Fragment Growing to Design Optimized Inhibitors for Human Blood Group B Galactosyltransferase (GTB)

Novel benzenesulfonamide-bearing pyrazoles and 1,2,4-thiadiazoles as selective carbonic anhydrase inhibitors

Two series comprising 20 novel benzenesulfonamides bearing thioureido-linked pyrazole 8 and amino-1,2,4-thiadiazole 10 were synthesized and assayed as human carbonic anhydrase (hCA) inhibitors against isoforms I and II as well as the tumor-associated isoforms IX and XII. Molecular modeling studies of some potent derivatives (8a, 8c, 10a, and 10c) were also performed against isoforms hCA I, II, and XII. Both the promising series of compounds were synthesized by using commercially available mtethyl ketones and sulfanilamide as the starting materials. Interestingly, this paper also reports a novel methodology for the synthesis of amino-1,2,4-thiadiazoles 10 using 3-amino isoxazoles and 4-isothiocyanatobenzenesulfonamide as reactants. The activity profile of all the newly synthesized compounds reveals that amino-linked 1,2,4-thiadiazoles 10 were better inhibitors of the cytosolic isoform, hCA I, as compared to thioureido-linked pyrazoles 8. Further, hCA II was strongly inhibited by nearly all the newly synthesized sulfonamides, while all the compounds were less effective as hCA IX and XII inhibitors compared to the standard drug acetazolamide. However, in terms of selectivity, compound 8e was found to be the most selective inhibitor of hCA II, which is the isoform associated with glaucoma, edema, altitude sickness, and epilepsy.

Iridium-catalyzed regioselective C-H sulfonamidation of 1,2,4-thiadiazoles with sulfonyl azides in water

We have developed a regioselective C-N cross-coupling of 1,2,4-thiadiazoles with sulfonyl azides through iridium catalysis in water. This method tactically linked the 1,2,4-thiadiazoles and sulfonamides together, and the novel molecules increased the diversity of 1,2,4-thiadiazoles which may have potential applications.

In silico Strategies to Support Fragment-to-Lead Optimization in Drug Discovery

Fragment-based drug (or lead) discovery (FBDD or FBLD) has developed in the last two decades to become a successful key technology in the pharmaceutical industry for early stage drug discovery and development. The FBDD strategy consists of screening low molecular weight compounds against macromolecular targets (usually proteins) of clinical relevance. These small molecular fragments can bind at one or more sites on the target and act as starting points for the development of lead compounds. In developing the fragments attractive features that can translate into compounds with favorable physical, pharmacokinetics and toxicity (ADMET-absorption, distribution, metabolism, excretion, and toxicity) properties can be integrated. Structure-enabled fragment screening campaigns use a combination of screening by a range of biophysical techniques, such as differential scanning fluorimetry, surface plasmon resonance, and thermophoresis, followed by structural characterization of fragment binding using NMR or X-ray crystallography. Structural characterization is also used in subsequent analysis for growing fragments of selected screening hits. The latest iteration of the FBDD workflow employs a high-throughput methodology of massively parallel screening by X-ray crystallography of individually soaked fragments. In this review we will outline the FBDD strategies and explore a variety of in silico approaches to support the follow-up fragment-to-lead optimization of either: growing, linking, and merging. These fragment expansion strategies include hot spot analysis, druggability prediction, SAR (structure-activity relationships) by catalog methods, application of machine learning/deep learning models for virtual screening and several de novo design methods for proposing synthesizable new compounds. Finally, we will highlight recent case studies in fragment-based drug discovery where in silico methods have successfully contributed to the development of lead compounds.