Phenolic profile, antibacterial and cytotoxic properties of second grade date extract from Tunisian cultivars (Phoenix dactylifera L.).

The present study aimed to investigate the phenolic profile of second grade date extracts and evaluate their antimicrobial and cytotoxic activities with regard to some pathogenic microorganisms. Phenolic content was analyzed by HPLC. Antimicrobial activity was evaluated by the agar disk diffusion method, and in vitro cytotoxic activity was examined by cell proliferation assay. The results revealed that second grade dates presented three benzoic acids, five cinnamic acids and two flavonoids, with the predominance of ρ-coumaric acid (1998.80µg/100g). The antimicrobial activities showed that the date extracts were active against Gram (+) and Gram (-) bacteria, showing marked activity against Escherichia coli with an inhibition zone of 25mm. Cytotoxicity assays showed that the date extracts were able to inhibit the proliferation of HeLa cell lines. The results confirmed that the date extracts were rich in biologically active compounds that are highly valued in the functional food and nutraceutical industries.

Effect of concentration temperature on some bioactive compounds and antioxidant proprieties of date syrup.

The effect of the concentration temperature on the antioxidant activity, carotenoid and phenolic compounds of date syrup was investigated. Date juice was concentrated at 100 and at "60 in vacuum". After concentration, total phenolic, tannin, non-tannin, flavonoid and carotenoid content were determined spectrophotometrically and high-performance liquid chromatography was used for determination of 5-Hydroxymethyl-2-furfuraldehyde content. The antioxidant activity of date syrup was evaluated by various antioxidant methods including total antioxidant, 2,2-diphenyl-1-picrylhydrazyl free radical scavenging test, ferric reducing antioxidant power and ß-carotene bleaching. All date syrups showed strong antioxidant activity accompanied by high total phenolic contents. Results showed that concentration at 100 significantly enhanced the antioxidant activities and total phenolic contents of date syrups compared to vacuum concentration at 60 . A good correlation between the antioxidant activity and total phenolic content and flavonoid was observed.