抄録
Jellyfish, sea anemone and coral are classified as members of the phylum
Cnidaria. All cnidarians have a stinging cell, cnidocyte, and its stinging
organelle nematocysts. Nematocyst stores venom and coiled needle inside and
discharge the needle and inject venom into their prey. Both physical and
chemical stimuli trigger nematocyst discharge. A lot of studies on the venom of
cnidarians have been accomplished. As the results, it has been revealed that
most of cnidarian venoms consisted of proteinaceous toxins. However, there are
few studies on the low molecular weight compounds from the cnidarian
nematocysts. Therefore, we started the search of low molecular weight
compounds in the nematocyst. First target was the venomous jellyfish Chironex
yamaguchii (Habu-kurage in Japanese). Nematocysts were isolated from C.
yamaguchii tentacles. The isolated nematocyst and C. yamaguchii tentacle
without nematocyst were extracted with 1 M NaCl solution using a mini-bead
beater machine. The extracts were screened with LC-MS. It was clearly shown
that three compounds all of which have [M+H]+ 517 were existed especially in
nematocysts. Three compounds were isolated with HPLCs. NMR and MS spectra
data of isolated compounds revealed their planar structure as cyclic γ-tetra
glutamic acids. The determination of absolute stereochemistry of these
compounds was established with organic synthesis, comparing optical rotation
values and Marfey’s analysis. Three cyclic γ-tetra glutamic acids were designated
as cnidarin4A (1a), cnidarin4B (1b) and cnidarin4C (1c), respectively.
Cnidarin4A and cnidarin4B were new compounds. Cnidarin4C was first
obtained as the natural product in this study. The existence of these compounds
in marine animals has been studied using LC-MS. Cnidarin4s were detected
from all the nine tested cnidarians, on the contrary no cnidarin4s were detected
from all the seven tested the other phylum animals. Cnidarin4s are especially
existed in animals of the phylum Cnidaria. The ecological role of cnidarin4s in
cnidarians is a challenging subject to be elucidated.
