Phytochemical Investigation, Evaluation of The Antibacterial and Antioxidant Activities of the Leaves Extracts of Leonotis ocymifolia

Abstract

Leonotis ocymifolia (Burm. f.) Iwarsson, usually recognized as Ras-kimir or Yeferes Zeng; is a therapeutic plant that belongs to Lamiaceae family. The extracts of this plant were obtained by the maceration method. Phytochemical analysis outlined the existence of alkaloids, saponins, flavonoids, phenols, terpenoids, and tannins in the n-hexane solvent; alkaloids, saponins, terpenoids, tannins, flavonoid, and phenols in EtOAc solvent; and alkaloids, flavonoids, steroids, saponins, terpenoids, anthraquinones, phenols and tannins from MeOH solvent extracts of L. ocymifolia leaves. The solvent extracts were tested against one Gram-positive bacterial species (Listeria monocytogen) and one Gram-negative bacteria (Klebsiella pneumonia) using disc diffusion method at (50 mg/mL, 100 mg/mL and 200 mg/mL) concentrations. The results of the invitro antibacterial activity tests were compared with the commercially available antimicrobial agent (chloramphenicol) and Dimethyl sulfoxide was the negative control. MeOH and n-hexane fraction revealed more potent antibacterial activities against the growth of the bacterial strains than EtOAc extract. The radical scavenging performance of the extracts were measured by utilizing DPPH. The percentage inhibitions of MeOH, EtOAc, and n-hexane extracts were compared with the control ascorbic acid (200 ppm to 1000 ppm) have the value ranges from 88.46% - 95.25%, 77.55% - 91.48%, and 60.61% - 79.19%, respectively. Generally, MeOH was higher in percentage yield and antioxidant activities than EtOAc and n-hexane. One compound (1) was isolated from the EtOAc extract using silica gel column chromatography. The structure of the isolated component was characterized by using a combination of spectroscopic techniques such as FTIR, 1H NMR, 13C NMR, UV and DEPT-135.