Bioactive Potential of Date Palm By-Products (Phoenix dactylifera L.): Optimized Extraction and Antimicrobial Activity Against Veterinary Pathogens

The sustainable utilization of agricultural by-products is essential for environmental and economic benefits. This study uses response surface methodology to extract bioactive compounds from date palm by-products (seeds, perianths, spikelets). Extracts’ analyses included total phenolic content, antioxidant activity, antimicrobial activity, and phenolic profiles via UHPLC-UV-MS. Optimal extraction conditions were identified as follows: for seeds, 5 minutes at 20°C with 60% ethanol; for perianths, 4 minutes at 17°C with 61% ethanol; and for spikelets, 4.5 minutes at 50°C with 60% ethanol. Mass spectrometry analysis revealed the presence of 28 secondary metabolites, including phenolic acids, flavonoids, glycosides, and sulfated flavonoids. The extracts showed significant antioxidant activity, with the perianth extract exhibiting the highest DPPH inhibition percentage. The extracts’ antimicrobial activity was tested against nine pathogenic bacteria. The spikelet extract showed the strongest inhibition of E. coli, while the perianth extract effectively inhibited S. marcescens, S. typhimurium, and E. faecalis. Minimum inhibitory concentrations for S. aureus were 0.1 mg/mL for the perianth extract, 0.5 mg/mL for the spikelet extract, and 2.5 mg/mL for the seed extract. Besides optimizing the extraction procedure for phenolic compounds from date palm by-products, the present study demonstrated their antioxidant and antimicrobial properties. These findings underscore the significance of date palm by-products as valuable resources for developing functional products, thereby contributing to sustainability and a circular economy.