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 (22S)-22-hydroxycampesterol (22-hydroxyCR, 22-OHCR) to (22S,24R)-22-hydroxyergost-4-en-3-one (22-hydroxy-campesta-4-en-3-one, 22-OH-4-en-3-one) and of 6-deoxoteasterone (6-deoxoTE) to 3-dehydro-6-deoxoteasterone (6-deoxo3DT, 6-deoxo3DHT) (PubMed:32146811). (22S)-22-hydroxycampesterol + O2 + reduced [NADPH--hemoprotein reductase] = (22S)-22-hydroxycampest-4-en-3-one + H(+) + 2 H2O + oxidized [NADPH--hemoprotein reductase] 6-deoxoteasterone + O2 + reduced [NADPH--hemoprotein reductase] = 3-dehydro-6-deoxoteasterone + H(+) + 2 H2O + oxidized [NADPH--hemoprotein reductase] Plant hormone biosynthesis; brassinosteroid biosynthesis. Belongs to the cytochrome P450 family.