Phytochemical Evaluation Of Roots And Leaves Extracts Of Ocimum Cufodontii For Antibacterial And Antioxidant Activities

Abstract

Ocimum cufodontii (Lamiaceae) is an indigenous plant to Ethiopia used traditionally for the treatment of relieving pain, fever and inflammatory disorders. In view of its traditional uses and limited scientific report, the roots and leaves were extracted with hexane, EtOAc and MeOH which furnished 1%, 1.7 % and 2.3 % for the root and 1.8%, 2% and 2.5 % for the leaves respectively. The leaves were hydro-distilled using Clevenger type apparatus to afford 16.66% yellowish oil. The essential oil was also analyzed for its chemical constituents using GC-MS which gave eleven major compounds with the most abundant constituent found to be βcaryophyllene (31.3%). The presence of this compound in significant amount was likely responsible for anti-inflammatory activity. The leaves extract after silica gel column chromatography furnished betulinic acid (39). On the other hand, compound 40, 41, 42 and 43 were isolated from the hexane extracts of the roots of Ocimum cufodontii. Structure elucidation was done using spectroscopic methods including 1H-NMR, 13C-NMR, GC-MS and LC-MS. The antibacterial properties of Ocimum cufodontii essential oil from the leaves and hexane, EtOAc and methanol extract of root and leaves was studied on the standard gram-negative bacteria against (Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumonae ,Salmonella typhi) and gram-positive, Staphylococcus aureus. Results showed that the essential oil displayed zone of inhibition of 19.0 mm against S. aureus. This was significant compared with the positive control Chloroamphinicol which exhibited 28 mm zone of inhibition. On other hand, the hexane and MeOH extract of the root showed inhibition zone of 17 mm and 15 respectively. The antioxidant activities of Ocimum cufodontii was carried using DPPH (1, 1-diphenyl-2-picryl hydrazyl). Among the four fractions,the hexane root extract showed the highest scavenging activity, with an IC50 value of 1. 30 µg/mL. Besides, hexane leave extract with an IC50 value of 1.97µg/mL showed more efficient radical-scavenging abilities than ethyl acetate leave and root extract with an IC50 value of 55.83 µg/mL and 116.58 µg/mL respectively. The antibacterial and antioxidant activities observed in the present work corroborate the traditional use of this plant.