Phenolic fraction concentrate of Phoenix dactylifera L. seeds: A promising antioxidant and glucose regulator.

Context: The beneficial effects of natural polyphenolic compounds are increasingly emerging as powerful antioxidants and digestive boosters. Phoenix dactylifera seeds are recently identified as a healthy functional food with rich amounts of phenolic compounds. Aims: To analyzing the phenolic profile obtained from Moroccan variety of date seeds and evaluating the inhibitory capacity against digestive enzymes and the antioxidant potential of phenolic fraction concentrate (PFC) of date seeds as a promising antihyperglycemic agent. Methods: Lineweaver–Burk plot analysis was performed to evaluate PFC inhibitory effect against digestive enzyme activity in the presence of different doses of a substrate. Wistar rats were recruited to determine the acute and sub-acute oral toxicity of PFC. Finally, the optimal dose of PFC was selected and its effects on metabolic, hematological and biochemical parameters were determined. Results: High-performance liquid chromatography (HPLC) analysis revealed that PFC contains abundant amounts of phenolic acid: Caffeic acid, chlorogenic acid, 3,4-dihydroxybenzoic acid, p-hydroxybenzoic acid, and 3-hydroxybenzoic acid. PFC showed powerful antioxidant activity as determined by scavenging and reducing assays. PFC significantly inhibited alpha-amylase and alpha-glucosidase enzymes by 87.3% and 78.7%, respectively, via mixed manipulation of Km and Vmax. Acute toxicity examinations revealed PFC to be practically non-toxic with LD50 > 5000mg PFC/kg for both sexes of rats. The no-observed-adverse-effect-level (NOAEL) and lowest observed adverse effect level (LOAEL) for oral administration of PFC were 1000 and 2500 mg/kg for both sexes. Finally, the sub-acute study showed that a PFC dose of 50 mg/kg did not cause any changes in metabolic, biochemical and hematological parameters and was considered to be the optimal healthy dose for rats. Consequently, it induces improvement in glucose concentration in rats. Conclusions: The rational use of phenolic date seeds fraction presents powerful antioxidant and blood glucose regulating nutraceutical that could aid in diabetes mellitus management