Synthesis of stable genipin derivatives and studies of their neuroprotective activity in PC12 cells.

Modifications at C1, C7, C8, and C10 of genipin were conducted, and the neurotrophic effects of all derivatives were studied. Genipin derivatives 1-4 were obtained in mild to high yield. Compounds 1 and 4 are more stable than genipin if exposed to nucleophiles. All the derivatives display higher neurotrophic activities than genipin. Compound 4 is the most active, with the least optimal dose. Both genipin and 4 up-regulated the activity of nNOS in PC12 cells. The effect of 4 is inhibited not only by 7-NI, a specific inhibitor of nNOS, but also by L-NIO, a specific inhibitor of eNOS; in the case of genipin, its effect is only inhibited by 7-NI. All the results indicate that 4 is a promising lead compound for the development of new drugs in the treatment of neurodegenerative diseases with the ability to address multiple drug targets.