Phytoprostanes in almonds: identification, quantification, and impact of cultivar and type of cultivation

Recently, the relationship between oxidative stress and the phytoprostanes content in plants has been studied. In 1998, it was discovered that phytoprostanes are generated from alpha-linolenic acid, following a non-enzymatic pathway initiated by enhanced formation of free radicals. Almonds and other nuts have favorable contents of polyunsaturated fatty acids; one of the most-polyunsaturated fatty acids present in plants is alpha-linolenic acid. This study represents a first approach to the quantitative and qualitative determination of the phytoprostanes profile in 11 almond cultivars under different agronomic conditions (conventional versus ecological, rain-fed versus irrigated). In the kernels have been identified 9-F-1t-phytoprostane, 9-epi-9-F-1t-phytoprostane, ent-16-epi-16-F-1t-phytoprostane, ent-16-F-1t-phytoprostane, 9-D-1t-phytoprostane, 9-epi-9-D-1t-phytoprostane, 16-B-1-phytoprostane, and 9-L-1-phytoprostane. The total phytoprostane content was in the range of 4.0 to 23.8 ng per 100 g. F-1-phytoprostanes predominated and were identified in all almond cultivars. L-1-phytoprostanes were minor components while D-1-phytoprostanes were only detected in cultivars 'Colorada' and 'Avellanera'. The phytoprostane profile varied greatly depending on the genotype, but was also affected by factors such as the agricultural system (conventional or ecological) and irrigation. The ecological system promoted the synthesis of D-1-phytoprostanes. Almonds from rain-fed trees had lower individual and total phytoprostane concentrations than those under irrigation, even though non-irrigation led to the detection of the 16-F-1-phytoprostanes. Consequently, irrigation and ecological techniques applied to almonds could be considered as actions to enhance their phytoprostane content and hence their potential beneficial effects on human health.