Acts on both enantiomers of limonene by their NAD-dependent epoxidation at the 1,2 double bond forming limonene-1,2-epoxide. (4S)-limonene + H(+) + NADPH + O2 = H2O + limonene 1,2-epoxide + NADP(+) (4S)-limonene + H(+) + NADH + O2 = H2O + limonene 1,2-epoxide + NAD(+) (4R)-limonene + H(+) + NADH + O2 = H2O + limonene 1,2-epoxide + NAD(+) (4R)-limonene + H(+) + NADPH + O2 = H2O + limonene 1,2-epoxide + NADP(+) Terpene metabolism; (4R)-limonene degradation; (1S,4R)-1-hydroxylimonen-2-one from (4R)-limonene: step 1/3. Belongs to the bacterial luciferase oxidoreductase family.