ENHANCING ANTIOXIDANT ACTIVITY AND PHENOLIC CONTENT IN DATE PALM (Phoenix dactylifera L.) CALLUS CULTURES THROUGH TRACE ELEMENT SUPPLEMENTATION

Abstract

This study investigates the impact of trace element supplementation on phenolic content, antioxidant activity, and callus initiation in Hassawi date palm (Phoenix dactylifera L.) cultivars (Khalas, Ruziz, and Shishi) grown on Murashige and Skoog (MS) medium. Varying concentrations of trace elements (MgSO₄·7H₂O, MnSO₄·4H₂O, ZnSO₄·7H₂O, and CuSO₄·5H₂O at zero, half, full, and double Stock E) were tested to evaluate their effects on secondary metabolite production and oxidative stress management. Results demonstrated that double concentrations of Stock E significantly enhanced phenolic content (2.68 mg g^-1 GAE) and antioxidant activity (96.28 % inhibition and 978.69 mg g^-1 µM Trolox), with the Shishi cultivar showing the most pronounced response. The improved phenolic accumulation and antioxidant capacity were attributed to the activation of enzymatic pathways, including phenylalanine ammonia-lyase (PAL), and the regulation of reactive oxygen species (ROS) through enhanced antioxidant enzyme activity. Additionally, reduced browning in callus tissues indicated effective modulation of polyphenol oxidase (PPO) activity. The study underscores the potential for optimizing trace element concentrations to enhance bioactive compound production in date palms. These findings contribute to sustainable agricultural practices, offering practical applications in food, pharmaceutical, and nutraceutical industries. Future research should focus on molecular analyses to elucidate the precise pathways influenced by trace elements and explore large-scale production systems for commercial antioxidant extraction.