National Institute of Agrobiological Sciences, Tsukuba, Ibaraki 305 8634, Japan.
Phytochemistry. 2013 Oct;94:108-12. doi: 10.1016/j.phytochem.2013.05.023. Epub 2013 Jul 3.
Two flavonol glycosides along with four known flavonoids were isolated from the cocoon of the mulberry white caterpillar, Rondotia menciana (Lepidoptera: Bombycidae: Bombycinae), a closely related species of the domesticated silkworm Bombyx mori, both of which feed on leaves of mulberry (Morus alba). The two glycosides were characterized as quercetin 3-O-β-d-galactopyranosyl-(1→3)-β-d-galactopyranoside and kaempferol 3-O-β-d-galactopyranosyl-(1→3)-β-d-galactopyranoside, based on spectroscopic data and chemical evidence. The flavonol galactosides found in the cocoon were not present in the host plant, nor in the cocoon of the silkworm, B. mori. Notably, flavonol glucosides, which are the main constituents of cocoon flavonoids in B. mori mori, were not found in the R. menciana cocoon. The present result strongly suggests that R. menciana is quite unique in that they predominantly use an UDP-galactosyltransferase for conjugation of dietary flavonoids, whereas UDP-glucosyltransferases are generally used for conjugation of plant phenolics and xenobiotics in other insects.
从与家蚕（鳞翅目：蚕蛾科：蚕亚科）亲缘关系密切的野桑蚕（Rondotia menciana）的茧中分离得到两种黄酮醇糖苷和四种已知的类黄酮，两者均以桑叶（桑属）为食。这两种糖苷分别被鉴定为槲皮素 3-O-β-d-半乳糖吡喃糖苷基-（1→3）-β-d-半乳糖吡喃糖苷和山奈酚 3-O-β-d-半乳糖吡喃糖苷基-（1→3）-β-d-半乳糖吡喃糖苷，基于光谱数据和化学证据。在茧中发现的黄酮醇半乳糖苷不存在于宿主植物中，也不存在于家蚕茧中。值得注意的是，在野桑蚕茧中未发现黄酮醇葡萄糖苷，而黄酮醇葡萄糖苷是家蚕茧中主要的茧黄酮类化合物。本研究结果强烈表明，野桑蚕非常独特，它们主要使用 UDP-半乳糖基转移酶将饮食中的类黄酮进行缀合，而 UDP-葡萄糖基转移酶通常用于将植物酚类和其他昆虫中的外源性物质进行缀合。
