Phytochemical Profile and Antioxidant Properties of Italian Green Tea, a New High Quality Niche Product

Molecular Mechanisms Underlying the Therapeutic Potential of Plant-Based α-Amylase Inhibitors for Hyperglycemic Control in Diabetes

BACKGROUND

Diabetes mellitus (DM), arising from pancreatic β-cell dysfunction and disrupted alpha-amylase secretion, manifests as hyperglycemia. Synthetic inhibitors of alphaamylase like acarbose manage glucose but pose adverse effects, prompting interest in plantderived alternatives rich in antioxidants and anti-inflammatory properties.

OBJECTIVE

The current review investigates plant-based alpha-amylase inhibitors, exploring their potential therapeutic roles in managing DM. Focusing on their ability to modulate postprandial hyperglycemia by regulating alpha-amylase secretion, it assesses their efficacy, health benefits, and implications for diabetes treatment.

METHODS

This review examines plant-derived alpha-amylase inhibitors as prospective diabetic mellitus treatments using PubMed, Google Scholar, and Scopus data.

RESULTS

Plant-derived inhibitors, including A. deliciosa, B. egyptiaca, and N. nucifera, exhibit anti-inflammatory and antioxidant properties, effectively reducing alpha-amylase levels in diabetic conditions. Such alpha-amylase inhibitors showed promising alternative treatment in managing diabetes with reduced adverse effects.

CONCLUSION

The current literature concludes that plant-derived alpha-amylase inhibitors present viable therapeutic avenues for diabetes management by modulating alpha-amylase secretion by regulating inflammatory, oxidative stress, and apoptotic mechanisms involved in the pathogenesis of diabetes. Further investigation into their formulations and clinical efficacy may reveal their more comprehensive diabetes therapeutic significance, emphasizing their potential impact on glucose regulation and overall health.

Phytochemical Profiles and Biological Activities of Five Wild Camellia Species from Ta Dung, Vietnam

The C. luuana Orel & Curry (TD3), C. furfuracea (Merr.) Cohen-Stuard (TD4), C. bidoupensis Truong, Luong & Tran (TD6), C. sinensis (L.) Kuntze (TD7), and C. kissii var. spp (TD8), have been traditionally used as a health-promoting beverage by local people in Ta Dung, Dak Nong. Despite their potential health benefits, further scientific data on biological and phytochemical properties of these plants is needed. To address this issue, this study was conducted to investigate phytochemical and biological properties of five Camellia species extracts, using DPPH, ABTS radical scavenging, copper chelating (Cu-chelator), and tyrosinase inhibition (TI), α-amylase (Al-AI), and α-glucosidase (Al-GI) analyses. As results, ten compounds were identified using UPLC method, in which catechins (mainly EGCG and catechin (Cat)), were the most prevalent, and followed by chlorogenic acid (ChlA), quercitrin (Querci), rutin, and quercetin (Querce). Additionally, multiple factor analysis (MFA) also revealed that TD7, TD3, and TD4 containing high TPC, TFC, high concentrations of EGCG, ChlA, and caffeine were responsible for their high DPPH, ABTS radical scavenging activities, as well asTI, Al-AI and Al-GI. Furthemore, TD6 and TD8, possessing elevated levels of Apig, Querci, Rutin, Querce, Cat, and EA, exhibited a high Cu-chelator property, but a weak enzyme inhibition. From all above-mentioned results, the antioxidative and enzyme inhibitory potentials of Camellia species extracts collected in Dak Nong province in Vietnam were scientifically demonstrated paving a pathway to develop health supplement in further studies.

Effects of brewing water on the volatile composition of tea infusions

There is a huge demand for brewing water in tea consumption, and the sensory flavor of tea infusion is significantly affected by the water used for brewing. To investigate the impact of brewing water on the aroma of tea infusions made from Camelia senensis, the three tea infusions of green, oolong and black tea brewed by six different drinking waters were analyzed by sensory evaluation, solid-phase microextraction, gas chromatography-mass spectrometry, and chemometrics. Brewing water with high pH values (>8.10) and high TDS content (>140 ppm) resulted in a lower overall aroma acceptability for tea infusion, where HCO3-, Ca2+ and Mg2+ were key influencing ions. A total of 86, 106, and 131 volatiles were identified in green, oolong and black tea infusions, respectively, which were strongly influenced by six different brands of waters. Decanal, dimethyl sulfide, β-ionone and linalool were potent volatiles in tea aroma changes caused by brewing water.

Comparative Analysis of Hot and Cold Brews from Single-Estate Teas (Camellia sinensis) Grown across Europe: An Emerging Specialty Product

Tea is grown around the world under extremely diverse geographic and climatic conditions, namely, in China, India, the Far East and Africa. However, recently, growing tea also appears to be feasible in many regions of Europe, from where high-quality, chemical-free, organic, single-estate teas have been obtained. Hence, the aim of this study was to characterize the health-promoting properties in terms of the antioxidant capacity of traditional hot brews as well as cold brews of black, green and white teas produced across the European territory using a panel of antioxidant assays. Total polyphenol/flavonoid contents and metal chelating activity were also determined. For differentiating the characteristics of the different tea brews, ultraviolet-visible (UV-Vis) spectroscopy and ultra-high performance liquid chromatography coupled with high-resolution mass spectrometry were employed. Overall, our findings demonstrate for the first time that teas grown in Europe are good quality teas that are endowed with levels of health-promoting polyphenols and flavonoids and that have an antioxidant capacity similar to those grown in other parts of the world. This research is a vital contribution to the characterization of European teas, providing essential and important information for both European tea growers and consumers, and could be of guidance and support for the selection of teas grown in the old continent, along with having the best brewing conditions for maximizing the health benefits of tea.

Effect of Extraction Period on Total Phenolics, Total Flavonoids, and Antioxidant Capacity of Ugandan Camellia sinensis (L) Kuntze, Black Primary Grades and Green Tea

Introduction. Globally, the consumption and production of tea are on the rise because of its beneficial constituents. Scarce literature exists on the effects of extraction periods on the contents of the biologically important and protective phytochemicals such as phenolics, flavonoids, and antioxidants in locally produced teas in Uganda. Aim. This study determined the effects of extraction periods on the aqueous total phenolic content (TPC) of local Camella sinensis, black primary grades and green tea, and their ecological differences, their total flavonoid content (TFC), and antioxidant capacities (AOC). Methods. Samples of local tea were collected from Kigezi, Ankole, and Buganda regions, and those of green tea were purchased from a local supermarket in Uganda. Four- and 40-minute infusions were separately prepared for each sample. Total phenolic and flavonoid contents were determined using the Folin–Ciocalteu and aluminium chloride methods using garlic acid and quercetin as standards, respectively. Antioxidant content was determined using 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging and ferric reducing assay power (FRAP) methods, using ascorbic acid as the standard. Results. Green tea had the highest total phenolic content both with four-minute (9.50 ± 0.25 mgGAE/g) and 40-minute (25.81 ± 1.13 mgGAE/g) extractions, followed by D1 (4.14 ± 0.33 mgGAE/g) at four minutes and PF (23.60 ± 2.37 mgGAE/g) at 40 minutes. Regionally, Kigezi (4.71 ± 0.09 and 22.13 ± 0.85 mgGAE/g) at four and 40 minutes, respectively, gave the highest TPC. In TFC, tea from Buganda (4,371 ± 0.00 μgQE/g) was the highest. In DPPH and FRAP, GT (93.82 ± 0.03%, 39.04 ± 0.02 AAEμg/mL) was the best, followed by Buganda tea (88.71 ± 0.03%, 36.99 ± 0.01 AAEµg/mL), respectively. Conclusion. Longer extraction periods increase TPC in all teas. Green tea generates approximately twice the TPC generated by black tea in four-minute infusions. Green tea gives higher TPC, DPPH, and FRAP but less TFC than some black teas and is perhaps the best in terms of protection against oxidative damage to the body.

Antidiabetic Actions of Ethanol Extract of Camellia sinensis Leaf Ameliorates Insulin Secretion, Inhibits the DPP-IV Enzyme, Improves Glucose Tolerance, and Increases Active GLP-1 (7-36) Levels in High-Fat-Diet-Fed Rats

Camellia sinensis (green tea) is used in traditional medicine to treat a wide range of ailments. In the present study, the insulin-releasing and glucose-lowering effects of the ethanol extract of Camellia sinensis (EECS), along with molecular mechanism/s of action, were investigated in vitro and in vivo. The insulin secretion was measured using clonal pancreatic BRIN BD11 β cells, and mouse islets. In vitro models examined the additional glucose-lowering properties of EECS, and 3T3L1 adipocytes were used to assess glucose uptake and insulin action. Non-toxic doses of EECS increased insulin secretion in a concentration-dependent manner, and this regulatory effect was similar to that of glucagon-like peptide 1 (GLP-1). The insulin release was further enhanced when combined with isobutylmethylxanthine (IBMX), tolbutamide or 30 mM KCl, but was decreased in the presence of verapamil, diazoxide and Ca²⁺ chelation. EECS also depolarized the β-cell membrane and elevated intracellular Ca²⁺, suggesting the involvement of a K_ATP-dependent pathway. Furthermore, EECS increased glucose uptake and insulin action in 3T3-L1 cells and inhibited dipeptidyl peptidase IV (DPP-IV) enzyme activity, starch digestion and protein glycation in vitro. Oral administration of EECS improved glucose tolerance and plasma insulin as well as inhibited plasma DPP-IV and increased active GLP-1 (7-36) levels in high-fat-diet-fed rats. Flavonoids and other phytochemicals present in EECS could be responsible for these effects. Further research on the mechanism of action of EECS compounds could lead to the development of cost-effective treatments for type 2 diabetes.

Tannic Acid and Tea Prevents the Accumulation of Lead and Cadmium in the Lungs, Heart and Brain of Adolescent Male Wistar Rats—Possible Therapeutic Option

The protective effect of tannic acid and tea solutions on the lungs, hearts and brains of adolescent Wistar rats exposed to Pb and Cd was studied. Metals were administered with feed (7 mg Cd and 50 mg Pb/kg). Two experiments were carried. Experiment 1 aimed to determine the level of tannic acid (TA), most effectively reducing the adverse impact of Pb and Cd on the organs of adolescent rats (aged 5 weeks, weighing 169.3 ± 14.7 g) during combined exposure. TA was administered with drink (0, 0.5, 1, 1.5, 2 or 2.5% solutions). In Experiment 2, adolescent rats (aged 6 weeks, weighing 210.6 ± 12.1 g) received an aqueous solutions of black, green, red or white teas. TA and teas had a positive effect on reducing the accumulation of Cd in the organs. The results obtained suggest that long-term continuing administration of TA increases its effectiveness as a chelator for Pb. A 2% TA and white tea solution proved to be the most effective. In the analyzed tissues, increased activity of SOD and CAT was recorded as a result of the use of the TA and teas; thus, they can efficiently prevent the prooxidant effect of toxic metals.

Pilot-scale extraction of polyphenols from spent black tea by semi-continuous subcritical solvent extraction

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Subcritical solvent extraction is a novel method to recover polyphenols from spent black tea at pilot-scale.

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After hot water extraction, non-extractable polyphenols were found in spent black tea.

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Subcritical solvent extraction recovered the non-extractable polyphenols from spent black tea.

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Water–ethanol mixture at hot-pressurised conditions promoted the recovery of non-extractable polyphenols.

Spent black tea (SBT) is a residue from tea beverage production and considered as a potential source of active polyphenols. This study aimed to develop a pilot-scale process on semi-continuous subcritical solvent extraction (SSE) of polyphenols from SBT by exploiting the lab-scale knowledge. Treatment of SBT with ethanol–water (50% w/w) as solvent at 125 °C and 0.3 MPa achieved a significantly higher yield of polyphenols (80.82 g gallic acid equivalents/kg black tea) with antioxidant activity (64.20 g gallic acid equivalents/kg black tea), compared to hot water extraction (HWE). SSE increased the soluble matter content in extracts than HWE. Based on the results of LC-MS, theaflavin-3,3′-digallate was the most abundant polyphenol from a total of 12 compounds to be extracted by SBT with 50% ethanol. The results suggested that SSE can be used as a scale-up extraction method to recover polyphenols from SBT.

Nutritional and Antioxidant Value of Horticulturae Products

The recent growing interest towards the nutraceutical and antioxidant value of fruit and vegetables has arisen from their content of phytochemicals, which provide desirable health benefits, beyond basic nutrition, to reduce the risk of major chronic diseases [...]

Untargeted Metabolomics Combined with Bioassay Reveals the Change in Critical Bioactive Compounds during the Processing of Qingzhuan Tea

Qingzhuan tea (QZT) is a typical Chinese dark tea that has a long-time manufacturing process. In the present study, liquid chromatography coupled with tandem mass spectrometry was used to study the chemical changes of tea samples during QZT processing. Untargeted metabolomics analysis revealed that the pile-fermentation and turnover (post-fermentation, FT) was the crucial stage in transforming the main compounds of QZT, whose contents of flavan-3-ols and flavonoids glycosides were decreased significantly. The bioactivities, including the antioxidant capacities and inhibitory effects on α-amylase and α-glucosidase, were also reduced after the FT process. It was suggested that although the QZT sensory properties improved following pile-fermentation and aging, the bioactivities remained restrained. Correlation analysis indicated that the main galloylated catechins and flavonoid glycosides were highly related to their antioxidant capacity and inhibitory effects on α-amylase and α-glucosidase.