Anti-inflammatory activities of crocetin derivatives from processed Gardenia jasminoides

Abstract

This study was designed to investigate changes of anti-oxidant and anti-nitric oxide (NO) production activities of Gardenia jasminoides (Gj) by roast processing, and anti-inflammatory activities of crocetin derivatives isolated from Gj. In order to evaluate anti-oxidant and anti-inflammatory activities, DPPH radical scavenging activities and inhibitory activities against lipopolysaccharide (LPS)-induced NO production were determined. Then we isolated crocin (1), gentiobiosyl glucosyl crocetin (3), and mono-gentiobiosyl crocetin (4) from the fruit of Gj, and crocetin (2) from the processed fruit of Gj (PGj) by column chromatography. Their structures were based on spectroscopic methods including IR, MS, and NMR (1D and 2D). Then we assayed contents of crocetin derivatives by HPLC analysis. These crocetin derivatives were evaluated the inhibitory activities on NO production in LPS-stimulated macrophage RAW 264.7 cells and expressions of protein and m-RNA of iNOS and COX-2 by western blot analysis and RT-PCR experiment. The DPPH radical scavenging activities were increased and NO productions in LPS-stimulated RAW 264.7 cells were decreased dose-dependently by processing. Crocin contents were decreased and crocetin contents were increased by processing in HPLC analysis. Compounds 1, 2, 3 and 4 reduced NO production in a dose-dependent manner with IC50 values of 58.9 μM (1), 29.9 μM (2), 31.1 μM (3), and 37.6 μM (4) respectively. Crocetin (2) showed the most potent anti-inflammatory activity (IC₅₀ = 29.9 μM), and compound 3 and 4 were firstly measured for inhibitory activities on NO production. Their correlation between structure and activity was not clear but the activity of aglycone type showed the most potent activity. They also suppressed the protein and m-RNA expressions of iNOS and COX-2 in LPS-activated macrophage. These results suggest that anti-oxidant and anti-NO production activities of Gj were increased by processing, and increased anti-inflammatory activities of Gj by processing were due to the increase of crocetin, the aglycone that has greater activity than crocin.