TOXIC PIPERIDINE ALKALOIDS FROM PINE (PINUS) AND SPRUCE (PICEA) TREES- NEW STRUCTURES AND A BIOSYNTHETIC HYPOTHESIS

A series of 2,6-disubstituted piperidine alkaloids have been isolated from several Pinus (pine) and Picea (spruce) species and characterized structurally. The pines appear to contain only cis-disubstituted pipe ridines, while the spruces contain both cis- and trans-disubstituted p iperidines. The structural relationships among the alkaloids suggest a plausible biosynthetic scheme and a reason why previous attempts to e lucidate the biosynthesis of pinidine failed beyond establishing its p olyketide origin. A mixture of alkaloids from needles of Pinus pondero sa proved to be highly teratogenic. The alkaloids might therefore be i nvolved in so-called pine needle abortion which occurs in pregnant ran ge cows which feed on Ponderosa pine needles.