Research Database

Author: Natalie Glube and Lea von Moos and Guus Duchateau

Purpose In vitro disintegration and dissolution are routine methods used to assess the performance and quality of oral dosage forms. The purpose of the current work was to determine the potential for interaction between capsule shell material and a green tea extract and the impact it can have on the release. Methods A green tea extract was formulated into simple powder-in-capsule formulations of which the capsule shell material was either of gelatin or HPMC origin. The disintegration times were determined together with the dissolution profiles in compendial and biorelevant media. Results All formulations disintegrated within 30 min, meeting the USP criteria for botanical formulations. An immediate release dissolution profile was achieved for gelatin capsules in all media but not for the specified HPMC formulations. Dissolution release was especially impaired for HPMCgell at pH 1.2 and for both HPMC formulations in FeSSIF media suggesting the potential for food interactions. Conclusions The delayed release from studied HPMC capsule materials is likely attributed to an interaction between the catechins, the major constituents of the green tea extract, and the capsule shell material. An assessment of in vitro dissolution is recommended prior to the release of a dietary supplement or clinical trial investigational product to ensure efficacy.

 

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Author: Heba-Alla H. Abd-ElSalam and Medhat A. Al-Ghobashy and Hala E. Zaazaa and Mohamed A. Ibrahim

Epigallocatechin gallate (EGCG) is a powerful antioxidant and commonly used nutraceutical. Accelerated stability of EGCG in tablet formulations was investigated. LLE and SPE were employed for sample clean-up and enrichment of EGCG over caffeine. Samples were analysed after spiking with fixed concentration of gallic acid (GA), in order to verify reproducibility of analysis. A TLC–densitometric assay was developed and validated for determination of % loss EGCG. EGCG, GA and caffeine were resolved with Rf values 0.54, 0.69 and 0.80, respectively. LC–MS/MS was used to verify identity and purity of the EGCG band. Determination was carried out over a concentration range of 0.50–5.00 μg/band and 0.20–2.40 μg/band for GA and caffeine, respectively. Results showed significant reduction in EGCG content after one, three and six months: 24.00%, 28.00% and 52.00% respectively. Results continue to demonstrate that stability of nutraceutical products should be investigated in-depth using industry-oriented protocols before granting marketing authorisation.

 

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Author: Wanchun Wang and Yu’e Yang and Wenyi Zhang and Wenlong Wu

Summary Objectives Epidemiological studies evaluating the association of tea consumption and the risk of oral cancer risk have produced inconsistent results. Thus, we conducted a meta-analysis to assess the relationship between tea consumption and oral cancer risk. Methods Pertinent studies were identified by a search in PubMed, Web of Knowledge and Wan Fang Med Online. The fixed or random effect model was used based on heterogeneity test. Publication bias was estimated using Egger’s regression asymmetry test. Results Finally, 14 articles with 19 studies comprising 4675 oral cancer cases were included in this meta-analysis. The relative risk (95% confidence interval) of oral cancer for the highest versus the lowest category of tea consumption was 0.853 (0.779–0.934), and the association was significant between oral cancer risk and green tea consumption [0.798 (0.673–0.947)] but not in the black tea consumption [0.953 (0.792–1.146)]. The associations were also significant in Asian and Caucasian. Conclusions Our analysis indicated that tea consumption may have a protective effect on oral cancer, especially in green tea consumption.

 

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Author: Chao-Ming Liu and Chung-Yu Chen and Yang-Wei Lin

A simple, inexpensive micellar electrokinetic chromatography (MEKC) method with UV detection was used to determine seven catechins and one xanthine (caffeine) in tea. All the compounds were successfully separated (15 kV) within a 15-min migration period with a high number of theoretical plates (>8.0 × 10 4) in a running buffer (pH 7) containing 10 mmol l−1 sodium tetraborate, 4 mmol l−1 sodium phosphate, and 25 mmol l−1 SDS. The regression lines of all standard catechins were linear within the range of 0.03–4 μg ml−1. Green tea infused at 95 °C for 10 min showed higher levels of catechins (especially epigallocatechin galate, epicatechin gallate, and epicatechin) than tea infused at 80 °C. In addition, major differences were observed in the levels of catechins in the first and second infusions (both brewed at 95 °C for 10 min). Finally, green tea leaves were infused separately with tap water, deionised water, spring water, reverse osmosis water, and distilled water at 95 °C, and the catechin content of the infusions was investigated by the proposed method. In the infusion brewed with tap water, catechins appeared to be epimerisation from the epistructure to the nonepistructure. This epimerisation may take place more readily in tap water than in distilled water owing to the complexity of the ions present in tap water.

 

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Author: Kentaro Kitadate and Kohei Homma and Ashley Roberts and Takahiro Maeda

Oligonol is a functional food containing catechin-type monomers and proanthocyanidin oligomer converted from polymer forms via a novel manufacturing process. The catechin component of green tea extract has been associated with nasal toxicity in rats following subchronic exposure. To assess the potential for Oligonol to induce nasal toxicity a 13-week repeated oral dose toxicity study was conducted in rats using doses of 100, 300, and 1000 mg/kg/d. Clinical signs and mortality were not affected by Oligonol treatment. Compound-colored stools and an increase in food consumption were observed in some treated groups; however, there were no treatment-related differences in terminal body weights or with respect to the results of the gross postmortem examinations. Histopathological evaluation of the nasal cavity tissues revealed no treatment-related lesions. The results from this toxicity study indicate that Oligonol does not induce nasal toxicity and further supports the results of previous studies demonstrating the safety of Oligonol for human consumption.

 

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Author: A.A. Rahim and S. Nofrizal and Bahruddin Saad

A rapid reversed-phase high performance liquid chromatographic method using a monolithic column for the determination of eight catechin monomers and caffeine was developed. Using a mobile phase of water:acetonitrile:methanol (83:6:11) at a flow rate of 1.4 mL min−1, the catechins and caffeine were isocratically separated in about 7 min. The limits of detection and quantification were in the range of 0.11–0.29 and 0.33–0.87 mg L−1, respectively. Satisfactory recoveries were obtained (94.2–105.2 ± 1.8%) for all samples when spiked at three concentrations (5, 40 and 70 mg L−1). In combination with microwave-assisted extraction (MAE), the method was applied to the determination of the catechins and caffeine in eleven tea samples (6 green, 3 black and 2 oolong teas). Relatively high levels of caffeine were found in black tea, but higher levels of the catechins, especially epigallocatechin gallate (EGCG) were found in green teas.

 

 

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Author: Xinzhong Zhang and Fengjian Luo and Zhengyun Lou and Meiling Lu and Zongmao Chen

A novel and sensitive method for simultaneous enantiomeric analysis of two pesticides—cis-epoxiconazole and indoxacarb—in various teas, black tea infusion, and soil samples has been developed. The samples were initially subjected to acetonitrile extraction followed by cleanup using lab-made florisil/graphitized carbon black mixed solid phase extraction (SPE) column (for the different teas and soil samples) and a BondElut C18-SPE column (for the black tea infusion samples). Separation of the analytes was performed on a chiral stationary phase using high performance liquid chromatography (HPLC) under a reversed-phase isocratic elution mode followed by tandem quadrupole time-of-flight mass spectrometry (Q-TOF/MS) detection. The mobile phase components, mobile phase ratios, flow rates, column temperatures, and MS parameters were all optimized to reach high sensitivity and selectivity, good peak shape, and satisfactory resolution. The performance of the method was evaluated based on the sensitivity, linearity, accuracy, precision, and matrix effects. Under optimal conditions, for the various teas (green tea, black tea, and puer tea), fresh tea leaf, soil and black tea infusion samples spiked at low, medium, and high levels, the mean recoveries for the four enantiomers ranged from 61.0% to 129.7% with most relative standard deviations (RSDs) being 17.1% or below. Good linearity can be achieved with regression coefficients (R) of 0.9915 or above for all target enantiomers, and matrix-matched calibration concentration ranging from 5.0 to 1000 μg/L. The limits of detection (LODs) for all four target enantiomers were 1.4 μg/kg or below in the different teas and soil samples and 0.05 μg/kg or below in the black tea infusion, whereas the limits of quantification (LOQs) for those did not exceed 5.0 μg/kg and 0.2 μg/L, respectively. The proposed method is convenient and reliable and has been applied to real tea samples screening. It has also been extended for studies on the degradation kinetics and environmental behaviors in the field trials, providing additional information for reliable risk assessment of these chiral pesticides.

 

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Author: Min-Seuk Lee and Young-Sun Hwang and Jinwook Lee and Myoung-Gun Choung

Near-infrared reflectance spectroscopy (NIRS) was used to determine the contents of caffeine and nine individual catechins in tea leaves. A total of 665 samples were scanned by NIRS, and also by high performance liquid chromatography coupled to a diode array detector to determine the contents of caffeine and nine individual catechins. The calibration models for caffeine, EGC, C, EGCG, EC, ECG, and total catechins had high r2 (more than 0.90) and RSP (the ratio of standard deviation of reference data to SEP(C) in the external validation set) values (more than 4.1), indicating a good correlation between reference values and NIRS predicted values. In contrast, the calibration models of GC and EGCG-3Me had low r2 and RSP values (below 0.8 and 2.0). Therefore, these results suggest that NIRS could be applied for the rapid determination of the contents of caffeine, EGC, C, EGCG, EC, ECG, and total catechins in tea leaves for breeding programs that develop high-quality tea plants.

 

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Author: Jian-Hui Ye and Na-Na Li and Jian-Liang Lu and Xin-Qiang Zheng and Yue-Rong Liang

(−)-Epigallocatechin gallate (EGCg)-rich extract (EGCg > 700 mg g−1) was prepared from green tea leaves through a three-stage process consisting of liquid–liquid extraction and silica column purification. Crude tea extract was dissolved in ethyl acetate. After filtration, the solution was extracted by 10 g L−1 citric acid solution twice, and then passed through silica column. The catechins compounds in the ethyl acetate eluate were back extracted to the aqueous phase, then extracted with a mixed solution of n-hexane/ethyl acetate (2/5, v/v) 3 times, concentrated, and freeze dried. 12.8 g EGCg-rich extract containing 709 mg g−1 EGCg and 965 mg g−1 total catechins was obtained from 300 g green tea leaves, with an EGCg recovery of 26.1% and a yield of 4.3%. This method was suitable for bulk preparation of EGCg-rich catechins from green tea leaves.

 

 

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Author: R. Shahakbari and M. Eshghpour and A. Rajaei and N.M. Rezaei and P. Golfakhrabadi and A. Nejat

The objective of this study was to evaluate the effectiveness of green tea mouthwash in controlling the pain and trismus associated with acute pericoronitis in comparison to chlorhexidine (CHX) mouthwash. Ninety-seven patients with acute pericoronitis underwent debridement and received 5% green tea mouthwash (study group) or 0.12% CHX mouth rinse (control group). Pain (visual analogue scale; VAS), number of analgesics, maximum mouth opening (MMO), and number of patients with trismus were determined. There were no significant differences in demographic variables (P > 0.05), or baseline VAS (P > 0.006), MMO (P > 0.017) or number of patients with trismus (P > 0.017) between the two groups. The mean VAS score of the study group was statistically lower than that of the control group between post-treatment days 3 and 5 (P < 0.006). A significantly lower number of analgesics were taken by the study group (P < 0.05). Although the MMO of the study group was significantly lower on day 3 (P < 0.017), no significant difference was observed on day 7 (P > 0.017). Fewer of the patients rinsing with green tea had trismus on days 3 and 7, but the difference was non-significant (P > 0.017). Hence, green tea mouth rinse could be an appropriate and effective choice for the control of pain and trismus in acute pericoronitis.

 

 

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