Browsing by Author "Sanchez, Patricio"

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    Mode of action of p-quinone derivatives with trypanocidal activity studied by experimental and in silico models
    (2023) Ballesteros-Casallas, Andres; Quiroga, Cristina; Ortiz, Cecilia; Benitez, Diego; Denis, Pablo A.; Figueroa, David; Salas, Cristian O.; Bertrand, Jeanluc; Tapia, Ricardo A.; Sanchez, Patricio; Miscione, Gian Pietro; Comini, Marcelo A.; Paulino, Margot
    Quinones are attractive pharmacological scaffolds for developing new agents for the treatment of different transmissible and non-transmissible human diseases due to their capacity to alter the cell redox homeostasis.The bioactivity and potential mode of action of 19 p-quinone derivatives fused to different aromatic rings (carbo or heterocycles) and harboring distinct substituents were investigated in infective Trypanosoma brucei brucei. All the compounds, except for a furanequinone (EC50=38 mu M), proved to be similarly or even more potent (EC50 = 0.5-5.5 mu M) than the clinical drug nifurtimox (EC50 = 5.3 mu M). Three furanequinones and one thia-zolequinone displayed a higher selectivity than nifurtimox. Two of these selective hits resulted potent inhibitors of T. cruzi proliferation (EC50=0.8-1.1 mu M) but proved inactive against Leishmania infantum amastigotes.Most of the p-quinones induced a rapid and marked intracellular oxidation in T. b. brucei. DFT calculations on the oxidized quinone (Q), semiquinone (Q center dot-) and hydroquinone (QH2) suggest that all quinones have negative Delta G for the formation of Q center dot-. Qualitative and quantitative structure-activity relationship analyses in two or three dimensions of different electronic and biophysical descriptors of quinones and their corresponding bioactivities (killing potency and oxidative capacity) were performed.Charge distribution over the quinone ring carbons of Q and Q.-and the frontier orbitals energies of SUMO (Q.-) and LUMO (Q) correlate with their oxidative and trypanocidal activity. QSAR analysis also highlighted that both bromine substitution in the p-quinone ring and a bulky phenyl group attached to the furane and thiazole rings (which generates a negative charge due to the 7C electron system polarized by the nearby heteroatoms) are favorable for activity.By combining experimental and in silico procedures, this study disclosed important information about p-qui-nones that may help to rationally tune their electronic properties and biological activities.
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    Phenoxy- and Phenylamino-Heterocyclic Quinones: Synthesis and Preliminary Anti-Pancreatic Cancer Activity
    (WILEY-V C H VERLAG GMBH, 2022) Sanchez, Patricio; Salas, Cristian O.; Gallardo-Fuentes, Sebastian; Villegas, Alondra; Veloso, Nicolas; Honores, Jessica; Inman, Martyn; Isaacs, Mauricio; Contreras, Renato; Moody, Christopher J.; Cisterna, Jonathan; Brito, Ivan; Tapia, Ricardo A.
    The successful application of fragment-based drug discovery strategy for the efficient synthesis of phenoxy- or phenylamino-2-phenyl-benzofuran, -benzoxazole and -benzothiazole quinones is described. Interestingly, in the final step of the synthesis of the target compounds, unusual results were observed on the regiochemistry of the reaction of bromoquinones with phenol and aniline. A theoretical study was carried out for better understanding the factors that control the regiochemistry of these reactions. The substituted heterocyclic quinones were evaluated in vitro to determine their cytotoxicity by the MTT method in three pancreatic cancer cell lines (MIA-PaCa-2, BxPC-3, and AsPC-1). Phenoxy benzothiazole quinone 26a showed potent cytotoxic activity against BxPC-3 cell lines, while phenylamino benzoxazole quinone 20 was the most potent on MIA-PaCa-2 cells. Finally, electrochemical properties of these quinones were determined to correlate with a potential mechanism of action. All these results, indicate that the phenoxy quinone fragment led to compounds with increased activity against pancreatic cancer cells.