The Role of Oxidative Stress and Antioxidants in Liver Diseases

Abstract

A complex antioxidant system has been developed in mammals to relieve oxidative stress. However, excessive reactive species derived from oxygen and nitrogen may still lead to oxidative damage to tissue and organs. Oxidative stress has been considered as a conjoint pathological mechanism, and it contributes to initiation and progression of liver injury. A lot of risk factors, including alcohol, drugs, environmental pollutants and irradiation, may induce oxidative stress in liver, which in turn results in severe liver diseases, such as alcoholic liver disease and non-alcoholic steatohepatitis. Application of antioxidants signifies a rational curative strategy to prevent and cure liver diseases involving oxidative stress. Although conclusions drawn from clinical studies remain uncertain, animal studies have revealed the promising in vivo therapeutic effect of antioxidants on liver diseases. Natural antioxidants contained in edible or medicinal plants often possess strong antioxidant and free radical scavenging abilities as well as anti-inflammatory action, which are also supposed to be the basis of other bioactivities and health benefits. In this review, PubMed was extensively searched for literature research. The keywords for searching oxidative stress were free radicals, reactive oxygen, nitrogen species, anti-oxidative therapy, Chinese medicines, natural products, antioxidants and liver diseases. The literature, including ours, with studies on oxidative stress and anti-oxidative therapy in liver diseases were the focus. Various factors that cause oxidative stress in liver and effects of antioxidants in the prevention and treatment of liver diseases were summarized, questioned, and discussed.

Assessment of antioxidant activity of metformin in ethanol induced liver damage in Sprague Dawley rats

“…Similar increase in SOD levels expressed the antioxidant property. 12 The liver damage was assessed by histopathological scoring (HPS) on 22 nd day in all groups considering various parameters. The scoring system comprised various histological features and it suggests the extent of liver injury.…”

Antioxidative features of whey and its application in liver protection

“…Kiseonični slobodni radikali, kao što su superoksid i hidroksi radikal su kiseoničke reaktivne vrste i stvaraju se u metaboličkim procesima [3]. U reaktivne azotne vrste spadaju azot dioksid, azot oksid -radikali, i peroksinitriti koji nastaju u procesu sinteze azot oksida pomoću inducibilne azot oksid sintetaze (iNOS-inducibile nitric oxide synthase) i nikotinamid adenin dinukleotid fosfat (NADPH-nicotinamide adenine dinucleotide phosphate) oksidaze [3]. Slobodni radikali su aktivni u fiziološkim i patofiziološkim procesima, a odgovorni su za sintezu prostaglandina, fagocitozu i reakcije hidroksilacije [2].…”

“…U biološkom sistemu postoje kiseonične i azotne reaktivne vrste (ROS-reactive oxygene species) i (RNS-reactive nitrogen species) [2]. Kiseonični slobodni radikali, kao što su superoksid i hidroksi radikal su kiseoničke reaktivne vrste i stvaraju se u metaboličkim procesima [3]. U reaktivne azotne vrste spadaju azot dioksid, azot oksid -radikali, i peroksinitriti koji nastaju u procesu sinteze azot oksida pomoću inducibilne azot oksid sintetaze (iNOS-inducibile nitric oxide synthase) i nikotinamid adenin dinukleotid fosfat (NADPH-nicotinamide adenine dinucleotide phosphate) oksidaze [3].…”

“…Serije studija, izvedene in vivo i in vitro na animalnim modelima bavile su se procenjivanjem efikasnosti različitih antioksidanata u terapiji pacijenata sa različitim bolestima jetre [3].…”

“…Kao značajan antioksidans, askorbinska kiselina ima važnu ulogu u prevenciji i ublažavanju posledica oksidacionog stresa [12]. Prirodni antioksidansi prisutni su u mnogim namirnicama kao što su cerealije, voće, povrće i čajevi [3]. U tradicionalnoj ishrani mnogih naroda, prisutne su brojne hepatoprotektivne supstance, koje još uvek nisu dovoljno eksperimentalno ispitane, tako da ne znamo da li su zaista efiksne ili je to tradicionalna zabluda.…”