Molecular insights into the AT1 antagonism based on biophysical and in silico studies of telmisartan

On the Rational Drug Design for Hypertension through NMR Spectroscopy

Antagonists of the AT1receptor (AT1R) are beneficial molecules that can prevent the peptide hormone angiotensin II from binding and activating the specific receptor causing hypertension in pathological states. This review article summarizes the multifaced applications of solid and liquid state high resolution nuclear magnetic resonance (NMR) spectroscopy in antihypertensive commercial drugs that act as AT1R antagonists. The 3D architecture of these compounds is explored through 2D NOESY spectroscopy and their interactions with micelles and lipid bilayers are described using solid state 13CP/MAS, 31P and 2H static solid state NMR spectroscopy. Due to their hydrophobic character, AT1R antagonists do not exert their optimum profile on the AT1R. Therefore, various vehicles are explored so as to effectively deliver these molecules to the site of action and to enhance their pharmaceutical efficacy. Cyclodextrins and polymers comprise successful examples of effective drug delivery vehicles, widely used for the delivery of hydrophobic drugs to the active site of the receptor. High resolution NMR spectroscopy provides valuable information on the physical-chemical forces that govern these drug:vehicle interactions, knowledge required to get a deeper understanding on the stability of the formed complexes and therefore the appropriateness and usefulness of the drug delivery system. In addition, it provides valuable information on the rational design towards the synthesis of more stable and efficient drug formulations.

Oligomerization and cooperativity in GPCRs from the perspective of the angiotensin AT1 and dopamine D2 receptors

G Protein-Coupled Receptors (GPCRs) can form homo- and heterodimers or constitute higher oligomeric clusters with other heptahelical GPCRs. In this article, multiscale molecular modeling approaches as well as experimental techniques which are used to study oligomerization of GPCRs are reviewed. In particular, the effect of dimerization/oligomerization to the ligand binding affinity of individual protomers and also on the efficacy of the oligomer are discussed by including diverse examples from the literature. In addition, possible allosteric effects that may emerge upon interaction of GPCRs with membrane components, like cholesterol, is also discussed. Investigation of these above-mentioned interactions may greatly contribute to the candidate molecule screening studies and development of novel therapeutics with fewer adverse effects.

Structure-based design of hERG-neutral antihypertensive oxazalone and imidazolone derivatives

Angiotensin II receptor type 1 (AT1) antagonists are the most recent drug class against hypertension. Recently first crystal structure of AT1 receptor is deposited to the protein data bank (PDB ID: 4YAY). In this work, several molecular screening methods such as molecular docking and de novo design studies were performed and it is found that oxazolone and imidazolone derivatives reveal similar/better interaction energy profiles compared to the FDA approved sartan molecules at the binding site of the AT1 receptor. A database consisting of 3500-fragments were used to enumerate de novo designed imidazolone and oxazolone derivatives and hereby more than 50000 novel small molecules were generated. These derivatives were then used in high throughput virtual screening simulations (Glide/HTVS) to find potent hit molecules. In addition, virtual screening of around 18 million small drug-like compounds from ZINC database were screened at the binding pocket of the AT1 receptor via Glide/HTVS method. Filtered structures were then used in more sophisticated molecular docking simulations protocols (i.e., Glide/SP; Glide/XP; Glide/IFD; Glide/QPLD, and GOLD). However, the K⁺ ion channel/drug interactions should also be considered in studies implemented in molecular level against their cardiovascular risks. Thus, selected compounds with high docking scores via all diverse docking algorithms are also screened at the pore domain regions of human ether-a-go-go-related gene (hERG1) K⁺ channel to remove the high affinity hERG1 blocking compounds. High docking scored compounds at the AT1 with low hERG1 affinity is considered for long molecular dynamics (MD) simulations. Post-processing analysis of MD simulations assisted for better understanding of molecular mechanism of studied compounds at the binding cavity of AT1 receptor. Results of this study can be useful for designing of novel and safe AT1 inhibitors.

Rational drug design and synthesis of molecules targeting the angiotensin II type 1 and type 2 receptors

The angiotensin II (Ang II) type 1 and type 2 receptors (AT1R and AT2R) orchestrate an array of biological processes that regulate human health. Aberrant function of these receptors triggers pathophysiological responses that can ultimately lead to death. Therefore, it is important to design and synthesize compounds that affect beneficially these two receptors. Cardiovascular disease, which is attributed to the overactivation of the vasoactive peptide hormone Αng II, can now be treated with commercial AT1R antagonists. Herein, recent achievements in rational drug design and synthesis of molecules acting on the two AT receptors are reviewed. Quantitative structure activity relationships (QSAR) and molecular modeling on the two receptors aim to assist the search for new active compounds. As AT1R and AT2R are GPCRs and drug action is localized in the transmembrane region the role of membrane bilayers is exploited. The future perspectives in this field are outlined. Tremendous progress in the field is expected if the two receptors are crystallized, as this will assist the structure based screening of the chemical space and lead to new potent therapeutic agents in cardiovascular and other diseases.