Evaluation of Phytoprostanes and Phytofurans in different nuts and seed

Abstract

Phytoprostanes (PhytoPs) and phytofurans (PhytoFs) are non-enzymatic lipid peroxidation products of α-linolenic acid (ALA) in plants. Recently, it is discovered that both PhytoPs and PhytoFs are present in some nuts and seeds, which indicate these are readily available in our daily diet. Furthermore, PhytoPs showed some protection on oxidant-induced neuroblastoma cells. To evaluate sources of PhytoPs and PhytoFs from daily food items, we investigated the level of ALA, PhytoPs and PhytoFs in 9 different kinds of common dietary nuts and seeds including almond, peanut, pine nut, walnut, chia seed, flaxseed, sunflower seed, black sesame seed and white sesame seed. The oil was extracted from nuts and seeds by Soxhlet extraction, and analysed by LCMS/MS. We found the ALA content of seeds in particular chia seed exceeded those of nuts. Further, seeds such as chia seed and flaxseed had significantly high amount of PhytoPs whereas nuts such as almond had the highest amount of PhytoFs. Surprisingly, antioxidant rich walnut had relatively low amount of ALA but a high amount of PhytoPs and PhytoFs. We also tested the antioxidant capacity and phenolic content of these samples by ABTS assay and Folin-Ciocalteu assay respectively. However, we observed no relationship between the level of antioxidant capacity and the level of PhytoPs and PhytoFs, and moreover no relationship between the phenolic content and the level of PhytoPs and PhytoFs were identified. This study showed that PhytoPs and PhytoFs are found commonly in nuts and seeds, and the level of ALA did not necessarily indicate higher PhytoPs and PhytoFs. Further investigation on the health benefits and bioavailability of PhytoPs and PhytoFs are currently being conducted in our laboratory.