ANTIBACTERIAL ACTIVITIES OF VITEX DONIANA (OORI NLA) LEAF EXTRACTS ON SOME COMMON PATHOGENS

Abstract

This study investigated the antibacterial activities of methanol and n-hexane leaf extracts of Vitexdoniana using agar well and disc diffusion methods against some selected test organisms. The crude extracts were obtained using the cold extraction method. They were subjected to qualitative and quantitative phytochemical screening for the presence of phytochemical constituents. The minimum inhibitory concentration test was carried out. Crude extracts were purified using the column chromatography and purified extracts were subjected to infra-red assay to assess the functional groups present. Percentage recovery of the extract showed that methanolic extract was higher with 16.25% and n-hexane had14.50%. Phytochemical screening revealed the presence of alkaloid, tannin, saponin, steroid, flavonoid, and terpenoid, in both methanol and n-hexane extracts. However, phlobatannin, anthraquinone, and cardiac glycosides were absent in both extracts. Quantitative analysis showed that tannin was present in both extracts in almost same quantity, while flavonoid was higher in n-hexane extract with a value of 12.478mg/g as to 8.409mg/g in methanolic extracts. The highest value of saponin was recorded in n-hexane extract at 77.999mg/g to 38.363mg/g in methanolic extract while the least value of tannin occurred in n-hexane extract at a level of 2.546mg/g. The results obtained showed that n-hexane extract had no inhibitory effect on Shigellaflexnerii (ATTCC 12022), Serratiamarcescens (ATCC 39000), Salmonella typhimurium (ATCC 6539) and Enterobacteraerogenes (ATCC 13048). The highest zone of inhibition of 6.33mm was recorded against Enterobacteraerogenes (ATCC 13048) with methanolic extract. Minimum inhibitory concentrations of the extracts ranged from between 2.5mg/ml and 30mg/ml. Methanolic extract recorded a value of MIC at 30mg/ml for both Bacillus subtilis and Serratiamarcescens (ATCC 3900). N-hexane also recorded 30mg/ml for Echerichia coli (ATCC 25922) only. Methanolic extract recorded its lowest value of 2.5mg/ml against Citrobacterfreundii (ATCC 8090) while n-hexane recorded its lowest of6.25mg/ml for the same organisms. Antimicrobial activities of methanolic column fractions had the highest zone of inhibition of 15mm against Serratiamarcescens and the lowest zone of inhibition of 1mm was against Shigellaflexnerii (ATCC 12022) and Salmonella typhimurium (ATCC 6539). The column fractions n-hexane extract however recorded the highest zone of inhibition of 24mm against Citrobacterfreundii (ATCC 8090) and the lowest on Bacillus subtilis (ATCC 6633) and Echerichia coli (ATCC 25922) with 2mm zones of inhibiton diameter. The rate at which the extract was able to kill the test organism showed decrease in the number of colonies with increase in time of exposure to the extract. Infrared analysis of the leaf extract reveals various absorption bands signifying the presence of different chemical groups such as phenol in the extract .