Human intestinal bacterium, strain END-2 is responsible for demethylation as well as lactonization during plant lignan metabolism.

A human intestinal bacterium, strain END-2, which enantioselectively oxidizes (+)-enterodiol (END) to (+)-enterolactone (ENL) through enterolactol is also responsible for demethylation during plant lignan metabolism. A free hydroxyl group adjacent to the methoxy group is required for demethylation. The bacterium transformed (+)- and (-)-secoisolariciresinol to (+)-ENL and (-)-END, respectively, by co-incubation with strain ARC-1, which is responsible for dehydroxylation.