Phenolic Compounds, Evaluation of Alpha-Amylase Inhibitory Activity, and Antioxidant Effects of Phoenix dactylifera L. Date Seeds

Recent research trends emphasize the valorization of food industry waste to enhance economic gain, food security, environmental safety, and sustainable development. Among the significant wastes from the date industry are date seeds, which represent substantial economic resources. Typically discarded or used as animal feed, date seeds possess a valuable chemical composition, particularly high levels of phenolic compounds, making them suitable for various applications. This study focuses on the valorization of date seeds from the Takerboucht variety in the Adrar region. The objective was to evaluate the in vitro antioxidant and antidiabetic properties of the crude seed extract. The phenolic and flavonoid contents of the extract were determined using the Folin–Ciocalteu and aluminum chloride colorimetric methods, respectively. Antioxidant activity was assessed through DPPH, FRAP, and ABTS assays, while antidiabetic activity was evaluated by examining the inhibitory effect of the extract on the key diabetes enzyme, α-amylase. The date seed extract demonstrated significant antioxidant activity, reducing both DPPH and ABTS radicals in a dose-dependent manner, with IC₅₀ values of 2.7 μg/ml and 42.9 μg/ml, respectively. The extract also exhibited considerable potential in the FRAP assay (0.114 mg/ml), comparable to standards BHT and BHA. This antioxidant activity was well correlated with the total phenolic content (100.20 mg GAE/g DW) and flavonoid content (44.618 mg CE/g DW). Moreover, the extract showed strong inhibitory activity against α-amylase, with an IC₅₀ of 0.24 mg/ml, compared to the positive control, acarbose (0.17 mg/ml). These findings suggest that date by-products, particularly Takerboucht seeds, are a rich source of phenolics with significant antioxidant and antidiabetic properties. Consequently, they could be considered inexpensive sources of natural antioxidants for use in food and non-food applications and in preventing metabolic disorders such as hyperglycemia.