銅綠微囊藻M.TY-1之天然物研究

Abstract

銅綠微囊藻 (Microcystis aeruginosa) 是被研究很廣泛的藻種，實驗室中的藻株M.TY-1主要的用途為生產微囊藻毒，而其提純之剩餘物質並未被研究。.由過去研究可知，微囊藻除了會產生微囊藻毒外，還會產生許多種類的活性天然物，這些天然物常具有蛋白酶的抑制活性，在過去研究中發現其可能與微囊藻的自我保護機制或是做為他感物質的應用有關，而本研究也期待能自微囊藻中夠發現更多活性天然物，以利後續之研究。 本實驗中共純化出五個可能具有活性的化合物，分別為兩個micropeptin類：Micropeptin TY1046 (1)、Micropeptin TY1042 (2) 與三個monogalactosyl monoacylglycerols (MGMGs)：1-O-(4,7,10,13-hexadecatetraenoyl)-3-O-β-D-galactopyranosylglycerol (3)、1-O-(6,9,12-octadecatrienoyl)-3-O-β-D-galactopyranosylglycerol (4)、1-O-(7,10-hexadecadienoyl)-3-O-β-D-galactopyranosylglycerol (5)，其中化合物1、2、4為新的化合物。由前人文獻推測micropeptin TY1046與TY1042可能具有chymotrypsin之抑制活性，而從NMR之氫譜顯示，micropeptins很可能存在一分子內氫鍵的作用力。 三個MGMGs則具有iNOS之抑制活性，其IC50分別為42.16 μM、39.24 μM與27.85 μM，而由實驗結果推論，其iNOS之抑制活性會隨其長鏈上不飽和度的減少而變強。

The freshwater cyanobacterium Microcystis aeruginosa has been extensively studied. The use of strain M•TY-1in our laboratory is to produce MC-LR. However, the fractions without MC-LR was not studied. It is known that Microcystis aeruginosa produces many classes of natural products. Several hypotheses on the function of these compounds in the physiology and ecology of cyanobacteria have been discussed, mostly related either to grazing protection or to allelopathy. Here we investigated the chemical components of M•TY-1 for their structures and possible activities. Two micropeptins and three monogalactosyl monoacylglycerols (MGMGs) was isolated and structure determinated on the basis of spectroscopic analysis. They are Micropeptin TY1046 (1), Micropeptin TY1042 (2), 1-O-(4,7,10,13-hexadecatetraenoyl)-3-O-β-D-galactopyranosylglycerol (3), 1-O-(6,9,12-octadecatrienoyl)-3-O-β-D-galactopyranosylglycerol (4) and 1-O-(7,10-hexadecadienoyl)-3-O-β-D-galactopyranosylglycerol (5). Compound (1) and (2) may exhibit the inhibitory of chymotrypsin. In addition, the proton NMR data of compound (1) in DMSO indicated an intermolecular hydrogen bond within the ring structure of micropeptins. compound (3), (4) and (5) are iNOS inhibitors. Their IC50 are 42.16 μM, 39.24 μM, and 27.85 μM， Decreasing unsaturation of the fatty acid side chain enhances the NO inhibitory activity.