Involved in the biosynthetic pathway of maesasaponins, which are oleanane-type saponins with diverse biological activities (PubMed:25578277). Catalyzes the C-16alpha oxidation of beta-amyrin to form 16alpha-hydroxy-beta-amyrin (PubMed:25578277). beta-amyrin + O2 + reduced [NADPH--hemoprotein reductase] = 16alpha-hydroxy-beta-amyrin + H(+) + H2O + oxidized [NADPH--hemoprotein reductase] Belongs to the cytochrome P450 family.