Radical Scavenging Glycoprotein Inhibiting Cyclooxygenase-2 and Thromboxane A₂ Synthase from Aloe vera Gel

Abstract

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 A₂ 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

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