Integrated Optimisation and LC-ESI-QToF-MS/MS Profiling of Phenolics Extracted from Green Tea Herbal Dust

The rise of the global tea industry market, influenced by the growing demands for healthier diet options, resulted in the constant increase in herbal tea production. In accordance, increased production leads to increased waste generation, especially in the area of filter tea production, which generates waste in the form of powdered plant material with particle sizes lower than 0.315 mm. The generated amount of this powdered plant material, also called herbal dust, can vary in the range from 10 to 40% of the total processed plant, and it is often considered waste only due to its size. Therefore, within this study, ultrasound-assisted extraction (UAE) was utilized for the extraction of green tea (Camellia sinensis L.), lemon balm (Melissa officinalis L.), and hibiscus (Hibiscus sabdariffa L.) herbal dust, and the quality of the obtained extracts was evaluated in terms of total phenolic content (TPC) and phenolic profile. In addition, UAE was conducted on the three different amplitudes (20, 60, and 100%) and two different extraction times (5 and 10 min) in order to investigate and compare the influence of different extraction parameters. The results showed that the maximum TPC for green tea, hibiscus, and lemon balm herbal dust was 152.91 ± 0.74, 60.63 ± 0.10, and 356.22 ± 3.13 mg GAE/g DE, respectively. HPLC analysis conducted for all of the obtained extracts confirmed the presence of several phenolic compounds, with the highest concentrations of epigallocatechin gallate (EGCG) for the extracts of green tea, and neochlorogenic acid for hibiscus herbal dust extracts. The HPLC analysis of the lemon balm extracts recorded the highest concentration of rosmarinic acid for all of the UAE conditions. The results reported within this study indicate that previously considered waste, herbal dust plant material can be successfully extracted by application of UAE and that the obtained extracts exhibit concentrations of bioactive compounds comparable to the extracts of the commercially available plant material.

Microalgae are gaining attention as promising natural sources of bioactives due to their rich nutrient content. This study investigates the effects of ultrasound-assisted extraction (UAE) parameters (i.e., solvent composition, temperature, solid-to-solvent ratio, and time) on the extraction of phenolic compounds from Tetraselmis tetrahele. The UAE parameters were determined at a solid-to-solvent ratio of 1:75, a temperature of 25°C, and an extraction time of 15min with 75% ethanol as the solvent. Phenolic profile, total phenolic content, total flavonoid content, radical scavenging activity of DPPH and ABTS, photosynthesis pigment (chlorophyll a, b, and total carotenoid), anti-collagenase activity, and metabolic profile of Tetraselmis tetrahele extract obtained using UAE were determined. Tetraselmis tetrahele extracts obtained using the selected UAE method demonstrated significantly higher (p<0.05) levels in gallic acid (1.81%), 4-hydroxybenzoic acid (7.0%), total phenolic content (84.0%), total flavonoid content (56.2%), ABTS (101.3%), chlorophyll a (119.4%), chlorophyll b (174.3%), total carotenoids (173.2%) and anti-collagenase activity (15.9%) compared to the maceration method. These findings provide UAE as a green and scalable method for maximizing the phenolic yield and support the application of Tetraselmis tetrahele in the development of high-value products across pharmaceutical, cosmetic, and functional food industries.

Reading the Tea Leaves: Anticarcinogenic Properties of (-)-Epigallocatechin-3-Gallate

Reading the Tea Leaves: Anticarcinogenic Properties of (-)-Epigallocatechin-3-Gallate

Effects of fermentation time on phenolic composition, antioxidant and antimicrobial activities of green, oolong, and black teas

Optimizing the extraction parameters of epigallocatechin gallate using conventional hot water and ultrasound assisted methods from green tea

The stability of tea phenolic compounds is influenced by pH value and digestive processes. However, the complex mixture of constituents in tea may modulate the stability of these compounds during digestion. In this study, tea infusions obtained from green, black, and Oolong tea leaves were exposed to in vitro simulated gastrointestinal digestion, and the stability of ( +)-catechin, caffeine, (−)-epicatechin, epigallocatechin-3-gallate (EGCG), and gallic acid was compared to that of isolated compounds. Changes in antioxidant activity were also evaluated by means of DPPH assay and in a H2O2-induced in vitro oxidative stress model, using Caco-2 cells. The stability of teas antioxidant constituents was different when using teas extract, compared to the reference compound alone, with the total phenolic content being more stable in extracts containing them in higher amount. EGCG degradation correlated well with changes in the DPPH inhibition assay, confirming its pivotal role in the antioxidant activity of tea. Differently, the antioxidant effect in the in vitro cell-based model was much more related to the initial total phenolic content of the extracts, with green tea being more effective than black tea and Oolong tea. Moreover, the antioxidant activity of teas was strongly affected by gastrointestinal digestion. Taken together, these findings suggest a protective role of teas phytocomplex against gastrointestinal digestion of antioxidant constituents. In conclusion, the effect of gastrointestinal digestion on the antioxidant activity of tea should be taken into account, as this may be different from one extract to another and information on the stability of active constituents cannot be extrapolated from data obtained using single compounds.

In the present study, twelve different types of commercial tea samples were assayed to determine their phenolic composition and antioxidant activity. Reverse phase high performance liquid chromatography using a binary gradient system was used for the identification and quantification of individual catechins. Subsequently, total phenolic content was determined spectrophotometrically according to the Folin-ciocalteus method. Total theaflavins and thearubigins were also determined. The radical scavenging behavior of the polyphenols on 2,2-diphenyl-1-picrylhydrazyl radical (DPPH) was also studied spectrophotometrically. The results showed that total polyphenols, total catechins and antioxidant activity were significantly (P<0.05) different in the commercial tea samples. Green tea had the highest levels of catechins, total polyphenols and total antioxidant activity. White tea (silvery tip) a rare specialty type of tea was not significantly different from green tea. Statistical analysis showed an essential catechin content influence of the tea extracts on antioxidant activity. Epigallocatechin gallate (EGCG) was the most potent catechin and the most potent in antioxidant activity (r = 0.989***). Epigallocatechin (EGC) (r = 0.787, P<0.001), epicatechin (EC) + catechin (+C) and epicatechigallate (ECG) also showed significant (P<0.05) antioxidant activity. Black tea contained high levels of theaflavins and thearubigins, which accounted for most of the antioxidant potential in this type of tea product (r = 0.930*** and r = 0.930*** respectively). These results suggest that conversion of catechins during black tea processing did not affect the free-radical potency of black tea. Gallic acid (GA) also showed significant(r = 0.530*) contribution to the antioxidant activity in black tea. Green, black and white tea products processed from Kenyan tea cultivars originally selected for black tea had significantly (P<0.05) higher antioxidant activity than green tea processed from tea cultivars from Japan and China. These results seem to suggest that the cultivar type is critical in determining the antioxidant potency of tea product and that black teas processed from suitable cultivars could be potent in antioxidant activity when compared to green teas.

We examined the anti-allergic effect of epigallocatechin-3-O-(3-O-methyl) gallate (EGCG3″Me) and epigallocatechin-3-O-(4-O-methyl) gallate (EGCG4″Me) isolated from Japanese or Taiwanese tea (Camellia sinensis L.) leaves. These O-methylated catechins strongly inhibit mast cell activation and histamine release after Fc epsilon RI cross-linking through the suppression of tyrosine phosphorylation of cellular protein kinase (Lyn) and the suppression of myosin light chain phosphorylation and high-affinity immunoglobulin E (IgE) receptor expression via binding to the 67 kDa laminin receptor. A double-blind clinical study on subjects with Japanese cedar pollinosis or perennial allergic rhinitis was carried out. At 11 weeks after starting ingestion, during the most severe cedar pollen scattering period, symptoms (i.e. nose blowing and itchy eyes) were significantly relieved by "Benifuuki" green tea containing 34 mg/day of EGCG3″Me compared with a placebo "Yabukita" green tea that did not contain EGCG3″Me. One consecutive month of ingestion of "Benifuuki" green tea was useful for the reduction of some symptoms caused by Japanese cedar pollinosis and did not affect any normal immune responses in subjects with Japanese cedar pollinosis. In addition, the "Benifuuki" green tea was found to significantly relieve the symptoms of perennial rhinitis compared with the placebo "Yabukita" green tea. Based on the investigation of the effects of cultivars, tea crops, and manufacturing methods, green or semi-fermented teas made from fully-matured "Benifuuki" from the second crop should be consumed. The green tea components strictinins and theogallin showed anti-allergic action by inhibiting histamine release through suppressing the biosynthesis of IgE. It was reported that epigallocatechin (EGC) and polysaccharides in tea leaves had immunostimulating activities. Oral administration of a mixture with a high EGC ratio (1:2 to 3=epigallocatechin gallate (EGCG/EGC)) resulted in greater immunoglobulin A production by murine Peyer's patch cells. The EGCG/EGC ratio in a 4°C green tea extract was around 1:3 to 4, whereas in a 100°C extract, it was around 1:0.7. It was identified that EGC-induced phagocytosis can be blocked by catalase and an inhibitor of transient receptor potential melastatin 2. Moreover, it was found that a crude tea polysaccharide from immature tea leaves included a considerable amount of RNA as compared with that from mature tea leaves and increased the phagocytic activity in macrophage-like cells through Toll-like receptor 7.

Ultrasound assisted phytochemical extraction of red cabbage by using deep eutectic solvent: Modelling using ANFIS and optimization by genetic algorithms

CN06-03: Green tea and pomegranate: The role of metabolites in chemoprevention

Blood brain barrier permeability of (−)-epigallocatechin gallate, its proliferation-enhancing activity of human neuroblastoma SH-SY5Y cells, and its preventive effect on age-related cognitive dysfunction in mice

Epigallocatechin gallate (EGCG) is the major active polyphenol in green tea. Protein interaction with EGCG is a critical step in the effects of EGCG on the regulation of various key proteins involved in signal transduction. We have identified a novel molecular target of EGCG using affinity chromatography, two-dimensional electrophoresis, and mass spectrometry for protein identification. Spots of interest were identified as the intermediate filament, vimentin. The identification was confirmed by Western blot analysis using an anti-vimentin antibody. Experiments using a pull-down assay with [3H]EGCG demonstrate binding of EGCG to vimentin with a Kd of 3.3 nm. EGCG inhibited phosphorylation of vimentin at serines 50 and 55 and phosphorylation of vimentin by cyclin-dependent kinase 2 and cAMP-dependent protein kinase. EGCG specifically inhibits cell proliferation by binding to vimentin. Because vimentin is important for maintaining cellular functions and is essential in maintaining the structure and mechanical integration of the cellular space, the inhibitory effect of EGCG on vimentin may further explain its anti-tumor-promoting effect.

The traditional beverage that people consume more after water is a tea. The ethanolic extract of green and black tea have antioxidant and antimicrobial activity and these activities may differ in their processing methods. In this study, physiochemical analysis of green and black tea was carried out. The physiochemical analysis showed that green tea has higher moisture content, crude fat and crude fiber except for crude protein and ash content which is found higher in black tea. The maceration process was used for extraction purposes. This extract was used to analyze the total phenolic and flavonoid content, antioxidant potential, and antimicrobial activity. A significant difference was found in the total phenolic content (TPC), total flavonoid content (TFC), and antioxidant activity of green and black tea. The flavonoids and phenolic content in T1 (ethanol 100%) acquired average and significant in the extract of green and black tea. The maximum value of TPC was observed in green tea extract 152.17a ± 0.28 mg GAE/g in treatment T1, and the value of TFC in green tea was found 40.26±11.387mg QE/g and the minimum value was found in black tea at 36.85±13.68 mg QE/g of extract. Antioxidant activity of green tea extract ranged from 90.64% to 69.07%, and black tea extract ranged from 89.05% to 50.93% in each extract. The parallel determination of the inhibitory effect of gram-negative and positive bacterial strains (Streptococcus pyogenes, Escherichia coli, Staphylococcus aureus, and Pseudomonas aeruginosa) was found sensitivity and resistivity towards extract of tea. The positive and negative effect was found in antimicrobial activity by using antibiotics against these bacterial strains.

The aim of this study was to model the extraction of phenolic compounds and antioxidant activity from mixtures of green, white and black teas (Camellia sinensis) using a simplex-centroid design coupled with multiple regression analysis. White tea showed the highest content of phenolic compounds and in vitro antioxidant activity, while black tea presented the opposite behaviour. The lowest values found in black tea are due to the oxidation of phenolic antioxidants during the fermentation. Gallic acid, chlorogenic acid, epicatechin, epigallocatechin gallate, epigallocatechin, and epicatechin gallate showed a significant correlation (P < 0.05) between all the antioxidant assays. All the mathematical models proposed were significant (P < 0.05) and showed high determination coefficients (R2 adj > 0.80). A simultaneous optimization was performed using the desirability function and the optimum condition to maximize the extraction of epicatechin, epigallocatechin gallate, epicatechin gallate, as well as the antioxidant activity (DPPH and FRAP). The results showed that pure white tea was the best solution for obtaining a higher content of antioxidants.