Antioxidative activities and components of Gardenia jasminoides

From the total methanolic extract of Gardenia jasminoides (Rubiaceae), various antioxidative characteristics were identified in terms of nitrite scavenging ability, 2,2′-azino-bis (3-ethylbenzthiazoline-6-sulphonic acid) (ABTS) radical cation inhibition, superoxide dismutase (SOD)-like activity, and elongation effect of lipid peroxidation using Rancimat. After successive partitioning with n-hexane, chloroform, n-butanol, and water, potent nitrite scavenging abilities were shown in the n-butanol fraction and water fraction, and IC₅₀ values were 183 ppm and 194 ppm, respectively. As for ABTS radical cation inhibition, the chloroform fraction was most potent and its IC₅₀ was 159 ppm. SOD-like activity was slightly low in all of the fractions. The elongation effect of lipid peroxidation also increased dose-dependently and the antioxidative index (AI) of the total methanolic extract was 2.93 in 1000 ppm, which was more effective than 1.66 of butylated hydroxy anisol in the same concentration. The compounds I and II were isolated through silica gel column chromatography of the active fractions, and identified as geniposide and crocin, respectively, by ¹H-NMR spectral data. The IC₅₀ values for the nitrite scavenging abilities of geniposide and crocin were 940 ppm and 77 ppm, respectively. In ABTS radical cation inhibition, the IC₅₀ values of geniposide and crocin were 684 ppm and 549 ppm, respectively. And the EC₅₀ value for SOD-like activity of crocin was 259 ppm, which was much smaller than 453 ppm by the positive control, chlorogenic acid. The EC₅₀ value of geniposide could not be identified.