Development of 3D-QSAR CoMSIA models for 5-(biphenyl-2-yl)-1H-tetrazole derivatives as angiotensin II receptor type 1 (AT1) antagonists

Application of QSAR models for acute toxicity of tetrazole compounds administrated orally and intraperitoneally in rat and mouse

Tetrazoles and their derivatives possess various biological activities, such as antibacterial, anti-fungal, and other activities. However, these compounds may induce specific cumulative and toxic effects in living organisms. Therefore, quantitative structure-activity relationship (QSAR) models were constructed to study the acute oral toxicity of tetrazoles in rats and mice. The toxicity data of 111 tetrazole compounds were collected using the ChemIDplus, ChEMBL and ECHA databases as response variables, while the PaDEL-descriptor generated the 2D descriptors as independent variables. The models were developed and validated following the OECD guidelines by the DTC-QSAR tool. Three QSAR models were successfully established for the oral routes of rat and mouse and the intraperitoneal route of mouse, respectively. The scatter plots showed high consistency between the training and test data sets. All the models successfully met the external and internal validation criteria. Most of the descriptors kept in the final models exhibited positive correlations with toxicity, whereas only 6 descriptors exhibited negative associations. Several chemicals were identified as response or structural outliers, based on the standardized residuals and leverage values. In conclusion, the findings of this investigation demonstrate that the proposed QSAR models hold promise in forecasting the acute toxicity of recently developed or synthesized tetrazole compounds, thereby mitigating potential risks to human health and the environment.

In Silico Based Structural and Fingerprint Analysis of Structurally Diverse AT1 inhibitors

Background and Objective:

The development of pharmacologically active molecules for the treatment of hypertension and other cardiovascular diseases are important nowadays. In the present investigation, computational techniques have been implemented on Angiotensin II Type 1 (AT1) antagonists to develop better predictive models.

Methods:

Quantitative Structure Activity Relationship (QSAR) and structural patterns/fragments analyses were performed using physicochemical descriptors and MACCS Fingerprints calculaced from AT1 inhibitors collected from the literature.

Results:

The significant models developed have been validated by Leave One Out (LOO) and test set methods, which exhibit considerable Q2 values (>0.65 for the training set and >0.5 for the test set) and the R2pred values for the models are also >0.5. The applicability of the contributed descriptors in these models revealed that the chlorine atom, dipole moment, hydrogen bond donor atoms and electrostatic potential are negatively contributing, and the presence of bond between heavy atoms and the carbon atom connected with small side chain and topological polar vdW surface area are favorable for the AT1 antagonistic activity. The MACCS Fingerprints showed that the presence of atoms (kind of heavy atoms), such as N, O, and S, connected with other heteroatoms or carbon or any other atoms, through single or double bonds are predominantly present in highly active molecules. The presence of halogens, long chain alkanes, halogenated alkanes, and sulfur atoms attached with nitrogen through any atoms are responsible for decreased AT1 antagonistic activity.

Conclusion:

The results have provided additional information on the structural patterns of the compounds based on its MACCS Fingerprints, which may be used for further characterization and design of novel AT1 inhibitors.

Ultrasound assisted synthesis of tetrazole based pyrazolines and isoxazolines as potent anticancer agents via inhibition of tubulin polymerization

In search of new active molecules against MCF-7, A549 and HepG2, tetrazole based pyrazoline and isoxazoline derivatives under both conventional and ultrasonic irradiation method were designed and efficiently synthesized. Structures of newly synthesized compounds 5a-h and 6a-h were characterized by ¹H NMR, ¹³C NMR, MS and elemental analysis. Several derivatives were found to be excellent cytotoxic against MCF-7, A549 and HepG2 cell lines characterized by lower IC₅₀ values (0.78-3.12 µg/mL). Compounds 5b and 5c demonstrated an antiproliferative effect comparable to that of CA-4. Western blot analysis revealed that, reported compounds accumulate more tubulin in the soluble fraction. Docking studies suggested that, binding of these compounds mimics at the colchicine site of tubulin. In vitro study revealed that the tetrazole based pyrazolines and isoxazolines may possess ideal structural requirements for further development of novel therapeutic agents.

Synthesis and biological evaluation of tetrazole derivatives as TNF-α, IL-6 and COX-2 inhibitors with antimicrobial activity: Computational analysis, molecular modeling study and region-specific cyclization using 2D NMR tools

A group of tetrazole bearing compounds were synthesized and evaluated for their in vitro cyclooxygenase (COX) isozymes (COX-1/COX-2) inhibitory activity, in vitro anti-inflammatory activity through measuring levels of expression of IL-6 and TNF-α and antimicrobial activity. Cyclization of pyridine derivative 5b was confirmed using 2D NMR such as NOESY and HMBC experiments. Within the synthesized compounds, compound 7c was identified as effective and selective COX-2 inhibitors (COX-2 IC₅₀ = 0.23 uM; COX-2 selectivity index = 16.91). Moreover 7c was the most effective derivative on TNF-α (37.6 pg/ml). While, the most active compound on IL-6 was isoxazole derivative 6 (42.8 pg/ml). Dual inhibitory activity on both IL-6 and TNF-α was exhibited by compounds 2 and 3 (IL-6 = 47.5 and 82.7 pg/ml, respectively) and (TNF-α = 31.7 and 33.8 pg/ml, sequentially). Additionally, compound 7a, showed broad spectrum antimicrobial activity against Gram positive cocci, Gram positive rods and yeast fungus (inhibition zone = 20 and 19 mm). None of the test compounds exhibited activity against Gram negative rods. Compounds 3 and 7c exhibited good antifungal activity at MIC equal to 64.5 µg/ml. While compound 6 showed antibacterial activities against Micrococcus lysodicticus and Bacillus subtilis at MIC = 32.25 and 64.5 µg/ml, respectively. Computational analysis was used to predict molecular properties and bioactivity of the target compounds. To confirm the mode of action of the synthesized compounds as anti-inflammatory agents, molecular docking was done. Appreciable binding interactions were observed for compound 7c containing COX-2 pharmacophore (SO₂NH₂), with binding energy -10.6652 Kcal/mol, forming two hydrogen bonding interactions with His90 and Tyr355 amino acids. It was fully fitted within COX-2 active site having the highest COX-2 selectivity index between all the test compounds (S.I. = 16.91).

Pharmacological Profiles of a Highly Potent and Long-Acting Angiotensin II Receptor Antagonist, Fimasartan, in Rats and Dogs after Oral Administration

The pharmacological profile of fimasartan, [2-n-butyl-5-dimethylamino-thiocarbonyl-methyl-6-methyl-3-{[2-(1H-tetrazole-5-yl)biphenyl-4-yl]methyl}-pyrimidin-4(3H)-one, a new non-peptide angiotensin type 1 (AT₁)-selective angiotensin receptor antagonist, has been investigated in a variety of in vitro and in vivo experimental models. In the present study, fimasartan showed slow dissociation and irreversible binding to AT₁ subtype receptors in membrane fractions of HEK-293 cells with a K_d of 0.03 nM and a T_1/2 of 63.7 min. The inhibitory effect of fimasartan on angiotensin II (Ang II)-induced contraction persisted longer after washout than that of losartan or candesartan. In conscious rats, a single dose of fimasartan (0.3, 1, or 3 mg/kg; per os (p.o.)) dose-dependently antagonized Ang II-induced pressor responses. Both orally administrated fimasartan and losartan dose-dependently decreased mean arterial pressure in furosemide-treated rats and dogs, and fimasartan administered orally at 1, 3, or 10 mg/kg reduced blood pressure in conscious spontaneously hypertensive rats. Taken together, these findings indicate that fimasartan has potent and sustained binding affinity at the AT₁ receptor subtype, and reveal the molecular basis responsible for the marked lowering of blood pressure in various conscious rats and dogs models after its oral administration.

Integration of multi-scale molecular modeling approaches with experiments for the in silico guided design and discovery of novel hERG-Neutral antihypertensive oxazalone and imidazolone derivatives and analysis of their potential restrictive effects on cell proliferation

AT1 antagonists is the most recent drug class of molecules against hypertension and they mediate their actions through blocking detrimental effects of angiotensin II (A-II) when acts on type I (AT1) A-II receptor. The effects of AT1 antagonists are not limited to cardiovascular diseases. AT1 receptor blockers may be used as potential anti-cancer agents - due to the inhibition of cell proliferation stimulated by A-II. Therefore, AT1 receptors and the A-II biosynthesis mechanisms are targets for the development of new synthetic drugs and therapeutic treatment of various cardiovascular and other diseases. In this work, multi-scale molecular modeling approaches 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. In silico-guided designed hit molecules were then synthesized and tested for their binding affinities to human AT1 receptor in radioligand binding studies, using [¹²⁵I-Sar¹-Ile⁸] AngII. Among the compounds tested, 19d and 9j molecules bound to receptor in a dose response manner and with relatively high affinities. Next, cytotoxicity and wound healing assays were performed for these hit molecules. Since hit molecule 19d led to deceleration of cell motility in all three cell lines (NIH3T3, A549, and H358) tested in this study, this molecule is investigated in further tests. In two cell lines (HUVEC and MCF-7) tested, 19d induced G2/M cell cycle arrest in a concentration dependent manner. Adherent cells detached from the plates and underwent cell death possibly due to apoptosis at 19d concentrations that induced cell cycle arrest.

Tetrazolium compounds: synthesis and applications in medicine

Tetrazoles represent a class of five-membered heterocyclic compounds with polynitrogen electron-rich planar structural features. This special structure makes tetrazole derivatives useful drugs, explosives, and other functional materials with a wide range of applications in many fields of medicine, agriculture, material science, etc. Based on our research works on azoles and other references in recent years, this review covers reported work on the synthesis and biological activities of tetrazole derivatives.

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.