Isolation and characterization of antioxidative monoterpenes from Cynanchum atratum roots.

One novel monoterpene rhamnoside (1) and 7 known monoterpenes (2-8) were isolated from the ethanol extract of Cynanchum atratum for the first time. Their structures were identified by comprehensive spectroscopic data analysis such as nuclear magnetic resonance, high-resolution electrospray ionization mass spectra, optical rotatory dispersion, and acid hydrolysis. In the subsequent antioxidant assay, compound 8 exhibited obvious 2,2-diphenyl-2-picrylhydrazyl hydrate radical scavenging activity.

Two new iridoid glycosides from Gardeniae Fructus.

Two new iridoid glycosides, genipin 1,10-di-O-α-l-rhamnoside (1) and genipin 1,10-di-O-ß-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 µM, 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%).