NotesNudibranchs are colorful, slow-moving, and shell-less mollusks. Their aposematic coloration and possession of toxic substances are believed to function synergetically for their protection from predators and microorganisms. 1,2) In our survey for the metabolites of nudibranchs collected along the coast of Okinawa, we often isolate exactly the same molecules obtained from their prey sponges. Some examples are isocyanoterpenes, latrunculin A, a spongian diterpene, 3) and reticulidins 4) which have been isolated from both sponges and nudibranchs. However, when we examined the contents of Chromodoris willani, the extract appeared to be different from the metabolites of their prey sponge, which contained two sesterterpenes, manoalide (3) and secomanoalide (4). 5) Manoalide was first discovered as an antimicrobial constituent of the sponge Luffariella variabilis 5) and later shown to have anti-inflammatory activity against phospholipase A2 (PLA2) 6) in addition to cytotoxicity. 7) In this note, we report the structures and biological activities of two manoalide analogs isolated from C. willani. Results and DiscussionFive specimens of C. willani and its prey sponge were collected at the same spot in Okinawa and were separately extracted. The lipophilic extract of C. willani was subjected to conventional chromatography to give two molecules 1 and 2 as major metabolites. The sponge extract was similarly treated to give manoalide (3) and secomanoalide (4) which have been identified by the same spectral data as those reported. 8) The results indicated negative Dd values for H-2 (Ϫ0.07) and H-4 (Ϫ0.09, Ϫ0.04) and positive values for H-5 (ϩ0.03), H-6 (ϩ0.11) and H-24 (ϩ0.09) concluding the 4R configuration. This is the first report on compounds 1 and 2 from a natural source, although 1 has been known as a synthetic entity. 6)Both compounds are believed to be biotransformed by the Two sesterterpenes, deoxymanoalide (1) and deoxysecomanoalide (2), were isolated from the nudibranch Chromodoris willani collected in Okinawa and their structures determined on the basis of spectroscopic data and chemical conversions. The mollusk feeds on a sponge containing manoalide (3) and secomanoalide (4) and is likely to biotransform them into 1 and 2. Both 1 and 2 showed moderate antimicrobial activity against Escherichia coli and Bacillus subtilis and inhibited snake venom phospholipase A2 at 0.2 to 0.5 m mM. Deoxymanoalides from the Nudibranch Chromodoris willani
Ciguatoxins CTXs responsible for ciguatera fish poisoning CFP in Amami Islands, Kagoshima, Japan in 2008 were determined by LC-MS/MS analysis. Ciguatoxin-1B CTX1B , 54-deoxyCTX1B, and 52-epi-54-deoxyCTX1B were detected in Variola louti and Lutjanus monostigma. The toxin profile distinctly differed from that of a CFP-related fish from Miyazaki, which mainly contained ciguatoxin-3C type toxins. Toxin profiles were species-specific, as observed in fish from Okinawa. The LC-MS/MS and mouse bioassay MBA methods produced comparable data, though 54-deoxyCTX1B was not taken into consideration owing to the lack of toxicity data. To improve assessment, toxicity data for this compound are needed. A reef fish caught on the same occasion and judged nontoxic by MBA 0.025 MU/g was found to contain low levels of CTX, indicating a potential risk for CFP.
In this paper we report two incidents of ciguatera fish poisoning (CFP) that occurred in 2008 on Kakeroma Island in Kagoshima Prefecture, Japan. A family consisting of father (42 y.o.), mother (39 y.o.), daughter (11 y.o.) and son (6 y.o.), as well as a friend of the family (male, 78 y.o.) consumed sliced flesh (sashimi) and developed typical symptoms of CPF 4-5 h later: diarrhea, vomiting, and paresthesia of the extremities. Additionally, the two male adults (42 and 78 y.o.) developed mild hypotention (84/48 and 94/40 mmHg, respectively) and bradycardia (36 and 50 bpm, respectively) and were rushed to the ER of the nearest hospital, located on an adjacent island. The implicated fish were caught together off the west coast of the island and were identified as Variola louti and Lutjanus monostigma based on analysis of 16S rRNA gene coded on mtDNA. Remnants of the implicated fish and other fish caught on the same occasion were examined by the official mouse bioassay method (MBA), which defines the minimum amount of CFP toxin needed to kill a male mouse of ddY strain of 20 g body weight within 24 h as one mouse unit (MU). A significantly high toxicity was detected in the V. louti (0.2 MU/g) eaten by the family and the L. monostigma (0.8 MU/g) eaten by the elderly man. Other specimens of Lethrinus nebulosus, Variola albimarginata, Lutjanus gibbus (2 specimens), Aphareus rutilans, and Sphyraena forsteri (2 specimens) were found to be nontoxic (< 0.025 MU/g). The medical records regarding island inhabitants (ca. 1,500) kept at Kakeroma Tokushukai Clinic, the only medical facility on the Island, and also at Setouchi Tokushukai Hospital, a nearest hospital on an adjacent island (Amami) revealed 6 CFP outbreaks involving 13 cases between 2005 and 2008. The estimated frequency of CFP was 10.0 incidents/10,000 persons/year and the morbidity rate was 21.7 cases/10,000 persons/year. The symptoms and signs observed in the patients and the implicated fish species, L. monostigma and V. louti, were typical of CFP in this region.
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