The triterpene glycosides of Holothuria forskali: usefulness and efficiency as a chemical defense mechanism against predatory fish
The triterpene glycosides of Holothuria forskali: usefulness and efficiency as a chemical defense mechanism against predatory fish
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DOI：
10.1242/jeb.050930
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发表时间：
2011-04-01
影响因子：
2.8
通讯作者：
Flammang, Patrick
中科院分区：
文献类型：
--
作者：
Van Dyck, Severine;Caulier, Guillaume;Flammang, Patrick
在过去的几十年里，已经有超过100种三萜糖苷（皂苷）被鉴定为海参类。特别是，Holothuria forskali在其Cuvierian小管中含有26种皂苷，在其体壁中含有12种皂苷。这种高度的多样性可能与化学防御机制有关，这是这些次级代谢产物最普遍接受的生物学作用。对H. forskali。皂苷主要位于表皮和体壁的间皮中，并且似乎在海参受到压力时释放。在表皮中存在的皂苷中，在非应激海参周围的海水中检测到一种（海参苷G），并且当动物应激时分泌另外三种（海参苷C和F，以及去海参苷A）。此外，两种新的同系物（检测到m/z 1301和1317）也存在于应激海参的周围环境中。这些新的皂苷不是来自表皮，而是可能来自内脏。与体壁和Cuvierian小管浓度相比，分泌的皂苷的浓度非常低。在自然浓度下，皂苷不会对食肉鱼类的健康构成威胁。因此，皂苷的威慑作用似乎是一种警戒信号，警告潜在的捕食者海参组织的不适口性。
More than 100 triterpene glycosides (saponins) have been characterized in holothuroids in the past several decades. In particular, Holothuria forskali contains 26 saponins in its Cuvierian tubules and 12 in its body wall. This high diversity could be linked to a chemical defense mechanism, the most commonly accepted biological role for these secondary metabolites. We performed an integrated study of the body-wall saponins of H. forskali. The saponins are mainly localized in the epidermis and in the mesothelium of the body wall and appear to be released when the holothuroid is stressed. Among the saponins present in the epidermis, one (holothurinoside G) was detected in the seawater surrounding non-stressed holothuroids and three others (holohurinosides C and F, and desholothurin A) were secreted when the animals were stressed. In addition, two new congeners (detected at m/z 1301 and 1317) were also present in the immediate surroundings of stressed holothuroids. These new saponins do not originate from the epidermis and could come from an internal organ. Quantities of secreted saponins were very low compared with the body wall and Cuvierian tubules concentrations. At natural concentrations, saponins do not represent a threat to the health of predatory fish. The deterrent effect of saponins seems therefore to act as an aposematic signal, warning potential predators of the unpalatability of the holothuroid tissues.