3',5-dihydroxy-3,4',7-trimethoxyflavone + S-adenosyl-L-methionine <=> 5-hydroxy-3,7,3',4'-tetramethoxyflavone + S-adenosyl-L-homocysteine + H(+)
3',5-dihydroxy-3,4',7-trimethoxyflavone + s-adenosyl-l-methionine <=> 5-hydroxy-3,7,3',4'-tetramethoxyflavone + s-adenosyl-l-homocysteine + h(+)