Reactivity of vitamin A derivatives and analogues with vitamin A antibodies

Vitamin A antibodies were obtained using retinoic acid conjugated to human serum albumin as an immunogen. The following constraints governed the reactivity of vitamin A analogues with such an anti-serum. The stereochemistry of the side chain is relatively unimportant, and 9- and 13-cis retinal react almost as well as all-trans retinal. The nature of the ring is important; all of the compounds that react readily carry a beta-ionic ring; all of the compounds bearing an aromatic ring react poorly; the two compounds that display intermediate reactivity have non-aromatic 6- and 5-membered rings, respectively.