Gallocatechin Gallate Research Articles

Comparative analysis of fecal phenolic content between normal and obese rats after oral administration of tea polyphenols.

Tea polyphenols (TP) have many health benefits, but most are metabolized into low molecular-weight phenolic acids after oral administration. In the present study, the absorption, metabolism, and excretion of catechins in rats fed a normal chow diet and in obese rats fed a high-fat and high-sugar (HFHS) diet were compared. After a ten-day oral administration of TP (500 mg per kg bw), the plasma levels of (-)-epigallocatechin gallate (EGCG) and (-)-gallocatechin gallate (GCG) in obese rats were significantly lower than those in the normal group. In obese rats, the fecal levels of EGCG, (-)-epicatechin gallate (ECG) and GCG were significantly enhanced. Ten phenolic metabolites of TP were quantitatively analyzed, and the results showed that 4-hydroxyphenylacetic acid was the primary metabolite in feces and plasma. The plasma and fecal concentrations of 4-hydroxyphenylacetic acid in the obese group were significantly lower than those in normal rats, but the levels of 4-hydroxyphenylpropionic acid in plasma and feces were increased. The content of other phenolic acids was also dramatically changed. These results suggested that a HFHS diet might influence the excretion of tea catechins, leading to insufficient metabolism of catechins by the gut microflora.

Nanoemulsion delivery system of tea polyphenols enhanced the bioavailability of catechins in rats

Tea polyphenols (TP) were emulsified with corn oil and polysorbate 80 by high-pressure homogenization. The oil in water (O/W) TP nanoemulsion had droplet sizes of 99.42±1.25nm after preparation. The TP nanoemulsion was stable during storage at 4, 25 or 40°C for 20days. An in vitro simulated digestion assay showed that the bioaccessibility of (−)-epigallocatechin gallate (EGCG) was increased in the nanoemulsion compared to that in aqueous solution, but that the bioaccessibilities of (−)-epigallocatechin (EGC), (−)-epicatechin (EC) and (−)-gallocatechin gallate (GCG) were greatly decreased. Compared with rats fed an aqueous TP solution, rats fed the TP nanoemulsion had significantly lower maximum plasma concentrations (Cmax) of EGCG and EGC, but the area under the plasma concentration-time curve (AUC0–t) was increased. The data show that use of a nanoemulsion system to deliver tea polyphenols may enhance the absorption of EGCG through controlled release.

Fungal community succession and major components change during manufacturing process of Fu brick tea

Fu brick tea is a unique post-fermented tea product which is fermented with microorganism during the manufacturing process. Metabolic analysis showed that most metabolites content were decreased during the manufacturing process of Fu brick tea, except GA (gallic acid). Illumina MiSeq sequencing of ITS gene amplicons was applied to analyze the fungal community succession. The genera Aspergillus, Cyberlindnera and Candida were predominant at the early stage of manufacturing process (from “primary dark tea” to “fermentation for 3 days”), but after the stage of “fermentation for 3 days” only Aspergillus was still dominated, and maintain a relatively constant until to the end of manufacturing process. The effects of metabolites on the structure of the fungal community were analyzed by redundancy analysis (RDA) and variation partitioning analysis (VPA). The results indicated that GCG (gallocatechin gallate), EGCG (epigallocatechin gallate) and GA as well as the interactions among them were the most probably ones to influence, or be influenced by the fungal communities during the fermentation process of Fu brick tea. This study revealed fungal succession, metabolite changes and their relationships, provided new insights into the mechanisms for manufacturing process of Fu brick tea.

Expression of Key Structural Genes of the Phenylpropanoid Pathway Associated with Catechin Epimerization in Tea Cultivars.

Catechin epimerization is an important factor affecting tea catechin compositions and thereby tea quality. However, a lack of tea germplasms with high non-epicatechins limits relative research. Here, a tea cultivar Y510 with high non-epicatechins was firstly reported and used for catechin and RNA sequencing (RNA-Seq) analysis. Results showed that the (-)-gallocatechin gallate and (+)-catechin (C) contents in Y510 were at least 136 and 6 times higher than those in Fudingdabaicha and 0306I, but the epicatechins (-)-epigallocatechin and (-)-epicatechin (EC) were significantly lower. Eleven unigenes potentially involved in catechin epimerization were identified by RNA-Seq analysis. Based on a combination of catechin and gene expression analysis, it was hypothesized that two anthocyanidin reductase genes (CsANR1, CsANR2) and an anthocyanidin synthase gene (CsANS) are the key genes affecting catechin epimerization in tea. Non-epicatechin formations were hypothesized to be mainly influenced by the expression ratio of CsANR2 to CsANR1 and the expression of CsANS. Overexpression of CsANS in an Arabidopsis mutant tds4-2 led to a significant increase of EC accumulation in seeds, revealing CsANS is important for catechin epimerization. These results shed new light on breeding tea cultivars with special catechin compositions.

Content of flavan-3-ol monomers and gallic acid in grape seeds by variety and year

The content of flavan-3-ol monomers and gallic acid in grape seeds in the samples from the gene collection of Viticulture Research Station Karlstejn (Czech Republic) was investigated. Presence of catechin, epicatechin, epigallocatechin, epicatechin gallate and gallic acid was confirmed in these samples, other flavan-3-ol monomers like gallocatechin or epigallocatechin gallate were below limit of detection. As major flavan-3-ol monomers catechin and epicatechin with 85 % were detected. Average content of catechin in grape seed was 4454 ± 148 µg·g-1, 3085 ± 98 µg·g-1 epicatechin, 600 ± 41 µg·g-1 epigallocatechin, 457 ± 19 µg·g-1 gallic acid, and 352 ± 16 µg·g-1 epicatechin gallate. Variety had main impact on phenolic content followed by vintage. Average sum of flavan-3-ol monomers in grape seeds in white varietes was 7601 ± 273 µg·g-1 and 10869 ± 430 µg·g-1 in red varieties, with 10050 ± 425 µg·g-1 in 2012 and 7846 ± 219 µg·g-1 in 2013 were found on average in all varieties, respectively. The highest phenolic content was characteristic for 'Pinot Noir', 'Muskat Donskoi', 'Aromriesling' and 'Hibernal' and may contribute to their health properties.

Antimicrobial mechanism of epigallocatechin gallate and gallocatechin gallate: They target 1-deoxy-d-xylulose 5-phosphate reductoisomerase, the key enzyme of the MEP terpenoid biosynthetic pathway

The catechins EGCG and GCG show a variety of pharmacological activities, especially an antibacterial capacity, but their modes of antimicrobial action have not been fully elucidated. 1-Deoxy-d-xylulose 5-phosphate reductoisomerase (DXR), the first key enzyme in the MEP pathway for terpenoid biosynthesis, is a recently validated antimicrobial target. In order to disclose the antibacterial mechanism of EGCG and GCG, the DXR inhibitory activity of them was investigated in this study. The data show that EGCG and GCG both could specifically suppress the activity of DXR, with EGCG exhibiting relatively low effect against DXR (IC50 about 210 μM) and GCG displaying strong activity (IC50 27.5 μM). In addition, studies on inhibition kinetics of the catechins against DXR demonstrate that they are competitive inhibitors of DXR against DXP and uncompetitive inhibitors with respect to NADPH. Meanwhile, the possible interactions between DXR and the catechine, esyth onlols were simulated via docking experiments.

Characterization of Active Anthocyanin Degradation in the Petals of Rosa chinensis and Brunfelsia calycina Reveals the Effect of Gallated Catechins on Pigment Maintenance.

Anthocyanin degradation decreases ornamental or nutritional values of horticultural products. To investigate factors that may influence colour change in flower development, anthocyanin degradation was compared between the flowers of Brunfelsia calycina and Rosa chinensis, which show rapid and slow degradation, respectively. In-gel activity assays, high performance liquid chromatography (HPLC) analysis of tannins, enzyme kinetics measurement and immune-detection of anthocyanin degradation related-perioxidases (PODs) were carried out for the comparison. Rose petals possessed significantly lower anthocyanin degradation-related POD activities than Brunfelsia petals, which may be related to the high tannin contents. Epicatechin gallate (ECG) and gallocatechin gallate (GCG) were detected in rose as 161.3 ± 12.34 and 273.56 ± 41.23 μg/g FW (Fresh Weight) respectively, while not detected in Brunfelsia. ECG and GCG inhibited the activities of the Brunfelsia POD with half maximal inhibitory concentrations (IC50s) as 21.5 and 29.7 μM respectively, and increased the colour intensities of the anthocyanins. Catechin and epicatechin did not inhibit the POD activity, while serving as POD substrates, with Km (the Michaelis constant) as 0.48 and 1.23 mM. Similar protein levels of the anthocyanin degradation-related 40-kDa PODs were detected in Brunfelsia and rose. In summary, high amount of tannins, particularly ECG and GCG, in red rose petals may inhibit the degradation-related enzymes, leading to the maintenance of anthocyanins in vivo.

Development of novel monoclonal antibodies directed against catechins for investigation of antibacterial mechanism of catechins

Catechins are major polyphenolic compounds of green tea. To investigate mechanism for antibacterial action of catechins, 11 monoclonal antibodies (MAbs) were raised against a 3-succinyl-epicatechin (EC)-keyhole limpet hemocyanin (KLH) conjugate. Amino acid sequences of variable regions determined for MAbs b-1058, b-1565, and b-2106 confirmed their innovative character. MAb b-1058 strongly interacted with its target substances in the following order of magnitude: theaflavin-3,3′-di-O-gallate (TFDG)>theaflavin-3-O-gallate (TF3G)≥theaflavin-3′-O-gallate (TF3’G)>gallocatechin gallate (GCg)>penta-O-galloyl-β-d-glucose (PGG)>epigallocatechin gallate (EGCg), as determined using surface plasmon resonance (SPR) on MAb-immobilized sensor chips. The affinity profiles of MAbs b-1058 and b-2106 to the various polyphenols tested suggested that flavan skeletons with both carbonyl oxygen and hydroxyl groups are important for this interaction to take place. S. aureus cells treated with EGCg showed green fluorescence around the cells after incubation with FITC-labeled MAb b-1058. The fluorescence intensity increased with increasing concentrations of EGCg. These MAbs are effective to investigate antibacterial mechanism of catechins and theaflavins.

Gallocatechin gallate (GCG) inhibits 3T3-L1 differentiation and lipopolysaccharide induced inflammation through MAPK and NF-κB signaling

Gallocatechin gallate (GCG), as the epimer of Epigallocatechin gallate (EGCG), the content is low in traditional tea made from Camellia sinensis and C. assamica. However, previous studies found that the content of GCG was almost the same as EGCG in canned and bottled tea drinks. Accumulating evidences indicated that GCG possessed multiple biological activities, but the anti-obesity study of GCG is poorly reported. In this study, the anti-adipogenic activities of GCG were investigated. The results showed that as EGCG, GCG significantly reduced the intracellular lipid droplets and expressions of major adipogenic transcription factors, such as PPAR γ, SREBP-1c and C/EBP α. Further study revealed that the expressions of FAS, ACC, FAT and SCD-1 were decreased in 3T3-L1 cells treated with GCG. GCG treatment also dose-dependently decreased the intracellular ROS level, attenuated MAPK pathway activation in 3T3-L1 differentiations. Additionally, GCG decreased the activation of NF-κB, and down-regulated the production of IL-6 and MCP-1 induced by LPS.

AB016: Metabolomic studies of green tea catechins and its applications in ocular research

: Tea is the second most popular beverage worldwide after water. Green tea has the highest nutraceutical values with well-established general health benefits and wide safety margins. Natural polyphenols found in green tea, including (+)-catechin (C), (–)-epicatechin (EC), (+)-gallocatechin (GC), (–)-epigallocatechin (EGC), (–)-epicatechin-3-gallate (ECG), (–)-gallocatechin-3-gallate (GCG) and (–)-epigallocatehin-3-gallate (EGCG). They have many potent biological properties and therapeutic effects in human health and diseases. These small molecules have high bioavailability and specific therapeutic potential in eye tissues. Recently some researchers studied the metabolomic responses to the green tea. In this talk, summary of these studies will be reviewed and its potential applications in the ocular research will be discussed.

Influence of shooting period and extraction conditions on bioactive compounds in Turkish green tea

The aim of this study was to investigate the influence of different extraction temperatures (75, 85 and 95 °C) and times (3, 5, 10, 15 and 20 min) on bioactive compounds in Turkish green tea produced and classified as Turkuaz, Kardelen and Antikyeşil by ÇAYKUR (the Turkish Tea Board) over three shooting periods. Green tea extracts were subjected to analyses of extraction yield, antioxidant capacity, total phenolic and flavonoid contents, and the phenolic and flavonoid composition. Total phenolic and flavonoid contents and the antioxidant capacity of samples increased when extraction temperatures and times were increased. Extraction yield, total phenolics, total flavonoids and the antioxidant capacity of the green teas were found in the range of 21.52-37.40 g 100 g-1, 68.13-131.31 mg GAE g-1 dw, 17.97-32.04 mg CE g-1 dw and 0.48-1.16 mg dw mg-1 DPPH, respectively. The average amounts of individual catechins, i.e. catechin, epicatechin, epigallocatechin, epicatechin gallate, epigallocatechin gallate, gallocatechin gallate, gallocatechin and catechin gallate were found in the range of 8.91-17.09, 4.29-9.55, 28.03-59.42, 8.02-14.61, 38.05-69.66, 2.53-18.53, 2.30-12.97 and 0.04-1.78 mg g-1 dw, respectively.

Extract from Mulberry (Morus australis) leaf decelerate acetaminophen induced hepatic inflammation involving downregulation of myeloid differentiation factor 88 (MyD88) signals

Acetaminophen (APAP) induced inflammation and oxidative stress can cause cell death to induce liver damage. The antioxidative and anti-inflammatory effect of Mulberry (Morus australis) leaf extract (MLE) was shown in previous studies. In this study, we investigated the modulation of MLE on APAP induced inflammation and oxidative stress in rat liver injury or liver cancer cell (HepG2). Wistar rat was fed orally with MLE (0.5% or 1.0 %) for 1 week, and then, 900 mg/kg of APAP was injected intraperitoneally (i.p.). Pretreatment of MLE decreased obvious foci of inflammatory cell infiltration in liver. It also reduced the expression of inflammatory parameters including cyclooxygenase-2 (COX-2), inducible nitric oxide synthase (iNOS), and nuclear factor kappa B (NF-κB) in liver. Treating with MLE increased the antioxidative enzymes such as superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), and catalase. Giving APAP to HepG2 hepatocyte was conducted to elucidate the mechanism of MLE or its functional components. The result showed that APAP upregulated hepatic protein expression of (myeloid differentiation factor 88) MyD88, nuclear factor kappa B (NF-kB), inhibitor of kappa B (IkB), c-Jun N-terminal kinases (JNK), and receptor interacting proteins (RIP1 and RIP3). Pretreatment of MLE, gallic acid (GA), gallocatechin gallate (GCG), or protocatechuic acid (PCA) suppressed the indicated protein expression. These findings confirmed that MLE has the potential to protect liver from APAP-induced inflammation, and the protecting mechanism might involve decreasing oxidative stress and regulating the innate immunity involving MyD88.

Accumulation of catechins and expression of catechin synthetic genes in Camellia sinensis at different developmental stages.

BackgroundCatechins are the main polyphenol compounds in tea (Camellia sinensis). To understand the relationship between gene expression and product accumulation, the levels of catechins and relative expressions of key genes in tea leaves of different developmental stages were analyzed.ResultsThe amounts of catechins differed significantly in leaves of different stages, except for gallocatechin gallate. Close correlations between the expression of synthesis genes and the accumulation of catechins were identified. Correlation analysis showed that the expressions of chalcone synthase 1, chalcone synthase 3, anthocyanidin reductase 1, anthocyanidin reductase 2 and leucoanthocyanidin reductase genes were significantly and positively correlated with total catechin contents, suggesting their expression may largely affect total catechin accumulation. Anthocyanidin synthase was significantly correlated with catechin. While both ANRs and LAR were significantly and positively correlated with the contents of (−)-epigallocatechin gallate and (−)-epicatechin gallate.ConclusionOur results suggest synergistic changes between the expression of synthetic genes and the accumulation of catechins. Based on our findings, anthocyanidin synthase may regulate earlier steps in the conversion of catechin, while the anthocyanidin reductase and leucoanthocyanidin reductase genes may both play important roles in the biosynthesis of galloylated catechins.

Impact of Clonal Variability on Phenolics and Radical Scavenging Activity of Grapes and Wines: A Study on the Recently Developed Merlot and Cabernet Franc Clones (Vitis vinifera L.).

In this study, grapes and corresponding wines of Merlot /No 022, 025 and 029/ and Cabernet Franc /No 02, 010 and 012/ clones (recently developed) were evaluated regarding the total phenolic content, total anthocyanin content, and radical scavenging activity, aiming to better understand their quality and market potential. The nineteen individual polyphenols were quantified in studied grape samples using UHPLC coupled to a triple-quadrupole mass spectrometer. The mother grapes and wines were used as the relevant standards. In the grape, studied characteristics were monitored at three stages of berry development: green berry, véraison and mature berry. The mature grape of clones presented high values of total phenolics (3.81–10.89 g gallic acid equivalent kg-1 frozen weight), anthocyanin content (359.00–1668.18 mg malvidin-3-O-glucoside kg-1 frozen weight) and the radical scavenging activity (41.37–80.48 mmol trolox equivalent kg-1 frozen weight) depending on the clone. Grapes and wines of Merlot No 025 and Cabernet Franc No 010 stood out with the highest values of all three parameters. Generally, the high correlation was observed between TPC and RSA values for green berries and mature grapes, as well as for wine samples. The most abundant phenolics in both Merlot and Cabernet Franc grapes were gallic acid, p-hydroxybenzoic acid, ferulic acid, catechin, epicatechin, gallocatechin gallate, catechin gallate, and rutin. Catechin, epicatechin, epigallocatechin, and catechin gallate, typical for the ripe grape of Merlot and Cabernet Franc clones, showed significant correlation with RSA values. Concentrations of individual polyphenols varied depending on the sample being studied and berry development stages. Merlot No 025 and Cabernet Franc No 010 grapes showed particularly interesting attributes for the production of high quality wines.

Variation of theanine, phenolic, and methylxanthine compounds in 21 cultivars of Camellia sinensis harvested in different seasons.

This is the first study to use chemometric methods to differentiate among 21 cultivars of Camellia sinensis from China and between leaves harvested at different times of the year using 30 compounds implicated in the taste and quality of tea. Unique patterns of catechin derivatives were observed among cultivars and across harvest seasons. C. sinensis var. pubilimba (You 510) differed from the cultivars of C. sinensis var. sinensis, with higher levels of theobromine, (+)-catechin, gallocatechin, gallocatechin gallate and theasinensin B, and lower levels of (-)-epicatechin, (-)-epigallocatechin (EGC) and (-)-epigallocatechin gallate (EGCG), respectively. Three cultivars of C. sinensis var. sinensis, Fuyun 7, Qiancha 7 and Zijuan contained significantly more caffeoylquinic acids than others cultivars. A Linear Discriminant Analysis model based on the abundance of 12 compounds was able to discriminate amongst all 21 tea cultivars. Harvest time impacted the abundance of EGC, theanine and afzelechin gallate.

The Synthesis of trans‐Flavan‐3‐ol Gallates by Regioselective Oxidative Etherification and Their Cytotoxicity Mediated by 67 LR

We report on a chiral pool approach for the synthesis of trans-flavan-3-ol gallates from epichlorohydrin. The trans-flavan-3-ol gallates were prepared by the cycloetherification of the phenol at the C2 benzylic position of 2-acylozyl-1,3-diarylpropane during regioselective C-H oxidation. The 1,3-diarylpropanes were prepared starting from epichlorohydrin by epoxide opening with A and B ring precursors, followed by acylation of the resultant alcohol with galloyl chloride. The availability of both the enantiomers of epichlorohydrin allowed the preparation of the corresponding enantiomer using the same procedure. The cytotoxicity of the compounds against U266 cells was tested, in which 5-deoxy-7,3'-O-dimethyl gallocatechin gallate exhibited cytotoxicity that was more than ten times stronger than natural (-)-EGCG. In addition, the absolute configuration of the derivatives did not critically affect the biological activity.

Altitudinal effects on the quality of green tea in east China: a climate change perspective

Climate change differentially affects tea yield at various altitudes; however, its impact on tea quality is less acknowledged. To understand the divergence in tea quality, we collected green tea samples from five sites (with varying altitude from 212 to 1020 m) on Lushan Mountain in Jiangxi Province, eastern China. Results showed that an increase in cultivation altitude decreased total tea polyphenols (TP) but increased amino acids (AA) concentration, leading to a remarkable decrease in TP/AA, one of the most important parameters that determine the taste of green tea. The constituents of AA, especially theanine, glutamic acid, arginine, serine, γ-aminobutyric acid and aspartic acid increased with increasing elevational gradients. Nonetheless, the constituents of polyphenolic compounds, especially individual catechins, were differentially altered with the change in cultivation altitude. In particular, with increasing elevation, the epigallocatechin-3-gallate and epicatechin gallate decreased, while the epigallocatechin and gallocatechin gallate increased, that eventually caused no significant variation in the total catechins in different sites. Additionally, the percentage of catechins to TP was increased with increasing altitude. Given that temperature is being increased due to climate change, rising temperatures particularly at lower altitude, perhaps, will deteriorate tea quality as a consequence of climate warming. This observation demands development of effective measures for sustaining green tea quality in the face of climate change.

Inhibition of green tea and the catechins against 1-deoxy-d-xylulose 5-phosphate reductoisomerase, the key enzyme of the MEP terpenoid biosynthetic pathway

1-Deoxy-d-xylulose 5-phosphate reductoisomerase (DXR) is the first committed enzyme in the MEP terpenoid biosynthetic pathway and also a validated antimicrobial target. Green tea which is rich in polyphenolic components such as the catechins, possesses a plenty of pharmacological activities, in particular an antibacterial effect. To uncover the antibacterial mechanism of green tea and to seek new DXR inhibitors from natural sources, the DXR inhibitory activity of green tea and its main antimicrobial catechins were investigated in this study. The results show that the raw extract of green tea and its ethyl acetate fraction are able to suppress DXR activity explicitly. Further determination of the DXR inhibitory capacity of eight catechin compounds demonstrates that the most active compound is gallocatechin gallate that is able to inhibit around 50% activity of DXR at 25μM. Based on these data, the primary structure-activity relationship of the catechins against DXR is discussed. This study would be very helpful to elucidate the antimicrobial mechanism of green tea and the catechins and also would be very useful to direct the rational utilization of them as food additives.

Abstract 3733: Augmentation of response to therapeutic agents by (-)-gallocatechin gallate through inhibition of RAD51 nuclear translocation

Abstract Lung cancer is the most common cancer worldwide. Platinum-based combination chemotherapy is one of first line treatments for patients with lung cancer. Most of the cytotoxic drugs are targeting DNA, interfere with DNA synthesis, and triggering DNA damage response (DDR). Since DDR usually activates important defensive pathways to repair damaged DNA, DDR is known as a key factor determining the outcome of chemotherapy. Among them, RAD51, playing a central role in homologous recombination (HR) DNA repair, has been shown to interfere with the prognosis of patients treated with chemoradiotherapy. Since we have demonstrated that inhibition of RAD51 nuclear focus formation synergistically enhances the anticancer activity of cisplatin, we further screened purified natural products in order to find products with activity to inhibit RAD51 nuclear focus formation. In the present study, we found that a green tea catechin derivative, the (-)-Gallocatechin gallate (GCG) has potent inhibitory activity against RAD51 nuclear focus formation in cisplatin-treated H460 cells. The in vitro cytotoxicity assay showed that the combination of cisplatin or irinotecan with GCG significantly increases the sensitivity of H460 cells to these DNA damage agents. We also evaluated the anti-tumor growth activity of cisplatin or irinotecan in combination with GCG using H460 xenografts. Our results showed that cisplatin and irinotecan suppresses tumor growth by 17.6% and 33.8%, while in combination with GCG suppresses tumor growth by 52.2% and 68.9%, respectively. We further demonstrated that GCG is able to inhibit cisplatin-induced ATM and Chk2 phosphorylation. Together, our results suggest that GCG may interfere with ATM-Chk2 pathway and hence suppress RAD51 nuclear focus formation and DNA repair activities. Citation Format: Ming-Hsi Wu, Lie-Chwen Lin, Te-Chang Lee. Augmentation of response to therapeutic agents by (-)-gallocatechin gallate through inhibition of RAD51 nuclear translocation. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 3733.

Determination of Contents of Catechins in Oolong Teas by Quantitative Analysis of Multi-components Via a Single Marker (QAMS) Method

The catechins in oolong tea are related to its flavor and health benefits. In this paper, a new strategy for a quantitative analysis of multi-components via a single marker (QAMS) was developed and validated to analyze six catechins (epigallocatechin, catechin, epicatechin, epigallocatechin gallate, gallocatechin gallate, and epicatechin gallate) in oolong tea by HPLC. Catechin was chosen as the internal reference substance. The relative correction factors (RCFs) between catechin and the other five catechins were investigated for the QAMS calculation using five different types of chromatographic columns. Meanwhile, the content of each of the six analytes was also determined by a conventional external standard method. Finally, the angle cosine value revealed that there was no significant difference between the QAMS method and the external standard method. The QAMS method established in this study solved the problem of the availability and high cost of some standard substances and would be useful for providing an efficient and feasible quality assessment method for oolong tea and other botanic samples.