Photochemical transformation of 20-hydroxyecdysone:: production of monomeric and dimeric ecdysteroid analogues

Structural modification of 20-hydroxyecdysone (20E) based on photochemical trans formation yielded dimeric ecdysteroid 7alphaH,7'alphaH-bis-[(20R,22R)-20,3p,2beta,3beta,20,22,25-pentahydroxy-5beta-cholest-8(14)-en-6-one-7-yl] as a main product. Its structure was determined by detailed NMR analysis. Furthermore, two new monomeric analogues: 14-epi-20-hydroxyecdysone and 14-deoxy-14,18-cyclo-20-hydroxyecdysone were identified in addition to the earlier described 14-deoxy and t4-hydroperoxy derivatives of 20E. Formation of the specific and so far unique ecdysteroid dimer has not been observed in earlier photo-transformation studies. The transformed dimeric analogue of 20-hydroxyecdysone retained the high agonistic activity on the ecdysone receptor in the B-II-bioassay compared with the original 20E. (C) 2002 Elsevier Science Inc. All rights reserved.