HPLC Analyses of Compounds in Spring and Summer Leaves. In our previous study, carpinins A (4), B (5), C (6), and D (7) were isolated from leaves of C. japonica collected in June (Figure 2). However, HPLC analyses of the fresh young leaves collected in April revealed that tannins 1 and 2 were the major tannins (Figure 1). In mature leaves collected in August, tannins 1 and 2 had almost disappeared and 3, 4, 5, and the uncharacterized tannin 3 were the major components.