Phenolic profile, antioxidant activity and enzyme inhibitory capacities of fruit and seed extracts from different Algerian cultivars of date (Phoenix dactylifera L.) were affected by in vitro simulated gastrointestinal digestion

Abstract

Abstract The aim of the present study was to evaluate the influence of the digestive process (gastric and intestinal phases) on the stability of the individual and total phenolic (TPC) and flavonoid (TFC) contents, antioxidant activity and enzymes inhibitory potential of extracts from date fruits (pulp) and seeds from eight Algerian cultivars of date palm (Phoenix dactylifera). The obtained results showed a considerable increase in the TPC for both samples when exposed to digestion conditions. The TFC was higher after gastric digestion compared to intestinal digestion. Along the digestion process, the release of individual phenolics (phenolic acids and flavonoids) analyzed by ultra-high-performance liquid chromatography (UHPLC) showed different behavior in seed and fruit extracts. The digestion increased the scavenging of 2,2′-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid (ABTS) and peroxyl (oxygen radical absorbance capacity, ORAC) radicals in both samples. However, ferric reducing antioxidant power (FRAP) and 2,2-diphenyl-1-picrylhydrazyl (DPPH) scavenging capacity were reduced in date seed extracts, while the fruit extracts showed an increase at the end of digestion process. The enzymes inhibitory potential of date seeds extracts decreased after digestion and was maintained or enhanced in fruit extracts. Thus, it seems that the date fruit extracts had more bioaccessible components compared to seed extracts.