CHEMICAL COMPOSITION AND EVALUATION OF ANTIMICROBIAL AND ANTIOXIDANT ACTIVITIES OF SEED EXTRACT OF CAESALP INIA DECAPETALA

Abstract

This study was undertaken to determine the chemical composition, antimicrobial and antioxidant activities of the seed oil extracted from Caesalpinia decapetala collected from Haramaya University, Eastern Ethiopia. The seed oil was obtained by Soxhlet extraction and it was found to be clear and yellow in color with a pleasant smell. The oil was analyzed by GC/MS and 38 compounds were identified which corresponds to 99.95% of the total oil. The major components of the oil were found to be 4-(2,7,7-trimethyl Bicyclo[3,2,0] Hept-2-en-1-yl) but-3- en-2-one (22.98%) and 9,12-Octadienoicacid (22.25%), 17-(Acetloxy)-4,4-dimethyl-3-Oxandroste (18.80%), 1,2-Benzenedicarbo-xylic acid (5.67%), Hexadecanoic acid (3.42%), Atractylone (3.44%), di-α- tocopherol (3.10%) and Caryophyllene (2.59%). In this study the classes of compounds identified from the oil of Caesalpinia decapetala includes oxygenated monoterpene, terpenoides, fatty acids and hydrocarbons and derivatives of hydrocarbons. In vitro antimicrobial activities of the seed oil was determined by paper disk diffusion method and showed wide zone of inhibition against both bacteria and fungi at 20 μL dose level. Gram (+) bacteria (Staphylococcus aureus and Streptococcus agalactiae) and Gram (-) bacteria (E. coli and Shigella flexneri) were used as test bacterial species where as Apergillus niger and Fusarium oxysporum were selected as test fungi. The antioxidant activity of this plant was also evaluated and moderate antioxidant property of Caesalpinia decapetala was revealed.The IC50 (the concentration required to inhibit a radical formation by 50%) of extract was found to be 18.31 μg/mL whereas the IC50 value of standard ascorbic acid was found to be 26.21 μg/mL. The results of this study showed in the antimicrobial activities, antioxidant activities and chemical composition of the seed oil of Caesalpinia decapetala. The presence of monoterpene, oxygenated monoterpene, fatty acids, steroids and flavonoids as the major constituents of the seed oil might be responsible for the antimicrobial activities observed in this study.