Évaluation de quelques activités biologiques des extraits aqueux et polysaccharidiques de dattes (Phoenix dactylifera L.) de la région de Ghardaïa

Abstract

The richness of dates in bioactive compounds makes them a valuable natural source of molecules with therapeutic potential, particularly in the prevention and management of metabolic diseases such as type 2 diabetes. This study assessed the antioxidant and antidiabetic activities of aqueous (EAT, EAO) and polysaccharide (EPT, EPO) extracts of two local date varieties from Ghardaïa, T’dalet and Ouarous. Extraction yields revealed high rates for aqueous extracts 59.63% for T’dalet and 62.31% for Ouarous, reflecting the richness of these fruits in water-soluble compounds, while polysaccharide extracts showed modest yields 9.8% and 11.02%, respectively. Nevertheless, it should be noted that, despite being lower than those of the aqueous extracts, these yields are substantial and rank among the highest reported in the literature. Antioxidant activity, assessed by the DPPH and FRAP tests, showed that the polysaccharide extracts generally possessed a higher antioxidant power than the aqueous extracts, with lower IC50 values 1.65 ± 0.13 mg/mL for EPT and 2.34 ± 0.37 mg/mL for EPO in the DPPH test; 1.48 ± 0.06 and 1.53 ± 0.14 mg/mL in the FRAP test, although still lower than the efficacy of vitamin c 0.0027 mg/mL. Regarding antidiabetic activity, measured by the α-amylase inhibition test, the extracts showed IC50 values between 0.57 and 1.07 mg/mL, reflecting a significant inhibition of the enzyme. Compared to acarbose, the reference drug, whose IC50 reported in the literature generally varies between 0.1 and 0.5 mg/mL, date extracts are in an interesting efficacy zone: the aqueous extract of the Ouarous variety (0.57 ± 0.09 mg/mL) is close to the performance of the control, while the other extracts show a slightly lower activity. These results suggest that local dates, particularly the Ouarous variety, constitute a promising source of natural compounds with antioxidant and antidiabetic potential, which can serve as a basis for the development of food supplements or functional ingredients for the prevention and management of type 2 diabetes.