Browsing by Author "Ismaeel, R.O."
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Item Comparative studies of constituents and antibacterial activities of leaf and fruit essential oils of Ocimium basilicum grown in north central Nigeria.(International Scientific Organization, 2013) Usman, L.A.; Ismaeel, R.O.; Zubair, M.F.; Saliu, Bolanle Kudirat; Olawore, N.O.; Elelu, N.Leaves and fruits (500g each) of Ocimum basilicum that were separately hydrodistilled, yielded 0.4 and 0.5% (v/w) of the oils respectively. Analyses of the oils using GC and GC-MS showed that, bulk of the oils were constituted by oxygenated monoterpenes. The principal constituents of the leaf and fruit oils were; linalool (61.7 and 62.9%), 1,8-cineole (17.2 and 18.7%), borneol (8.5 and 6.4%), eugenol (5.7 and 5.4%) and α-caryophyllene (4.3 and 4.0%). With the predominance of linalool in the oils, they are of linalool chemotypes. The antibacterial activities of the oils were evaluated on ten clinical bacterial isolates using disc diffusion method. The oils were found to inhibit three Gram-positive and three Gram-negative bacteria. The bacteria inhibited were Bacillus megaterium, Bacillus cereus, Streptococcus pyogenes, Escherichia coli, Proteus mirabilis and Klebsiella pneumonia. Bacillus megaterium had the highest susceptibility with minimum inhibitory concentration (MIC) of 2.5 mg ml-1 .Bacillus cereus, Streptococcus pyogenes, Serratia marcescens and Pseudomonas aeruginosa showed resistance to the oils.Item Effects of Seasonal Variation on Chemical Constituents and Insecticidal Activity of Leaf Essential Oil of Citrus limonium(Nigerian Society of Biochemistry and Molecular Biology, 2015) Usman, L.A; Olanipekun, B.E; Ismaeel, R.O.; Oguntoye, S.O.; Ojumoola, A.OLeaves (500g) of Citrus limonium harvested in the morning (7.00 am) during dry and rainy seasons were separately hydrodistilled and yielded 0.46 and 0.30 % (w/w) of essential oils. GC and GC-MS analysis revealed that the oils obtained from dry and rainy season harvests were predominated by monoterpenoids (84.2% and 77.2%). The most abundant constituent of the oils from dry and rainy season harvests was; limonene (17.9% and 15.3%). Other principal constituents of the oils were; β-pinene (8.0% and 1.5%), terpinolene (7.0% and 7.1%), citronellal (12.9% and 8.3%), carveol (8.0% and 9.0%), neral (7.9% and 8.5%). citronellol (4.4% and 5.9%) and β-caryophyllene (3.3% and 5.2%). Contact toxicity bioassay was used to investigate the insecticidal activity of the oils against Callosobruchus maculatus. Irrespective of the season of harvest the oils were active against the insect. Interestingly, oils from the two harvests had comparable activity against the adult C. maculatus. Hence, seasonal variation has no significant effect on insecticidal activity of the oil on the postharvest insect pest.