Catalyzes C3-oxidation steps in brassinosteroids biosynthesis (PubMed:22822057). Converts (22S)-22-hydroxycampesterol (22-OHCR) to (22S,24R)-22-hydroxyergost-4-en-3-one (22-hydroxy-campesta-4-en-3-one, 22-OH-4-en-3-one), 6-deoxocathasterone (6-deoxoCT) to (22S,24R)-22-hydroxy-5alpha-ergostan-3-one (22-hydroxy-campesta-3-one, 22-OH-3-one), (22R,23R)-22,23-dihydroxycampesterol (22,23-diOHCR) to (22R,23R)-22,23-dihydroxy-campest-4-en-3-one (22,23-diOH-4-en-3-one), and 6-deoxoteasterone (6-deoxoTE) to 3-dehydro-6-deoxoteasterone (6-deoxo3DT, 6-deoxo-3-DHT) (PubMed:22822057). (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] 6-deoxycathasterone + O2 + reduced [NADPH--hemoprotein reductase] = (22S,24R)-22-hydroxy-5alpha-ergostan-3-one + H(+) + 2 H2O + oxidized [NADPH--hemoprotein reductase] (22R,23R)-22,23-dihydroxycampesterol + O2 + reduced [NADPH--hemoprotein reductase] = (22R,23R)-22,23-dihydroxycampest-4-en-3-one + H(+) + 2 H2O + oxidized [NADPH--hemoprotein reductase] kcat is 0.74 min(-1) for (22S)-22-hydroxycampesterol (PubMed:22822057). kcat is 0.11 min(-1) for (22R,23R)-22,23-dihydroxycampesterol (PubMed:22822057). Plant hormone biosynthesis; brassinosteroid biosynthesis. A number of isoforms are produced. According to EST sequences. Dwarf plants containing severely reduced levels of castasterone (CS) and brassinolide (BL) and of their precursor molecules. Belongs to the cytochrome P450 family.