1-1-diphenyl-2-picrylhydrazyl and gallocatechol

Advanced glycation end products (AGEs) and their important intermediate products (α-dicarbonyl compounds) that are generated by the Maillard reaction are closely related to diabetes. Our study first investigated the mechanisms of the anti-glycation effects of epicatechin (EC), (-)-epicatechin gallate (ECG), (-)-epigallocatechin (EGC), and (-)-epigallocatechin gallate (EGCG) in an alcoholic environment. The results showed that catechins played an important role in the inhibition of AGE formation, and the effect of EC was the best. Their corresponding mechanisms included total antioxidant capacity (TAOC), 1,1-diphenyl-2-picrylhydrazyl (DPPH) scavenging ability, trapping of methylglyoxal (MGO), protection of the protein structure, and inhibition of the activities of α-amylase, α-glucosidase, and β-glucosidase, which were consistent with the study of molecular docking. This study will offer a theoretical basis for the applications of different types of catechins to alcoholic beverages as natural AGE formation inhibitors.

Topics: alpha-Amylases; alpha-Glucosidases; Antioxidants; Binding Sites; Biphenyl Compounds; Catechin; Glucosidases; Glycation End Products, Advanced; Glycosylation; Molecular Docking Simulation; Picrates; Pyruvaldehyde

In the present study, we aimed to develop a novel fermented tea (NFT) product and to evaluate their in vitro antioxidant potential and chemical composition. We found that NFT contained a high level of total phenolic compounds (102.98 mg gallic acid equivalents/g extract) and exhibited diverse antioxidant activities, such as scavenging of 1,1-diphenyl-2-picryl-hydrazyl (DPPH) and hydroxyl radicals, as well as reducing power. The total catechins in NFT were comparable to those of Lipton black tea (LBT), but lower than those of Boseong green tea (BGT) or Tieguanyin oolong tea (TOT). Among all catechins tested, epigallocatechin (EGC) and epigallocatechin-3-O-gallate (EGCG) were the predominant compounds in NFT. In particular, the contents of total theaflavins (TFs), theaflavin (TF), theaflavin-3-gallate (TF3G), and theaflavin-3'-gallate (TF3'G) in NFT were significantly higher than that of BGT, TOT, or LBT. NFT had the highest level of total essential amino acid and γ-aminobutyric acid (GABA) compared with BGT, TOT and LBT. Furthermore, the sensory evaluation results showed that NFT had satisfactory color, aroma, taste, and overall acceptability scores. Our results highlight the potential usefulness of this novel fermented tea as a nutraceutical food/ingredient with special functional activities.

Topics: Antioxidants; Biflavonoids; Biphenyl Compounds; Camellia sinensis; Catechin; Color; Fermentation; Flavonoids; Gallic Acid; gamma-Aminobutyric Acid; Humans; Hydroxyl Radical; Odorants; Picrates; Taste; Tea

Potentilla fruticosa L. leaves are widely used as tea in China, with many commercial "Jinlaomei" teas available in markets. It has been confirmed to possess significant antioxidant activity than that of butylated hydroxytoluene. In this study, the synergistic effects of P. fruticosa leaves extracts (PFE) combined with green tea polyphenols (GTP) were studied to elucidate their use in combination and find specific combinations with least concentrations that enhance the antioxidant activity. Isobolographic analysis indicated that the combination of PFE and GTP demonstrated extensive synergism (22/28 of the tests showed significant synergy) with 3:1 (PFE:GTP) exhibiting the best synergistic effect. Chemical compositions and content of 7 phenolic compounds in PFE, GTP, and their mixtures were evaluated by reverse-phase-high-performance liquid chromatography. While chemical composition did not seem to change after the combination, as no new peaks appeared in the chromatogram, and no existing peaks disappeared. However, the content of (+)-catechin, (-)-epigallocatechin (EGC), and , (-)-epigallocatechin gallate (EGCG) changed. Besides, antioxidant interactions of extracts and compounds were evaluated, EGC with hyperoside exhibited the greatest synergistic effect and the combination of 3:1 exhibited the strongest synergism (DPPH γ = 0.86, ABTS γ = 1.12, FRAP γ = 1.16). Therefore, interaction of phytochemicals may be one reason for the synergistic effects in PFE + GTP, with EGC + hyperoside likely playing an important role. This report provides a theoretical basis for the concomitant use of P. fruticosa blended with GTP, which can be effectively used as a compounded tea, dietary supplements, and substituent of synthetic antioxidant.

Topics: Antioxidants; Benzothiazoles; Biphenyl Compounds; Camellia sinensis; Catechin; China; Chromatography, High Pressure Liquid; Dietary Supplements; Drug Synergism; Oxidation-Reduction; Phenols; Picrates; Plant Extracts; Plant Leaves; Polyphenols; Potentilla; Sulfonic Acids; Tea

The present study was designed to investigate the bioactive constituents of Xanthoceras sorbifolia in terms of amounts and their antioxidant, DNA scission protection, and α-glucosidase inhibitory activities. Simultaneous quantification of 10 X. sorbifolia constituents was carried out by a newly established ultra-high performance liquid chromatography-quadrupole mass spectrometry method (UHPLC-MS). The antioxidant activities were evaluated by measuring DPPH radical scavenging and DNA scission protective activities. The α-glucosidase inhibitory activities were investigated by using an assay with α-glucosidase from Bacillus Stearothermophilus and disaccharidases from mouse intestine. We found that the wood of X. sorbifolia was rich in phenolic compounds with the contents of catechin, epicatechin, myricetin, and dihydromyricetin being 0.12-0.19, 1.94-2.16, 0.77-0.91, and 6.76-7.89 mg·g(-1), respectively. The four constituents strongly scavenged DPPH radicals (with EC50 being 4.2, 3.8 and 5.7 μg·mL(-1), respectively) and remarkably protected peroxyl radical-induced DNA strand scission (92.10%, 94.66%, 75.44% and 89.95% of protection, respectively, at a concentration of 10 μmol·L(-1)). A dimeric flavan 3-ol, epigallocatechin-(4β→8, 2β→O-7)-epicatechin potently inhibited α-glucosidase with an IC50 value being as low as 1.2 μg·mL(-1). The established UHPLC-MS method could serve as a quality control tool for X. sorbifolia. In conclusion, the high contents of antioxidant and α-glucosidase inhibitory constituents in X. sorbifolia support its use as complementation of other therapeutic agents for metabolic disorders, such as diabetes and hypertension.

Topics: alpha-Glucosidases; Antioxidants; Biphenyl Compounds; Catechin; Chromatography, High Pressure Liquid; DNA; DNA Damage; Flavonoids; Glycoside Hydrolase Inhibitors; Mass Spectrometry; Picrates; Plant Extracts; Sapindaceae; Triterpenes; Wood

This study describes increases in extraction efficiency and the bioconversion of catechins after treatment with several commercial enzymes. Tannase was also used to improve the anti-radical activities of green tea extracts. Enzymatic treatment with various commercial enzymes was introduced to improve the extraction efficiency of polyphenols. The total polyphenol, flavonoid, and catechin contents and the 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity of the green tea extract treated with Viscozyme (VG) were significantly higher than those treated with other commercial enzymatic extractions (p<0.05). More than 95% of the epigallocatechingallate (EGCG) and of the epicatechingallate (ECG) was hydrolyzed to epigallocatechin (EGC) and to epicatechin (EC) in successive 20 min treatments with Viscozyme and tannase (TG). Due to its hydrolytic activity, treatment involving tannase resulted in a significant release of gallic acid (GA), EGC, and EC, leading to greater radical scavenging activities. Regarding the IC(50) values of the DPPH and 2,2-azino-di-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radicals, the green tea extract treated with TG showed values of 131.23 and 28.83 µg/mL, VG showed values of 224.70 and 32.54 µg/mL, and normal green tea extract (NG) showed values of 241.11 and 66.27 µg/mL, respectively. These results indicate that successive treatment with Viscozyme and tannase improves the extraction efficiency of polyphenols and increases radical scavenging activities.

Topics: Antioxidants; Benzothiazoles; Biphenyl Compounds; Carboxylic Ester Hydrolases; Catechin; Cellulases; Endo-1,4-beta Xylanases; Fungal Proteins; Gallic Acid; Glycoside Hydrolases; Picrates; Plant Extracts; Plant Leaves; Sulfonic Acids; Tea; Thiazoles