Involved in the biosynthesis of (+)-sesamin, a furofuran class lignan (PubMed:16785429). Functions in a dual catalytic mode (PubMed:16785429). Catalyzes the synthesis of (+)-sesamin from (+)- pinoresinol by formation of two successive methylenedioxy bridges on (+)-pinoresinol and (+)-piperitol, respectively (PubMed:16785429). (+)-piperitol + O2 + reduced [NADPH--hemoprotein reductase] = (+)-sesamin + H(+) + 2 H2O + oxidized [NADPH--hemoprotein reductase] (+)-pinoresinol + O2 + reduced [NADPH--hemoprotein reductase] = (+)-piperitol + H(+) + 2 H2O + oxidized [NADPH--hemoprotein reductase] Expressed in seeds and leaves. Belongs to the cytochrome P450 family.