4',7,8-trihydroxyflavone + S-adenosyl-L-methionine <=> 7,8-dihydroxy-4'-methoxyflavone + S-adenosyl-L-homocysteine + H(+)
4',7,8-trihydroxyflavone + s-adenosyl-l-methionine <=> 7,8-dihydroxy-4'-methoxyflavone + s-adenosyl-l-homocysteine + h(+)
4',7,8-trihydroxyflavone + S-adenosyl-L-methionine <=> 7,8-dihydroxy-4'-methoxyflavone + S-adenosyl-L-homocysteine + H(+)
4',7,8-trihydroxyflavone + s-adenosyl-l-methionine <=> 7,8-dihydroxy-4'-methoxyflavone + s-adenosyl-l-homocysteine + h(+)