Reductase involved in lignan biosynthesis (PubMed:26359402). Also involved in the biosynthesis of etoposide, a chemotherapeutic compound of the topoisomerase inhibitor family (PubMed:26359402). Catalyzes the enantioselective sequential conversion of (+)-pinoresinol into (+)-lariciresinol and of (+)-lariciresinol into (-)-secoisolariciresinol (PubMed:26359402). Abstracts the 4R-hydride from the NADPH cofactor during catalysis (PubMed:26359402). (-)-secoisolariciresinol + NADP(+) = (+)-lariciresinol + H(+) + NADPH (+)-lariciresinol + NADP(+) = (+)-pinoresinol + H(+) + NADPH Aromatic compound metabolism; phenylpropanoid biosynthesis. Dimer. Expressed in rhizomes, stems, and leaves. Transiently induced after wounding and by jasmonic acid (MeJA) (PubMed:26359402, PubMed:23653238). After an exposition to UV-light, first transiently induced before fading out (PubMed:23653238). Combinatorially expression of Sinopodophyllum hexandrum (mayapple) genes of the podophyllotoxin pathway (e.g. DIR, PLR, SDH, CYP719A23, OMT3, CYP71CU1, OMT1, 2-ODD, CYP71BE54 and CYP82D61) in Nicotiana benthamiana (tobacco) results in the production of the chemotherapeutic compound etoposide. Belongs to the NmrA-type oxidoreductase family. Isoflavone reductase subfamily.