Persimmon leaves, which are a good source of important dietary antioxidants, such as vitamin A & C, and flavonoids, have been widely used as a tea in oriental countries. In particular, several tannins and flavonoids isolated from persimmon leaf were recently found to have antihypertensive, anticarcinogenic, and antimutagenic actions. It is highly possible, therefore, that persimmon leaves may be developed into potential sources of natural antioxidants and therapeutic drugs. We have selected persimmon cultivar suitable for manufacturing persimmon leaf tea, through the experimental methods described below.
Our objectives were to determine the levels of antioxidative substances in thirteen different cultivars of persimmon leaf during growth, and further to investigate their antioxidative activities.
The antioxidative substances of persimmon leaves were quantified by using HPLC, and the antioxidative activities of their methanol extracts were evaluated by using rat liver microsomal lipid peroxidation induced by 2,2'-azobis(2-amidino -propane) dihydrochloride(AAPH) and FeSO4/H2O2.
The total soluble phenol, L-ascorbic acid and flavonoid contents of astringent persimmon leaves were higher than those of nonastringent persimmon leaves, although thier contents vary considerably with cultivar and growth. "Kojongsi" and "Bansi" persimmon leaves harvested at the early stage of growth(6/4) had greater total souble phenol, L-ascorbic acid and flavonoid contents, and antioxidant activities than other persimmon leaves. Fermented persimmon leaves had lower the L-ascorbic acid and flavonoid contents, and especially a greater reductions were detected in steamed persimmon leaves and dried persimmon leaves.
These results suggest that astringent persimmon leaves may be useful as potential sources of natural antioxidants. In particular, "Kojongsi" and "Bansi" persimmon leaves harvested at the early stage of growth can be used as a source of persimmon leaf tea.