ABSTRACT
Ecdysteroids are chiral, and therefore rotate the plane of polarized light. Measurements of the optical activity of ecdysteroids have usually been made in methanolic solution using the sodium D line. The Ultraviolet absorption of the ecdysteroids, due to the unsaturated carbonyl in the B ring, results in two cotton effects. The amplitude of the positive cotton effect can be used to obtain structural information about the A/B ring fusion. The Optical Rotatory Dispersion curves of most ecdysteroids are superimposable, since the majority of ecdysteroids differ in regions distant from the six-one. The amplitude of the cotton effects for trans ring-fused ecdysteroids is greater than that for the corresponding cis fused compounds. Mass Spectrometry (MS) has been invaluable in the elucidation of ecdysteroid structure. It has been particularly useful for insect samples containing low levels of ecdysteroids as MS requires only small quantities of material.
