Sicana odorifera seeds as a new source of punicic acid determined by NMR analyses

Abstract

The seed oil composition of South American cucurbits, including the Chilean giant pumpkin (Cucurbita maxima) and the Paraguayan Sicana odorifera, was assessed by high-field nuclear magnetic resonance (NMR). The main objective of the study was to describe the composition of the seed oils using NMR as the main analytical tool and to detect possible conjugated linolenic acid isomers (CLnA). A previous study of S. odorifera seed oil identified linolenic and linoleic acids as the main fatty acids (FAs). Reexamination of the S. odorifera seed oil by NMR showed that the C18:3 fatty acid previously reported is the CLnA isomer punicic acid (PA). PA occurs in S. odorifera cultivars atropurpurea and fragans, with higher content in atropurpurea (37.42 and 31.70%, respectively). The identification of PA as a major constituent in S. odorifera oil opens new perspectives on the possible applications and consumption of seeds as a healthy food. The new source of PA is a fast-growing cucurbit, adapted to tropical and subtropical climates. The seed oil composition of the Chilean giant pumpkin is like that of other C. maxima cultivated in South America and Europe. NMR spectroscopy was a rapid and reliable method for identifying and quantifying the main constituents in the seed lipids, clearly differentiating CLnA isomers and linolenic acid.