SYNTHESIS OF 1,3,4-OXADIAZOLES AS SELECTIVE T-TYPE CALCIUM CHANNEL INHIBITORS

Development of acylhydrazone linked thiazoles as non-covalent dual inhibitors of SARS-CoV-2 proteases

SARS-CoV-2's papain-like protease (PLPro) and main protease (MPro) are essential for viral maturation and replication. Currently, Paxlovid is recommended to treat viral infections, but the emergence of Nirmatrelvir resistance new variants poses serious global risks. Dual targeting agents restrict viral replication, act on other crucial viral pathways, or exert simultaneous protease inhibition, increasing the complexity for the virus to develop resistance, and the design of dual inhibitors is an attractive strategy. Herein, we present research on new thiazole-aryl and thiazole-ester compounds that function as cysteine specific non-covalent competitive dual inhibitors of SARS-CoV-2's papain-like protease (PLPro) and main protease (MPro). Twelve of the 36 compounds demonstrated dual inhibition in the range of nanomolar to low micromolar concentrations while five others exhibit selective PLPro inhibition. Minimal cytotoxicity against two mammalian cell lines and no oral toxicity in rats (LD50 > 2000 mg/kg) were observed. SARS-CoV-2 viral load was successfully reduced by several compounds tested. N-acyl hydrazone (NAH)-thiazole core while forms π-π interactions with the catalytic histidine side chain (H41) in MPro active site, it exhibits a series of hydrophobic and hydrophilic interaction in the interface of BL2 loop and the active site of PLPro. Non-covalent dual inhibition demonstrated by novel NAH-thiazole derivatives in this study provides a path for the development of efficient antiviral agents against coronaviruses.

An Understanding of Mechanism-Based Approaches for 1,3,4-Oxadiazole Scaffolds as Cytotoxic Agents and Enzyme Inhibitors

The world's health system is plagued by cancer and a worldwide effort is underway to find new drugs to treat cancer. There has been a significant improvement in understanding the pathogenesis of cancer, but it remains one of the leading causes of death. The imperative 1,3,4-oxadiazole scaffold possesses a wide variety of biological activities, particularly for cancer treatment. In the development of novel 1,3,4-oxadiazole-based drugs, structural modifications are important to ensure high cytotoxicity towards malignant cells. These structural modification strategies have shown promising results when combined with outstanding oxadiazole scaffolds, which selectively interact with nucleic acids, enzymes, and globular proteins. A variety of mechanisms, such as the inhibition of growth factors, enzymes, and kinases, contribute to their antiproliferative effects. The activity of different 1,3,4-oxadiazole conjugates were tested on the different cell lines of different types of cancer. It is demonstrated that 1,3,4-oxadiazole hybridization with other anticancer pharmacophores have different mechanisms of action by targeting various enzymes (thymidylate synthase, HDAC, topoisomerase II, telomerase, thymidine phosphorylase) and many of the proteins that contribute to cancer cell proliferation. The focus of this review is to highlight the anticancer potential, molecular docking, and SAR studies of 1,3,4-oxadiazole derivatives by inhibiting specific cancer biological targets, such as inhibiting telomerase activity, HDAC, thymidylate synthase, and the thymidine phosphorylase enzyme. The purpose of this review is to summarize recent developments and discoveries in the field of anticancer drugs using 1,3,4-oxadiazoles.

1,3,4, Oxadiazole Compound A3 Provides Robust Protection Against PTZ-Induced Neuroinflammation and Oxidative Stress by Regulating Nrf2-Pathway

Background

Epilepsy is a common neurological disorder that is characterized by recurrent episodes of seizures. Various studies have demonstrated a direct association between oxidative stress and inflammation in several neurological disorders including epilepsy. This study aimed to investigate the neuroprotective effects of a synthetic 1,3,4, oxadiazole compound A3 against pentylenetetrazole (PTZ)-induced kindling and seizure model.

Methodology

PTZ was administered in a sub-convulsive dose of 40 mg/kg for 15 days, at 48-hour intervals to male Swiss-Albino mice until animals were fully kindled. Two different doses of A3 (10 mg/kg and 30 mg/kg) were administered to find out the effective dose of A3 and to further demonstrate the relative role of nuclear factor E2-related factor (Nrf2) in the PTZ-induced kindled model.

Results

Our results demonstrated a compromised antioxidant capacity associated with a low level of catalase (CAT), superoxide dismutase (SOD), glutathione (GST), and glutathione S-transferase (GSH) in the kindled group. However, the PTZ-induced group demonstrated an elevated level of lipid peroxidation (LPO) level parallel to pro-inflammatory cytokines such as tumor necrosis factor-alpha (TNF-α), mediators as cyclooxygenase (COX-2), and nuclear factor kappa B (NFκB). Furthermore, the A3 treatment reversed these changes and overexpressed the antioxidant Nrf2 gene and its downstream HO-1. To further investigate the involvement of Nrf2, we employed an Nrf2-inhibitor, ie, all-trans retinoic acid (ATRA), that further aggravated the PTZ toxicity. Moreover, vascular endothelial growth factor (VEGF) expression was evaluated to assess the extent of BBB disruption.

Conclusion

The findings of this study suggest that A3 could mediate neuroprotection possibly by activating Nrf2 dependent downregulation of inflammatory cascades.