Biosynthesis of cyclopentenyl fatty acids. Cyclopentenylglycine, a non-proteinogenic amino acid as precursor of cyclic fatty acids in Flacourtiaceae.

In seeds of Hydnocarpus anthelminthica of Flacourtiaceae, cyclopentenylglycine and cyclopentenyl fatty acids are found naturally. The non-proteinogenic amino acid may serve as precursor of cyclopentenyl fatty acids via aleprolic acid, the starter molecule for these long-chain compounds. After administration of cyclopentenyl[2-14C]glycine to maturing seeds of H. anthelminthica, labelled cyclopentenyl fatty acids were synthesized. Comparative activities were observed, when [1-14C]aleprolic acid was supplied to the seeds. Incorporation studies with [1-14C]acetate revealed that the chain-lengthening systems for straight-chain and cyclic fatty acids were still functioning in mature seeds. Endosperm and embryo of H. Anthelminthica seeds synthesized cyclopentenyl fatty acids from cyclopentenyl[2-14C]glycine, [1-14C]aleprolic acid and [1-14C]acetate. In embryonic tissue, a dilution experiment proved the following path for cyclopentenyl fatty acid biosynthesis: cyclopentenylglycine leads to aleprolic acid leads to cyclopentenyl fatty acids. The conversion of cyclopentenylglycine to aleprolic acid may occur via transamination and oxidative decarboxylation; activated aleprolic acid is then lengthened by C2-units to cyclopentenyl fatty acids.