Beta-ecdysone

It is of interest that the structure of brassinolide resembles that of the insect molting hormone, ecdysone, which also is of plant origin. The structure of ecdysone is shown in Figure 1 and differs from the structure of brassinolide in that the orientation of the vicinal hydroxyl group at C-2 and C-3 is beta, the A/B junction is cis rather than trans as in the brassinolide structure and that ecdysone lacks the lactone oxygen in the B-ring. 

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