Bioactive phytochemicals of tree nuts. Determination of the melatonin and sphingolipid content in almonds and pistachios

Tree nuts are healthy foods rich in bioactive phytochemicals. Their regular, moderate consumption has been associated with a reduced risk of chronic-degenerative diseases, in the context of a healthy diet and lifestyle. This study aimed to investigate the phytochemical profile of almonds and pistachios, in order to add new elements in the complex scenario of nut chemistry. A LC-MS/MS method was developed to quantify melatonin and ceramides in almonds and pistachios. In general, pistachios were richer in melatonin (2609 ± 3096 vs 1222 ± 500 pg/g) and total ceramides (302 ± 77 vs 165 ± 21 pmol/g) than almonds. Among total ceramides fatty acyl homologs, the most represented was the C16:0 species, both for ceramides and dihydroceramides, and both in almonds (37-40%) and pistachios (51-74%). Overall, these results add a piece of information to elucidate the chemical composition of almonds and pistachios and provide a rationale for the nutraceutical potential of nuts in the Mediterranean diet.