Two new iridoid glycosides from Gardeniae Fructus

Two new iridoid glycosides, genipin 1,10-di-O-alpha-L-rhamnoside (1) and genipin 1,10-di-beta-D-xylopyranoside (2), along with thirteen known compounds (3-15) were isolated from Gardeniae Fructus. Their structures were elucidated by physical data analyses such as NMR, UV, IR, HR-ESI-MS, as well as chemical hydrolysis. All compounds were tested for their tyrosinase inhibitory and antioxidant activities. At a concentration of 25 mu M, compound 13 showed obvious mushroom tyrosinase inhibition activity with % inhibition value of 36.52 +/- 1.98%, with kojic acid used as the positive control (46.09 +/- 1.29%). At a concentration of 1 mM, compounds 8 and 9 exhibited considerable DPPH radical scavenging activities, with radical scavenging rates of 48.54 +/- 0.47%, 58.59 +/- 0.39%, respectively, with L-ascorbic acid used as the positive control (59.02 +/- 0.77%).