Phytochemical Analysis Of The Roots Of Syzygium Guineense For Antibacterial Activity

Abstract

Syzygium guineense (Myrtaceae) is widely used in folk medicine in different countries for the treatment of various ailments including stomachache, dysentery, diarrhea, hypertension, leprosy, gonorrhea, hemorrhoid, snack bit, malaria, tuberculosis and liver problem. In view of its traditional uses, however, to the best of our knowledge, there was no phytochemical study that has been carried out to identify the active metabolites from the roots of Syzygium guineense. In this report, an attempt was made to explore the chemicals and to evaluate antibacterial activities of the solvent extracts and isolated compounds of the roots of S. guineense. In this regard the powdered roots (500 g) of S. guineense were successively extracted with dichloromethane/methanol (1:1) (4L) and methanol (2.5L) at room temperature on maceration to give 1.90% and, 5.24% respectively. Phytochemical screening tests revealed the presence of terpenoids, saponins, flavonoids, tannins, alkaloids, phenols and glycosides in both roots extracts. Silica gel column chromatographic separation of the roots extracts of dichloromethane/methanol (1:1) afforded arjunolic acid (5) whereas the methanol extract afforded compound (18) which is derivative of steroid lupeol (17). Structural elucidations of these compounds were done by employing IR and NMR and comparison with literature data. The extracts and isolated compounds were also evaluated for their antibacterial activities by disc diffusion method against four bacterial strains; one gram positive staphylococcus aureus and three gram- negative Escherichia coli, Klebsiella pneumoniae, and Salmonella typhi. DCM: MeOH and MeOH extracts both showed significant antibacterial activities against the four bacterial strains at concentrations of 200 μg/mL with zone of inhibition 12 mm and above with methanol extract showing highest activity against salmonella typhi (17 mm) were as the two compounds showed insignificant activities against S. aureus with zone of inhibition 8 mm each. These results support some of the uses of the plant in folk medicine.