Recent progress in the marine sterol field

Abstract

-This paper covers recent work -much of it from the authors' laboratory -dealing with novel 3-hydroxy marine sterols possessing unusual side chains, which have hitherto not been encountered in terrestrial sources. Aside from a description of the proof of structure and stereochemistry of these sterols, attention is also drawn to plausible models of biosynthesis and to the possible biological role in membrane function.

Organic Geochemistry of Sediments from the Southern California Borderland, Deep Sea Drilling Project Leg 63

“…7). The presence of norcholestane may indicate an origin from marine biogenic sources (e.g., Djerassi et al, 1979). The dominance of the C 27 sterane in all samples is more characteristic of an origin from marine planktonic detritus (Huang and Meinschein, 1979).…”

Bioactive Compounds from Marine Invertebrates for Potential Medicines - An Overview

“…(Coleman et al 1995 Capelle et al, (1980) from the same species diterpenes have also been isolated. Gonzalez et al, (1984) reported diterpenoids containing a purine or a 9-methyladenine unit (Djerassi, et al, 1979). These compounds exhibit antimicrobial and Na, K-ATPase inhibitory activities.…”

Biosynthesis of marine sterols

“…This sterol (Scheme 9) possesses a unique symmetrical double extension at C-26 and C-27 and a 24-methylene substituent. The biosynthesis again involves three successive biomethylations of desmosterol (34), epicodisterol (51) and 25(26)-dehydroaplysterol (68) (Scheme 9), a very similar sequence to that found for strongylosterol (63) and mutasterol (65). However, in this case, complete lack of stereospecificity was observed in the bioalkylation of codisterol (52) and epicodisterol (51).…”

“…[63] and Cribrochatina vasculum [64]. The most likely biosynthetic route (Scheme 14A) to petrosterol [65] is by SAM methylation of epicodisterol (51) as is known to occur for aplysterol (54). Feeding radiolabeled epicodisterol to P. fic~ormis resulted in no incorporation of radioactivity in petrosterol; however [28-1~C] 24-methylenecholesterol (97) was efficiently transformed to the target sterol [65].…”

“…The most likely biosynthetic route (Scheme 14A) to petrosterol [65] is by SAM methylation of epicodisterol (51) as is known to occur for aplysterol (54). Feeding radiolabeled epicodisterol to P. fic~ormis resulted in no incorporation of radioactivity in petrosterol; however [28-1~C] 24-methylenecholesterol (97) was efficiently transformed to the target sterol [65]. Experiments with C. vasculum [64] demonstrated that conversion of 24-methylenecholesterol to petrosterol proceeded via an unprecedented cyclopropane-cyctopropane rearrangement involving a protonated dihydrocalysterol intermediate (98) (Scheme 14B).…”