7-hydroxy sulfonation of liquiritigenin by recombinant SULT1A3 enzyme and HEK-SULT1A3 cells / 中国中药杂志

In this study,liquiritigenin sulfonation was characterized using recombinant human sulfotransferases( SULTs). The chemical structure of liquiritigenin sulfate was determined by ultra-high performance liquid chromatography-quadrupole time-of-flight mass spectrometry( UPLC-Q-TOF-MS/MS). Then model fitting and parameter estimation were performed using the Graphpad Prism V5 software. Various SULT enzymes( SULT1 A1,1 A2,1 A3,1 B1,1 C2,1 C4,1 E1 and 2 A1) were able to catalyze the formation of liquiritigenin-7-O-sulfate. Sulfonation of liquiritigenin-7-hydroxy( 7-OH) by these eight SULT enzymes consistently displayed the classical Michaelis-Menten profile. According to the intrinsic clearance( CLint) value,the sulfonation rates of liquiritigenin-7-OH by expressed SULT enzymes followed the following rank order: SULT1 C4 > SULT1 A3 > SULT1 E1 > SULT1 A1 > SULT1 A2 > SULT1 B1 >SULT1 C2>SULT2 A1. Further,liquiritigenin-7-O-sulfonation was significantly correlated with the SULT1 A3 protein levels( P<0. 05).Then,human embryonic kidney( HEK) 293 cells over expressing SULT1 A3( named as HEK-SULT1 A3 cells) were conducted. As a result,liquiritigenin-7-O-sulfate( L-7-S) was rapidly generated upon incubation of the cells with liquiritigenin. Consistent with SULT1 A3,sulfonation of liquiritigenin-7-OH in HEK-SULT1 A3 cells also followed the Michaelis-Menten kinetics. The derived Vmaxvalues was( 0. 315±0. 009) μmol·min-1·g-1,Kmwas( 7. 04±0. 680) μmol·L-1,and CLintwas( 0. 045±0. 005) L·min-1·g-1. Moreover,the sulfonation characters of liquiritigenin( 7-OH) in SULT1 A3 were strongly correlated with that in HEK-SULT1 A3 cells( P<0. 001).The results indicated that HEK-SULT1 A3 cells have shown the catalytic function of SULT1 A3 enzymes. In conclusion,liquiritigenin was subjected to efficient sulfonation,and SULT1 A3 enzyme plays an important role in the sulfonation of liquiritigenin-7-OH. Significant sulfonation should be the main reason for the low bioavailability of liquiritigenin. In addition,HEK-SULT1 A3 cells were conducted and successfully used to evaluate liquiritigenin sulfonation,which will provide an appropriate tool to accurately depict the sulfonation disposition of liquiritigenin in vivo.

Study on kinectics characteristics of the sulfation of apigenin by SULTIA3 / 中国生化药物杂志

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.

Metabolism profile of sulfation of chrysin in human small intestine S9 / 中国生化药物杂志

Objective To investigate the metabolic profile of chrysin in SULT1A3 and human small intestine S9.Methods After incubation of chrysin using in vitro SULT1A3 and human small intestine S9 system, high-performance liquid chromatography was utilized to determine the sulfates of chrysin.Mass spectrum(MS) were employed to elucidate the structures of metabolite.Results In the SULT1A3 with PAPS, Km were (3.06 ±1.04) and (0.41±0.06) μM, Vmax were (12.13 ±1.30) and (6.72 ±1.61) nmol/(min· mg), Vmax/Km were 3.96 and 16.39 mL/(min· mg), respectively.In the human small intestine S9 with PAPS, Km were (1.92 ±0.35) and (0.01 ±0.00) μM, Vmax were (0.52 ±0.02) and (0.08 ± 0.02) nmol/(min· mg), Vmax/Km were 0.27 and 8.00 mL/(min· mg).The metabolic behavior of chrysin in SULT1A3 and human small intestine S9 both were followed biphasic kinetics.The sulfation of chrysin in SULT1A3 showed a significant correlation with that in human small intestine S9(R2 =0.985).Conclusion The result indicates that SULT1A3 is the major enzyme to the metabolism of chrysin, human small intestine may be the main metabolic organs of chrysin.