Hypoglycemic and Hypolipidemic Effects of a Novel Pan-Peroxisome Proliferator-Activated Receptor Agonist, MBT1805, in db/db Mice

Research Article

Austin Hepatol. 2021; 6(1): 1016.

Hypoglycemic and Hypolipidemic Effects of a Novel Pan-Peroxisome Proliferator-Activated Receptor Agonist, MBT1805, in db/db Mices

Wang C¹, Jin X², Jin Q¹, Shi Y¹*, Zhong B³ and Niu J¹*

¹Department of Hepatology, The First Hospital of Jilin University, Changchun, Jilin, China

²International Center for Liver Disease Treatment, Fifth Medical Center of Chinese PLA General Hospital, Beijing, China

³Beijing JK HuaYuan Med Tech Company LTD, Beijing, China

*Corresponding author: Junqi Niu, MD, PhD, Department of Hepatology, The First Hospital of Jilin University, No.71, Xinmin Street, Changchun 130021, Jilin Province, China

Ying Shi, Department of Hepatology, The First Hospital of Jilin University, No.71, Xinmin Street, Changchun 130021, Jilin Province, China

Received: March 17, 2021; Accepted: April 16, 2021; Published: April 23, 2021


Background: MBT1805 is a novel pan-Peroxisome Proliferator-Activated Receptor (PPAR) agonist.

Materials and Methods: In vitro, transfection and luciferase assays tested EC50 values of MBT1805. In vivo, hypoglycemic and hypolipidemic effects of MBT1805 were observed in db/db mice compared with Rosiglitazone.

Results: In vitro, MBT1805 activates human PPARα, PPARγ and PPARδ with EC50 values of 8.46μM, 11.94μM, 11.15μM, respectively. Results showed that the bodyweight of db/db mice treated with MBT1805 was not changed. By contrast, Rosiglitazone-treated mice showed significant weight gain (p<0.05). MTB1805 decreased blood glucose level without causing noticeable hepatocytes damage.

Conclusion: The novel balanced pan-PPAR agonist, MBT1805 has moderate hypoglycemic and hypolipidemic effects, and does not cause weight gain, hepatocyte damage and hepatic lipid deposition. These experimental results indicate that MBT1805 is safe in the treatment of type 2 diabetes.

Keywords: Peroxisome proliferator-activated receptor; PPARs agonist; Diabetes; MBT1805; Rosiglitazone


PPARs: Peroxisome Proliferator-Activated Receptors; T2DM: Type 2 Diabetes Mellitus; OGTT: Oral Glucose Tolerance Test; AUC: Area Under the Curve; TC: Total Cholesterol; TG: Triglyceride; Tbil: Total Bilirubin; FFAS: Free Fatty Acids; EC50: Half Maximal Effective Concentration


Rosiglitazone is FDA approved for the treatment of Type 2 Diabetes Mellitus (T2DM). It effectively lowers glucose levels by improving targets cells response to insulin without enhancing insulin release by pancreatic beta cells [1]. However, side effects, including weight gain, fluid retention, and heart failure constrain the use of TZDs. Troglitazone has been withdrawn from the market due to liver toxicity [2]. Peroxisome Proliferator-Activated Receptors (PPARs) have exhibited potential benefits against diabetes. Balanced regulation of PPARα, PPARγ and PPARδ may be beneficial, while minimizing harmful side effects.

PPARs are ligand dependent transcription factors, belonging to the nuclear hormone receptor superfamily. Three PPAR isoforms are known, PPARα (NR1C1), PPARβ/δ (NR1C2), and PPARγ (NR1C3), which are all involved in fat and carbohydrate metabolism and homeostasis. PPARs also influence proliferation and differentiation, inflammation, vascular biology and cancer [3]. The 3 PPAR isoforms have distinct but complementary physiological functions due to different tissue distribution, ligand sensitivities and target genes [4]. PPARα is highly expressed in tissues rich in Fatty Acid Oxidation (FAO), including liver, heart, skeletal muscle, brown adipose tissue, and kidney. PPARα activation stimulates fatty acid and triglyceride metabolism. PPARβ/δ is broadly expressed and is crucial for the activation of fatty acids in skeletal muscles. Its expression is markedly enhanced by fasting and exercise [5]. PPARβ/δ activation also improves hepatic insulin response by suppressing hepatic gluconeogenesis at the postprandial stage. There are 2 PPARγ isoforms, PPARγ1 and PPARγ2. PPARγ activation elevates insulin sensitivity in the whole body [4,6-9]. A variety of endogenous ligands activate PPARs and the degree of receptor activation depends on the balance between ligands production and inactivation. Endogenous ligands may come from diet, de novo Lipogenesis (DNL), or lipolysis, and they include n-3 and n-6 Fatty Acids (FAs), eicosanoids, some endocannabinoids and phospholipids [6-8]. The synthetic ligands also potently modulate PPARs function. Except for PPARβ/δ, for which selective modulators have not entered the clinic, selective PPARα and PPARγ agonists are used clinically. Moreover, dual, and pan-PPAR agonists are under development and will enable exploration of PPAR complementary roles. Treatment of dyslipidemia and type 2 diabetes is relatively advanced. Fibrates (Fenofibrate and Bezafibrate) are often used in combination with satins to treat atherogenic hyperlipidemia and hypertriglyceridemia [10,11]. Similarly, TZDs are used to treat T2DM [12]. Ideally, PPAR modulators should possess superior bioavailability and pharmacokinetics, with minimal off-target and side effects [13].

Multiple novel drugs targeting PPARs are under development. Here, we treated db/db mice with MBT1805, a novel pan-PPARs agonist and evaluated its hypoglycemic and hypolipidemic effect, as well as side effects, relative to rosiglitazone. The db/db mice carry spontaneous mutations in the gene encoding the long isoform of leptin receptor in hypothalamus, resulting in persistent and severe glucose intolerance, hyperglycemia and hyperinsulinemia. This mouse is an established model of T2DM [14,15].

Materials and Methods


Hepatoma cell line was purchased from ATCC. FuGENE6 transfection reagent was purchased from Roche (Cat No11814443001). MBT1805 (Cat No190509), fenofibrate and rosiglitazone maleate (HBW190503-6) were supplied by Beijing JK HuaYuan Med Tech Company LTD free for charge (Beijing, China). Tween80 (Cat NoA0341586) was purchased from Acros Organics. CMC-Na (Cat No16774) was purchased from jingchun (Shanghai, China). DMSO (Cat NoD8371) were purchased from Solarbio (Beijing, China). Sterile water (Cat No180416205) was purchased from Aixide (Guangdong, China). Anhydrous glucose (Cat No20140106) was purchased from Guoyao (Shanghai, China).

In vitro transfection and luciferase assays

Our method was adopted from Zhibin Li [16]. A Nuclear Receptor DNA incorporating sequence (NRE) was cloned into pcDNA3.1 expression vector, upstream of luciferase gene, and insertion confirmed by sequencing (data not shown). When PPARs are activated, the binding with NRE is enhanced, thus increasing expression of Luciferase gene in the downstream. Luciferase intensity indirectly reflect the activation of PPARs. HepG2 cells were cultured in DMEM supplemented with 10% FBS, at 37ºC, in a humidified incubator with 5% CO2. Cells were seeded in 96-well plates the day before transfection to allow for 50-80 % confluence at transfection. They were then transfected with indicated plasmids using FuGENE6 according to manufacturer instructions. A GFP plasmid was transfected as negative control. 24 hours after transfection, media was replaced with fresh complete media. MBT1805 and fenofibrate were dissolved in DMSO. Cells were treated with MBT1805 and fenofibrate at various final concentrations. As negative control, vehicle only (DMSO) was used at a final concentration of 0.1%. Cells were cultured for 24 hours before they were directly harvested into cell lysis buffer. Luciferase and GFP activities were measured, and values from all test wells normalized to GFP. Results were presented as fold changes relative to the negative control. The value obtained was directly proportional to activation strength.

Animal treatment

34 db/db and 12 C57BL/6J mice (male), 9-10-weeks old, were purchased from Jicuiyaolkang (Jiangsu, China). 8 healthy C57 mice were used as blank control group. The 34 db/db mice were randomly divided into 4 groups, model control (vehicle), rosiglitazone (10mg/ kg), and MBT1805 (15mg/kg and 30mg/kg), 8-9 mice per group. Mice were maintained under controlled temperature and humidity (23±2ºC, 40-70 % respectively) and a 12h light/dark cycle. The animals had access to normal chow and water ad libitum. Where indicated, mice were fasted according to our animal protocol. All mice were raised adaptively for 13 days. After the adaption period, blood glucose levels in experimental animals were taken 4h after fasting. Compounds were dissolved at specified concentrations in a pre-formulated solvent of 0.05% Tween80/0.5% CMC-Na in sterile H2O. Drugs were administered once daily for 14 days. Mouse weight was taken twice weekly. On the 14th day, mice were fasted for 4h, and then treated. 1h later, blood samples were collected by tail bleeding and blood glucose measured.

Oral glucose tolerance test

On the 15th day, 16h after fasting, animals were weighted and their blood glucose measured using a blood glucose meter (Xpress) at 0min. Glucose solution (2mg/kg) was immediately administered by oral gavage at the time of compounds administration. Blood glucose was measured 30, 60, 120 and 180 min later, and the area under blood glucose time curve (AUC) calculated.

Serum and organ collection

Animals were anesthetized with CO2 and blood collected from the heart into 1.5mL centrifuge tubes and stored for 30min at room temperature. They were then centrifuged at 12000rpm for 5min. The serum was then collected, and serum TC, TG, ALT, AST, Tbil, FFA and CREA detected using an automatic biochemical analyzer (Rili, 76000). The animals were then euthanized by inhaling excessive CO2. Livers were then collected, weighted and liver coefficient calculated. About 150mg of liver was snap-frozen in liquid and stored at -80ºC for TC and TG detection.

Statistical analysis

Statistical analysis was done using SPSS version 21 (Chicago, IL, USA) and data plotted on GraphPad 8.0 (GraphPad Software, La Jolla, CA). Quantitative date is presented as mean ± SEM. Unpaired t test was used for comparisons between 2 groups. P value ≤0.05 indicates statistical significance.


Separated EC50 values of MBT1805 or fenofibrate in activating PPARs

Half maximal Effective Concentration (EC50) is an important index for accessing the pharmacological activity of compounds. PPARs activation using 6 concentrations of MBT1805 or fenofibrate was assessed. We iteratively calculated and fitted the concentration effect curve, and calculated corresponding EC50. We observe that MBT1805 markedly activates PPARα, PPARγ and PPARδ. EC50 values for PPARα, PPARγ and PPARδ are 8.455μM, 11.94μM and 11.15μM, respectively (Table 1). It was worth noting that lower luciferase values were detected when PPARγ and PPARδ was activated by higher MBT1805 dosage (100μM). This may be because activation of PPARs by MBT1805 triggers intracellular negative feedback regulation. Fenofibrate, a selective PPARα agonist, exhibited a significantly lower EC50 value of PPARα relative to the other 2 receptors, (Table 2). MBT1805 activated PPARα more potently than fenofibrate at the same concentration. The ability of MBT1805 to activate PPARγ and PPARδ was significantly higher than that of fenofibrate.