Cytochrome P450 monooxygenase; part of the gene cluster that mediates the biosynthesis of the asperterpenoids, sesterterpenes that exhibit anti-tuberculosis activity (PubMed:30548032). The first step of the pathway is performed by the sesterterpene synthase astC that possesses both prenyl transferase and terpene cyclase activity, converting isopentenyl diphosphate and dimethylallyl diphosphate into geranylfarnesyl diphosphate (GFPP) and further converting GFPP into preasperterpenoid A, respectively (PubMed:30548032). The cytochrome P450 monooxygenase astB then dually oxidizes preasperterpenoid A to produce asperterpenoid A along with a minor product, asperterpenoid B (PubMed:30548032). Finally, the cytochrome P450 monooxygenase astA converts asperterpenoid A into asperterpenoid C (PubMed:30548032). 4 O2 + preasperterpenoid A + 4 reduced [NADPH--hemoprotein reductase] = asperterpenoid A + 5 H(+) + 5 H2O + 4 oxidized [NADPH--hemoprotein reductase] asperterpenoid A + 2 O2 + 2 reduced [NADPH--hemoprotein reductase] = asperterpenoid B + 3 H(+) + 3 H2O + 2 oxidized [NADPH--hemoprotein reductase] Secondary metabolite biosynthesis; terpenoid biosynthesis. Asperterpenoids A and B, but not the final product asperterpenoid C, exhibit potent inhibitory activity against Mycobacterium tuberculosis protein tyrosine phosphatase B with IC(50) values of 3 to 6 uM. Belongs to the cytochrome P450 family.