Metabolite profiling indicates comparative effects of magnesium oxide nanoparticle vs. its bulk priming on lead...

Lead (Pb) toxicity threatens the nutritional quality of edible sprouts. Whether MgO nanoparticles (MgO-NP) outperform bulk MgO in protecting mungbean sprouts against Pb toxicity remains unclear. Pb stress reduced seed germination, and sprout growth. A dose-response experiment showed that increasing MgO-bulk up to 600 mg L^-1 did not reproduce the MgO-NP response, with higher bulk concentrations proving phytotoxic. MgO-NP priming at 100 mg L^-1 improved germination (93% vs. 87% with MgO-bulk) and reduced total Pb accumulation (62.5% vs. 36.4%) and bioaccessible Pb by 76.3% while maintaining higher Mg bioavailability (21% vs. 18% with MgO bulk) in edible tissues. MgO-NP priming further enhanced T-AOC (138% vs. 104%), DPPH scavenging activity (61% vs. 50%), total flavonoids (102% vs. 85%), and total phenolics (63% vs. 51%) relative to Pb stress, associated with enrichment of phenylpropanoid and flavonoid pathways. These findings demonstrate that MgO-NP outperforms MgO-bulk in mitigating Pb toxicity while improving nutritional quality.