A new C5429-sterol, 23,24-dimethylcholesta-5,23-dien-3.BETA.-ol from soft coral.

Biosynthesis and Metabolism of Cyclopropane Rings in Natural Compounds

“…Sterols with a cyclopropane ring have been isolated almost exclusively from marine sources. Some of them have been known for decades, e.g., gorgosterol, 23-demethylgorgosterol, 4-methylgorgosterol, calysterol, petrosterol ( 47 ), or hebesterol, whereas others are relatively new, like 23-epidihydrocalysterol. − These compounds mostly stem from coelenterates, soft corals, or sponges. , They are usually isolated in very small amounts, and their function in nature has not yet been clarified. Endogenous bacteria living within these organisms may be the real producers. − …”

“…Some of them have been known for decades, e.g., gorgosterol, 23-demethylgorgosterol, 4-methylgorgosterol, calysterol, petrosterol (47), or hebesterol, whereas others are relatively new, like 23-epidihydrocalysterol. [83][84][85][86][87][88] These compounds mostly stem from coelenterates, 89 soft corals, 90 or sponges. 83,83 They are usually isolated in very small amounts, and their function in nature has not yet been clarified.…”

“…CmaT probably hydrolyzes the thioester bond to CmaA. The amide of coronamic acid, with the bicyclic coronafacic acid, forms coronatine (90), which is a chlorosisinducing phytotoxin produced by several pathovars of Pseudomonas syringae and acts as a potent elicitor of plant defense mechanisms. [126][127][128][129] The stereochemistry of the amino acid proved to be crucial for biological activity.…”

Recent progress in the marine sterol field

“…38) have shown that gorgosterol (38) and its congeners occur in the zooxanthellae rather than the soft coral hosts with which these syrnbionts live. They have also isolated trace amounts of 4-methylgorgosterol (40), which raises the as yet unanswered question whether the unique side chain substitution pattern is generated at the stage of lanosterol (or of a partially C-4 and C-14 demethylated lanosterol precursor) with complete ring demethylation being the last step in the biosynthesis of gorgosterol, or whether the 4-methyl analog (40) (47) is present in nature, it has been mistaken for one of the common 24-methyl isomers.…”