Phenolics from Larix needles. XII. Seasonal variation of main flavonoids in leaves of L. leptolepis

The metabolic fate of six flavonoids during development and growth of larch needles wai investigated. One flavonoid, dihydroquercetin, appeared to be a special bud-flavonoid. Four compounds were isolated both from buds and leaves, a maximum concentration was found in developing young leaves. A sixth flavonoid, kaempferol-3-(p-coumarylglucoside), was nearly absent in the buds, its highest concentration in the leaves occurred about two months later than that of the other compounds. Only one compound, naringenin-7-glucoside, tended to reaccumulate in late summer.