Pyridoxal phosphate promotes the γ-aminobutyric acid accumulation, antioxidant and anti-hypertensive activity of germinated tartary buckwheat

Abstract

γ-Aminobutyric acid (GABA), a main inhibitory neurotransmitter, is essential for various biofunctions but is inadequately synthesized by the body. Tartary buckwheat (TB), with its medicinal and culinary uses, is a potential GABA source, yet its natural GABA content is low. Herein, the application of pyridoxal phosphate (PLP) led to a significant increase in GABA content, reaching 3.82 g kg⁻¹ in PLP-treated germinated TB (PLP-GTB), which is a 9.67-fold increase compared to ungerminated TB (UTB). This elevation in GABA was associated with the activation of glutamate decarboxylase (GAD), an increase in the substrate glutamate (Glu), and the up-regulation of key gene expression (GAD, GS1/2 and GOGAT). Furthermore, PLP-GTB displayed the strongest inhibitory effect on angiotensin-converting enzyme (ACE) activity and exhibited the highest levels of DPPH and ABTS radical scavenging capabilities. Collectively, our findings present a strategy for GABA enrichment in TB, potentially enhancing its anti-hypertensive and antioxidant properties.