Regular, but not acute, green tea supplementation increases total antioxidant status and reduces exercise-induced oxidative stress: a systematic review

Analysis of non-volatile and volatile metabolites reveals the influence of second-drying heat transfer methods on green tea quality

•

Effect of second-drying heat-transfer modes on green tea quality was investigated.

•

Microwave second-drying (MWSD) was the optimal method for green tea aroma and color.

•

Seventeen non-volatile and eight volatile differential metabolites were identified.

•

Nonanal, trans-β-ionone, linalool, and jasmone had highest content in MWSD.

•

MWSD was beneficial to the retention of chlorophyll, theanine, and soluble sugars.

Second-drying is a key process of green tea manufacturing, however, hitherto the effect of second-drying methods on green tea quality has not been assessed. In this study, we compared the effect of three heat transfer drying methods (heat radiation, heat convection, and heat conduction) on green tea quality. Gas chromatography-tandem dual mass spectrometry was used to detect volatile compounds, while absolute quantitative methods were used to detect the non-volatile ones. We identified 45 non-volatile metabolites, 101 volatile metabolites, and 15 objective flavor indicators. Seventeen differential non-volatiles and 8 differential volatiles were screened. Microwave second-drying in heat radiation was the optimal method for green tea flavor, as it can promote the retention of chlorophyll, the degradation of flavonoid glycosides, and the enrichment of amino acids, soluble sugars, nonanal, trans-β-ionone, linalool, and jasmone. The results provide a theoretical basis and technical guidance for the precise and directional processing of high-quality green tea.

Phenolics Profile and Protective Effect on Injuried HUVEC Cells of Epicarp Extracts from Kadsura coccinea

This study evaluated the phenolics profile and the antioxidative properties of K. coccinea fruits epicarp. A total of 13 phenolic compounds (six phenolic acids, four anthocyanins, two flavonols, and one flavone) were identified by ultra performance liquid chromatography coupled with quadrupole time-of-flight tandem mass spetrometry(UPLC-QTOF-MS/MS). Two anthocyanins, cyanidin-3-xylosylrutinoside and cyanidin-3-rutinoside, comprise 30.89~74.76% and 13.90~46.17% of the total amount of anthocyanins in K. Coccinea. Cytoprotective effect results evidenced that pretreatment of Human umbilical vein endothelial cells(HUVECs) with Kadsura. coccinea fruits’ epicarp phenolic extracts at the concentrations of 50–200 µg/mL improved the cell viability after exposure to H₂O₂ significantly, and inhibited malonaldehyde(MDA) and reactive oxygen species(ROS) overproduction, as well as enhancing the content of superoxide dismutase (SOD) and glutathione Reductase (GR. This study proved that K. coccinea is a natural resource of phenolics rich with potential antioxidant ability, which may be valuable for developing nutraceuticals and dietary supplements.

Mental Performance and Sport: Caffeine and Co-consumed Bioactive Ingredients

The plant defence compound caffeine is widely consumed as a performance enhancer in a sporting context, with potential benefits expected in both physiological and psychological terms. However, although caffeine modestly but consistently improves alertness and fatigue, its effects on mental performance are largely restricted to improved attention or concentration. It has no consistent effect within other cognitive domains that are important to sporting performance, including working memory, executive function and long-term memory. Although caffeine's central nervous system effects are often attributed to blockade of the receptors for the inhibitory neuromodulator adenosine, it also inhibits a number of enzymes involved both in neurotransmission and in cellular homeostasis and signal propagation. Furthermore, it modulates the pharmacokinetics of other endogenous and exogenous bioactive molecules, in part via interactions with shared cytochrome P450 enzymes. Caffeine therefore enjoys interactive relationships with a wide range of bioactive medicinal and dietary compounds, potentially broadening, increasing, decreasing, or modulating the time course of their functional effects, or vice versa. This narrative review explores the mechanisms of action and efficacy of caffeine and the potential for combinations of caffeine and other dietary compounds to exert psychological effects in excess of those expected following caffeine alone. The review focusses on, and indeed restricted its untargeted search to, the most commonly consumed sources of caffeine: products derived from caffeine-synthesising plants that give us tea (Camellia sinensis), coffee (Coffea genus), cocoa (Theabroma cacao) and guaraná (Paullinia cupana), plus multi-component energy drinks and shots. This literature suggests relevant benefits to mental performance that exceed those associated with caffeine for multi-ingredient energy drinks/shots and several low-caffeine extracts, including high-flavanol cocoa and guarana. However, there is a general lack of research conducted in such a way as to disentangle the relative contributions of the component parts of these products.