label: rhamnetin + S-adenosyl-L-methionine => 3',4',5-trihydroxy-3,7-dimethoxyflavone + S-adenosyl-L-homocysteine + H(+)
label_lc: rhamnetin + s-adenosyl-l-methionine => 3',4',5-trihydroxy-3,7-dimethoxyflavone + s-adenosyl-l-homocysteine + h(+)