Green tea produced from Camellia sinensis is a popular beverage and is consumed worldwide. Green tea produced from Camellia leaves are mainly consumed in East Asian countries including China, Japan and Taiwan; whereas in western parts and south Asian countries, black tea is relatively popular (Chan, et.al. 2011). Green tea produced from Camellia is believed to have several health benefits. The tea from Camellia mainly contains flavanols or catechins, epigallocatechins, epicatechin gallate and epicatechin. The tea is manufactured in such a way that the catechin oxidation by polyphenol oxidase is prevented (Chan, et.al. 2011). Although all of these components in green tea are reported to have several health benefits, in this study only the role of epicatechin in green tea from Camellia has been extensively reviewed. Epicatechin is a strong antioxidant, which has been suggested to have several health benefits (Ravindranath, et.al. 2009).
1.1. Project Aims
Considering the antioxidant activities of epicatechin content in Camellia sinensis, and having reviewed available literature on the subject area, this project therefore aims to; identify and quantify epicatechin content in herbal supplements by using standard compound. Understand and evaluate the antioxidant property of the standard compound that has been reported to be the antioxidant activity of the supplements. These aims were targeted with the views to providing clearer understanding of the role of antioxidants, present in green tea, as well as the health benefits associated to it.
1.2 Standardization of plant extracts
Herbal supplements are the complex mixtures containing organic chemicals derived from different plant sources including leaves, stems, flowers, roots and seeds. Although most herbal supplements and their compounds present in them are safe, many have been reported to have biologically active compounds that can alter several physiological processes within the body, as well as may interact with drugs. Thus, it is important to know the presence of active ingredients in the herbal supplement (Bent, 2008). Moreover, plant extracts are found to be rich in free radical and reactive oxygen species that are implicated in the alterations of various metabolic processes, and may lead to human diseases (Cases, et.al. 2010). Information on the biologically active compounds in herbal products will also help consumers in many aspects. Higher therapeutics effects can be seen in standardized extracts compared to the whole herb or non-standardized extracts; this is because, active principal is concentrated to a much higher level in the extracts than in the plant itself. Thus, purchasers of herbal products will get health benefits if extracts are standardized (Cases, et.al. 2010).
Antioxidants are the compounds that are commonly derived from enzymes such as superoxide dismutase, catalase, and glutathione peroxidase and glutathione reductase; from minerals such as selenium, manganese, copper and zinc; as well as naturally from A, C and E vitamins (Lobo, et.al. 2010). Natural antioxidants are commonly found in plants consumed in the diet including carotenoids and phenolic compounds.
Moreover, plants contain high concentrations of numerous antioxidants that include polyphenols, carotenoids, tocopherols, tocotrienols, glutathione and ascorbic acid (Charles, 2013). Their most important role in the body is to protect cells against the effects of free radicals. Free radicals are the unstable molecular species containing an unpaired electron that are able to exist independently. Most of these species are highly reactive and are potentially damaging to the cells (Lobo, et.al. 2010).
Some of the common oxygen- free radicals that are involved in many human diseases include hydroxyl radical, superoxide anion radical, hydrogen peroxide, oxygen singlet, hypochlorite, nitric oxide radical, and peroxynitrite radical. Increased levels of these reactive species in the body cells induce damage of the DNA, proteins, carbohydrates and lipids. Thus, a balance between free radicals and antioxidants is necessary for proper physiological function (Lobo, et.al. 2010). Any dis-balance in this may result the initiation of various diseases including cancer, vascular diseases and degenerative diseases. Hence, the study of antioxidants and their sources have been the focus of intense research.
1.4. Brief information on herbal supplements to use in the project
This project studies the presence of epicatechin content in Camellia sinensis; thus, the project uses herbal capsules from Camellia sinensis as herbal supplements. Camellia sinenis is taken as green tea and contains antioxidants in it, which is why it is commonly used in herbal medicine. Epicatechin is abundantly found in Camellia sinensis herbal supplement. Cameillia sinensis also contains various active compounds as extracts. Some of the major active compounds found in Camellia sinensis include catechins, caffeine, flavonols and proanthocyanidins (Charles, 2013). The health benefits of green tea (Camellia sinensis) epicatechins are being extensively studied and explained . Endothelial cells are associated to vascular function and homeostasis whose dysfunction may have implication in cardiovascular disease including atherogenesis. (Moore, et.al. 2009). Moreover, some studies suggest their anticancer role by enchaining apoptosis (Ravindranath, et.al. 2009). With findings emerging from several new studies regarding the health benefits of the green tea from Camellia sinensis, it is being increasingly popular among the people.
Simple and reliable techniques will be chosen in this project to investigate epicatechin content in Camellia sinenis. Experiments will be carried out using reflux extraction to determine the biologically active compounds present in the test supplement (herbal capsules from Camellia sinensis). This will be confirmed by NMR analysis. NMR analysis will be done to confirm that determination of correct biological compound including antioxidants from Camellia sinensis. Crude extract will be made from the material extracted from herbal capsules using a suitable solvent under reflux, which will then be run on thin layer chromatography (TLC) to see if a corresponding band for the standard also appears in the extract. This will tell whether or not the compound is present in the extract, as the study of organic compounds present in the supplement of Camellia sinensis can be made using this technique. To cut of the evaporation time, rotary evaporation method will be employed while evaporating the solvent. Reverse phase analytical high performance liquid chromatography (HPLC) will be used to identify the standard compound in the extract and then to quantify the amount of compound in it. Finally, the antioxidant assay will be carried out to determine the antioxidant activity of the extracted compound; as a control, plant Flavonoid quercetin, which has antioxidant activity, will be used.
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