Design and synthesis of benzoxazole containing indole analogs as peroxisome proliferator-activated receptor-γ/δ dual agonists

Identification of a Novel PPAR-γ Agonist through a Scaffold Tuning Approach

Peroxisome proliferator-activated receptors (PPARs) are important targets in metabolic diseases including obesity, metabolic syndrome, diabetes, and non-alcoholic fatty liver disease. Recently, they have been highlighted as attractive targets for the treatment of cardiovascular diseases and chronic myeloid leukemia. The PPAR agonist structure is consists of a polar head, a hydrophobic tail, and a linker. Each part interacts with PPARs through hydrogen bonds or hydrophobic interactions to stabilize target protein conformation, thus increasing its activity. Acidic head is essential for PPAR agonist activity. The aromatic linker plays an important role in making hydrophobic interactions with PPAR as well as adjusting the head-to-tail distance and conformation of the whole molecule. By tuning the scaffold of compound, the whole molecule could fit into the ligand-binding domain to achieve proper binding mode. We modified indol-3-ylacetic acid scaffold to (indol-1-ylmethyl)benzoic acid, whereas 2,4-dichloroanilide was fixed as the hydrophobic tail. We designed, synthesized, and assayed the in vitro activity of novel indole compounds with (indol-1-ylmethyl)benzoic acid scaffold. Compound 12 was a more potent PPAR-γ agonist than pioglitazone and our previous hit compound. Molecular docking studies may suggest the binding between compound 12 and PPAR-γ, rationalizing its high activity.

Current Advances in the Biochemical and Physiological Aspects of the Treatment of Type 2 Diabetes Mellitus with Thiazolidinediones

The present review summarizes the current advances in the biochemical and physiological aspects in the treatment of type 2 diabetes mellitus (DM2) with thiazolidinediones (TZDs). DM2 is a metabolic disorder characterized by hyperglycemia, triggering the abnormal activation of physiological pathways such as glucose autooxidation, polyol's pathway, formation of advance glycation end (AGE) products, and glycolysis, leading to the overproduction of reactive oxygen species (ROS) and proinflammatory cytokines, which are responsible for the micro- and macrovascular complications of the disease. The treatment of DM2 has been directed toward the reduction of hyperglycemia using different drugs such as insulin sensitizers, as the case of TZDs, which are able to lower blood glucose levels and circulating triglycerides by binding to the nuclear peroxisome proliferator-activated receptor gamma (PPARγ) as full agonists. When TZDs interact with PPARγ, the receptor regulates the transcription of different genes involved in glucose homeostasis, insulin resistance, and adipogenesis. However, TZDs exhibit some adverse effects such as fluid retention, weight gain, hepatotoxicity, plasma-volume expansion, hemodilution, edema, bone fractures, and congestive heart failure, which limits their use in DM2 patients.

Design, synthesis, and biological evaluation of a series of alkoxy-3-indolylacetic acids as peroxisome proliferator-activated receptor γ/δ agonists

A series of alkoxy-3-indolylacetic acid analogs has been discovered as peroxisome proliferator-activated receptor (PPAR) agonists. Structure-activity relationship study indicated that PPARα/γ/δ activities were dependent on the nature of the hydrophobic group, the attachment position of the alkoxy linker to the indole ring, and N-alkylation of indole nitrogen. Some compounds presented significant PPARγ/δ activity and molecular modeling suggested their putative binding modes in the ligand binding domain of PPARγ. Of these, compound 51 was selected for in vivo study via an evaluation of microsomal stability in mouse and human liver. Compound 51 lowered the levels of fasting blood glucose, insulin, and HbA1c without gain in body weight in db/db mice. When compound 51 was treated, hepatic triglycerides level and the size of adipocytes in white adipose tissue of db/db mice were also reduced as opposed to treatment with rosiglitazone. Taken together, compound 51 shows high potential warranting further studies in models for diabetes and related metabolic disorders and may be in use as a chemical tool for the understanding of PPAR biology.

Unique regioselectivity in the C(sp3)-H α-alkylation of amines: the benzoxazole moiety as a removable directing group

The benzoxazol-2-yl- substituent was found to act as a removable activating and directing group in the Ir-catalyzed alkylation of C(sp(3))-H bonds adjacent to nitrogen in secondary amines. It can be easily introduced by oxidative coupling or by an SNAr reaction, and it can be removed by hydroxide or by hydride reduction. For 1,2,3,4-tetrahydroisoquinolines, activation exclusively takes place in the 3-position. A variety of activated as well as unactivated terminal olefins are suitable reaction partners.