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The different cultivation methods affect tea quality by altering the basic metabolite profiles. In this study, the metabolome changes were investigated in green tea and shade cultured green tea (tencha) by liquid chromatography-mass spectrometry (LC-MS) and gas chromatography-mass spectrometry (GC-MS) coupled with a multivariate data set. The principal component analysis (PCA) and orthogonal projection to latent structures discriminate analysis (OPLS-DA) of green tea clearly showed higher levels of galloylquinic acid, epigallocatechin, epicatechin, succinic acid, and fructose, together with lower levels of gallocatechin, strictinin, apigenin glucosyl arabinoside, quercetin p-coumaroylglucosyl-rhamnosylgalactoside, kaempferol p-coumaroylglucosylrhamnosylgalactoside, malic acid, and pyroglutamic acid than tencha. The effects of some seasonal variations were also observed in the primary metabolite concentrations such as amino acids and organic acids. In addition, green tea showed stronger antioxidant activity than tencha in both April and July. The antioxidant activity of green tea samples were significantly correlated with their total phenol and total flavonoid contents. This present study delineates the possibility to get high umami and less astringent green teas in shade culture. It highlights the metabolomic approaches to find out the effect of cultivation methods on chemical composition in plants and the relationship with antioxidant activity.

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Liquid chromatography-mass and multivariate analyses were employed to measure the composition of pu-erh teas and to determine the general changes in the compositional patterns of pu-erh teas during postfermentation. Principle component analysis of pu-erh teas indicated two large distinct clusters in the score plot: ripened pu-erh teas and raw pu-erh teas. The raw pu-erh teas contained more antioxidant compounds compared to ripened pu-erh teas. As a result, the raw pu-erh teas showed significantly higher antioxidant activities than the ripened pu-erh teas in the 1,1-diphenyl-2-picrylhydrazyl, Trolox equivalent antioxidant capacity, and ferric reducing antioxidant power assays. In addition, raw pu-erh teas showed significantly higher NO inhibitory and cell protective activities than the ripened pu-erh teas. Significant correlations between compounds and postfermentation year were observed in raw pu-erh teas; epigallocatechin-3-gallate, epigallocatechin, epicatechin-3-gallate, and quinic acid were decreased and gallic acid was increased in a year-dependent manner. The antioxidant activity was shown to decrease as the number of antioxidant compounds in raw pu-erh tea decreased. These findings indicate that a metabolomic approach is a useful tool for analyzing manufacturing type, postfermentation year, and antioxidant activity of pu-erh tea.

Germinated soybean (GS) cultivated with Cordyceps militaris (GSC) might be a promising efficacious source of novel bioactive compounds. In this study, the metabolome changes between GS and GSC were investigated by liquid chromatography-mass spectrometry (LC-MS) and gas chromatography-mass spectrometry (GC-MS) analysis coupled with a multivariate data set. Principal component analysis (PCA) and orthogonal projection to latent structures discriminate analysis (OPLS-DA) of GSC clearly showed higher levels of soyasaponin Bd, soyasaponin Bc(II), daidzein, genistein, four isoflavones (compounds 1-4), glycerol, proline, glutamine, pentitol, fructose, inositol, octadecanoic acid, and sucrose together with lower levels of pyroglutamic acid, citric acid, histidine, and palmitic acid in GSC than in GS. The structures of compounds 1-4 were analyzed by mass and NMR spectroscopy and were determined to be novel isoflavone methyl-glycosides (daidzein 7-O-beta-d-glucoside 4''-O-methylate (1), glycitein 7-O-beta-d-glucoside 4''-O-methylate (2), genistein 7-O-beta-d-glucoside 4''-O-methylate (3), and genistein 4'-O-beta-d-glucoside 4''-O-methylate (4)). Multivariate statistical models showed that metabolic changes of GSC were maximal within 1 week after the C. militaris inoculation, consistent with the strongest antioxidant activity of GSC cultivated for 1 week. This metabolomics study provides valuable information in regard to optimizing the cultivation process for bioactive compound production and describes an efficient way to screen for novel bioactive compounds from GSC.