Flavonoids are formed in plants from the aromatic amino acids phenylalanine and tyrosine and malonate. Among the many classes of flavonoids, those of particular interest to this review are flavones, flavanones, isoflavones, flavonols, flavanonols, flavan-3-ols and anthocyanidins. Other flavonoid classes include biflavones, chalcones, aurones, and coumarins. Hydrolysable tannins, proanthocyanidins (flavan- 3-ol oligomers), caffeates, and lignans are all plant phenols and they are usually classified separately.
Natural products have shown great promise in combating against the toxicity of several commonly used drugs, including acetaminophen. Additionally, some of these natural products, such as resveratrol and curcumin, are now widely accepted chemopreventive agents. Due to easy availability and dietary nature, it is time to promote the natural products as supplementary medication with drugs that also cause toxicity to cells. Use of herbs in treatment of various liver disorders is common in China. Now these medicines are being gradually accepted worldwide, particularly in Asia, Europe and North America. Nevertheless, the application strategy may differ in East and West due to variety of reasons, such as, philosophical viewpoint, concept of diseases, and treatment approaches . A variety of dietary plants including grams, legumes, fruits, vegetables, tea as well as wine contain antioxidants. The prophylactic properties of dietary plants have been attributed to the antioxidants / polyphenols present in them. Polyphenols with over 8000 structural variants are secondary metabolites of plants and represent a huge extent of substances having aromatic ring(s) bearing one or more hydroxyl moieties . Polyphenols are effective ROS scavengers and metal chelators because of the presence of multiple hydroxyl groups. Examples of polyphenolic natural antioxidants derived from plant sources include vitamin E, flavonoids, cinnamic acid derivatives, curcumin, caffeine, catechins, gallic acid derivatives, salicylic acid derivatives, chlorogenic acid, resveratrol, folate, anthocyanins and tannins . Apart from polyphenols there are also some plant derived non-phenolic secondary metabolites such as melatonin, carotenoids, retinal, thiols, jasmonic acid, eicosapentaenoic acid, ascopyrones and allicin that show
In husks and skins of oilseeds, the same sub- stances are usually present as those in kernels, and different tannins and proanthocyanidins are also present. Several types of proanthocyanidins and flavonoids were identified in peanut skin (LOU et al. 2004). High molecular weight oleoresins found on the surfaces of oilseeds are co-extracted with phenolics and contribute significantly to the antioxidant activity of the extracts (MURPHY et al. 1993). Rapeseed hulls have a high content (between 2–6 %) of condensed tannins (AMAROWICZ et al. 2001; NACZK et al. 2000). Peanut hulls (skins) are a particularly rich source of phenolics, containing tannins, procyanidins, catechin and epicatechin oli- gomers, resveratrol, and other phenolic substances (KARCHESY & HEMMINGWAY 1986). Sunflower seed shells are rich in chlorogenic acids; caffeic acid can be isolated from the aqueous-ethanolic extract after saponification (DELEONARDIS et al. 2005). Hazelnut hulls contain high concentrations of phenolics (MOURE et al. 2003).
In the study entitled “Quantitative estimation of antioxidants in five native tuber crops in Kerala”, antioxidants named alkaloid, flavonoid, phenol, saponin, tannin and terpenoid were quantitatively estimated in five native tubers namely, Amorphophallus paeoniifolus, Maranta arundinacea, Plectranthus rotundifolius, Colocasia esculenta and Dioscorea alata. In this study, it was found that Amorphophallus paeoniifolus showed high amount of phenol (0.1785mg/100g) and flavonoid (203mg/100g). Both were found to be less in Colocasia esculenta (0.0468mg/100g and 0.1785mg/100g respectively). The highest amount of saponin was found in Maranta arundinacea (47.873mg/100g) and it was less in Amorphophallus paeoniifolus (6.61mg/100g). High amount of alkaloid was present in Plectranthus rotundifolius (876.98mg/100g) and was less in Dioscorea alata (464.93mg/100g). The high amount of terpenoid was found in Plectranthus rotundifolius (102.573mg/100g) and was found to be less in Colocasia esculenta (15.581mg/100g). There has been growing evidence that oxidative stress and specific human diseases can be prevented by including in the diet plant foods that contain large amounts of antioxidants such as vitamins C, E or natural antioxidants such as flavonoids, tannins, coumarins, phenolic and terpenoids (Perumalla & Hettiarachchy, 2011). These compounds play an important role in plant growth and reproduction, providing an efficient protection against pathogens and predators. So the above mentioned tubers should be included in our daily diet according to their antioxidant property.
Among the non-enzymic antioxidants that were studied, vitamin C, flavonoids and tannins were found to be present in an excess amount in aril when compared with the rind. However, poylphenols and vitamin E were found to be increased in rind than aril. The high content of antioxidant activity in Punica granatum indicates that they may impart health benefits when consumed and should be regarded as a valuable source of antioxidants.
In the present report, we examined mitochondrial ROS production in cultured cells under three pathophysiologi- cally relevant situations where mitochondrially generated oxidative stress is directly related to cell death: oxidative glutamate toxicity, state IV respiration (respiration in the absence of ADP) artificially induced with oligomycin, and tumor necrosis factor α (TNFα)-induced cell death. We also tested the effectiveness of various antioxidants on ROS generation and cell death under these situations. It is shown that the mitochondrial sites of ROS generation are stressor-specific and that the accessibility of antioxidants to ROS generated at each site within the ETC is distinct. Based on these results and other evidence in the literature, it is inferred that there are at least four ROS-generating sites in the mitochondrial ETC in living cells: the FMN group of complex I and the three ubiquinone-binding sites in complexes I, II and III.
Oxidative injury contributes to pathophysiology of Schizophrenia, which is indicated by the increased lipid peroxidation products and a decrease in antioxidants namely vitamin C, vitamin E, whole blood Glutathione and β-Carotene. The oxidative damage that occurs in schizophrenic patients exhausts the antioxidant defense of the body leading to low levels of antioxidants. Intense oxidative stress and decreased antioxidants in Schizophrenia can be recognised as a modifiable risk factor and in turn new modalities can be formed to decrease the severity of the disease by dietary intervention and lifestyle modification.
10) Lipoic acid, an endogenous antioxidant, is a sulphurcontaining molecule that catalyzes the oxidative decarboxylation of alpha-keto acids, such as pyruvate and alpha- ketoglutarate, in the Krebs cycle. Lipoic acid and its reduced form, dihydrolipoic acid (DHLA), quench free radicals in both lipid and aqueous domains and hence is called as a “universal antioxidant.”Lipoic exert its antioxidant effect by chelating with prooxidant metals. Research further suggests that lipoic acid has a sparing effect on other antioxidants.  Animal studies have demonstrated supplemental lipoic acid to protect against the symptoms of vitamin E or vitamin C deficiency. 
stress can be counteracted by the presence of molecules called antioxidants which are of natural or synthetic sources. But due to the adverse side effects of synthetic antioxidants, search for effective and natural antioxidants has become crucial 3,4 . Several epidemiological studies suggest that plants
Many dietary antioxidants may contribute to cellular protection against radicals and other ROS. Many food products are rich sources of antioxidants. The main source of antioxidants in food are fruit and vegetables containing vitamins C and E, selenium and carotenoids such as beta-carotene, lycopene, lutein and zeaxanthin. Vitamin E (8 structural isomers of tocopherols/tocotri- enols) is one of the most widely distributed antioxidants in nature; α–tocopherol is the best known and shows the most antioxidant activity. 12 Vitamin E can to some degree
A litterbag experiment was conducted to investigate the changes of tannins and nutrients in branchlets at different decomposition stages of Casuarina equisetifolia in southern subtropical coastal zone, China, using the colorimetric assays. The time required for the loss of half of the initial dry weight (t 50 ) was 9.13 months. Total phenolics (TP), extractable condensed tannins (ECT), protein-bound condensed tannins (PBCT), total condensed tannins (TCT) and protein precipitation capacity (PPC) of branchlets litter decreased rapidly, while fibre-bound condensed tan- nins (FBCT) increased during decomposition. Nitrogen and phosphorus concentration of the branchlet litter both increased gradually during decay. Negative correlations between TP and nitrogen or phosphorus, as well as TCT and nitrogen or phosphorus were found. These chemical changes enhanced the current knowledge on the potential ecological role of nutrient transformation in tannins in C. equisetifolia plantations.
The present study, report the phytochemical analysis and invitro antimalarial activity of plants Acalypha indica (L.) and Cocculus hirsutus (L.). The A. indica and C. hirsutus plant was collected from Kadaparajupalle at Dornalamandal, Prakasam district, Andhra Pradesh, India. Leaf, stem bark and root crude extracts prepared in Soxhlet apparatus with chloroform, ethyl acetate and methanol solvents. The preliminary phytochemical screening of these extracts was conducted by following the standard methods. These extracts were tested for in vitroanti malarial activity against 3D7 and K1 strains of Plasmodium falciparum by standard laboratory protocol. In vitrocyto toxicity of the extracts was also tested by following standard laboratory method. The phytochemical screening has revealed the presence of alkaloids, saponins, terpenoids & steroids, tannins, anthocyanidins, phenolic compounds, coumarins, quinones, resins and glycosides. Amongst all the extracts screened for antimalarial activity, the leaf chloroform and ethyl acetate extracts of A. indica shown IC 50 values of 3.34 µg/mL and 3.71 µg/mL respectively against 3D7 strain; the leaf chloroform and ethyl acetate extracts of A. indica shown IC 50 values of 1.47 µg/mL and 2.32 µg/mL respectively against K1 strain; the root chloroform and methanol extracts of C. hirsutus shown IC 50 values of <0.78 µg/mL and 3.714 µg/mL respectively against 3D7 strain; the root chloroform and methanol extracts of C. hirsutus shown IC 50 values of <0.78 µg/mL and 2.10 µg/mL respectively against K1 strain. Thus, the above extracts have shown very active antimalarial activity against 3D7 and K1 strains. And all the extracts were non-toxic showing CC 50 values of >20 µg/mL against Vero cell line. The presence of high alkaloids, flavonoids and terpenoids of the plant extracts suggest their antioxidant potential and justifies their therapeutic action which could be used for the drug formulation. The chloroform root extract of C. hirsutus has shown excellent antimalarial activity which can be used for the development of new antimalarial drug policies.
Vegetable tannins are natural polyphenols ubiquitously distributed in plants, frequently occurring in a variety of foods such as vegetables, fruits, seeds, and plant-derived beverages. Commercially tannins are used in the wine industry for a multitude of reasons: to stabilize the color of red wines, to ensure palate balance and complexity in wines, to inhibit lacasse in botrytis- infected fruit and to serve as fining agents to reduce protein concentrations .
Oxidative stability and consistency of the grease matrix control a wide variety of per- formance properties in grease lubrication . In particular, phenolic antioxidants boast greater benefits when added into grease, since they themselves make stable radicals that help to terminate chain reactions while they donate hydrogen atoms . Most phenolic How to cite this paper: Hussein, M.F.,
In studies of red wine grapes, tannins derived from different parts of the berry have been characterised by their molecular mass and subunit composition, and these properties have been found to influence aspects of wine character such as flavour, mouth-feel and colour stability of the wine (Somers, 1971, Vidal et al., 2004b, Ducasse et al., 2010a, Mercurio et al., 2010, McRae and Kennedy, 2011). The presence of seeds in the must of Pinot Noir ferments compensates for the low concentrations of tannin in the skin and these seed- derived tannins are likely to have a central role in colour stability and mouth feel of the wine. The relative contribution of anatomically distinct berry tissues (skin, seed, pulp) to wine quality has been difficult to differentiate because of the disruption of the component tissues caused by de-stemming and crushing prior to vinification. By contrast, the phenolic composition of wine grapes has been assessed using a range of different extraction techniques and solvents (Saint-Criq et al., 1998, Cayla et al., 2002, Iland et al., 2004, Sarneckis et al., 2006) however, studies have shown that less than 50% of the grape tannin becomes incorporated into the wine (Harbertson et al., 2002, Adams and Scholz, 2008). In order to more accurately predict the proportion of tannin extracted from grapes to wine, grape tannin extraction during fermentation have been explored using a more wine-like medium, for example consisting of 12% aqueous ethanol, sulphur dioxide and tartaric acid, adjusted to pH 3.2, (Mattivi et al., 2009). However, Scollary (2010) cautioned that a wine- like medium did not account for changing sugar concentration and temperature variability that occurs during fermentation.
Qualitative phytochemical screening of Gbolo species was carried out on the powdery samples, after extraction with aqueous solvent, using the standardly employed precipitation and coloration reactions as described by Houghton and Raman  and Dougnon et al.. Major secondary metabolites essayed and the methods used were as follow: Alkaloids (Mayer’s test), Quinone derivatives (born-trager reaction), Cathetic tannins (stiasny test), Gallic tannins (ferric chloride test after saturation with sodium acetate), Flavonoids (shinoda test and magnesium powder), Cyanogenic derivatives (picric acid test), Triterpenoids (acetic acid test + mixture of acetic an hydride and sulfuric acid), Steroids (kedde reaction), Saponins (test index foam), Cardiac glycosides (Raymond Marthoud reaction), Anthocyanins (test with hydrochloric acid and ammonia diluted to half), Leucoanthocyanes (shinoda test), Mucilage (test of absolute alcohol), Reducing compounds (test with fehling’s solution), Coumarins (test with ether andammonia), Free anthracene derivatives (test with chloroform andammonia), Combined anthracene derivatives (test with chloroform andammonia).
mainly VEGFR2 (Flk-1/KDR), and angiopoietin-I/Tie-2 receptors. The major source of ROS in endothelial cells is the enzyme NAD(P)H oxidase, but the role of nitric oxide (NO • ), from endothelial nitric oxide synthase (eNOS), should not be neglected. Moreover, oxidized phospholipids and products from arachidonic acid metabolism can participate in angiogenesis induction. Then, it would be likely that antioxidants could inhibit angiogenesis. Really, a number of studies demonstrated that several antioxidants found in natural products (catechins from teas, resveratrol, polyphenols, flavonoids, isoflavones, lycopene, pigment epithelium- derived factor, glutathione); nutritional components (vitamins C, D, E, β-carotene and selenium); and semi-synthetic and synthetic compounds (N-acetylcysteine, L-NAME, L-NIO, sodium piruvate, pyrrolidine dithiocarbamate, and organoselenium compounds) were able to inhibit angiogenesis. These compounds were tested in several in vitro assays and in vivo animal models and inhibited angiogenesis via redox-sensitive and insensitive mechanisms. Thus, the consumption of antioxidants from natural sources can be recommended in face to benefic effects related to angiogenesis inhibition, while high fat diet can be undesired. In addition, some semi-synthetic and synthetic compounds has potential as future drugs for inhibiting tumoural angiogenesis, but it needs more detailed studies in terms of efficacy and security.
The present study was aimed to investigate the pharmacognostical, phytochemical, in-vitro toxicity and in-vitro hepatoprotective activity of Bridelia tomentosa root. Pharmacognostical and phytochemical analysis were carried out as per standard procedures. In-vitro toxicity study was performed using MTT assay on BRL3A cell line. In-vitro hepatoprotective activity was performed using MTT assay on paracetamol treated BRL3A cell line. The phytochemical screening showed the presence of different phytoconstituents. Petroleum ether extracts showed the presence of phytosterols, gums and mucilage’s. Chloroform extracts showed the presence of glycosides and steroids. Methanol extract showed the presence of saponins, tannins, phenolic compounds and flavonoids. HPLC analysis showed the presence of various phytochemical. However, Gallic acid, Rutin and Quercetin were the major phytochemical. The CTC 50 of Bridelia tomentosa root was greater than 1000 µg/ml.