Abstract
Various amides of tetrahydroabietic, Δ8-dihydroabietic, abietic and dehydroabietic acids were prepared and tested for hypocholesterolemic activity in cholesterol-fed rats. The introduction of an aromatic ring into the amine moiety of secondary amides markedly enhanced the activity of the parent acids. The secondary amides having an aliphatic ring were slightly less active than those having an aromatic ring, but those having an alkyl or allyl group were completely inactive. Tetrahydroabietic and dihydroabietic acids appear to be preferable (in terms of activity) to abietic or dehydroabietic acid as the acid moiety of these amide derivatives. N-Phenyltetrahydro (18)- or N-phenyl-Δ8-dihydroabietamide (19) and N-benzyltetrahydro (20)- or N-benzyl-Δ8-dihydroabietamide (21) are considered to be promising parent compounds for potent hypocholesterolemic drugs. In the case of benzyl derivatives of Δ8-dihydroabietamide, N-(4-methoxybenzyl)-Δ8-dihydroabietamide (49) and N-(α-benzylbenzyl)-Δ8-dihydroabietamide (58) were the most active, being more than 10 times as potent as the corresponding parent compounds.
