CONIFER SEED CONE PROANTHOCYANIDIN POLYMERS - CHARACTERIZATION BY C-13 NMR-SPECTROSCOPY AND DETERMINATION OF ANTIFUNGAL ACTIVITIES

Proanthocyanidin polymers (condensed tannins) in extracts from Picea g lauca, Pinus banksiana, Pinus nigra, Pinus ponderosa, and Pinus taeda seed cones were isolated by chromatography over Sephadex LH-20 and cha racterized by C-13 nuclear magnetic resonance (NMR) spectroscopy. Rang ing in molecular weight (MW(n)) from 1520 to 2460, the seed cone proan thocyanidins were comprised primarily of procyanidin monomer units wit h the 2,3-cis stereochemistry predominating in the heterocyclic rings. Incorporated into agar media, a proanthocyanidin polymer preparation inhibited the growth of fungal cultures of Ceratocystis coerulescens a nd Schizophyllum commune but not Trametes versicolor. However, under c onditions more representative of those found in nature, the polymer pr eparation did impart significant decay resistance to T. versicolor in wood test specimens normally susceptible to decay by this fungus. It i s apparent from these results that proanthocyanidin polymers contribut e to the natural resistance of conifer seed cones to fungal degradatio n.