Bifunctional oxidoreductase probably ables to act both on prenyl naphthoquinones and on prenyl benzoquinones (PubMed:26023160). Catalyzes the penultimate step in the biosynthesis of vitamin K1 (PubMed:26023160). demethylphylloquinone + H(+) + NADPH = demethylphylloquinol + NADP(+) Binds 1 FAD per subunit. Inhibited by dicumarol. kcat is 3.2 sec(-1) for menadione. Cofactor biosynthesis; phylloquinone biosynthesis. Increased photosensitivity to high light. Belongs to the NADH dehydrogenase family.