Sulfotransferase(SULT) for DDI Research, Metabolic Stability, and Enzyme Inhibition

Key words: drug-drug interaction (DDI), sulfotransferase (SULT), enzyme inhibition, SULT metabolic, metabolic stability, human SULT1A1 enzyme, human SULT1A3 enzyme, human SULT1B1 enzyme, human SULT1C2, human SULT1C4 enzyme, human SULT1E1 enzyme, human SULT2A1 enzyme

1 IPHASE Produces

2 Enzymatic Research in Drug Development

In drug development, the study of metabolic phenotypes and enzyme inhibition of metabolic enzymes such as CYP450, UGT, SULT, etc. is crucial. Metabolic phenotype research uses in vitro models combined with LC-MS/MS technology to identify the main metabolic pathways, key metabolic enzymes, and their kinetic parameters (such as Km/Vmax) of drugs, and evaluate the impact of gene polymorphism on personalized medication. Enzyme inhibition research focuses on the inhibitory effects of drugs or compounds on metabolic enzymes (such as reversible/irreversible inhibition), measuring IC50/Ki values to predict drug-drug interaction (DDI) risk. These studies provide scientific basis for optimizing drug design, evaluating safety (such as identifying toxic metabolites), and guiding precision medication. The core challenge lies in the conversion of in vitro to in vivo data and the detection sensitivity of low abundance metabolites. In the future, advanced models such as organoids can be used to further enhance research reliability.

3 Sulfotransferase (SULT)

Sulfotransferase (SULT) is a type of transferase that catalyzes the transfer of sulfate groups and is involved in the metabolism of endogenous compounds (such as hormones and neurotransmitters) and exogenous compounds (such as drugs and environmental pollutants). Sulfotransferases are mainly located in the cytoplasm and Golgi apparatus, involved in the sulfation of small molecule substrates (such as drugs, hormones, neurotransmitters) and large molecules (such as peptides, proteins, lipids, glycosaminoglycans). Sulfotransferases have been identified to have multiple subtypes, mainly including SULT1, SULT2, and SULT4. Dysfunction of sulfotransferase can lead to abnormal drug metabolism, cancer, endocrine disorders, and neurological disorders.

4 Sulfation/Sulfonation Metabolism

Sulfonation metabolism (also known as sulfation metabolism) plays an important role in the in vivo disposal of drugs and is an important foundation for new drug development and rational clinical drug use. Human sulfotransferase (also known as sulfatase) has a wide range of substrates in the body, mainly distributed in organs such as the liver, small intestine, kidneys, and lungs. Common human SULTs include SULT1A1, SULT1A3, SULT1B1, SULT1C2, and SULT1C4 (table 1). For most substrates, sulfotransferase mediated metabolism often exhibits typical substrate inhibition characteristics; Low substrate concentration levels typically induce enzyme expression.

Table 1 The distribution and function of the partly SULT superfamily in the human body

5 Key Applications of SULT in Drug Development

5.1 In Vitro Evaluation of DDI Based on Metabolism

The in vitro evaluation of SULT mediated DDI is mainly carried out through selective inhibitors (such as quercetin, DCNP) or recombinant enzyme systems in human hepatic cytoplasm or cell models expressing specific SULT subtypes. Experimental design typically includes:

Metabolic phenotype analysis: Quantify the rate of sulfated metabolite generation by LC-MS/MS and calculate the inhibition rate (IC50/Ki value).

Clinical risk prediction: If the inhibitor significantly reduces metabolite production (inhibition rate>50%), it suggests that it may interfere with the clearance of drugs dependent on SULT metabolism, and further in vivo validation is needed.

5.2 SULT Metabolic Stability Study

In drug development, the study of SULT metabolic stability is conducted through in vitro incubation (hepatic cytoplasm/APS) combined with LC-MS/MS analysis to determine drug sulfation rate and metabolite generation, identify key SULT subtype contributions, evaluate metabolic clearance risks, and guide structural optimization.

5.3 Metabolic Substrate Research

The substrate research method (metabolic pathway identification method) of SULT can directly refer to the design of CYP enzymes, which first uses chemical inhibition to screen for relevant subtypes, and then verifies them with gene recombinases and calculates their relative contribution.

The main principle and technical route of the chemical inhibition test of SULT is to evaluate whether maternal metabolism or metabolite production is inhibited by modifying the selective inhibitors Quercetin and DCNP of SULT in the human hepatic cytoplasm system.

5.4 Enzyme Inhibition Research

SULT is involved in the metabolism of multiple endogenous substances and drugs. If drugs are being developed to inhibit the activity of SULT, there may be potential safety issues when sharing drugs. The main principle and technical route of SULT enzyme inhibition assay is to use a SULT pure enzyme system to detect whether the production of metabolite p-nitrophenol sulfate is inhibited by adding investigational drugs and probe substrates such as p-nitrophenol.

6 Conclusion

Sulfotransferase (SULT) plays a critical role in drug metabolism, drug-drug interactions (DDI), and safety assessment. The sulfation metabolism mediated by it affects drug clearance, activation, or toxicity (such as the metabolism of hormone drugs and environmental pollutants), while enzyme inhibition studies can predict clinical DDI risk. By combining in vitro models (liver cytoplasm, recombinant enzymes) with LC-MS/MS technology, the metabolic contributions of SULT subtypes (such as SULT1A1, SULT2A1) can be clarified, guiding drug structure optimization and personalized medication. In the future, advanced models such as organoids will further enhance the translational value of SULT research, providing more accurate evaluation criteria for metabolic stability and safety in drug development.

Reference

Li, Y., Lindsay, J., Wang, L. L., & Zhou, S. F. (2008). Structure, function and polymorphism of human cytosolic sulfotransferases. Current drug metabolism, 9(2), 99-105.