Phenolic compounds recovery from date seed and assessment of their antioxidant and enzyme inhibitory properties

Abstract

Date fruit is a highly important crop cultivated in arid and semi-arid regions, known for its nutritional value and health benefits. Dates' benefits extend beyond their edible portion and include seeds, which are a by-product of different industries, often considered waste, and have untapped potential. This work aimed to optimize the extraction conditions of antioxidant compounds from date seeds and assess their ability to inhibit disease-related enzymes. The optimization was carried out by examining the main parameters, including solvent type (acetone, ethanol, methanol, and water), solvent concentration (25–100%), sample-to-solvent ratio (10–60/20 mg/ml), and extraction time (15–90 min). Phenolic content (PC) was determined using the Folin-Ciocalteu method, while antioxidant activity was evaluated by ABTS and DPPH scavenging assays, as well as ferric reducing power (FRP). Based on the statistical analysis, 75% acetone, 10 mg/20 ml, and 45 min were found to be the best extraction conditions, manifesting a PC of 128.65 mg GAE/g dw, antiradical powers of 244.91 mg TE/g dw (ABTS) and 64.27 mg GAE/g dw (DPPH), and a FRP of 64.27 mg GAE/g dw. Moreover, the extract of date seed demonstrated a promising inhibitory property against some key enzymes such as tyrosinase, acetylcholinesterase, and α-glucosidase, which may be considered a good candidate for managing diabetes, Alzheimer's disease, and neurodegenerative disorders.