Comparative evaluation for phytochemical composition and regulation of blood glucose, hepatic oxidative stress and insulin resistance in mice and HepG2 models of four typical Chinese dark teas.

BACKGROUND: Dark tea, comprising one of the six major teas, has many biological activities, which originate from their active substrates, such as polyphenols, polysaccharides, and so on. The hypoglycemic effect is one of its most prominent activities, although less is known about their evaluation and potential role in the hypoglycemic mechanism. RESULTS: In the present study, we separately analyzed the phytochemical composition, glycosidase inhibition and free radical scavenging activities, and hypoglycemic activity in type 2 diabetes mellitus mice, as well as the alleviation of insulin resistance in HepG2 cells of four dark tea aqueous extracts. The results showed that the phytochemical composition of dark tea aqueous extracts was significantly different, and they all had good glycosidase inhibition and free radical scavenging activities, in vivo hypoglycemic activity and alleviation of insulin resistance, and could also activate the phosphatidylinositol 3-kinase-Akt-perixisome proliferation-activated receptor cascade signaling pathway to regulate glucose and lipid metabolism, change the key enzyme activities related to glucose metabolism and antioxidant activity, and reduce oxidative stress and inflammatory factor levels. Among them, Liubao brick tea (LBT) and Pu-erh tea (PET) possessed better glycosidase inhibitory activity, in vivo hypoglycemic activity and improved insulin resistance activity, whereas Qingzhuan brick tea and Fuzhuan brick tea had better free radical scavenging activity, which may be explained by their distinct phytochemical compositions, such as tea proteins, polysaccharides, polyphenols, catechins, and tea pigments and some elements. CONCLUSION: Dark tea is a highly attractive candidate for developing antidiabetic food, LBT and PET may be good natural sources of agricultural products with anti-diabetic effects. © 2021 Society of Chemical Industry.

Effects of extraction methods on physicochemical properties and hypoglycemic activities of polysaccharides from coarse green tea.

Coarse tea is made of mature tea plant (Camellia sinensis L.) shoots and is generally discarded as a worthless crop product, but has been proved an excellent material for the treatment of diabetes. This study aims to evaluate the effects of the extraction techniques WE (water extraction), UAE (ultrasound-assisted extraction), MAE (microwave-assisted extraction), and EE (enzyme extraction) on the physicochemical properties and antidiabetic activities of polysaccharides from coarse tea (CTPSs). The results showed that all four CTPSs had homogeneity in the monosaccharide types and similar IR (Infrared spectroscopy) characteristic absorption peaks, but differed in monosaccharide proportion and molecular weight distribution. Compared with the other three extraction techniques, CCTPS extracted by EE had the lowest protein content, the highest total sugar content of 71.83% and a polysaccharide yield of 4.52%. In addition, EE-CTPS had the best hypoglycemic activity that was better than ordinary green tea polysaccharides, the α-glucosidase and α-amylase inhibitory activities of EE-CTPS were highest in the range of 2-10 mg/mL compared with the other three CTPSs, which may be related to its smaller molecular weight and porous structure. The results suggested that the EE method was a good way to extract polysaccharides from coarse tea for food and pharmaceutical production.

Comparative analysis of existence form for selenium and structural characteristics in artificial selenium-enriched and synthetic selenized green tea polysaccharides.

In recent years, selenium-enriched polysaccharides (Se-PS) have been paid more and more attention, and the activity of many Se-PSs has been studied but little on their structure. This study aimed to investigate the activity, structural characterization and present forms of selenium in two different artificial selenium-enriched tea polysaccharides (Se-TPS). The physicochemical analysis showed that both CSe-tps1 and ASe-tps1 were acidic heteropolysaccharides with different monosaccharide composition, molar ratio, and selenium content. Structural investigations including FT-IR, Raman spectra and 1D, 2D NMR analysis revealed that selenium in CSe-tps1 replaced the hydroxyl group at the C-6 position in the polysaccharide with the form of selenyl ester, while most of the selenium in ASe-tps1 replaced the hydroxyl group at the C-1 and C-6 position in the form of the SeH bond on the branch of the polysaccharide. Besides, a series of studies on the structural characteristics of the Congo red test, I2-KI reaction, FESEM, DSC, and XRD analysis showed that the two artificial Se-TPSs had a triple helix structure and more branches. However, there were significant differences in crystal morphology, apparent morphology, heat release ability, and the α-glucosidase inhibition activity. These results indicated that the difference in artificial selenization methods not only made the polysaccharide exhibit different structural characteristics and the hypoglycemic activity, but also had a significant effect on the form of selenium in polysaccharides.

Comparison and structural characterization of polysaccharides from natural and artificial Se-enriched green tea.

Se-enriched green tea has been widely used as a functional food and disease prevention. In this study, two kinds of homogeneous polysaccharides namely ASe-TPS2 and NSe-TPS2 were obtained from artificial and natural Se-enriched teas with the molecular weights of 6.73 × 103 Da and 2.44 × 105 Da. The structures of ASe-TPS2 and NSe-TPS2 were characterized by monosaccharide composition analysis, partial acid hydrolysis, methylation, FT-IR spectroscopy, NMR spectroscopy, SEM and TGA analysis. It showed that ASe-TPS2 and NSe-TPS2 were acidic polysaccharides containing high amount of uronic acid. The structure of the ASe-TPS2 was mainly composed of ß­D­(1 → 3)­Glcp, α­D­(1 → 4)­GalpA, (1 → 4)­Glcp, α­L­(1 → 2)­Rhap and α­D­(1 → 4)­GalpA, and the non-reducing ends were mainly composed of Araf and Xylp. However, the NSe-TPS2 was mainly composed of ß­D-(1 → 4)­Glcp and α­D­(1 → 4)-GalpA, and the branches were mainly composed of ß­L­(1 → 2)­Araf, α­D­(1 → 3)­Galp and ß­L­(1 → 2)­Rhap whereas the non-reducing ends were mainly composed of Glcp and Galp residues. These results suggested that the distinction of selenylation methods could present different polysaccharide chain structures.

Therapeutic effect of Pseudomonas aeruginosa phage YH30 on mink hemorrhagic pneumonia.

Hemorrhagic pneumonia caused by Pseudomonas aeruginosa remains one of the most costly infectious diseases among farmed mink and commonly leads to large economic losses during mink production. The objective of this study was to investigate the potential of using phages as a therapy against hemorrhagic pneumonia in mink. A broad-host-range phage from the Podoviridae family, YH30, was isolated using the mink-originating P. aeruginosa (serotype G) D7 strain as a host. The genome of YH30 was 72,192bp (54.92% G+C), contained 86 open reading frames and lacked regions encoding known virulence factors, integration-related proteins or antibiotic resistance determinants. These characteristics make YH30 eligible for use in phage therapy. The results of a curative treatment experiment demonstrated that a single intranasal administration of YH30 was sufficient to cure hemorrhagic pneumonia in mink. The mean colony count of P. aeruginosa in the blood and lung of YH30-protected mink was less than 10(3) CFU/mL (g) within 24h of bacterial challenge and ultimately became undetectable, whereas that in unprotected mink reached more than 10(8) CFU/mL (g). Additionally, YH30 dramatically improved the pathological manifestations of lung injury in mink with hemorrhagic pneumonia. Our work demonstrates the potential of phages to treat P. aeruginosa-caused hemorrhagic pneumonia in mink.

[Clinical study of SS syrup in treating xerostomia].

OBJECTIVE: To compare the clinical efficacy of SS syrup, a Chinese medicine, and pilocarpine in treating patients with xerostomia. METHODS: Thirty-eight patients conformed to the inclusive criteria were randomly divided into two groups, they were treated by SS syrup (SS group) and pilocarpine (control group) respectively. Three indexes, i.e. questionnaire of dryness in mouth, total static salivary flow and dynamic salivary flow, before treatment, 1, 2 and 4 weeks after treatment were recorded and statistically analyzed. RESULTS: Significant difference was shown in the 3 indexes in the SS group between before treatment and 1, 2 and 4 weeks after treatment (P < 0.05), while in the control group significant difference was shown between before treatment and 1, 2, and 4 weeks after treatment except for total dynamic salivary flow after I weck treatment (P < 0.05). CONCLUSION: SS syrup, which has no adverse reaction, no contraindication, could be taken chronically, and shows good efficacy in improving the symptoms of xerostomia.