Naturally Occurring Coumaranochroman-4-Ones: A New Class Of Isoflavonoids From Lupins And Jamaican Dogwood

Abstract

A further investigation of the isoflavonoid components of Piscidia erythrina, Lupinus alhus and L. luteus has revealed the presence of 3-hydroxy- and 3-methoxy-coumaranochroman- 4-ones. These compounds are the first known representatives of a new type of naturally occurring isoflavonoid. Using a combination of chemical and spectroscopic methods, the com pounds were identified as 3,5,7,4′-tetrahydroxy-5′-methoxy-3′-(3,3-dimethylallyl)coumaranochroman- 4-one (piscerythrol, 1), 3,5,7,4′-tetrahydroxy-6,3′-di(3,3-dimethylallyl)coumaranochroman- 4-one (lupinol A, 3), 5,7,4′-trihydroxy-3-methoxy-6,3′-di(3,3-dimethylallyl)- coumaranochroman-4-one (lupinol B, 6) and 3,5,7,4′-tetrahydroxy-6-(3,3-dimethylallyl)- coumaranochroman-4-one (lupinol C, 7). All four isoflavonoids were found to have the cis relative configuration at C-2/C-3. Possible biogenetic relationships between the coumaranochroman- 4-ones and other isoflavonoids (isoflavones and coumaronochrom ones) found in Piscidia and Lupinus are briefly discussed