zoanthids poisonous???
Posted: Mon Jan 09, 2006 2:05 pmeto pa......
Palytoxin
The crude ethanol extracts of the Palythoa toxica proved to be so toxic that an accurate LD50 was difficult to determine. More recently, the toxicity has been determined to be 50-100 ng/kg i.p. in mice. The compound is an intense vasoconstrictor; in dogs, it causes death within 5 min at 60 ng/kg. By extrapolation, a toxic dose in a human would be about 4 micrograms. It is the most toxic organic substance known!
Shimizu [27] and Moore [28] published the chemical structure of palytoxin and it was prepared synthetically in 1989 [29,30]. Palytoxin is a fabulously interesting compound, with a bizarre structure and many extraordinary signs (Fig. 6). Palytoxin is a large, very complex molecule with lipophilic and hydrophilic areas. The palytoxin molecule has the longest continuous chain of carbon atoms known to exist in a natural product. In the molecule of palytoxin, C129H223N3O54, 115 of the 129 carbons are in a continuous chain.. There are 54 atoms of oxygen, but only 3 atoms of nitrogen. Another unusual structure of palytoxin is that it contains 64 stereogenic centers, which means that palytoxin can have 264 stereoisomers! Added to this, the double bonds can exhibit cis/***** isomerism, which means that palytoxin can have more than 1021 (one sextilion) stereoisomers! This staggering molecular complexity should indicate the difficult nature of designing a stereocontrolled synthetic strategy that will produce just the one correct (natural) stereocenter out of >1021 possible stereoisomers.
Palytoxin induces powerful membrane depolarization and ionic channeling [31,32]. Palytoxin is a potent hemolysin, histamine releaser, inhibitor of Na/K ATPase, and a cation ionophore [33]. It is also a non-TPA-type tumor promoter [34,35].
natakot ako bigla dun ah!!!