Biosynthetic Pathway and Origin of the Chlorinated Methyl Group in Barbamide and Dechlorobarbamide, Metabolites from the Marine Cyanobacterium Lyngbya majuscula

摘要: Abstract Structural and biosynthetic studies have been conducted on the barbamide class of molluscicidal agent. Dechlorobarbamide was isolated from a Curacao collection marine cyanobacterium Lyngbya majuscula its structure determined through spectroscopic analysis comparisons with barbamide. The absolute stereochemistry dolaphenine moiety to be S , defining configuration as 2 ,7 . Stable isotope feeding experiments cultured L. provided clear evidence that biosynthesis involves chlorination unactivated pro - R methyl group leucine. Experiments l -[ H 10 ]leucine demonstrated pro- occurs without detectable activation via leucine-catabolic pathway. Moreover, an extremely high level incorporation fed [2- 13 C]-5,5,5-trichloroleucine into indicates leucine is probable substrate for reaction. Incorporations [1,2- C ]acetate [1- C, 1- 18 O]acetate confirmed origins C-5 C-6 whereas -[3- C]phenylalanine supported hypothesis phenyl three carbon side-chain in (C-7, C-8 C-10–C-16) arise phenylalanine. thiazole ring (C-17–C-18) 1 shown likely cysteine 15 N]glycine experiment. Detection intact C– N bond observed by application new GHNMBC NMR Results this latter experiment also indicated N–CH 3 O–CH groups originate pool; enrichment these when cultures were -[methyl- C]methionine.