Comparative studies on the physicochemical and antioxidant properties of different tea extracts

Isolation and antioxidant characterization of theaflavin for neuroprotective effect in mice model

The mandate of the current investigation was to elucidate the therapeutic and antioxidant perspective of black tea. Purposely, black tea compositional analysis followed by polyphenol extraction and antioxidant characterization was done. Moreover, the theaflavin from black tea extract was also isolated through the solvent partition method. Lastly, the neuroprotective effect of isolated theaflavin was assessed through a bio-efficacy trial. The outcomes delineated that black tea showed promising nutritional composition with special reference to protein and fiber. Among the extraction solvent, ethanol performed better as compared to methanol and water likewise, higher extraction was noticed at 60 min followed by 90 and 30 min. All the extracts indicated antioxidant activity reflected through significant DPPH, TPC, FRAP, and beta carotene as-69.13 ± 3.00, 1148.92 ± 14.01, 752.44 ± 10.30, and 65.74 ± 3.28, respectively. However, isolated theaflavin exhibited higher antioxidant capacity as-737.74 ± 12.55, 82.60 ± 2.33, and 853.77 ± 9.55, for TPC, DPPH, and FRAP, respectively, as compared to extracts. In 15 days' efficacy was physically induced with sciatic nerve injury h sciatic nerve injury physically and treated with isolated theaflavin. A total of 12 healthy albino mice were randomly assigned to either the control (n = 6) or theaflavin (5.0 mg/kg (n = 6)) groups. In these groups, behavioral tests were used to assess and compare enhanced functional recovery as well as skeletal muscle mass measurement. Serum samples included oxidative stress markers. In theaflavin leaves, behavioral tests revealed a statistically significant (p < .001) improvement in sensorimotor function restoration, muscle mass restoration, a substantial decrease in TOS, a significant increase in TAC, and enhanced antioxidative enzyme activity. Considering the above-mentioned therapeutic perspectives of theaflavin, the current research was planned to optimize the isolation of theaflavin from black tea and probed for their neuroprotective effect in mice models.

Hormonal regulation of health-promoting compounds in tea (Camellia sinensis L.)

Tea is the most frequently consumed natural beverage across the world produced with the young leaves and shoots of the evergreen perennial plant Camellia sinensis (L.) O. Kuntze. The expanding global appeal of tea is partly attributed to its health-promoting benefits such as anti-inflammation, anti-cancer, anti-allergy, anti-hypertension, anti-obesity, and anti- SARS-CoV-2 activity. The many advantages of healthy tea intake are linked to its bioactive substances such as tea polyphenols, flavonoids (catechins), amino acids (theanine), alkaloids (caffeine), anthocyanins, proanthocyanidins, etc. that are produced through secondary metabolic pathways. Phytohormones regulate secondary metabolite biosynthesis in a variety of plants, including tea. There is a strong hormonal response in the biosynthesis of polyphenols, catechins, theanine and caffeine in tea under control and perturbed environmental conditions. In addition to the impact of preharvest plant hormone manipulation on green tea quality, changes in hormones of postharvest tea also regulate quality-related metabolites in tea. In this review, we discuss the health benefits of major tea constituents and the role of various plant hormones in improving the endogenous levels of these compounds for human health benefits. The fact that the ratio of tea polyphenols to amino acids and the concentrations of tea components are changed by environmental conditions, most notably by climate change-associated variables, the selection and usage of optimal hormone combinations may aid in sustaining tea quality, and thus can be beneficial to both consumers and producers.

Determination of pesticide residues in rooibos (Aspalathus linearis) teas in South Africa

An efficient gas chromatography-mass spectrometry approach was used in this study to quantify 13 pesticide residues in rooibos teas purchased from registered retail outlets in South Africa between November 2019 and April 2020. A QuEChERS (Quick, easy, cheap, effective, rugged, and safe) procedure was used to extract pesticides using 7.5 mg of graphitized carbon black (GCB), 50 mg of primary secondary amine (PSA), and 150 mg of anhydrous MgSO4. In order to compensate for the matrix effect, matrix matched calibration curves ranging from 10 µg/kg-500 µg/kg were applied for accurate quantification. For validation purposes, accuracy tests were conducted using a blank tea sample spiked with pesticide standards at two different concentrations (10 and 100 μg/kg). Most of the analytes were recovered within acceptable recovery ranges (72-106%), with a relative standard deviation of less than 20%. The limits of quantification were low, all falling below 10 μg/kg which meets the maximum residue limits (MRLs). The validated method was used to analyze 100 tea samples, and among the pesticides analyzed, deltamethrin and lambda-cyhalothrin were detected in only one samples at a concentration (92.11 and 66.41 μg/kg, respectively) below the MRLs stipulated by the European Union. The level of pesticides that are commonly used in tea should be checked often.

A novel and sensitive method for determining vitamin B3 and B7 by pre-column derivatization and high-performance liquid chromatography method with fluorescence detection

A new labeling reagent for vitamin analysis, 2-amino-10-ethyl acridine ketone (AEAO), has been synthesized and successfully applied to the analysis of vitamin B3 and vitamin B7 in different tea samples. The reaction of AEAO with vitamins could proceed easily and quickly in the presence of 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide hydrochloride (EDC) as condensing reagent within 45 min. The derivatives exhibited excellent fluorescence property with excitation and emission wavelengths of 290 nm and 430 nm, respectively. Response surface methodology (RSM) was applied to the optimization of pre-column derivatization. Solid phase extraction with HLB cartridges was used for the extraction and purification of water-soluble vitamins in tea samples. The LODs for vitamin B3 and vitamin B7 were 2.56 and 2.22 ng mL^-1, respectively. The proposed method was successfully applied to the analysis of vitamin B3 and vitamin B7 in different tea samples. The study provided a highly sensitive method for accurate analysis of trace vitamins from natural products.

On-line high-performance liquid chromatography coupled with biochemical detection method for screening of α-glucosidase inhibitors in green tea

An on-line high-performance liquid chromatography-biochemical detection (HPLC-BCD) method, in which compounds separated by HPLC were on-line reacted with enzyme and substrate solutions delivered by flow injection and the enzyme inhibition signal was collected by UV detection, was developed to rapidly screen α-glucosidase inhibitors from green tea extracts in this study. The chromatographic fingerprints and enzyme inhibition profiles of the different brands of green tea could be simultaneously detected by the on-line HPLC-BCD method. Enzyme inhibition profiles were detected by the UV detector at 415 nm based on the reaction of α-glucosidase and p-nitrophenyl α-d-glucopyranoside (PNPG). PNPG (1.25 mm), α-glucosidase (0.4 U/mL) and the flow rate 0.07 mL/min were applied as optimized parameters to detect α-glucosidase inhibitors in green tea. Four components in green tea showed α-glucosidase inhibition action and three of them were identified as HHDP-galloyl glucose, (-)-epigallocatechin-3-gallate and (-)-epicatechin-3-gallate by HPLC-fourier-transform mass spectrometry (HPLC-FTMS). Two brands of green tea derived from Mengding and Enshi mountainous areas might be superior to the other samples in the prevention and treatment of diabetes owing to their stronger activities of enzyme inhibitors. The proposed on-line HPLC-BCD method could be used to rapidly identify the potential enzyme inhibitors in complex matrixes.

The identification and evaluation of two different color variations of tea

BACKGROUND

The tea plant, Camellia sinensis (L.) O. Kuntz, is a perennial woody plant widely cultivated for the production of a popular non-alcoholic beverage. To rapidly identify and evaluate two different color tea varieties (yellowish and purplish), the main phenotypic traits and quality components were tested in the present study. The metabolic profiles of tea shoots and leaves were also analyzed using liquid chromatography-tandem mass spectrometry.

RESULTS

The yellowish variation had a higher active level with respect to metabolism of catechins, and the contents of luteolin and kaempferol 3-α-d-glucoside were much higher compared to in the other variations. However, the purplish variation had a low content of theanine and a high content of caffeine. The contents of quercetin and kaempferol 3-α-d-galactoside were highest in purplish leaves. Moreover, the yellowish variation had the highest total quality scores for green teas and black teas, whereas the purplish variation had the highest scores for oolong teas.

CONCLUSION

Both the yellowish variation and the purplish variation represent excellent breeding materials and are worthy of breeding as new tea cultivars. The yellowish variation is more suitable for making high-grade green teas or black teas, whereas the purplish variation is suitable for producing fine quality oolong teas. © 2016 Society of Chemical Industry.

Epigallocatechin-3-gallate (EGCG) inhibits imiquimod-induced psoriasis-like inflammation of BALB/c mice

Background

Psoriasis is a chronic inflammatory immune disease with undefined pathogenesis. It is associated with T cells, and the IL-23/IL17 axis is believed to be crucial in the pathogenesis. The present treatments have side effects that influence the compliance of patients. Tea polyphenol is extracted from tea polyphenols, and its main active ingredient is Epigallocatechin-3-gallate (EGCG), which has been shown to have antioxidant, anti-tumor, and anti-ultraviolet radiation effects. Here, we aim to report that EGCG can inhibit imiquimod (IMQ)-induced psoriasis-like inflammation.

Methods

We used BALB/c mice, which were topically treated with IMQ for 6 consecutive days, as a psoriasis mouse model. Topical application of EGCG and treatment with EGCG were conducted in the experiments. Then observed the effects of the two methods on psoriasis-like mice dermatitis. Statistics are presented as the means ± standard error of mean (SEM) and compared using unpaired two-tailed Student’s t tests or one-way ANOVA.

Results

Topical application of EGCG alleviated psoriasiform dermatitis, improved the skin pathological structure by reduce the expression of epidermal PCNA, promoted the expression of caspase-14. Treatment with EGCG attenuated skin inflammation, accompanied by reduced infiltrations of T cells; reduced percentages of CD11c⁺ DC in the composition of immunocytes of spleens; reduced levels of interleukin (IL)-17A, IL-17F, IL-22, IL-23 and malondialdehyde (MDA) in plasma; increased percentages of CD4⁺ T cells in the composition of immunocytes of spleens; and increased bioactivities of superoxide dismutase (SOD) and catalase (CAT) in plasma.

Conclusions

All the results demonstrated that EGCG had anti-inflammatory, immune regulatory and antioxidant effects. It is a promising intervention in psoriasis in the future.

Effects of alternative steeping methods on composition, antioxidant property and colour of green, black and oolong tea infusions

Cold water steeping is reported to maximise tea health benefits, but requires long infusion time. In this work, the employment of a brief hot infusion step followed by ice addition was evaluated. The comparison of this innovative method with hot and cold steeping was investigated on green, black and oolong teas. Catechins, xanthines and gallic acid content, antioxidant power, total phenolics and colour analysis were evaluated. Hot infusion shown rapid extractive power, but relevant compound degradation. On the contrary, cold infusion extracted higher level of healthy molecules with slow kinetic. The innovative method achieved in short time similar properties of cold infusion in terms of antioxidant power. As for bioactive compounds, such as gallic acid and epigallocatechin gallate, highest values, about double than in hot infusion, were recorded for green and black teas. This steeping method may represent an alternative approach for industrial beverage preparation.

Neuroprotective Properties of the Standardized Extract from Camellia sinensis (Green Tea) and Its Main Bioactive Components, Epicatechin and Epigallocatechin Gallate, in the 6-OHDA Model of Parkinson's Disease

Camellia sinensis (green tea) is largely consumed, mainly in Asia. It possesses several biological effects such as antioxidant and anti-inflammatory properties. The objectives were to investigate the neuroprotective actions of the standardized extract (CS), epicatechin (EC) and epigallocatechin gallate (EGCG), on a model of Parkinson's disease. Male Wistar rats were divided into SO (sham-operated controls), untreated 6-OHDA-lesioned and 6-OHDA-lesioned treated for 2 weeks with CS (25, 50, or 100 mg/kg), EC (10 mg/kg), or EGCG (10 mg/kg) groups. One hour after the last administration, animals were submitted to behavioral tests and euthanized and their striata and hippocampi were dissected for neurochemical (DA, DOPAC, and HVA) and antioxidant activity determinations, as well as immunohistochemistry evaluations (TH, COX-2, and iNOS). The results showed that CS and catechins reverted behavioral changes, indicating neuroprotection manifested as decreased rotational behavior, increased locomotor activity, antidepressive effects, and improvement of cognitive dysfunction, as compared to the untreated 6-OHDA-lesioned group. Besides, CS, EP, and EGCG reversed the striatal oxidative stress and immunohistochemistry alterations. These results show that the neuroprotective effects of CS and its catechins are probably and in great part due to its powerful antioxidant and anti-inflammatory properties, pointing out their potential for the prevention and treatment of PD.

Effects of tea polyphenol on quality and shelf life of pork sausages

The effects of tea polyphenol on quality and shelf life of pork sausages stored at 20 °C for 42 days were examined. The control and the treated sausage samples added with 0.03 % tea polyphenol were analyzed periodically for microbiological (total viable counts and lactic acid bacteria counts), physical (Hunter color of L(*), a(*), b(*)), chemical (pH, TBA value) and sensory characteristics. It was found that samples added with tea polyphenol showed lower changes in total viable count, pH, TBA value and sensory characteristics than control samples, respectively. The results indicated that the sausage samples with tea polyphenol added was to enable the good quality and sensory characteristics than the control sausage samples and prolonged the shelf life of the sausages.

Influence of the addition of natural antioxidant from mate leaves (Ilex paraguariensis St. Hill) on the chemical, microbiological and sensory characteristics of different formulations of Prato cheese

The objective of this work is to evaluate the effects of the addition of dried extract from mate leaves and mesophilic cultures (Lactococcus lactis ssp. lactis and cremoris) on the chemical, microbiological and sensory characteristics of Prato cheese. The Prato cheese presented high moisture contents (49 to 53 %) and mean pH values of 5.15 for all tested formulations. The addition of mate leaves extract in the product did not influence the growth of the microbial cultures. During the maturation time, all formulations with the addition of adjunct cultures and mate leaves extract presented lower levels of lipid and protein oxidation compared to the control, proving the antioxidant effect of mate extract. The formulation of Prato cheese added of 0.1 wt.% of extract presented acceptability of about 80 % after 30 days of maturation. The sensory evaluation showed that only the formulation added by adjunct culture and 0.2 wt.% of mate extract presented lower values for the attributes global acceptance, texture and flavor, compared to the control. The formulations added of mate leaves extract presented residual bitter flavor after 45 days of storage.

Antioxidant and functional properties of tea protein as affected by the different tea processing methods

The Box-Behnken design combined with response surface methodology was used to optimize alkali extraction of protein from tea. Three independent extraction variables (extraction time: X1; extraction temperature: X2; alkali concentration: X3) were evaluated. The antioxidant and functional properties of tea protein as affected by different tea processing were compared. The optimum conditions were: extraction time of 85 min, extraction temperature of 80 °C, and alkali concentration of 0.15 M. Under such conditions, the predicted maximum protein extracted yield was 20.73 %, which coincided with the experimental values. Three kinds of tea protein showed good antioxidant and functional properties. Tea processing method had a significant impact on the properties of tea protein. Protein from oolong tea showed the best properties and it might be used as a good source of potential antioxidant and additives in food industry.

Functional properties of autolysate and enzymatic hydrolysates from yam tsukuneimo (Dioscorea opposita Thunb.) tuber mucilage tororo: antioxidative activity and antihypertensive activity

Yam tsukuneimo tuber mucilage tororo hydrolysates were prepared by autolysis and three different peptic enzymes. Except for pepsin hydrolysate, tororo was perfectly digested. Each hydrolysate for 100 mg/ml significantly prolonged the induction period of auto-oxidation of linoleic acid, which was similar to 5 mM ascorbic acid. These hydrolysates also possessed high scavenging activities such as superoxide anion radicals, hydroxyl radicals, and DPPH radicals. Moreover, high antihypertensive activities were detected in these hydrolysates except for autolysate, which were similar to various fermented foods such as miso, natto, sake, cheese, and so on. Present findings suggest that yam tsukuneimo tuber mucilage tororo may be useful for preventing diseases associated with reactive oxygen species and blood pressure in the body system and it can fully absorb the useful components from it to digest using the gastrointestinal enzymes.

Purification and antioxidant activities of baicalin isolated from the root of huangqin (Scutellaria baicalensis gcorsi)

Baicalin is a flavonoid from the root of huangqin (Scutellaria baicalensis gcorsi, a kind of Traditional Chinese Medicine and food condiment) with two pro phenolic hydroxyls. In this manuscript, high purity of baicalin (95.5 %) was isolated from the root of huangqin and its antioxidant activities were investigated. The antioxidant properties of baicalin were evaluated by scavenging of the diphenylpicrylhydrazyl radical (DPPH), reducing power, and iron-chelating assays, compared to ascorbic acid and BHT. The results of antioxidant activity showed that the activities of baicalin were significantly better than these of ascorbic acid and BHT, and the linear correlations were good in these three assays.

Cloud-point extraction and reversed-phase high performance liquid chromatography for analysis of phenolic compounds and their antioxidant activity in Thai local wines

A cloud-point extraction (CPE) was developed for the determination of 12 phenolic compounds (i.e. gallic acid, procatechuic acid, p-hydroxybenzoic acid, vanillic acid, caffeic acid, syringic acid, p-coumaric acid, ferulic acid, guaiacol, p-cresol, o-cresol and 3,5-xylenol) using reversed-phase high performance liquid chromatography (RP-HPLC) with photodiode array (PDA) detection. The optimum CPE conditions were 2.0% (w/v) Triton X-114, 3.0% (w/v) Na2SO4 and 20-min equilibrated at 45 °C. The surfactant-rich phase was then analyzed by HPLC using a Symmetry C18 column, gradient mobile phase of acetonitrile and 1% (v/v) acetic acid, and PDA detection at 280 nm. Under the optimum condition, the target phenolic compounds were separated within 25 min. CPE gave higher enrichment factor up to 15-fold compared to that of direct analysis. The proposed method showed good analytical performances with limits of detection in the range 0.01-0.1 mg L(-1) and precisions with relative standard deviation (RSD) lower than 5% for retention time and 10% for peak area. The method was successfully applied to the analysis of phenolic compounds in Thai local wine samples. Gallic acid, procatechuic acid, and vanillic acid were the highest phenolics found in the studied wines with the contents up to 172.4, 99.1, and 26.6 mg L(-1), respectively. The recovery of the spiked wine samples (0.5, 1.0, and 2.0 mg L(-1)) were obtained in the range of 90.4-110%. High total phenolic content, total flavonoids, and antioxidant activity (DPPH method) in the studied wines were also observed.

Rapid determination of main constituents of packed juices by reverse phase-high performance liquid chromatography: an insight in to commercial fruit drinks

The present work reports the compositional analysis of thirteen different packed fruit juices using high performance liquid chromatography (HPLC). Vitamin C, organic acids (citric and malic) and sugars (fructose, glucose and sucrose) were separated, analyzed and quantified using different reverse phase methods. A new rapid reverse phase HPLC method was developed for routine analysis of vitamin C in fruit juices. The precision results of the methods showed that the relative standard deviations of the repeatability and reproducibility were <0.05 and <0.1 respectively. Correlation coefficient of the calibration models developed was found to be higher than 0.99 in each case. It has been found that the content of Vitamin C was less variable amongst different varieties involved in the study. It is also observed that in comparison to fresh juices, the packed juices contain lesser amounts of vitamin C. Citric acid was found as the major organic acids present in packed juices while maximum portion of sugars was of sucrose. Comparison of the amount of vitamin C, organic acids and sugars in same fruit juice of different commercial brands is also reported.