Involved in reduction steps of the biosynthesis of plant campesterol-derivative steroids, ending to castasterone (CS) but missing brassinolide (BL) (PubMed:32146811). Catalyzes the conversion of campesterol (CR) to (22S)-22-hydroxycampesterol (22-OHCR, 22-hydroxyCR) and of campestanol (CN) to 6-deoxycathasterone (6-deoxoCT) (PubMed:32146811). campesterol + O2 + reduced [NADPH--hemoprotein reductase] = (22S)-22-hydroxycampesterol + H(+) + H2O + oxidized [NADPH--hemoprotein reductase] campestanol + O2 + reduced [NADPH--hemoprotein reductase] = 6-deoxycathasterone + H(+) + H2O + oxidized [NADPH--hemoprotein reductase] Plant hormone biosynthesis; brassinosteroid biosynthesis. Belongs to the cytochrome P450 family.