Antioxidant, inhibition of alpha-glucosidase and suppression of nitric oxide production in LPS-induced murine macrophages by different fractions of Actinidia arguta stem

In traditional systems of medicine, fruits, leaves, and stems of Actinidia arguta (Sieb. et Zucc.) Planch. exMiq. have been used to treat various inflammatory diseases. The present study determined the proximate composition, antioxidant, anti-inflammatory, and hypoglycemic potential of A. arguta stem. Phenolic composition of hot water extract and its sub-fractions was determined by Folin-Ciocalteu's reagent method. In vitro antioxidant activities of the samples were evaluated using 1,1-diphenyl-2-picrylhydrazyl (DPPH) and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS) radical scavenging assays. Anti-inflammatory activity of different fractions was investigated through the inhibition of nitric oxide (NO) production in lipopolysaccharide (1 mu g/ml) stimulated RAW 264.7 cells. In addition, inhibition of alpha-glucosidase activity of hotwater extract was determined using p-nitrophenyl-a-Dglucopyranoside (pNPG) as a substrate. Ethyl acetate (557.23 mg GAE/g) fraction contains higher level of total phenolic content. The antioxidant activity evaluated by DPPH radical scavenging assay showed a strong activity for ethyl acetate (IC50 of 14.28 mu g/ml) and n-butanol fractions (IC50 of 48.27 lg/ml). Further, ethyl acetate fraction effectively inhibited NO production in RAW 264.7 cells induced by lipopolysaccharide (LPS) than other fractions (nitrite level to 32.14 mu M at 200 mu g/ ml). In addition, hot water extract of A. arguta stemexhibited appreciable inhibitory activity against alpha-glucosidase enzymewith IC50 of 1.71 mg/ ml. The obtained results have important consequence of using A. arguta stem toward the development of effective anti-inflammatory drugs. (C) 2014 Production and hosting by Elsevier B. V. on behalf of King Saud University.