Pyrrolidine, also known as tetrahydropyrrole, is a saturated five-membered heterocyclic ring, which is miscible with water. Pyrrolidine exists in many alkaloids and drug molecules, such as kappa opioids, antagonists of dopamine D4 receptors, and HIV reverse transcriptase inhibitors.
Cyclopropane is the smallest cyclic compound with unique structural features and physicochemical properties, which is widely used in the design of small molecule drugs. In drug design, it is often used to increase activity, fix conformation and improve PK and water solubility. The introduction of cyclopropyl groups into drugs can change various properties of molecules, such as improving metabolic stability; increasing biological activity; enhancing drug efficacy; limiting polypeptide conformation and slowing down its hydrolysis; reducing plasma clearance; improving drug dissociation and many more. Cyclopropane rings are widely found in marketed drugs, including cardiovascular drugs, central nervous system (CNS) drugs, anticancer drugs, autoimmune and anti-inflammatory drugs.
The ADC linker is one of the three main components of antibody drug conjugates (ADCs), linking the antibody to the effective drug (payload) through chemical bonds. ADC linkers play a key role in determining the overall success of antibody drug conjugates. One of the major challenges in developing safe and effective ADC drugs is to assemble an ideal chemical linker between the cytotoxic payload and the mAb. Well-designed ADC linkers can help the selective delivery of antibodies at the tumor site and the accurate release of cytotoxic drugs.