Algerian date palm (Phoenix dactylifera L.) fruit cultivars: HPLC fingerprinting and antibacterial activity

The abusive use of antibiotics causes the destruction of intestinal flora and the proliferation of antibiotic-resistant pathogens. Date palm is used in traditional medicine in the Saharan regions due to its biological properties. The study aimed to identify the phytochemical composition and assess the antibacterial activity of the methanolic extracts of three date cultivars from Algeria. Their total phenolic, flavonoid, and flavonol contents were measured spectrophotometrically. The phytochemical screening was conducted by HPLC fingerprinting using twenty-three pure phenolic compounds as standards. The antibacterial activity against pathogenic bacterial species was assessed using the disk diffusion method. The colorimetric methods showed that the total phenolic, flavonoid, and flavonol contents ranged from 2.13 ± 0.09 to 2.67 ± 0.02 mg GAE/100 g DW, 1.33 ± 0.21 to 1.55 ± 0.13 mg CEQ/100 g DW, and 0.41 ± 0.23 to 0.47 ± 0.05 mg REQ/100 g DW, respectively. HPLC fingerprinting showed that the extracts of date cultivars served as an excellent source of bioactive compounds (gallic acid, tannic acid, ferulic acid, vanillin, caffeine, quercetin, luteolin, rutin, aspegenin, isorhamnetin, and hesperidin). They also exhibited an antibacterial potential with an inhibition zone diameter ranging from 8.40 to 12.50 mm. The results clearly demonstrate the antibacterial potency of date palm fruits, which could be attributed to their considerable content of phenolic compounds such as gallic acid, rutin, quercetin, and luteolin.