Activity on Trypanosoma cruzi, erythrocytes lysis and biologically relevant physicochemical properties of Pd(II) and Pt(II) complexes of thiosemicarbazones derived from 1-indanones.

American trypanosomiasis or Chagas disease, caused by the protist parasite Trypanosoma cruzi (T. cruzi), is a major health concern in Latin America. In the search for new bioactive compounds, eight Pd(II) and Pt(II) complexes of thiosemicarbazones derived from 1-indanones (HL) were evaluated as potential anti-T. cruzi compounds. Their unspecific cytotoxicity was determined on human erythrocytes. Two physicochemical features, lipophilicity and redox behavior, that could be potentially relevant for the biological activity of these complexes, were determined. Crystal structure of [Pd(HL1)(L1)]Cl·CH(3)OH, where HL1=1-indanone thiosemicarbazone, was solved by X-ray diffraction methods. Five of the eight metal complexes showed activity against T. cruzi with IC(50) values in the low micromolar range and showed significantly higher activity than the corresponding free ligands. Four of them resulted more active against the parasite than the reference antitrypanosomal drug Nifurtimox. Anti-T. cruzi activity and selectivity towards the parasite were both higher for the Pd(II) compounds than for the Pt(II) analogues, showing the effect of the metal center selection on the biological behavior. Among both physicochemical features tested for this series of compounds, lipophilicity and redox behavior, only the former seemed to show correlation with the antiproliferative effects observed. Metal coordination improved bioactivity but lead to an increase of mammalian cytotoxicity. Nevertheless, some of the metal complexes tested in this work still show suitable selectivity indexes and deserve further developments.

Synthesis and biological evaluation of some novel 1-indanone thiazolylhydrazone derivatives as anti-Trypanosoma cruzi agents.

A series of novel 4-arylthiazolylhydrazones (TZHs) derived from 1-indanones were synthesized in good yields (66-92%) in a simple procedure using microwave irradiation and then characterized by spectroscopy studies. The compounds were evaluated for their in vitro anti-Trypanosoma cruzi activity against the epimastigote, trypomastigote and amastigote forms of the parasite. Most TZHs displayed excellent activity, and were more potent and selective than the reference drug Benznidazole, used in the current chemotherapy. Analysis of the free sterols from parasite incubated with the compounds showed that inhibition of ergosterol biosynthesis is a possible target for the action of these new TZHs. In particular, TZH 9 emerged as a promising antichagasic compound to be evaluated in animal models.

Thiosemicarbazones derived from 1-indanones as new anti-Trypanosoma cruzi agents.

In the present work, we synthesized a series of thiosemicarbazones derived from 1-indanones with good anti-Trypanosoma cruzi activity. Most of them displayed remarkable trypanosomicidal activity. All the compounds showed nonspecific cytotoxicity on human erythrocytes. The ability of the new compounds to inhibit cruzipain, the major cysteine protease of T. cruzi, was also explored. Thiosemicarbazones 12 and 24 inhibited this enzyme at the dose assayed. This interaction was also studied in terms of molecular docking.

Inhibition of bovine viral diarrhea virus RNA synthesis by thiosemicarbazone derived from 5,6-dimethoxy-1-indanone.

In the present work, we described the activity of the thiosemicarbazone derived from 5,6-dimethoxy-1-indanone (TSC), which we previously characterized as a new compound that inhibits bovine viral diarrhea virus (BVDV) infection. We showed that TSC acts at a point of time that coincides with the onset of viral RNA synthesis and that it inhibits the activity of BVDV replication complexes (RCs). Moreover, we have selected five BVDV mutants that turned out to be highly resistant to TSC but still susceptible to ribavirin (RBV). Four of these resistant mutants carried an N264D mutation in the viral RNA-dependent RNA polymerase (RdRp). The remaining mutant showed an A392E mutation within the same protein. Some of these mutants replicated slower than the wild-type (wt) virus in the absence of TSC, whereas others showed a partial reversion to the wt phenotype over several passages in the absence of the compound. The docking of TSC in the crystal structure of the BVDV RdRp revealed a close contact between the indane ring of the compound and several residues within the fingers domain of the enzyme, some hydrophobic contacts, and hydrogen bonds with the thiosemicarbazone group. Finally, in the mutated RdRp from resistant BVDV, these interactions with TSC could not be achieved. Interestingly, TSC inhibited BVDV replication in cell culture synergistically with RBV. In conclusion, TSC emerges as a new nonnucleoside inhibitor of BVDV RdRp that is synergistic with RBV, a feature that turns it into a potential compound to be evaluated against hepatitis C virus (HCV).