label: 3',4',7-trihydroxyflavone + S-adenosyl-L-methionine <=> 4',7-dihydroxy-3'-methoxyflavone + S-adenosyl-L-homocysteine + H(+)
label_lc: 3',4',7-trihydroxyflavone + s-adenosyl-l-methionine <=> 4',7-dihydroxy-3'-methoxyflavone + s-adenosyl-l-homocysteine + h(+)