Involved in the biosynthesis of Glycyrrhetinic acid (GA), a natural product which exhibits anti-inflammatory activity (PubMed:31138208). Catalyzes 2 successive oxidations of beta-amyrin, producing a precursor of the triterpene sweetener glycyrrhizin (PubMed:18779566). Unable to use 11-deoxoglycyrrhetinic acid or ent-kaurenoic acid as substrates (PubMed:18779566). beta-amyrin + 2 O2 + 2 reduced [NADPH--hemoprotein reductase] = 11-oxo-beta-amyrin + 2 H(+) + 3 H2O + 2 oxidized [NADPH--hemoprotein reductase] beta-amyrin + O2 + reduced [NADPH--hemoprotein reductase] = 11alpha-hydroxy-beta-amyrin + H(+) + H2O + oxidized [NADPH--hemoprotein reductase] 11alpha-hydroxy-beta-amyrin + O2 + reduced [NADPH--hemoprotein reductase] = 11-oxo-beta-amyrin + H(+) + 2 H2O + oxidized [NADPH--hemoprotein reductase] Expressed in roots and stolons. Not detected in leaves and stems. Saccharomyces cerevisiae expressing Glycyrrhiza uralensis CYP88D6 and CYP72A154, combined with the expression of Arabidopsis thaliana beta-amyrin synthase (beta-AS) and NADPH-cytochrome P450 reductase 1 (ATR1), accumulates glycyrrhetinic acid (GA) and, to lower levels, beta-amyrin; these GA production was increased in the presence of G.uralensis cytochrome b5 (GuCYB5). The CYP88D subfamily seems to be restricted to the Fabaceae. Belongs to the cytochrome P450 family.