Antioxidant components and activity in the peel of Ziziphus Jujuba Mill.

The aim of the present study was to compare the antioxidant components and antioxidant activity of the raw and cooked peel of Ziziphus Jujuha Mill. The peel was analyzed for polyphenols, glutathione and tannin contents. In addn. methanol and aq. exts. were analyzed for flavonoid, saponin contents and antioxidant activity. The antioxidant activity of exts. was detd. by DPPH and reducing power assay. Polyphenol and tannin contents were significantly (p<0.05) higher in the raw peel (1.67 ± 0.07 and 7.69 ± 0.09 g/100g resp.), while glutathione (GSH) content of cooked peel (125.75 ± 5.04 I¼Mol/100g) was significantly (p<0.05) higher than raw peel (99.49 ± 8.84 I¼Mol/100g). The methanolic ext. of raw peel had the highest flavonoid and total saponin content (3.52 ± 0.02 and 83.07 ± 3.39 g/100g resp.). The steroidal saponins content (6.13 ± 0.63 g/100g) was higher in the hot aq. ext. (HA) of cooked peel. It was found that antioxidant activities of all the exts. increased with increasing concn. except in HA of raw peel. In the raw peel, methanolic ext. with highest antioxidant capacity revealed the same antioxidant activity as compared to std. of butylated hydroxytoluene (BHT). The three exts. of cooked peel were found to be significantly (p<0.01) inferior in antioxidant efficacy than BHT. Reducing power assay indicated varying degrees of efficacy in a dose-dependent manner in all peel exts. HA ext. was the most potent antioxidant in the raw and cooked exts. Data indicates the raw and cooked peel of Ziziphus Jujuba Mill. have a great potential for utilization as a source of natural antioxidant. [on SciFinder(R)]