Highly lipophilic 3-epi-betulinic acid derivatives as potent and selective TGR5 agonists with improved cellular efficacy
Abstract
Xiao-yin WANG, Shu-yong ZHANG, Jing LI, Hua-nan LIU, Xin XIE*, Fa-jun NAN*
State Key Laboratory of Drug Research, CAS Key Laboratory of Receptor Research, the National Center for Drug Screening, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, China
Aim: TGR5 is a G protein-coupled receptor that is expressed in intestinal L-cells and stimulates glucagon-like peptide 1 (GLP-1)secretion. TGR5 may represent a novel target for the treatment of metabolic disorder. Here, we sought to design and synthesize a series of TGR5 agonists derived from the natural product betulinic acid.
Methods: A series of betulinic acid derivatives were designed and synthesized. A cAMP assay was established using a HEK293 cell line expressing human TGR5. Luciferase reporter assay was established using HEK293 cells transfected with plasmids encoding human FXR and luciferase reporter. A human intestinal L-cell line NCI-H716 was used to evaluate the effects of the betulinic acid derivatives on GLP-1 secretion in vitro.
Results: Biological data revealed that the 3-α-OH triterpenoids consistently show increased potency for TGR5 compared to their 3-β-OH epimers. 3-OH esterification increased the lipophilicity and TGR5 activity of 3-α betulinic derivatives and enhanced the activity differences between 3-α and 3-β derivatives. The 3-α-acyloxy betulinic acids also exhibited a significant dose-dependent GLP-1 secretion effect.
Conclusion: This study demonstrates that highly lipophilic 3-epi-betulinic acid derivatives can be potent and selective TGR5 agonists with improved cellular efficacy, and our research here provides a new strategy for the design and development of potent TGR5 agonists.
Keywords: TGR5; activator; betulinic acid derivatives; GLP-1; lipophilic; structure modifications
This work was supported by grants from the National Science and Technology Major Projects for Major New Drugs Innovation and Development (No 2012ZX09304011, 2013ZX09507001, and 2012ZX09301001-005), National Basic Research Program of China (973 Program) (No 2014CB541906) and the National Natural Science Foundation of China (No 30725049 and 81202341).
* To whom correspondence should be addressed.
E-mail fjnan@simm.ac.cn (Fa-jun NAN); xxie@simm.ac.cn (Xin XIE)
Received 2014-04-21 Accepted 2014-05-17
Keywords:
State Key Laboratory of Drug Research, CAS Key Laboratory of Receptor Research, the National Center for Drug Screening, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, China
Aim: TGR5 is a G protein-coupled receptor that is expressed in intestinal L-cells and stimulates glucagon-like peptide 1 (GLP-1)secretion. TGR5 may represent a novel target for the treatment of metabolic disorder. Here, we sought to design and synthesize a series of TGR5 agonists derived from the natural product betulinic acid.
Methods: A series of betulinic acid derivatives were designed and synthesized. A cAMP assay was established using a HEK293 cell line expressing human TGR5. Luciferase reporter assay was established using HEK293 cells transfected with plasmids encoding human FXR and luciferase reporter. A human intestinal L-cell line NCI-H716 was used to evaluate the effects of the betulinic acid derivatives on GLP-1 secretion in vitro.
Results: Biological data revealed that the 3-α-OH triterpenoids consistently show increased potency for TGR5 compared to their 3-β-OH epimers. 3-OH esterification increased the lipophilicity and TGR5 activity of 3-α betulinic derivatives and enhanced the activity differences between 3-α and 3-β derivatives. The 3-α-acyloxy betulinic acids also exhibited a significant dose-dependent GLP-1 secretion effect.
Conclusion: This study demonstrates that highly lipophilic 3-epi-betulinic acid derivatives can be potent and selective TGR5 agonists with improved cellular efficacy, and our research here provides a new strategy for the design and development of potent TGR5 agonists.
Keywords: TGR5; activator; betulinic acid derivatives; GLP-1; lipophilic; structure modifications
This work was supported by grants from the National Science and Technology Major Projects for Major New Drugs Innovation and Development (No 2012ZX09304011, 2013ZX09507001, and 2012ZX09301001-005), National Basic Research Program of China (973 Program) (No 2014CB541906) and the National Natural Science Foundation of China (No 30725049 and 81202341).
* To whom correspondence should be addressed.
E-mail fjnan@simm.ac.cn (Fa-jun NAN); xxie@simm.ac.cn (Xin XIE)
Received 2014-04-21 Accepted 2014-05-17