Two Different Pathways Leading to Phenanthrenes and 9,10-Dihydrophenanthrenes of the Genus Dioscorea

Abstract

The bibenzyl batatasin III was formed de novo in aerial bulbils and tubes of Dioscoreaceae from dihydro-m-coumaric acid. In cell-free preparations, bibenzyl synthase activity and an O-methyltransferase converting 3,3′,5-trihydroxybibenzyl into batatasin III were detected. High rates of incorporation of dihydro-m-coumaric acid into a 9 ,10-dihydrophenanthrene (hircinol) showed that a pathway being known to occur in orchids is also effective in Dioscoreaceae. The biosynthesis of hircinol could be stimulated by infecting the aerial bulbils with various fungi. In parallel to the dihydro-w-coum aric acid pathway another biosynthetic reaction sequence leading to phenanthrenes was found to occur. The pathway was established in its principal steps: p-coumaric acid - trihydroxystilbene (resveratrol) - phenanthrene (batatasin I or iso-batatasin I)