PHYTOCHEMICAL, ANTIMICROBIAL, MODES OF ACTION AND PHARMACOKINETICS OF ANACARDIUM OCCIDENTALE (CASHEW) NUTS SHELL OIL ON SELECTED MICROBIAL PATHOGENS

Abstract

Cashew (Anacardium occidentale L.) tree is a tropical evergreen tree that produces the cashew nut and cashew apple. Herbs gotten from Anacardium occidentale L., are frequently used to treat infectious diseases in traditional medicine. The study focus on the Phytochemical, antimicrobial, modes of action and pharmacokinetics of Anacardium occidentale (cashew) nuts shell oil on selected microbial pathogens. Oil was extracted from cashew nuts shell using soxhlet appararus with methanol, n-hexane and petroleum ether as solvent. The antibacterial and antifungal activity was evaluated by agar well diffusion. Escherichia coli, Pseudomonas aeruginosa, Streptococcus pyogenes and Staphylococcus aureus were the bacteria while Tricophyton rubrum, Microsporum canis, Mucor pusillus, Penicilium species, Alternaria species were the fungi studied. Minimum inhibitory concentration and minimum bactericidal concentration was carried out using double fold serial dilution method and plating the MIC and subsequent tubes on agar to evaluate the MBC. To determined the compounds present in cashew nut shell oil (CNSO) this was done by Phytochemical and Gas Chromatography-Mass Spectrophotometer analysis. The pharmacokinetic of the extract was studied by evaluating the rate of killing of the bacteria. Modes of actions of CNSO were established by determined the leakage of cellular materials and proteins out of the bacteria cell. Petroleum ether gave the highest volume of the oil during extraction, followed by n-hexane and then methanol, this suggest that petroleum ether is the best solvent of extraction. Of the three oil extract methanol is the most active extract on both the bacteria and fungi followed by n-hexane and petroleum ether. Methanol CNSO had the highest zone of inhibition against Staphylococcus aureus and the least on Pseudomonas aeruginosa. Methanol extract had bacteriocidal activity on S. aureus and S. pyogenes both at the concentration. The methanol oil extract was found to had a definitive effect on S. aureus, E. coli were completely eliminated at the fifth hour while Pseudomonas aeruginosa and S. pyogenes were found viable. The highest amount of cellular material and protein leakage was recorded on S. aureus followed by E. coli, S. pyogenes and then P. aeruginosa. Saponin, flavonoid, tannin, phenol, reducing sugar, alkaloid, steroid, phlobotannins and terpenoid were found to be present in the CNSO extracts. Twenty-seven peaks were observed with the CNSO extract, the most abundant compound was 3-(pentadec-8-en-1-yl) phenol and the least was M-cresyl acetate. This phenol derivative might be the compound that give the oil it’s antimicrobial activity. The mode of action of CNSO on these pathogens is by causing membrane damage which leads to cellular materials within the cytoplasm to leak out of the cell into the external environment of the cell via osmosis and ultimately causing death of the pathogens. Cashew nuts shell oil had antimicrobial activity and it modes of action is by membrane damage. Hence, it should be use in the development of novel antibiotic drugs.