Abstract
Calystegia soldanella (Convolvulaceae), Vitex rotundifolia (Verbenaceae) and Lathyrus japonicus (Leguminosae) are originally growing in coast, but they are also native to inland Lake Biwa. The seashore is a harsh environment for plants to inhabit due to various stresses, e.g. sea water and strong UV radiation. Flavonoids are one of the most effective anti-stress substances that are synthesized in plants. In this survey, the flavonoid compounds of C. soldanella, V. rotundifolia and L. japonicus were qualitatively and quantitatively compared with those of inland Lake Biwa populations. In coastal C. soldanella, the content of quercetin glycosides having ortho-dihydroxyl groups in B-ring were from ca. 4.5 to 10.5 fold than those of kaempferol glycosides having mono-hydroxyl group in B-ring. On the other hand, inland populations were from 0.8 to 1.8 fold. The flavonoids of V. rotundifolia were qualitatively and quantitatively the same with both sites. In contrast, those of L. japonicus were qualitatively different.
