Development Of Mammalian Cell-Based Assay System To Screen For Pparγ Ligands From Natural Products And Identification Of Two Hypoglycaemic-Inducing Compounds From Momordica Charantia
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Date
2014
Authors
Ahmad Noruddin @ Nordin, Nur Adelina
Journal Title
Journal ISSN
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Publisher
Universiti Sains Malaysia
Abstract
Management of insulin resistance is vital since failure to do that leads to the onset of type II diabetes. Thiazolidinedione (TZD) drugs which are currently used for the treatment of insulin resistance were recognized as potent peroxisome proliferator-activated receptor γ (PPARγ) ligands. This class of synthetic PPARγ ligands comes together with some side-effects including induction of hepatotoxicity, cardiovascular events including heart failure, fluid retention and haemodilution. The purpose of this study was to develop a platform for the identification of new PPARγ ligands from the natural products which hypothetically are better candidates for the treatment of insulin resistance without causing severe side-effects. Hence, a mammalian cell-based assay system to screen for PPARγ ligands from natural products has been developed. This reporter gene based assay utilizes transient transfection of one reporter plasmids; pAcox PPREx3-Tk-Luc and pRL-CMV (as internal control plasmid), and two expression plasmids; pSV Sport PPARγ and pSV Sport RXRα in HepG2 cells. The assay successfully distinguished the presence of PPARγ ligands when tested with TZD drug as well as some plant extracts containing natural PPARγ ligands including Momordica charantia which is known to have ethno-pharmacology history in treatment of type II diabetes. Subsequently, two natural compounds which
were isolated from Momordica charantia and proven to induce PPARγ activity in the screening system were tested further for the properties of PPARγ ligands by the ability to induce pre-adipocyte differentiation and induction of PPARγ target genes expression. The compounds, 3β,7β,25-trihydroxycucurbita-5,23(E)-dien-19-al (THCB) and Kuguacin R (Kug. R) were also verified for the glucose uptake ability via GLUT4 translocation as well as activating AMPK signal transduction pathway as the major pathway and Akt as minor pathway to exert their effect. Therefore, in this study, we have developed a mammalian cell-based screening assay system to screen for natural PPARγ ligands in an effort to identify new candidate compounds or extracts for use in the treatment of type II diabetes mellitus.
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Keywords
Management of insulin , onset of type II diabetes