Lipoxygenase activity in seeds from New Zealand native plants

Abstract

Seeds from 48 New Zealand native plants, were tested for lipoxygenase enzymes and subsequent formation of products from linoleic and a‐linolenic acid. Lipoxygenases are of interest to the food and biotechnology industries as a means of producing natural flavour substances. Extracts of Gunnera hamiltonii possessed the highest lipoxygenase activity of 5.6 .tmol min^‐1 g^‐1. Analysis of the 13‐ and 9‐positional isomers of the oxidation products of linoleic acid showed that Melicystus lanceolatus × M. flexuosa, Pseudopanax arboreus, Carmichaelia kirkii, Dianella nigra, and Olearia paniculata produced higher proportions of the 13‐derivatives. Hoheria populnea, Solanum laciniatum, and Urtica australis produced predominately the 9‐isomers. Analysis of the 13‐ and 9‐positional isomers of the oxidation products of a‐linolenic acid showed that all species except Chionochloaflavescens were able to oxidise the trienoic acid to form 13‐positional isomers. Olearia ilicifolia produced only 13‐positional isomers. Only 11 of the species produced substantial amounts of the 9‐derivatives from a‐li‐nolenic acid. Chionochloaflavescens showed only the activity of a 9‐lipoxygenase.

Keywords:

• lipoxygenases
• polyunsaturated fatty acids
• hydroperoxide lyases
• 9‐ and 13‐positional isomers of hydroperoxy‐octadecadienoic acid
• hy‐droxy‐octadecadienoic acid
• hydroperoxy‐octadecatrienoic acid
• hydroxy‐octadecatrienoic acid