Influence of preparation procedures on the phenolic content, antioxidant and antidiabetic activities of green and black teas

The influence of common tea preparation procedures (temperature, infusion time, consumption time interval and tea bag/loose-leaf) and the type of water used, on the total phenolic content (TPC), the radical scavenging activity and the α-glucosidase inhibitory activity were assessed. Higher TPC and antioxidant activity were obtained when using lower mineralized waters. Tea bags also evidenced higher antioxidant activity than loose-leaf samples. Under the same conditions (90 ºC and five minutes of infusion time) green tea contains almost twice the quantity of polyphenols and the free radical scavenging ability of black tea. In the α-glucosidase assay all infusions were active (97-100 %). Furthermore, HPLC allowed to identify some of the polyphenols present in both teas and to monitor their composition change with time. After twenty-four hours, the antioxidant activity was maintained without significant changes, but a small decrease in enzyme inhibition was observed, although this activity was still very high

Green tea- A Healthy sip.

After water, tea is the most consumed popular drink in the world. Green tea which is a leading beverage in the Far East for thousands of years is regarded as a health product. It is nothing but a non-fermented tea which contains more catechins, than black tea or oolong tea. Catechins are strong antioxidants with its additional content of certain minerals and vitamins increasing its antioxidant potential. High-molecular-weight polyphenols isolated from green tea which includesepigallocatechin 3 gallate (EGCG) constitute the most interesting components in green tea leaves. Th e aqueous extract or the major polyphenols of green tea possess cariostatic, antimutagenic, antidiabetic, antioxidant, antibacterial, anti infl ammatory, antitumor, hypocholesterolemic, as well as cancer-preventive activities in a variety of experimental animal models system and have been demonstrated in various studies.

Avaliação da genotoxicidade da Ilex paraguariensis (erva mate) pelo teste do micronúcleo / Evaluation of the genotoxicity of Ilex paraguariensis (yerba mate) by micronucleus test

A Ilex paraguariensis é espécie nativa da América do Sul. O consumo de erva mate tem sido associado ao aumento nas taxas de câncer oral, de orofaringe, esôfago e laringe. O objetivo deste estudo foi investigar o potencial genotóxico da exposição a dose única de Ilex paraguariensis através do teste do micronúcleo. Para este estudo, foram utilizados 32 ratos Wistar albinos machos e adultos, divididos em 4 grupos: A - Composto por 8 ratos que receberam infusão de chá preparado na concentração de 5% de erva mate (concentração usualmente encontrada no chá de consumo humano); B - Composto por 8 ratos que receberam chá preparado por imersão em água fria na concentração de 5% de erva mate; C - Composto por 8 ratos, os quais receberam ciclofosfamida em dose única subcutânea (50mg/kg) no primeiro dia do experimento (grupo controle positivo); D - Composto por 8 ratos, os quais receberam somente água (grupo controle negativo). Todos os animais receberam ração ad libitum. Os animais dos grupos A, B e D foram submetidos à eutanásia 48 horas após o início do experimento e os do grupo C, 24 horas após. Foi coletado material da medula óssea de cada rato após a eutanásia para realização do teste do micronúcleo em eritrócito policromático, para avaliação do grau de genotoxicidade. A mediana de micronúcleos para o grupo A (chá mate preparado com infusão) foi de 0,00, do grupo B (chá mate em imersão em água fria) foi de 0,00, do grupo C (ciclofosfamida - controle positivo) foi de 9,00, e no grupo D (controle negativo) foi de 0,00. Não se observou genotoxicidade da Ilex paraguariensis, em ambas as formas de preparo do chá, através do teste de micronúcleo, ao nível de significância de 5%.

The Ilex paraguariensis is a native species of South America. Yerba mate consumption has been associated with increased rates of oral, oropharynx, esophagus and larynx cancer. The aim of this study was to investigate the genotoxic potential of the exposure to a single dose of Ilex paraguariensis by the micronucleus test. For this study, 32 male, adult Wistar rats were used, divided into 4 groups: A - Consisting of 8 rats, which received an infusion of tea prepared at a concentration of 5% of mate (concentration usually found in human consumption of tea); B - Consisting of 8 rats, which received tea prepared immersed in cold water at a concentration of 5% of mate; C - Consisting of 8 rats, which received a single subcutaneous dose of cyclophosphamide (50mg/kg) on the first day of the experiment (positive control group); D - Consisting of 8 rats, which received only water (negative control group). All animals received food ad libitum. The animals in groups A, B and D were sacrificed 48 hours after the beginning of the experiment and group C, 24 hours after. Material from the bone marrow of each rat was collected after euthanasia to perform the micronucleus test in polychromatic erythrocyte to assess the degree of genotoxicity. The median of micronuclei for group A (mate tea prepared with infusion) was 0.00, for group B (mate tea immersed in cold water) was 0.00, for group C (cyclophosphamide - positive control) was 9.00 and for group D (negative control) was 0.00. No genotoxicity of Ilex paraguariensis was observed in both tea preparation methods by the micronucleus test at a significance level of 5%.

Preparo e caracterização de tinturas das folhas de chá verde [Camellia sinensis (L.) O. Kuntze] Theaceae / Preparation and characterization of Theaceae green tea [Camellia sinensis (L.) O. Kuntze] leaf tinctures

Tinturas preparadas com as folhas de Camellia sinensis (chá verde), foram caracterizadas visando a obtenção de extratos enriquecidos em polifenóis. As tinturas foram obtidas por meio de maceração estática da droga pulverizada, com diferentes misturas de 60, 70, 80 e 94,5% de etanol em água. Em seguida foram filtradas e, após 8 dias de extração, realizaram-se as analises: organoléptica, pH, densidade, determinação do resíduo seco, perfil cromatográfico por camada delgada, e teor de polifenóis. Os resultados demonstraram que o solvente (mistura hidroalcoólica a 60 ou 70%) extraiu a maior quantidade de constituintes químicos do chá verde; também foi o mais seletivo ao extrair, especificamente os polifenóis. Estes dados sugerem que a utilização de álcool etílico a 60 ou 70% conduz à obtenção de tinturas mais ricas em polifenóis, a partir das folhas do chá verde (C. sinensis).

In this work, we prepared and characterized Camellia sinensis leaf tinctures aiming to obtain a polyphenol-enriched extract. The tinctures were prepared through the static maceration process of the powdered drug, at different mixtures 60, 70, 80 and 94.5% of ethanol in water. The tinctures were filtered, and after 8 days of extraction, submitted to organoleptic analysis, determination of pH, density analysis, dry residue analysis, thin layer chromatographic profile and polyphenol percentage analysis. The results showed that the 60 or 70% alcohol-water mixture has the best extraction of the constituents of green tea and it was more selective to extract, specifically, the polyphenols of the plant. These data suggest the use of 60 or 70% ethanol to carry out polyphenol-enriched tinctures from green tea leaves (C. sinensis).