Abstract
Known for many years as miracoulous plant, Aloe possesses many pharmaceutical activities, including laxative, antiinflammatory, immunostimulant, antiseptic, wound and burn healing, antiulcer, antitumor, and antidiabetic in which the mediation of the ROS levels could be involved. In order to evaluate the antioxidant potential of the plant, in the first part of this study, the antioxidant activities of the water extracts prepared separetely from the pulp and gel parts of the plant leaves, were evaluated by using several antioxidant tests. The present study demonstrated that the water extract from Aloe leaves pulp contained naturally occurring antioxidant components, including ascorbic acid, beta-carotene, alpha-tocopherol, phenols and flavonoids. It was concluded that Aloe leaf pulp aqueous extract exhibited an inhibitory capacity against posphatidylcholine liposome peroxidation, induced with iron and ascorbic acid, scavenged ABTS, DPPH and superoxide radicals and acted as reductant and thus can be used as natural antioxidant source in contrast, Aloe vera gel did not show any antioxidant activity as determined by DPPH radical scavenging test. In the second part of the study, a single lectin from the leaf pulp of Aloe vera was isolated by ammonium sulphate precipitation and affinity chromatography on cyanogen bromide activated Sepharose 4B coupled to ovalbumin. Native and SDS polyacrylamide gel electrophoresis were used to determine the degree of purity of the lectin and the apparent molecular weight. The molecular weight of the subunits of the purified lectin, migrating as one band in native PAGE was determined by SDS polyacrylamide gel electrophoresis. The lectin did not show any antioxidant activity as determined by the DPPH radical scavenging test.