Bioactive Compounds Responsible for Antioxidant Activity of Different Varieties of Date ( Phoenix dactylifera L.) Elucidated by ¹ H- NMR Based Metabolomics

Abstract

Several studies have demonstrated strong antioxidant activity of date fruits. Nevertheless, limited data is available for the bioactive compounds responsible for the activity. In this study, the antioxidant activity of five different date varieties (Ajwa, Anbara, Piyarom, Rabbi and Deglet Nour) extracted using 80% ethanol was determined using free radical scavenging (DPPH), ferric reducing power (FRAP) and antioxidant capacity (ABTS) assays. The 1 H-NMR was employed to profile the bioactive metabolites present in the dates. The obtained results demonstrated that the Piyarom extract had the highest total phenolic content (355 mg GAE/100g DW), total flavonoid content (57.07 mg/100g DW) and exhibited good antioxidant activity with IC 50 of 16.2 µg/mL, 26.38 mmol Fe (II)/g and 11.3 µg/mL for DPPH scavenging activity, FRAP antioxidant power and ABTS antioxidant capacity, respectively. The metabolites responsible for the variation between different date's varieties were successfully identified using 1 H-NMR-based metabolomics. The principal component analysis (PCA) and partial least squares (PLS) analysis depicted clear and distinct separations into three clusters representing the five date varieties. The metabolites responsible for the separation were identified as sucrose, betaine, fructose, ascorbic acid, glycine, and arginine. Correlation study from PLS biplot revealed that glucose, ascorbic acid, epicatechin, gallic acid, and citric acid are responsible for the antioxidant activity measured.

Total Polyphenol and Flavonoid Content and Antioxidant Capacity of Some Varieties of Persea americana Peels Consumed in Cameroon

“…One of the main properties of polyphenols is their antiradical activity which is itself attributed to their hydroxyl groups which contribute to their redox properties, electron-donating capacity, singlet antioxygen action, and metal chelating capacity. Indeed, the class of polyphenols has been proven to determine the free radical scavenging activity, the flavones being the most effective [ 41 ]. This result was corroborated by Nahak et al [ 42 ] who showed that an antioxidant that is effective in one test is not necessarily effective in another on the one hand.…”

Phytochemical Screening and Antioxidant Potential of Aqueous Extracts of Millettia laurenti, Lophira alata and Milicia excelsa, Commonly Used in the Cameroonian Pharmacopoeia

“…A very weak correlation with polyphenols content (r 2 = 0.09, P = .93) was observed, which is in contrast to many works generally linking both parameters [31,32], and which therefore questions the nature of polyphenols that are present in the extract. Indeed, the class of polyphenols has been proven to determine the free radical scavenging activity, the flavanols being the most effective [31,33]. These flavonols were not detected in Lophira procera barks aqueous extract [27].…”

“…That compound might be flavonoids as it showed the highest correlation with the total antioxidant capacity (r 2 = 1.00, P = .01) and the iron-reducing capacity (r 2 = 0.94, P = .22). It can, therefore, be suggested a quantitative dependence of TAC with flavonoids and tannins but rather a qualitative one (nature of the compounds) with polyphenols and alkaloids [33,40,41].…”

Metabolomics profiling and antimicrobial activity of fermented date fruit (Khastawi) used as functional ingredients for making Asian confectionary (Dodol)

“…The high antifungal and antibacterial activities of date fruit extract could be a result of their high content of free and bound polyphenols [19]. Date fruit extract was reported for it is strong antimicrobial activity due to the high phenolic compounds content determined using 1 H-NMR analysis [20]. However, very limited studies investigated the potential applications of date fruit as functional ingredient in making bakeries and confectionaries.…”