Biotransformation of artonin E by locally isolated microorganisms

Abstract

Biotransformation is a process that involves modification of the structure of a chemical compound by microbial activities. It has advantages over chemical synthesis as it is able to be operated at near room temperature, with non-extreme pH as well as it is a highly stereospecific reaction. The purpose of this research are to study the ability of selected microbes to transform artonin E, a flavonoid extracted from the bark of local plant, Artocarpus tesymanii and identify potential transformation products. 17 types of microbes were isolated from various sources, however 3 types of bacteria and 2 types of fungi were able to grow in the presence of artonin E. They were identified by 16S rRNA and Internal Transcrib Spacer Region for bacteria and fungi respectively. These microbes were Bacillus cereus, Bacillus subtilis, Bacillus pumillus, Aspergillus fumigatus and Aspergillus aculeatus. The transformation products were analysed by High Performance Liquid Chromatography (HPLC) and Thin Layer Chromatography (TLC). There was a significant peak which corresponded to the biotransformation product as shown in the HPLC chromatogram at retention time of approximately 3.9 minutes. The percentage area of the peak was shown to increase from 6.89% at day 0 to 11.80% at day 1 followed by decreasing of the percentage area of the remaining artonin E concentration in the reaction medium. This was further confirmed by TLC where a compound termed as P1 (transformation product) emerged at the Rf value of 0.37. Artonin E showed a moderate antioxidant property with IC50 value of 81.61µg/mL while the biotransformation product showed very weak antioxidant property with IC50 more than 200 µg/mL. Sample was sent for structure elucidation using Nuclear Magnetic Resonance Spectroscopy (NMR) but due to limited concentration of sample produced in the transformation, the structure could not be fully analyzed.