Isolation of Chemical Components and Antimicrobial Study of the Dichloromethane Berries Extract of Murraya Koeningii (L.) Spreng

Wong, Mei Khee (2019) Isolation of Chemical Components and Antimicrobial Study of the Dichloromethane Berries Extract of Murraya Koeningii (L.) Spreng. Final Year Project (Bachelor), Tunku Abdul Rahman University College.

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Abstract

Murraya koenigii (L.) Spreng (Rutaceae family) is a natural medicinal plant as it possesses various physiological properties such as antioxidant, antidiabetic, anticancer and antimicrobial activities. In this project, curry tree berries was chosen as there are insufficient information being reported for its phytochemical and antimicrobial studies. This project aimed to separate and isolate pure compounds for antimicrobial analysis. The dried Murraya koenigii berries were extracted by methanol to obtain methanolic crude extract. It is followed by solvent-solvent partitioning techniques by using of solvents with increasing polarities from hexane, dichloromethane, ethyl acetate and acetonitrile. Dichloromethane crude extract was chosen for the study. The crude extract was analysed for the antimicrobial analysis via disk diffusion method and microdilution. The crude was further analysed for TLC profiling, isolation and separation process with chromatographic methods such as thin layer chromatography and column chromatography. Three carbazole alkaloids such as (+)-mahanimbine, (±)-mahanimbine and koenimbine were successfully isolated. These compounds were analysed by various spectroscopic methods such as NMR, UV-Vis and FTIR spectroscopy, and confirmed by comparison with literature data. Furthermore, the isolated compounds were analysed for antimicrobial testing through microdilution assay. It was observed that the (+)-mahanimbine (IC50 = 9.70 μg/mL and 13.40 μg/mL) and koenimbine (IC50 = 11.20 μg/mL and 10.40 μg/mL) exhibited positive antimicrobial activity against E.coli and S. aureus, respectively. Interestingly, the (+)-mahanimbine and (±)-mahanimbine with different stereochemistry showed different potency towards antimicrobial assay. Therefore, the results could be useful for the development of new antibiotic drugs.