Phytochemical Analysis and Biological Activity Evaluation of the Hydromethanolic Extract of Date Palm (Phoenix dactylifera L.) Seeds from the ‘Ghars’ Cultivar Cultivated in the El Oued Region, Algeria

Abstract

The date palm (Phoenix dactylifera L., Arecaceae) is a keystone fruit crop of Saharan oasis agro￾ecosystems, and its seeds — long discarded as an agro-industrial by-product — are increasingly recognised as a rich yet underexploited reservoir of bioactive secondary metabolites; nevertheless, the phytochemical and biological value of locally grown seeds of the soft cultivar 'Ghars' remains insufficiently documented. The aim of this work was to characterise the hydromethanolic extract of P. dactylifera L. seeds of the 'Ghars' cultivar harvested in the El Oued region and to evaluate its in-vitro antioxidant, antidiabetic and anti-Alzheimer potential.Cleaned, shade-dried and ground seeds were macerated in methanol/water (75:25, v/v) through three successive 24-hour cycles at room temperature, and the combined macerates were filtered and concentrated under reduced pressure at 40 °C, affording a crude dried extract with a yield of 24.61% (w/w). Total phenolic, total flavonoid and condensed tannin contents were determined by the Folin–Ciocalteu, aluminium chloride and vanillin–HCl methods, respectively, while the phenolic profile was established by reversed-phase high￾performance liquid chromatography coupled with photodiode-array detection (HPLC–PDA); biological activities were assessed through DPPH and ABTS- ⁺ radical-scavenging assays, the o-phenanthroline reducing assay, and inhibition of α-amylase, α-glucosidase and acetylcholinesterase. The extract was particularly rich in polyphenols (284.19 ± 1.40 mg GAE/g), flavonoids (94.33 ± 3.90 mg QE/g) and condensed tannins (68.62 ± 1.20 mg CE/g), and fifteen phenolic and related compounds were targeted by HPLC–PDA, of which ten were detected and quantified, dominated by salicin (6949.30 µg/g extract), caffeic acid (431.74 µg/g extract) and esculin (207.34 µg/g extract). Marked radical-scavenging activity was recorded against DPPH- (IC₅₀ = 8.300 ± 0.231 µg/mL) and ABTS- ⁺ (IC₅₀ = 3.984 ± 0.033 µg/mL), together with an o-phenanthroline reducing capacity (A₀.₅ = 5.474 ± 0.156 µg/mL), closely approaching those of Trolox and ascorbic acid. Notably, the extract inhibited α-amylase (IC₅₀ = 50.03 ± 3.80 µg/mL) more strongly than the reference inhibitor acarbose (IC₅₀ = 60.86 ± 1.58 µg/mL), and exhibited complementary α-glucosidase (IC₅₀ = 120.00 ± 2.97 µg/mL) and acetylcholinesterase (IC₅₀ = 98.82 ± 5.25 µg/mL) inhibition compared with acarbose (IC₅₀ = 62.20 ± 1.38 µg/mL) and galantamine (IC₅₀ = 28.00 ± 0.30 µg/mL), respectively. These findings demonstrate that locally cultivated El Oued 'Ghars' date seeds constitute a promising antioxidant, antihyperglycaemic and neuroprotective phytotherapeutic and functional-food resource, valorising a Saharan agro-industrial by￾product within a circular-bioeconomy framework; nevertheless, the present results are restricted to in vitro models, and further in vivo, toxicological and clinical investigations are required to confirm efficacy, safety and optimal conditions of use.