Effects of Near-Ultraviolet Light on Alkaloid Production in Catharanthus roseus Plants

Artificial near-ultraviolet light with a peak at 370 nm and the light of natural radiation with wavelengths between 290 and 380 nm stimulated the synthesis of dimeric indole alkaloids in intact plants of CATHARANTHUS ROSEUS. The artificial light also specifically stimulated an IN VITRO FMN-mediated, non-enzymatic coupling of vindoline and catharanthine to synthesize an iminium intermediate, the IN VIVO precursor of dimeric alkaloid synthesis. These results suggest that near-ultraviolet light is necessary for catharanthine oxidation as a trigger reaction of dimer synthesis in the plants.