By anaerobic incubation with a bacterial mixture from human feces, aloesin (aloeresin B; 1) was converted to 2-acetonyl-7-hydroxy-5-methylchromone (aloesone; 3) and dl-7-hydroxy-2-(2'-hydroxypropyl)-5-methylchromone (aloesol; 4a+4b) through a cleavage of the C-glucosyl bond, followed by reduction of the acetonyl side chain. An analogous compound, aloeresin A (2), was converted to p-coumaric acid and aloesin (1), the latter being subsequently transformed to aloesone (3) and dl-aloesol (4a+4b). On the other hand, 7-O-methylated derivatives (7, 5a and 5b) of aloesin and of 8-C-glucosylaloesol were not cleaved to the corresponding aglycones, suggesting the importance of a free hydroxy group adjacent to the C-glucosyl group in the molecule for the bacterial cleavage of aloesin derivatives. This is the first report on the cleavage of the C-glycosyl bond of chromone C-glucosides by intestinal bacteria.
通过与来自人类粪便的细菌混合物进行厌氧培养,
芦荟素(
芦荟素 B;1)通过 C-
葡糖基键的裂解转化为 2-
丙酮基-7-羟基-5-甲基
色酮(芦荟酮;3)和 dl-7-羟基-2-(2'-羟基丙基)-5-甲基
色酮(芦荟醇;4a+4b),然后是
丙酮基侧链的还原。类似的化合物
芦荟素 A(2)被转化为对
香豆酸和
芦荟素(1),后者随后被转化为芦荟酮(3)和 dl-芦荟醇(4a+4b)。另一方面,
芦荟甙的 7-O-甲基化衍
生物(7、5a 和 5b)和 8-C-
葡糖基芦荟醇并没有被裂解成相应的苷元,这表明分子中邻近 C-
葡糖基的游离羟基对细菌裂解
芦荟甙衍
生物非常重要。这是有关肠道细菌裂解
铬酮 C-
葡萄糖苷的 C-糖基键的首次报道。