Phytochemical Screening and in vitro Antibacterial Activity of Aqueous Extracts of Phyllanthus muellerianus (Kuntze) Exell from Kasaï Oriental (DRC) on a Few Bacterial Strains

Abstract

Aims: To carry out a preliminary phytochemical study and to evaluate in vitro the antibacterial activities of aqueous extracts of different parts of P. muellerianus, a plant widely used traditionally in Kasai Oriental to treat various pathologies including several bacteriosis. Study Design: Based on the results of an ethnobotanical survey in Kasaï Oriental, P. muellerianus was selected because of the diversity of recipes involving it, its frequency of citation, its level of preference as well as the diversity of diseases treated and the plebiscite of its effectiveness by traditional healers. To contribute to the enhancement of this plant traditionally used against various bacteriosis and to confirm its therapeutic power, the phytochemical screening of its different parts was carried out and the antibacterial potential of various aqueous extracts was evaluated in vitro. Place and duration of Study: Analyzes were carried out from February to September 2017 at the Physico-chemical and microbiological analysis laboratories of the Congolese Office of Control of Mbujimayi as well as at the Biology and Chemistry laboratories of ISP Mbujimayi. Methodology: Fourteen bioactive chemical groups were investigated in the leaves, stem barks and those of the roots of this plant according to standard methods of characterization based on precipitation, coloring and moss reactions. In vitro, the diameters of the zones of inhibition as well as the MIC and MBC of each of different aqueous extracts were determined against 20 bacterial strains of 13 species responsible for bacterial diseases in humans. Results: The phytochemical screening revealed that all three parts of P. muellerianus contain abundant and diverse bioactive chemical groups. This species contains alkaloids, quinones, steroids, terpenes, saponins, tannins, and flavonoids. In vitro bacteria-aqueous extract interaction tests demonstrated that all three aqueous extracts have inhibitory activity on several of the 20 bacterial strains tested. According to MIC and MBC, inhibitory performance varies depending on the germs and extracts. The sensitivity of different bacterial strains to an extract is also variable; each extract having its spectrum of inhibitory actions. Conclusion: The results confirm the therapeutic potential of P. muellerianus by the presence of several bioactive substances in all its parts and by the diversity of the inhibitory activity of different extracts on several of a few bacterial strains submitted to the tests.