1-hydroxy-3-{[2-(1,1-dimethylallyl)-indol-3-yl]methyl}-6H,7H,8H-5lambda(5)-pyrrolo[1,2-a]pyrazine + NADPH + H(+) = 1-hydroxy-3-{[2-(1,1-dimethylallyl)-indol-3-yl]methyl}-4H,6H,7H,8H-pyrrolo[1,2-a]pyrazine + NADP(+) — reaction