Abstract
Cubozoan nematocyst venoms contain known cytolytic and hemolytic proteins, but small molecule components have not been previously reported from cubozoan venom. We screened nematocyst extracts of Alatina alata and Chironex yamaguchii by LC-MS for the presence of small molecule metabolites. Three isomeric compounds, cnidarins 4A (1), 4B (2), and 4C (3), were isolated from venom extracts and characterized by NMR and MS, which revealed their planar structure as cyclic γ-linked tetraglutamic acids. The full configurational assignments were established by syntheses of all six possible stereoisomers, comparison of spectral data and optical rotations, and stereochemical analysis of derivatized degradation products. Compounds 1–3 were subsequently detected by LC-MS in tissues of eight other cnidarian species. The most abundant of these compounds, cnidarin 4A (1), showed no mammalian cell toxicity or hemolytic activity, which may suggest a role for these cyclic tetraglutamates in nematocyst discharge.
Highlights
BackgroundJellyfish, sea anemones, hydrozoans, and corals comprise the phylum Cnidaria
LC-MS screening of the of nematocysts from excised tentacles, nematocysts were disrupted and venom was collected from venom extracts (Figure S1, Rt 18.6 min) consistently showed a constituent demonstrating a protonated supernatant after centrifugation
None were detected in the 8 non-cnidarian species. These results suggest cnidarins 4A–C (1–3) are specific to cnidarians
Summary
BackgroundJellyfish, sea anemones, hydrozoans, and corals comprise the phylum Cnidaria. Penetrant cnidae are called nematocysts, which store venom that is injected into prey upon discharge through the tubule. Both physical and chemical stimuli trigger nematocyst discharge. Cnidarians in the class Cubozoa, or box jellyfish, include about 50 described species [1] that can cause harm and even death to humans upon envenomation. Chironex fleckeri has caused more than 67 cardiac/respiratory related human fatalities [2,3,4,5]. Known as the Habu-kurage in Japan, is closely related to Chironex fleckeri [10] and has confirmed human fatalities associated with its sting. The majority of C. yamaguchii stings are not fatal [11]
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