Seasonal changes in the tannins of Liquidambar formosana reflecting their biogenesis

Fractionation of the tannins in the leaf of Liquidambar formosana collected at different seasons showed that tellimagrandin II is the main component in early spring, while casuarinin and pedunculagin are the main tannins in autumn. Hydrolysable tannins structurally related to them, tellimagrandin I, casuariin, 1,2,4,6-tetra-O-galloyl-β-D-glucose and casuarictin were isolated from the leaf collected in November, and 1,2,6-tri-O-galloyl-β-D-glucose from the leaf in May. From HPLC analyses of leaf extracts collected from April to November, it was clear that the composition changes most rapidly in the spring. The seasonal changes in the structures and amounts of these hydrolysable tannins indicate a particular biogenetic pathway for these substances.