Heme-containing cytochrome P450 involved in the biosynthesis of soyasaponins. Hydroxylates specifically the C-24 methyl group of the triterpenes beta-amyrin and sophoradiol. No activity with lupeol, butyrospermol, tirucalla-7,21-dien-3beta-ol, taraxasterol, psi-taraxasterol, bauerenol, alpha-amyrin and multiflorenol as substrates. beta-amyrin + O2 + reduced [NADPH--hemoprotein reductase] = 24-hydroxy-beta-amyrin + H(+) + H2O + oxidized [NADPH--hemoprotein reductase] O2 + reduced [NADPH--hemoprotein reductase] + sophoradiol = H(+) + H2O + oxidized [NADPH--hemoprotein reductase] + soyasapogenol B Belongs to the cytochrome P450 family.