Size-exclusion chromatography of tea tannins and intercepting potentials of peptides for the inhibition of trypsin-caseinolytic activity by tea tannins

Health Functions and Related Molecular Mechanisms of Tea Components: An Update Review

Tea is widely consumed all over the world. Generally, tea is divided into six categories: White, green, yellow, oolong, black, and dark teas, based on the fermentation degree. Tea contains abundant phytochemicals, such as polyphenols, pigments, polysaccharides, alkaloids, free amino acids, and saponins. However, the bioavailability of tea phytochemicals is relatively low. Thus, some novel technologies like nanotechnology have been developed to improve the bioavailability of tea bioactive components and consequently enhance the bioactivity. So far, many studies have demonstrated that tea shows various health functions, such as antioxidant, anti-inflammatory, immuno-regulatory, anticancer, cardiovascular-protective, anti-diabetic, anti-obesity, and hepato-protective effects. Moreover, it is also considered that drinking tea is safe to humans, since reports about the severe adverse effects of tea consumption are rare. In order to provide a better understanding of tea and its health potential, this review summarizes and discusses recent literature on the bioactive components, bioavailability, health functions, and safety issues of tea, with special attention paid to the related molecular mechanisms of tea health functions.

Novel technology for the preparation of self-assembled catechin/gelatin nanoparticles and their characterization

In this study, self-assembled tea catechin/gelatin nanoparticles were prepared by directly mixing the catechins and gelatin solutions. The mean particle sizes were almost less than 200 nm, and the zeta potential values were negatively charged. FT-IR spectral analysis indicated that hydrogen bonding between aliphatic and aromatic hydroxyl groups, respectively, on gelatin and catechins is responsible for the self-assembly of nanoparticles. Free radical (DPPH* and ABTS*(+)) scavenging assays showed that tea catechins could be protected by the nanoparticles and that the antioxidant activity of tea catechins was almost retained after three weeks of storage. The tea catechin/gelatin nanoparticles exhibited 28-41% inhibition to trypsin against the degradation of gelatin. This result suggested that the tea catechin/gelatin nanoparticles might be a useful antioxidant carrier because catechins and gelatin were, respectively, protected from oxidation and enzymatic digestion.