label: a 5'-hydroxy-3'-methoxyflavone + S-adenosyl-L-methionine = a 3',5'-dimethoxyflavone + S-adenosyl-L-homocysteine + H(+)
label_lc: a 5'-hydroxy-3'-methoxyflavone + s-adenosyl-l-methionine = a 3',5'-dimethoxyflavone + s-adenosyl-l-homocysteine + h(+)