Radical Scavenging Glycoprotein Inhibiting Cyclooxygenase-2 and Thromboxane A2Synthase fromAloe veraGel

An acitve glycoprotein fraction containing 58 % protein was isolated from Aloe vera gel by precipitation with 55 % ammonium sulfate followed by gel permeation using DEAE-Sephacel A-25, Sepharose 6B and Sephadex G-50 columns in a yield of 3 × 10 -3 %. The glycoprotein fraction showed a single band corresponding to a subunit of verectin at the same position when stained with both Coomassie brilliant blue and periodic acid-Schiff reagents on 18 % SDS-PAGE. The molecular weight (14 kDa) was confirmed by Sephadex G-50 column chromatography. The glycoprotein fraction showed a radical scavenging activity against superoxide anion generated by the xanthine-xanthine oxidase system as well as inhibition of cyclooxygenase-2 and reduction of thromboxane A 2 synthase level in vitro . Abbreviations BPB:bromo phenol blue BSA:bovine serum albumin CBB:coomassie brilliant blue DMPO:5,5-dimethyl-1-pyrroline N -oxide EDTA:edetic acid GSH:glutathione NBT:nitro blue tetrazolium SDS-PAGE:sodium dodecylsulfate polyacrylamide gel electrophoresis XOD:xanthine oxidase