Tea Phytochemicals Review: Determination of Azorean Green Tea Prophylatic Compounds

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... Since the end of 19 th century, tea has also been produced in one single place in Europe -S. Miguel Island (Azores Archipelago, Portugal) [14,15]. Today, tea is cultivated in more than thirty countries in the world [5,16] but China remains the principal producer, followed by India, Kenia, Sri Lanka, Indonesia, Turkey, and Vietnam [2]. ...
... The infusion of the leaves of C. sinensis (frequently in the proportion of 1 g of dried leaves to 100 ml of boiling water) is also known as tea, being the most ancient and widely consumed beverage all over the world. In fact, tea has been used for centuries by ancestral cultures for its sensorial properties, relatively low retail price, stimulating effects and potential health benefits [14,15,17]. ...
... When compared to black tea, oolong tea is semifermented and presents a mixture of catechins, theaflavins and thearubigins [5]. Phenolic acids (gallic, 5-O-galloylquinic, p-coumaroylquinic, 3-O-and 5-O-caffeoylquinic acids), flavonols (quercetin, kaempferol and myricetin and their glycosides) and flavones (vitexin and isovitexin) are also commonly found in white, green, oolong and black teas [14,15,17,38]. Besides polyphenols, tea contains other compounds with considerable interest for human health such as caffeine, theophylline, theobromine and L-theanine [2]. ...
The origins of tea (Camellia sinensis (L.) O. Kuntze) are almost lost in time, with narratives that mix reality with many legends. For centuries, green tea has been widely used as food and medicine, since it provides, not only essential nutrients required for human life, but also other bioactive compounds for health promotion and disease prevention. In fact, some of these phytochemicals have served as sources of inspiration for generations of medicinal chemists, pharmacists, and nutritionists and will continue to provide humankind with valuable agents of potential use in research, prevention, and treatment of a number of chronic pathologies. The chemistry of green tea is very complex, with thousands of phytochemicals, namely phenolic compounds, methylxanthines, organic acids, fibers, free amino acids, volatiles, between other classes of compounds. The potential bioactivities ascribed to this beverage include antioxidant, antimutagenic, anticarcinogenic, antimicrobial, anti-inflammatory, hypocholesterolemic, hypoglicemic and other clinically relevant activities. Several scientific studies indicate that green tea is an excellent and inexpensive natural source of polyphenols, especially of catechins (flavan-3-ols). These compounds are well known for their strong antioxidant properties and are considered by many researchers as the main responsible for the beneficial health effects of this beverage and its derivatives (extracts). In this chapter, I pretend to emphasize the virtues of this ancient drink in the light of the modern science. Thus, I will discuss briefly the aspects of its origin, cultivation and manufacturing process and will be focused in those related to its chemical composition and bioactivities, especially antioxidant and antitumor activities.
"Normal-season" (bud plus first two leaves processed as commercial tea between Apr-Sep), "unused" (remaining leaves collected in Sep and Apr) and "off-season" (all leaves collected between Sep Apr) green tea leaves samples from Camellia sinensis were extracted by water infusion followed by solvent -solvent partition to recover catechins, that were separated and quantified by HPLC methods. Total catechins content ranged between 23.72 and 73.61 mg/g of the dry weight (DW) leaves for the off-season samples and was 97.51, 115.12 and 184.62 mg/g DW for Apr, Sep and normal-season samples, respectively. The free radical scavenging activity of the off-season samples ranged between 45 and 80%, 79-90% and 90-92% for the 25, 50 and 100 ppm concentrations, respectively, after 20-min reaction time. The other samples presented values of 87%, 91% and 94% (Sep), 88%, 92% and 93% (Apr) and 89%, 93% and 95% (normal-season), using the same conditions. Total phenolics content ranged between 43.21 and 139.02 mg of gallic acid equivalents (GAE)/g DW for the off-season samples and was 182.23, 216.05 and 22132 mg of GAE/g DW for Apr, Sep and normal-season samples, respectively. Results revealed that the unused and off-season Azorean green tea leaves (catechins-rich waste products) have potential antiradical activity that can be used for food and cosmetics preservation.
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