THE PHYTOCHEMICHAL COMPOSITION AND ANTIBACTERIAL ACTIVITY OF ROOT, LEAF AND FLOWER EXTRACTS OF BITTER LEAF (Vernonia amygdalina)

Abstract

Vernonia leaf scientifically known as Vernonia amygdalina, of Asteraceae family is one of the traditional medicinal plants used found in Africa and Asia. Thus, the objective of the study was to investigate major secondary compounds from, roots, leaves and flowers extracts of Vernonia amygdalina and their antibacterial activities in vitro. The experiment was designed in a complete random design arranged as 2*3*2*3 multi-factor factorial. That is 2 test pathogens by -3 extract sources obtained in 2 solvents (ethanol and water) at 3 concentration levels a factorial design in three replications. Data was analysed using computer software SPSS, version 20. The phytochemical composition of ethanol and water extracts from Vernonia amygdalina leaf, root and flower showed the presence of flavonoids, saponins, tannins, alkaloids, terpenoids in all analysed plant parts. In this study, Steroids and phlobatannins were not detected in all plant parts. As indicated in the results, the leaves of V. amygdalina produced the highest yield of flavonoids in both extracts. The quantity of alkaloids, flavonoids, phenol and saponins were highest in leaves than root and flower. The study also indicated ethanol crude extracts contain more bioactive compounds than water extracts. The highest concentration of the ethanolic extract (200mg/ml) presented the strongest antibacterial activity with maximum zone of inhibition (16.0±0.9mm) for leaf ethanol extract against Staphylococcus aureus. The Vernonia amygdalina leaf, root and flower was observed that, ethanolic extract from leaf presented strongest antibacterial activity with minimum inhibitory concentration (62.5mg/ml) and corresponding minimum bactericidal concentration (125mg/ml) against Staphylococcus aureus. This indicates Staphylococcus aureus (gram positive) more susceptible than Escherichia coli (gram negative) in both minimum inhibitory concentration and zone of inhibition. In water extracts (flower and root) there is no minimum inhibitory concentration and minimum bactericidal concentration against both Escherichia coli and Staphylococcus aureus. Further studies are needed to isolate and separate the bioactive compounds responsible for, antibacterial activities using advanced tools and scientific techniques