2.1. Chemicals
Gallic acid (GA), methyl gallate (MEGA) and protocatechuic acid
(PCA) were purchased from Bomei biotechnology Co., LTD, 4-(2-
hydroxyethyl)-1-piperazineethanesulfonic acid (Hepes) and 3-(NMorpholino)
propanesulfonic acid (Mops) were obtained from
Amersco (Beijing, China). Stock Fe3+ solution was freshly prepared
in dilute anaerobic HCl solution (pH 2.00). All other reagents used
were of analytical grade or purer.