LAUSR

Purpose: To determine the antimicrobial activity and chemical constituents of ethyl acetate extract of Citrullus lanatus seeds. Methods: Antimicrobial activity of the ethyl acetate extract of the seeds of C. lanatus was evaluated against Staphylococus aureus ATCC 25923, Escherichia coli ATCC 25922 , Bacillus subtilis NCTC8236, Pseudomonas aeruginosa ATCC 10145 and Candida albicans ATCC 24433 using standard microbiological method. Chemical constituents of the extract were determined with Gas chromatography and mass spectrometry (GC MS) systems. Results: An oily, yellowish orange coloured extract with a yield of 18.7 % was obtained. The extract inhibited the growth of all test microorganisms at minimum inhibitory concentration range of 0.313 -2.5 mg/mL and minimum bactericidal concentration of 0.313-5 mg/mL. GC MS profile of the extract showed the presence of oleic acid (31.22 %), saturated fatty acid (23.85 %) and gamma tocopherol (8.79 %). Other organic compounds accounted for 36.16 % of the extract Conclusion: Ethyl acetate extract of the seeds of Citrullus lanatus has antimicrobial effect against some Gram positive and Gram negative bacteria as well as C. albicans . Twenty-one compounds including fatty acids, hexamethyl-2-ethylacridine, gamma tocopherol and methylphthalate have been identified in the seeds. Keywords: Citrulluslanatus seeds, ethyl acetate extract, antimicrobial activity