Design, synthesis and evaluation of targeted hypoxia-activated prodrugs applied to chondrosarcoma chemotherapy

Advances in the Synthesis of Biologically Active Quaternary Ammonium Compounds

This review provides a comprehensive overview of recent advancements in the design and synthesis of biologically active quaternary ammonium compounds (QACs). The covered scope extends beyond commonly reviewed antimicrobial derivatives to include synthetic agents with antifungal, anticancer, and antiviral properties. Additionally, this review highlights examples of quaternary ammonium compounds exhibiting activity against protozoa and herbicidal effects, as well as analgesic and anesthetic derivatives. The article also embraces the quaternary-ammonium-containing cholinesterase inhibitors and muscle relaxants. QACs, marked by their inherent permanent charge, also find widespread usage across diverse domains such as fabric softeners, hair conditioners, detergents, and disinfectants. The effectiveness of QACs hinges greatly on finding the right equilibrium between hydrophilicity and lipophilicity. The ideal length of the alkyl chain varies according to the unique structure of each QAC and its biological settings. It is expected that this review will provide comprehensive data for medicinal and industrial chemists to design and develop novel QAC-based products.

Design, Synthesis, and Biological Evaluation of Artemisinin-Piperazine-Phosphoramide Mustard Hybrids as Potential Anticancer Agents

A series of novel artemisinin-piperazine-phosphoramide mustard (PPM) hybrids were designed and synthesized by incorporating phosphoramide mustard (PM) into dihydroartemisinin (DHA) via an efficient, catalyst-free two-step sequential substitution. Artemisinin-PPM hybrids showed better cytotoxic potency against HepG2 cells than both the parent DHA and the reference, vincristine (VCR). Structure-activity relationship (SAR) studies showed that the cytotoxicity was significantly enhanced by the introduction of a thiazole moiety. Hybrid 7h, the most potent compound with the highest selectivity index IC50 (HEK-293T) / IC50 (HepG2) = 16, displayed 7.4-fold stronger potency than VCR against HepG2 cells. In addition, hybrid 7h was substantially more cytotoxic on all human cancer cells tested than on the corresponding non-cancerous cells. Flow cytometric analysis showed that 7h significantly blocked the cell cycle in the G0/G1 phase and induced apoptosis in a concentration-dependent manner.

Nitroaromatic Hypoxia-Activated Prodrugs for Cancer Therapy

The presence of “hypoxic” tissue (with O₂ levels of <0.1 mmHg) in solid tumours, resulting in quiescent tumour cells distant from blood vessels, but capable of being reactivated by reoxygenation following conventional therapy (radiation or drugs), have long been known as a limitation to successful cancer chemotherapy. This has resulted in a sustained effort to develop nitroaromatic “hypoxia-activated prodrugs” designed to undergo enzyme-based nitro group reduction selectively in these hypoxic regions, to generate active drugs. Such nitro-based prodrugs can be classified into two major groups; those activated either by electron redistribution or by fragmentation following nitro group reduction, relying on the extraordinary difference in electron demand between an aromatic nitro group and its reduction products. The vast majority of hypoxia-activated fall into the latter category and are discussed here classed by the nature of their nitroaromatic trigger units.

Development of hypoxia-activated PROTAC exerting a more potent effect in tumor hypoxia than in normoxia

Hypoxia is a hallmark of many solid tumors, and it causes the overexpression of a variety of proteins including the epidermal growth factor receptor (EGFR). Many antitumor prodrugs have been designed to target hypoxia. Here we report the identification of a kind of hypoxia-activated proteolysis targeting chimera (ha-PROTAC) by introducing the hypoxia-activated leaving group (1-methyl-2-nitro-1H-imidazol-5-yl)methyl or 4-nitrobenzyl into the structure of an EGFR^Del19-based PROTAC. Among the obtained molecules, ha-PROTAC 13 exhibits a more potent degradation activity for EGFR^Del19 in hypoxia than in normoxia in HCC4006 cells. This is the first example of identifying a PROTAC to selectively act on tumors utilizing the characteristic of tumor hypoxia and provides a new approach for PROTAC development.