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.
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