Anthocyanins are flavonoids that are responsible for blue, purple and red color of berries and many other plants. But they also posses strong antioxidant action and can help to protect cells against oxidative damage caused by free radicals. They could be used to treat diseases were free radical formation is involved. Cyanidin and its glycoside cyanidin 3-O-beta-D-glucoside showed protective effect on DNA cleavage and significantly inhibited xanthine oxidase acticity. It also showed a dose dependent free radical scavenging activity . Important is that this antioxidant effect of cyanidin occurs at pharmacological concentrations .
Seeram et al. found that antioxidant capacity of anthocyanins of cherries is superior to vitamin E and similar to other commercial antioxidants. The anthocyanins cyanidin-3-glucosylrutinoside and cyanidin-3-rutinoside were both present in cherries and raspberry. Blackberries and strawberries contained only cyanidin-3-rutinoside, whereas bilberries, blueberries, cranberries and elderberries did not contain either cyanidin glycosides. They also found that the anthocyanins from sweet cherry and raspberry showed cyclooxygenases inhibitory activities, comparable to those of the anti-inflammatory drugs ibuprofen and naproxen . Amorini et al. also confirmed the strong antioxidant capacity of cyanidin. Cyanidin-3-O-beta-glucopyranoside, the main anthocyanin of pigmented oranges, inhibited lipid peroxidation, as measured by malondialdehyde production. This antioxidant acidity was stronger than that of ascorbic acid and resveratrol. The antioxidant activity was not influenced by pH, indicating that cyanidin did not act by chelating metal ions. Cyanidin 3-O-beta-glucopyranoside quickly neutralizes reactive oxygen species such as hydrogen peroxide, reactive oxygen and hydroxyl radical. Feeding of cyanidin 3-O-beta-D-glucoside to rats increased oxidation resistance of the serum and reduced the generation of thiobarbituric acid reactive substances (low molecular weight end products, mainly malondialdehyde, that are formed during the decomposition of lipid peroxidation products). Cyanidin 3-O-beta-D-glucoside significantly inhibited lipid peroxidation initiated by 2,2'-azobis(2-amidinopropane)hydrochloride or cupper .
Liver fibrosis is a chronic liver disease characterized by replacement of liver tissue by fibrous scar tissue as well as regenerative nodules leading to progressive loss of liver function. Liver fibrosis is mainly caused by alcoholism and hepatitis C. Reactive oxygen species can activate stellate cells, which are fat-storing cells. When activated, the stellate cells proliferate and start forming collagen scar tissue, which can lead to cirrhosis and formation of scar tissue. Bendia et al tested in-vitro the effect of cyanidin 3-O-beta-glucopyranoside hepatic stellate cells proliferation and collagen production. They induced oxidative stress in hepatic stellate cells by incubating them with the pro-oxidant agent ferric nitrilotriacetate, which induces intracellular hydroperoxide formation, cell proliferation and activation of extracellular signal-regulated kinase 1/2. The cyanidin glycoside inhibited the formation of hydroperoxide, cell proliferation and activation of the kinase. It also reduced the production of type I collagen. Bendia et al concluded that this cyanidin glycoside may have a role in the prevention of liver fibrosis .
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 Bendia E, Benedetti A, Baroni GS, Candelaresi C, Macarri G, Trozzi L, Di Sario A. " Effect of cyanidin 3-O-beta-glucopyranoside on hepatic stellate cell proliferation and collagen synthesis induced by oxidative stress." Dig Liver Dis. 2005 May;37(5):342-8.