Chemical Studies Of A Mangrove Plant And An Algous Endophytic Fungus

This dissertation describes the investigation of the chemical constituents of a mangrove plant Bruguiera gymnorrhiza, aiming to find out the correlation between the metabolites and its folk medical uses. Furthermore, the chemical composition of a marine algous endophytic fungus EN21 ( Exophiala oligosperma ) which was isolated from Laurencia similis Namet Saito, was also carried out. The DPPH-radical scavenging and antibacterial activity of some isolated compounds from Bruguiera gymnorrhiza were evaluated .The compounds were separated from the organic solvents extracts by repeated column chromatography (CC) on silica gel, RP-18, preparative thin layer chromatography (PTLC) and Sephadex LH-20, as well as by semi-preparative HPLC and recrystallization. The structures of the isolated compounds were elucidated by means of modern spectroscopic methods including 1D-NMR (1H-NMR, 13C-NMR, DEPT) and 2D-NMR (1H-1H COSY, HMBC, HMQC), EI-MS, FAB-MS, as well as by chemical method. A total of 46 compounds were separated from the two organisms. From Bruguiera gymnorrhiza, 23 compounds were isolated with 20 of them were structurally elucidated, while from endophytic fungus EN21, 23 compounds were obtained with 20 of them were structurally elucidated. Among them, one compound ( EN21-2 ) was found to be firstly separated from natural resources and 4 flavonoids were isolated from Bruguiera gymnorrhiza for the first time. In addition, this is the first chemical investigation on Exophiala oligosperma(EN21).The test of DPPH radical scavenging activity was carried out on some of the pure compounds isolated from Bruguiera gymnorrhiza. The result revealed that flavonoids BRG-1,BRG-2,BRG-3 and BRG-4 possessing higher activity. However, none of the triterpenes showed any activity. In addition, none of the tested compounds showed any antibacterial activity.