Antioxidant properties of oleanolic acid from grape peel
The consumption of grape (Vitis labrusca B.) is associated with various health benefits. It is considered as good source of health benefiting phytochemicals such as phenolic compounds, having antioxidant properties. In this study 429 mg of oleanolic acid was obtained from 50 g of dried grape peel by using silica gel column chromatography. Methanol, ethyl acetate and n-hexane were used as solvents. 1H-NMR, 13C-NMR and EI-MS spectra were used for structure elucidation and identification of purified compound. Oleanolic acid from Vitis labrusca B. peel showed good antioxidant properties such as ferric acid reducing (0.77 FRAP value), lipid peroxidation inhibition (24.66%) and DPPH radical scavenging (85.3%). The antioxidant properties of oleanolic acid were comparable with those of commercial antioxidants.
Due to increasing health consciousness and more demand for natural products, bioactive compounds from plant sources can be incorporated in the diet or can be applied as natural therapeutic alternatives. In this context, terpenoids can be regarded as one of the most effective compounds because they possess strong pharmacological properties. Oleanolic acid is one type of triterpenoid from natural sources. It can be categorized as aglycone consisting of various saponins. Chemically it is described as 3β-hydroxy-olea-12-en-28-oic acid. Figure 1 shows the chemical structure of oleanolic acid. It is present in different types of foods such as vegetable oils, winter savory (1), and in the roots and leaves of Olea europaea, Viscum album L., Aralia chinensis L. It is estimated that this compound in present in plant species of 120 types (2-4). It is attributed to possess different pharmacological properties that include anti-inflammatory (5), anti-hyperlipidemic (6), antiulcer (7), antioxidant activity (8), hepatoprotective (9), anti-HIV (10), antimicrobial (11); anti-tumor (12) and hypoglycemic (13) properties, all of which are important for human h ...