Hepatoprotective effect of quercetin: From chemistry to medicine

Liver diseases caused by viral hepatitis infections have a negative impact on global health. Approximately 30 million people in the USA and 29 million people in the European Union suffer from chronic liver disease. There are many kinds of diseases of the liver, caused by viruses, such as hepatitis A, hepatitis B and hepatitis C, or by certain drugs and poisons including excessive alcohol consumption. Many herbal medicines are used in traditional medicine for their protective and therapeutic properties against liver diseases. Among their bioactive components, flavonoids have been found to be active against liver dysfunction and damage caused by liver diseases. Extensive evidences report that quercetin (QE), a major flavonol commonly found in apple, berries, onion, citrus fruits, cruciferous vegetables, tea, pepper, tomato, whole gain, cocoa and red wine, displays a wide range of healthy properties, including anti-oxidative, anti-inflammatory, anti-apoptotic and hepatoprotective activities against various hepatic ailments. This review aims to critically analyze the available literature regarding the hepatoprotective effects of QE with special emphasis on its mechanisms of actions. To provide a complete picture of QE, its distribution, chemistry, biosynthesis and bioavailability are reported. Overall, data in literature shows that QE appears to be a promising hepatoprotective compound.