Active Components, Antioxidant, Inhibition on Metabolic Syndrome Related Enzymes, and Monthly Variations in Mature Leaf Hawk Tea

Abstract

Hawk tea is a rich and edible resource, traditionally used as a beverage in South China. This drink has many pharmacologic effects, such as acting as an antioxidant and reducing blood sugar and lipids. The objective of this work was to explore the active compound contents, bioactivities and their monthly changes, and optimize the harvest time. In the present study, Hawk tea from each month in 2017 was collected and extracted with 70% (v/v) ethanol. The contents of the total flavonoids and total phenols were determined using the colorimetric method. We determined the contents of seven characteristic active substances—hyperin, isoquercitrin, trifolin, quercitrin, astragalin, quercetin, and kaempferol—using high-performance liquid chromatography. The crude extract was tested for its antioxidant and inhibitory properties on enzymes involved in metabolic syndrome. Specifically, 2,2-diphenyl-1-picrylhydrazyl, 2,2′-azino-bis (3-ethylbenzothiazoline-6-sulphonic acid), ferric-reducing power assay, and the inhibition capacity test on α-glucosidase and lipase were conducted to determine the antioxidant effect in vitro, as well as the reduction of blood sugar and lipids. Monthly variations in activities and components were determined by numeric analysis and comparison. Correlation analysis revealed that antioxidant effects are significantly correlated with the total flavonoids. The hierarchical cluster analysis of bioactivities and their contents indicates that October and November are the best harvesting months, which differs with the habitual collection of Hawk tea.

Antitumor Potential and Structure Characterization of Polysaccharides From Lagotis brevituba Maxim in the Tibetan Plateau

“…The reducing power was determined using the method described previously ( 13 ). The positive control was BHT.…”

“…The DPPH radical-scavenging activities of LBMP-2 were determined using the method described previously ( 13 ). BHT was used as the positive control.…”

Mechanistic Insights into the Inhibitory Activities of Chemical Constituents from the Fruits ofTerminalia boiviniion α‐Glucosidase

“…The lignans and phenolic compounds were assayed for inhibition of pancreatic lipase by a previously described method [51] with minor modifications. In this colorimetric assay, a lipase solution (0.21 mg/mL prepared in 0.1 M phosphate buffer (pH 7.0)) was pre‐incubated with various compound solutions (0–500 μM in DMSO) on ice.…”

Effect of storage time on biochemical characteristics and antioxidant activity of hawk tea (Litsea coreana) processed by boiling water fixation

“…A large number of studies have shown that polyphenols and flavonoids have strong antioxidant properties (Chen et al, 2020;Ji et al, 2020). It was found that the polysaccharide and flavonoid of hawk tea had good antioxidant activity (Chen et al, 2019;Tan et al, 2016;Xiao, et al 2017). However, it is unclear which kind of substance has a significant correlation with the antioxidant activity of hawk tea.…”

“…As a traditional heat‐relieving beverage in the hot and humid areas of Chishui River Basin, China, hawk tea can relieve heat and thirst and alleviate distention (Xi et al., 2015). It also has antidiabetic (Lu et al., 2010), hypolipidemic (Zhao, 2013), antioxidant (Chen et al., 2019), antimicrobial (Yu et al, 2016), and hepatoprotective activity (Jia and Yuan, 2019) as well as anti‐inflammatory properties (Liu et al., 2020).…”