Nontargeted and targeted metabolomics analysis for evaluating the effect of "golden flora" amount on the sensory quality, metabolites, and the alpha-amylase and lipase inhibitory activities of Fu brick tea.

To investigate the effects of "golden flora" amount on the sensory quality, metabolites and bioactivities of Fu brick tea (FBT), FBT samples with different "golden flora" amounts were prepared from the same materials by adjusting the water content before pressing. With the increase of "golden flora" in samples, the tea liquor color changed from yellow to orange red and the astringent taste gradually diminished. Targeted analysis demonstrated that (-)-epigallocatechin gallate, (-)-epicatechin gallate, and most amino acids gradually decreased as the increase of "golden flora". Seventy differential metabolites were identified by untargeted analysis. Among them, sixteen compounds including two Fuzhuanins and four EPSFs were positively correlated with "golden flora" amount (P < 0.05). The FBT samples with "golden flora" exhibited significantly higher inhibitory potency on α-amylase and lipase than the samples without "golden flora". Our results provide a theoretical basis of guiding FBT processing based on desired sensory quality and metabolites.

Isolation and Functional Characterization of Multiple NADPH-Cytochrome P450 Reductase Genes from Camellia sinensis in View of Catechin Biosynthesis.

Catechins are critical constituents for the sensory quality and health-promoting benefits of tea. Cytochrome P450 monooxygenases are required for catechin biosynthesis and are dependent on NADPH-cytochrome P450 reductases (CPRs) to provide reducing equivalents for their activities. However, CPRs have not been identified in tea, and their relationship to catechin accumulation also remains unknown. Thus, three CsCPR genes were identified in this study, all of which had five CPR-related conserved domains and were targeted to the endoplasmic reticulum. These three recombinant CsCPR proteins could reduce cytochrome c using NADPH as an electron donor. Heterologous co-expression in yeast demonstrated that all the three CsCPRs could support the enzyme activities of CsC4H and CsF3'H. Correlation analysis indicated that the expression level of CsCPR1 (or CsCPR2 or CsCPR3) was positively correlated with 3',4',5'-catechin (or total catechins) content. Our results indicate that the CsCPRs are involved in the biosynthesis of catechins in tea leaves.