Alhagi maurorum: A Medicinal Treasure Trove Empowered by Copper Oxide Nanoparticles for Enhanced Secondary Metabolite Synthesis

Abstract

This study investigated the potential of green-synthesized copper oxide nanoparticles (CuO NPs) to enhance biomass production and therapeutic metabolite yields in Alhagi maurorum, a medicinal plant of significant pharmaceutical value. CuO NPs were biosynthesized using A. maurorum leaf extract as a reducing and capping agent, with characterization confirmed via UV-Vis spectroscopy, FTIR, XRD, SEM, TEM, and zeta potential analysis. Nanoparticles ranged from 7-30 nm in size. Callus induction and proliferation were established using Murashige and Skoog (MS) media supplemented with varying concentrations (0-12 mg/L) of CuO NPs combined with plant growth regulators. Maximum callus fresh weight (9.02 mg in cotyledon and 8.46 mg in hypocotyl) was achieved in MS media containing 3.0 mg/L BAP, 0.1 mg/L NAA, and 0.50 mg/L kinetin without CuO NPs. However, CuO NPs significantly enhanced metabolite production in a dose-dependent manner. Analysis of variance revealed statistically significant differences (p=0.001) across all biochemical parameters tested, with high F-values for peroxidase activity (7,755.74), total flavonoids (5,195.02), and total soluble sugar (5,702.18). At 8 mg/L CuO NPs, callus cultures exhibited elevated levels of total free amino acids (12.49±0.023 mg/g DW) and total soluble protein (35.617±0.033 mg/g DW), while control samples produced higher starch (35.547±0.23 mg/g DW) and total soluble sugar (121.56±0.091 mg/g DW) content. Significantly, CuO NP-treated cultures demonstrated enhanced secondary metabolite synthesis, with maximum total phenolic compounds (156.477±0.167 mg/g DW GAE) and flavonoids (58.307±0.179 mg/g QE) at 8 and 10 mg/L CuO NPs, respectively. Antioxidant enzyme analysis revealed that cotyledon-derived callus exhibited peak activities at specific CuO NP concentrations: superoxide dismutase (84.5±0.254% inhibition) and glutathione reductase (0.75±0.006% inhibition) at 8 mg/L; peroxidase (3.137±0.009 U), catalase (77.35±0.152 U), and ascorbate peroxidase (0.43±0.006 mM/mg FW) at 10 mg/L. HPLC analysis confirmed the novel presence of lupeol, an anticancer compound, in regenerated roots. These findings demonstrate the potential of CuO NPs for enhancing therapeutic metabolite production in A. maurorum tissue culture while suggesting optimal concentration ranges (8-10 mg/L) for maximum benefits. Further research is necessary to elucidate the molecular mechanisms governing nanoparticle-plant interactions and to address potential health implications.

Keywords: Alhagi maurorum; Antioxidant enzymes; Copper oxide nanoparticles; Lupeol; Plant tissue culture; Secondary metabolites.