ABSTRACT
Objective To investigate the kinectics characteristics of sulfation of apigenin mediated by SULTIA3.Methods After incubation of apigenin using in vitro SULT1A3 system, high-performance liquid chromatography was utilized to determine the sulfates of apigenin.Mass spectrum(MS) were employed to elucidate the structure of metabolite.The program GraphPad Prism 5 was used to perform the kinetic characterization of SULT1A3 catalyzed metabolism of apigenin.Results A liner calibration curve for the assay of apigenin was validated in the range of 0.15625 ~30 μM with the recoveries of at least 80% and intra-day and inter-day RSD of less than 15%.Metabolic product of apigenin and SULT1A3 in the incubated system was identified one monosulfate.The metabolic behavior of apigenin in SULT1A3 was followed substrate inhibition kinetics.Apparent kinetic parameters of metabolism of apigenin by SULT1A3, Kmwas(0.355 ±1.04) μM and Ksi was(23.62 ±0.06) μM,Vmax was(65.71 ±1.30) nmol/(min? mg),Vmax/Km was 185.10 mL/(min? mg).Conclusion SULT1A3 can mediate the binding of apigenin sulfonated reaction, and the character of enzymatic kinetics shows substrate inhibition.Sulfation of apigenin mediated by SULTIA3 may play an important role in phaseⅡmetabolic in vivo.