumulation of Heavy Metals in Soil Invertebrtes: Part 1: Uptake and Accumulation of Lead and Chromium by Achatina marginata (Linnaeus) and Lymnaea stagnalis (Linnaeus)

Achatina marginata and Lymnaea stagnalis were each exposed to 4.15µg/g and 8.26µg/g diet of lead and chromium respectively over a period of 28 days. Comparative accumulation studies were carried out on the edible (soft) and gut tissues of both snails. The rates of accumulation of Cr by L. stagnalis were 0.025µg/g/week and 0.084µg/g/wee in the soft tissues for the lower and higher exposure concentrations respectively. The corresponding rates in the gut were 0.290µg/g/week and 0.537µg/g/week respectively. However, lower rates of accumulation of Pb were calculated for the tissues of the same species at the two exposure levels. Higher concentrations of Cr and Pb were measured in the gut tissues than the soft tissues. The rates of accumulation of Cr by A. marginata were 0.341µg/g/week and 0.518µg/g/week for the soft tissues at the lower and higher exposure concentrations respectively while the corresponding rates for the gut were 1.347µg/g/week (lower) and 1.477µg/g/week (higher). These values are 13.6 times and 6.2 times greater than those of L. stagnalis at the lower and higher concentrations of exposure respectively. A similar trend in the bioaccumulation of Pb by A. marginata rative to L. stagnalis was also observed. Bioaccumulation rates of Pb and Cr were greater in the gut than the soft tissues for both species. The moderate accumulation factors calculated for L. stagnalis and high values for A. marginata suggest that these species can be used as indicators of metal pollution in field experiments. KEY WORDS: L. stagnalis; A. marginata; Lead; Chromium; Bio-accumulation. Global Journal of Environmental Sciences Vol.3(1&2) 2004: 7-1