2018, Vol. 6, Issue 6, Part D

author(s)
Ebenebe I Ngozi, Ikegbunam N Moses, Maduagwu N Ukamaka and Esimone C Okechukwu

abstract
Piper guineense and Xylopia aethiopica are medicinal plants traditionally used as spices and seasoning in Nigerian food. Antimicrobial activity of the essential oils from Piper guineense and Xylopia aethiopica were evaluated using Agar well diffusion method. Ampicillin trihydrate and Clotrimazole were used as a positive control for the test bacteria and fungi respectively, and 1% v/v DMSO was also employed as a negative control for all the test microorganisms. The MIC, MBC and MFC of the essential oils were also evaluated against Staphylococcus aureus, Bacillus subtilis, Pseudomonas aeruginosa, E. coli, Salmonella typhi, Klebsiella pneumonia, Aspergillus niger, and Candida albicans using agar dilution method. The combined antimicrobial activity of the essential oils from Piper guineense and Xylopia aethiopica were determined using checker board technique. The preservative efficacy of the essential oils were evaluated at 1%, 3%, 5%, by combining the essential oil at each of this concentration in a continuous variation method. The combined ratios of each concentration were introduced into five different contaminated herbal samples respectively. Methyl- and propyl- paraben (2:1), and Sodium benzoate were respectively used as control preservative at 1%, 3%, 5%. Result of the antimicrobial screening test shows that essential oil from Piper guineense were effective against all the test microorganisms, while the essential oil from Xylopia aethiopica was not effective against E. coli and K. pneumonia. The combined antimicrobial effect of the Essential oil (EO’s) against test microorganisms were synergistic in most of the combined ratios used. The preservative effect of the EO’s reveals that their actions were concentration dependent, with the highest concentration of 5% being the most efficient. M-and p- paraben and Sodium benzoate were not as effective as they should with the contaminated herbal product at all the concentrations except with the enumeration of E. coli and Enterobacter sakazakii where they are excellently efficient as a preservative. Herbal medicines, if unpreserved, readily become contaminated with microorganisms leading to spoilage. Therefore, the combination of these two essential oils from the dried fruits of P. guineense and X. aethiopica may have a potential for further study as an alternative in the preservation of herbal preparations.