Liao Jieren, Wu Xiayuan, Xing Zhiqiang, Li Qinghui, Duan Yu, Fang Wanping, Zhu Xujun
College of Horticulture, Nanjing Agricultural University , Nanjing 210095, People's Republic of China.
College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University , Nanjing 211800, People's Republic of China.
J Agric Food Chem. 2017 Apr 12;65(14):3013-3018. doi: 10.1021/acs.jafc.7b00304. Epub 2017 Apr 4.
γ-Aminobutyric acid (GABA) is an important bioactive component of tea (Camellia sinensis) providing various health benefits. We studied GABA accumulation via the GABA shunt and polyamine degradation pathways under anoxia in tea leaves. Anoxia caused a ∼20-fold increment in GABA concentration, relative to fresh tea leaves. This increment was due to the increase of glutamate decarboxylase and diamine oxidase activities. Genes involved in GABA formation, such as CsGAD1 and CsGAD2, were significantly up-regulated by anoxia. The concentrations of putrescine and spermine, two substrates for GABA production, were also increased by anoxia. Treating tea leaves with aminoguanidine completely inhibited diamine oxidase activity during anoxia, but the concentration of GABA decreased by only ∼25%. We infer that about one-fourth of GABA formed in tea leaves under anoxia comes from the polyamine degradation pathway, opening the possibility of producing GABA tea based through the regulation of metabolism.
γ-氨基丁酸（GABA）是茶叶（茶树）的一种重要生物活性成分，具有多种健康益处。我们研究了茶叶在缺氧条件下通过GABA分流和多胺降解途径积累GABA的情况。与新鲜茶叶相比，缺氧使GABA浓度增加了约20倍。这种增加是由于谷氨酸脱羧酶和二胺氧化酶活性的提高。参与GABA形成的基因，如CsGAD1和CsGAD2，在缺氧条件下显著上调。GABA产生的两种底物腐胺和亚精胺的浓度在缺氧条件下也有所增加。用氨基胍处理茶叶在缺氧期间完全抑制了二胺氧化酶活性，但GABA浓度仅下降了约25%。我们推断，茶叶在缺氧条件下形成的GABA约四分之一来自多胺降解途径，这为通过调节代谢生产富含GABA的茶叶开辟了可能性。
