[(1'E)-3'-hydroxy-3',7'-dimethylocta-1',6'-dien-1'-yl]-quinolinone B + NADPH + O2 + H(+) = [(1'E)-5'-(3',3'-dimethyloxiran-2'-yl)-3'-hydroxy-3'-methylpent-1'-en-1'-yl]-quinolinone B + NADP(+) + H2O — reaction