label: 3',4',5,7-tetrahydroxy-3-methoxyflavone + S-adenosyl-L-methionine => 3,3'-O-dimethylquercetin + S-adenosyl-L-homocysteine + H(+)
label_lc: 3',4',5,7-tetrahydroxy-3-methoxyflavone + s-adenosyl-l-methionine => 3,3'-o-dimethylquercetin + s-adenosyl-l-homocysteine + h(+)