PHYSICOCHEMICAL PROPERTIES, ANTIOXIDANT AND ANTIMICROBIAL ACTIVITIES OF ROSEMARY (RosmarinusofficinalisL.) LEAF OIL

Abstract

Medicinal plants were used for centuries as remedies for human diseases because they contain components of therapeutic value, there is an increasing interest in phytochemicals as new sources of natural antioxidant and antimicrobial agents. Microbial infections have become one of the major problems of public health in the world and the development of resistance to the available antibiotics has lead researchers to investigate the antimicrobial activity of medicinal plants. Essential oil extracts of plants have many applications in medicines, cosmetics, food stuff and pharmaceutical industries. The present study was aimed to examine physicochemical properties, biological activities (as antioxidant and antimicrobial) of oil extract from rosemary leaves. The oil extraction was done in Soxhelt apparatus using hexane as a solvent. The result of physicochemical properties and antioxidant activities of Rosmarinusofficinalis (L.) leaf oil presented oil yield (38.5%), specific gravity (0.84), acid value (1.26 mg/g), free fatty acid (0.63%), peroxide value (4.70%). The assessment of antioxidant activities of R.officinalis (L) leaf oil extract was recorded high ascorbic acid content ( 20.43%), DPPH (6.75%), and hydrogen peroxide free radical scavenging activity (1.50%). The diameter of inhibition zone for R. officinalis (L.) leaf oil recorded the mean zone of inhibition at highest concentration (2μl/ml) against bacterial test pathogens ranged from 10.50±0.71mm to 14.50±0.63mm, while 13.65±0.50 to 21.45±0.64 mm against fungal test pathogens. The strongest antibacterial activity with maximum zone of inhibition (14.50mm) at highest concentration (2μl/ml) of the oil was recorded againstE. coli. On the other hand, the strongest antifungal activity with maximum zone of inhibition (21.45mm) was recorded against C. albicans. The oil from R. officinalis has also exhibited strongest bactericidal activity with Minimum inhibitory concentration (MIC, 0.06μl/ml) and the corresponding minimum bactericidal concentration (MBC, 0.12 μl/ml) against E. coli while the weakest bactericidal activity with MIC (0.75 μl/ml, the largest value) and MBC (1.12 μl/ml) was recorded against S. pyogenes indicating that E. coli was the most susceptiblet antifungal activity with MIC (0.03μl/ml, the least value) and minimum fungicidal concentration (MFC, 0.05μl/ml) against C. albicans. The rosemary leaf oil extract demonstrated remarkable potency against test pathogens. Thus promising as an alternative medicinal therapy against the broad-spectrum drug resistant pathogens.