Antioxidant and Hepatoprotective Effects of Cyathea phalerata Mart. (Cyatheaceae)

The present study investigated the antioxidant properties of Cyathea phalerata Mart. (Cyatheaceae) using in vitro and in vivo assays. The in vitro antioxidant potential of the crude extract (CE), precipitate (PPT), aqueous fraction (AQF), n-butanolic fraction (BUF) and ethyl acetate fraction (EAF) from C. phalerata was evaluated through the scavenging of diphenyl-1-picryl-hydrazyl-hydrate (DPPH), superoxide anion (O 2 • − ) (nitroblue tetrazolium assay) and hydroxyl radicals (OH • ) (deoxyribose assay), and lipid peroxidation in rat liver homogenate. In these assays, it was observed that EAF had marked antioxidant potential, especially as a scavenger of the OH • radical and in inhibiting lipid peroxidation. The in vivo evaluation of oxidative stress (DNA fragmentation, membrane lipoperoxidation and carbonyl protein formation) and the antioxidant defenses (concentration of reduced glutathione, as well as catalase and glutathione S-transferase activities) were measured in mice pre-treated with EAF (10, 30 or 100 mg/kg, orally) and later exposed to carbon tetrachloride (CCl 4 ). The EAF decreased thiobarbituric acid reactive substances levels, DNA damage and carbonyl protein contents, and increased catalase and glutathione S-transferase activities. Based on these results, it is concluded that the EAF from C. phalerata protects liver from oxidative stress induced by CCl 4 in mice and these effects are probably related to the antioxidant activity associated with the free radical scavenging property of this fraction. Cyathea phalerata Mart. (Cyatheaceae) is a tree fern that grows in the tropical and subtropical areas of Brazil and is commonly known as 'xaxim'. In folk medicine, its stem pith is used to treat several inflammatory diseases and the alco- hol extract of the pith is used for the treatment of varicose veins and hemorrhoids. In phytochemical studies of Cyathea genus, several classes of compounds were identified such as fernene, filicene and hopane triterpenes (1,2), phenolic acids (coumaric and caffeic), protocatechuic acids and flavonoids, mainly kaempferol glycosides (3-5). In a recent study, Pizzolatti et al . (6) isolated the cyathenosin A, a spiropyranosil derivative of protocatechuic acid, from the stem pith of C. phalerata . Studies on the pharmacological effects of C. phalerata are still limited. However, recently, Cazarolli et al . (7) demonstrated that the flavonoid, kaempferol-3- neohesperidoside, isolated from C. phalerata , has a hypogly- caemic effect in diabetes induced by alloxan in rats. Flavonoids exhibit a wide range of biological effects, includ- ing antibacterial, anti-inflammatory, anti-allergic, hepato- protective, antithrombotic, antiviral, anticarcinogenic and vasodilatory actions; many of these biological functions have been attributed to the free radical scavenging and antioxidant activity of these compounds (8-10). Oxidative stress plays an important role in the pathogenesis of several human pathologies, including ischaemia and reperfusion injury, atherosclerosis, neurodegenerative diseases and cancer (11). The excess of reactive oxygen species (ROS) can damage cellular lipids, proteins or DNA, thereby inhibiting their normal function (12). Thus, oxidative stress has been implicated in a number of human diseases as well as in the ageing process (11). Owing to the relative inefficiency of our endogenous defence systems and the existence of some pathophysiological situations (cigarette smoke, air pollutants, ultraviolet radiation, inflammation, ischaemia/ reperfusion, etc.) in which ROS are produced in excess and at the wrong time and place, dietary antioxidants are needed to diminish the cumulative effects of oxidative damage over the life span (13). In this regard, there has been a great deal of interest in the screening and characterization of novel, potentially therapeutic herbal products. Therefore, the aim of the present study was to investigate the antioxidant activity ( in vitro and in vivo ) of the crude extract and fractions obtained from C. phalerata .