TRANSFORMATION OF ETHYL-P-METHOXYCINNAMATE TO P –METHOXYCINNAMIC ACID FROM KENCUR (Kaempheria galanga L.) AND THEIR ANTIBACTERIAL ACTIVITY

Abstract

This study aimed to evaluate the antibacterial properties of ethyl-<em>p</em>-methoxycinnamate and <em>p</em>-methoxycinnamate acid from Kaempheria galanga L. Ethyl-<em>p</em>-methoxycinnamate was isolated from the <em>n</em>-hexane rhizome extract of <em>Kaempheria galanga L</em>. Separation and purification of this compound was carried out with vacuum liquid chromatography and column chromatography. Hydrolysis of ethyl-<em>p</em>-methoxycinnamic under alkaline conditions obtained <em>p</em>-methoxycinnamic acid with a good yield of 85 %. The structure of the compounds were charactrized with IR, NMR spectrophotometer (<sup>1</sup>H-NMR and <sup>13</sup>C-NMR) and mass spectrophotometer. The antibacterial properties of the compounds were evaluated using microdilution methods against <em>B. cereus</em> ATCC 11778, <em>L. monocytogenes</em> ATCC 7644, <em>E. coli</em> ATCC 25922, <em>S. enterica sv Typhimurium</em> ATCC 14028, and <em>E. aerogenes</em> ATCC 13048. The compounds showed weak antibacterial properties. Only ethyl <em>p</em>-methoxycinnamate showed the strongest antibacterial activity, especially against <em>B. cereus</em> ATCC 11778 bacteria with MIC values of 62.5 mg /mL. The change of the functional groups provided no significant impact on the antibacterial activity.