A practical access to four new halogen-substituted pyrrole building blocks was realized in two to five synthetic steps from commercially available starting materials. The target compounds were prepared on a 50 mg to 1 g scale, and their conversion to nanomolar inhibitors of bacterial DNA gyrase B was demonstrated for three of the prepared building blocks to showcase the usefulness of such chemical motifs in medicinal chemistry.

Current therapeutic protocols for the treatment of HIV infection consist of the combination of diverse anti-retroviral drugs in order to reduce the selection of resistant mutants and to allow for the use of lower doses of each single agent to reduce toxicity. However, avoiding drugs interactions and patient compliance are issues not fully accomplished so far. Pursuing on our investigation on potential anti HIV multi-target agents we have designed and synthesized a small library of biphenylhydrazo 4-arylthiazoles derivatives and evaluated to investigate the ability of the new derivatives to simultaneously inhibit both associated functions of HIV reverse transcriptase. All compounds were active towards the two functions, although at different concentrations. The substitution pattern on the biphenyl moiety appears relevant to determine the activity. In particular, compound 2-{3-[(2-{4-[4-(hydroxynitroso)phenyl]-1,3-thiazol-2-yl} hydrazin-1-ylidene) methyl]-4-methoxyphenyl} benzamide bromide (EMAC2063) was the most potent towards RNaseH (IC₅₀ = 4.5 mM)- and RDDP (IC₅₀ = 8.0 mM) HIV RT-associated functions.

A small library of novel thiazolidinone-based sulfonamide derivatives was designed, synthesized and evaluated for their ability to target human carbonic anhydrase (hCA) isoforms IX and XII, which are overexpressed in malignant cells and play a key role in metastasis and therapeutic response of cancer cells. A molecular hybridization approach was employed to design the molecules by combining different moieties identified as having antitumor activity. The thiazolidinone core was functionalized with benzenesulfonamide as a zinc-binding group and different isatin derivatives to enhance the chemical profile and optimize the hydrophilic/lipophilic balance. Biological evaluation against hCA I, II, IX and XII isoforms showed promising inhibitory activities, and some compounds exhibited selectivity and high inhibitory activity against hCA IX and hCA XII while not affecting off-target hCA I and hCA II. In particular, compound 3h demonstrated high selectivity with K_i values of 57.8 nM for hCA IX and 44.3 nM for hCA XII.

The SARS-CoV-2 non-structural protein 13 (nsp13) is a highly conserved helicase essential for viral replication and immune evasion. Its conservation across coronaviruses makes it an attractive target for the development of broad-spectrum antiviral agents. Hence, we rationally designed and synthesised 42 novel 2-iminothiazolidin-4-one derivatives as potential inhibitors. Several compounds displayed low-micromolar IC₅₀ values against both nsp13 NTPase and unwinding activities. Among these, 3i emerged as the lead compound, combining enzymatic inhibition (IC_50unwinding 2.65 ± 0.51 μM and IC_{50 NTPase} 8.52 ± 0.68 μM) with a favourable antiviral activity/cytotoxicity profile in two complementary cell models of SARS-CoV-2 infection (EC₅₀ 23.80 ± 1.80 μM in VeroE6-GFP, SI 18.15; EC₅₀ 6.7 ± 0.86 μM in Calu-3 cells, a human lung epithelial model). 3i also showed antiviral activity against hCoV-229E and MERS-CoV, with EC₅₀ values of 5.7 ± 0.1 and 4.6 ± 1.1 μM, respectively, supporting activity across human coronaviruses. The compound further demonstrated no marked hepatocellular cytotoxicity under the tested conditions in HepG2 cells, negligible inhibition of human helicases DDX3X and DDX5. Experimental biomimetic HPLC analyses provided an initial assessment of its physicochemical and distribution properties. Binding affinity evaluation by SPR revealed a K_D value of 6.20 μM, while enzyme kinetic studies indicated mixed-type NTPase inhibition. Exploratory docking and molecular dynamics analyses predicted possible binding regions that may account for the simultaneous modulation of the two nsp13 enzymatic functions. Finally, 3i showed a favourable antiviral combination profile with Remdesivir or Nirmatrelvir, mirroring established combination strategies in antiviral therapy.