Monosodium glutamate-induced sesame germination enriches phenolics and enhances antioxidant capacity: activation mechanism of phenylpropanoid enzymes

The effects of monosodium glutamate (MSG) stress on phenolic accumulation and antioxidant capacity of germinating sesame seeds were investigated. MSG treatment significantly promoted germination and increased total phenolic content (by 1.5 mg/g) and total flavonoid content (by 4.7 mg/g) at 48 h compared with the control. Antioxidant activities were also markedly enhanced: DPPH radical scavenging increased by 0.8 %, ABTS scavenging by 41.2 %, hydroxyl radical scavenging by 5.2 %, and ferric reducing antioxidant power (FRAP) by 35.0 %. UPLC-MS/MS analysis revealed that MSG specifically enriched free protocatechuic acid, baicalein (1.5-fold), and apigenin (1.5-fold), as well as bound ferulic acid (1.6-fold), p-hydroxybenzoic acid (1.7-fold), and naringin. Moreover, the activities of key enzymes of the phenylpropanoid pathway were significantly activated by MSG. This study is the first to systematically demonstrate that MSG stress enhances phenolic synthesis and antioxidant capacity in sesame sprouts through the activation of the phenylpropanoid pathway. These findings support the use of MSG as a functional germination elicitor and provide a basis for developing phenolic-enriched food ingredients.