PHARMACOLOGICAL ACTIVITIES OF THE PRENYLCOUMARINS, DEVELOPED FROM FOLK USAGE AS A MEDICINE OF PEUCEDANUM-JAPONICUM THUNB

In connection with the chemical structure of coumarin 1 (a mixture of acetylangeloylkhellactone and acetyltigloylkhellactone), a compound isolated from Peucedanum japonicum THUNB., we synthesized eight coumarin compounds (3-10) and performed pharmacological studies on, these nine compounds, as well as on another coumarin, praeruptorin A (= Pd-Ia) (2), a compound isolated from Peucedanum praeruptorum DUNN. We studied the effects of compounds 1-5 on isolated smooth muscle and of compounds 1-10 on the cardiovascular system. These compounds showed dose-related antagonistic effects on histamine- and Ca2+-induced contractions in smooth muscle and the potencies were in the order 2 > 1 > seselin (3) > xanthyletin (4) = 2,2,10-trimethyl-2H,8H-benzo[1,2-b:3,4-b']dipyran-8-one (5). All the compounds except 7-geranyloxy-4-methylcoumarin (10) produced a dose-related increase in vertebral, carotid and femoral blood flow. Compounds 1, 5, and 4-methyl-7-(3-methyl-2-butenyloxy)coumarin (8) caused an increase in blood pressure, but 3 and 4 caused a slight decrease. Compounds 2, 3, 4, 5, and 8 increased heart rate. Jatamansinone (6) and jatamansinol (7) caused only slight changes in blood pressure. All the compounds except 10 increased heart rate. Compound 1 also increased blood flow in the cerebral cortex. Thus, compound 1 was confirmed to have an inhibitory effect on contraction in isolated smooth muscle and an action increasing arterial blood flow. Among the compounds tested in this study, 3, as well as 6 and 7 synthesized on the basis of 3, showed actions similar to those of Ca2+ blockers and some compounds had papaverine-like activities. These results suggest that the chemical moiety of compound 3 may be the basis for the pharmacological activities of Peucedanum japonicum THUNB.