Symbioimines, Potential Antiresorptive Drugs

Large polyol and polyether compounds, such as palytoxin, halichondrin, ciguatoxin, and maitotoxin, are characteristic marine secondary metabolites. These compounds are composed of a long carbon backbone functionalized by oxygen, and have been called "super-carbon-chain compounds" [63]. Interestingly, several super-carbon-chain compounds consist of a single chain starting from a carboxylic acid (C-terminus) and an amine moiety (N-terminus, which are sometimes acylated), thus they can be considered to be huge amino acids, i.e., palytoxin (32) (115 straight carbon chain) [64], zooxanthellatoxin-A (33) (106 carbons) [65], and azaspiracid 1 (34) (40 carbons) [66,67] (Fig. 5). This concept may also be applicable to pinnatoxins and zoanthamines, which could be biosynthesized from a single carbon chain precursor possessing a terminal amino group, as shown in Figs. 2 and 4.

The symbiotic marine dinoflagellate Symbiodinium sp., which is a type of zooxanthellae, is found in a wide range of marine invertebrates, and produces several large bioactive polyol compounds, such as zooxanthellatoxins and zooxanthellamides [65,68-70]. In our continuing search for biologically active compounds, two unique amphoteric iminium compounds were isolated from this dinoflagellate: symbioimine (35) and neosymbioimine (36) [71-73].

Palytoxin (32)
Zooxanthellatoxin A (33) Azaspiroacid 1 (34)

Fig. 5 Super-carbon-chain compounds with a terminal amino group

Fig. 5 Super-carbon-chain compounds with a terminal amino group

0 0

Post a comment