No abstract

Continuing with a program to develop new quinone derivatives as biologically active compounds, we designed and synthesized a new series of aryloxy‐quinones, which were evaluated in vitro against Trypanosoma cruzi in epimastigote form. Chemical modifications in three specific moieties on the aryloxy‐quinone core were considered for developing new anti‐T. cruzi agents. The majority of our new quinones showed higher potency (IC50 values of <0.70 µM) than nifurtimox, a known pharmaceutical used as a baseline drug (IC50 values of 7.00 µM); however, only two of them elicited higher selectivity than nifurtimox against Vero cells. A structure–activity relationship analysis provided information about the stereoelectronic features of these compounds, which are responsible for an increase in trypanosomicidal activity. Using a pharmacophore model, we mapped the substitution patterns of the five pharmacophoric features of trypanosomicidal activity. We chose the Epc1 compounds and found no relationship with the trypanosomicidal effects. These results provided useful information about the structural characteristics for developing new aryloxy‐quinones with higher potency against the protozoan parasite T. cruzi.

A series of 2,6,9-trisubstituted purine derivatives have been synthesized and investigated for their potential role as antitumor agents. Twelve compounds were obtained by a three step synthetic procedure using microwave irradiation in a pivotal step. All compounds were evaluated in vitro to determine their potential effect on cell toxicity by the MTT method and flow cytometry analysis on four cancer cells lines and Vero cells. Three out of twelve compounds were found to be promising agents compared to a known and effective anticancer drug, etoposide, in three out of four cancer cell lines assayed with considerable selectivity. Preliminary flow cytometry data suggests that compounds mentioned above induce apoptosis on these cells. The main structural requirements for their activity for each cancer cell line were characterized with a preliminary pharmacophore model, which identified aromatic centers, hydrogen acceptor/donor center and a hydrophobic area. These features were consistent with the cytotoxic activity of the assayed compounds.

Since the Hedgehog signaling pathway has been associated with cancer, it has emerged as a therapeutic target for cancer therapy. The main target among the key Hedgehog proteins is the GPCR-like Smo receptor. Therefore, some Smo antagonists that have entered clinical trials, including the US FDA-approved drugs vismodegib and sonidegib, to treat basal cell carcinoma and medulloblastoma. However, early resistance of these drugs has spawned the need to understand the molecular bases of this phenomena. We therefore reviewed details about Smo receptor structures and the best Smo antagonist chemical structures. In addition, we discussed strategies that should be considered to develop new, safer generations of Smo antagonists that avoid current clinical limitations.

A series of chalcones and aurones were synthesized and evaluated in vitro as monoamine oxidase inhibitors (MAOi). Our results show that aurones, which had not been previously reported as MAOi, are MAO-B inhibitors. Thus, both families inhibited selectively the B isoform of MAO in the micromolar range, offering novel scaffolds for the design of new and potent MAO inhibitors. The main structural requirements for their activity were characterized with the aid of 3D-QSAR and docking studies.

We designed, synthesized, and evaluated novel 2,6,9-trisubstituted purine derivatives for their prospective role as antitumor compounds. Using simple and efficient methodologies, 31 compounds were obtained. We tested these compounds in vitro to draw conclusions about their cell toxicity on seven cancer cells lines and one non-neoplastic cell line. Structural requirements for antitumor activity on two different cancer cell lines were analyzed with SAR and 3D-QSAR. The 3D-QSAR models showed that steric properties could better explain the cytotoxicity of compounds than electronic properties (70% and 30% of contribution, respectively). From this analysis, we concluded that an arylpiperazinyl system connected at position 6 of the purine ring is beneficial for cytotoxic activity, while the use of bulky systems at position C-2 of the purine is not favorable. Compound 7h was found to be an effective potential agent when compared with a currently marketed drug, cisplatin, in four out of the seven cancer cell lines tested. Compound 7h showed the highest potency, unprecedented selectivity, and complied with all the Lipinski rules. Finally, it was demonstrated that 7h induced apoptosis and caused cell cycle arrest at the S-phase on HL-60 cells. Our study suggests that substitution in the purine core by arylpiperidine moiety is essential to obtain derivatives with potential anticancer activity.

In this paper, we explored the fluorescence properties of eight aurone derivatives bearing methoxy groups and bromine atoms as substituents in the benzene rings. All derivatives showed strong solvatochromic absorption and emission properties in solvents of different polarities. Some of them showed high fluorescence quantum yields, which make them potential compounds for sensing applications. The position of the methoxy groups in the benzofuranone moiety and the presence of bromine atoms in the benzene ring had a strong influence on the fluorescence behaviour of the aurones. DFT calculations allowed us to explain the emission properties of aurones and their solvatochromism, which was related to an excited state with strong charge-transfer character. Aurone 4 has the most promising characteristics showing a large difference in the quantum yields and large Stokes shifts depending on the solvent polarities. These results prompted us to explore some preliminary biological applications for aurone 4 such as the sensing of hydrophobic pockets of a protein and its thermotropic behaviour in liposomes.

A set of new aryloxy-quinones were synthesized and evaluated in vitro against the epimastigote form of Trypanosoma cruzi and their unspecific cytotoxicity was tested on murine macrophages J-774 cells.Most of these novel compounds were found to be extremely more potent and selective than the standard drug nifurtimox. Interestingly, 2-phenoxy-naphthoquinone 3b displayed a remarkable nanomolar inhibitory activity, IC 50 = 20 nM, and a high selectivity index, SI = 625. The E pc1 was determined for the most interesting compounds and no correlation with the trypanosomicidal effect was found. Therefore, an in silico study was carried out to obtain a pharmacophoric model and quantitative structure-trypanosomicidal activity relationship. The designed pharmacophore recognized the more potent and selective molecules, exhibiting five pharmacophoric features. A correlation coefficient R 2 of 0.99 of pIC 50 plotted against the predicted values indicated that the 3D-QSAR equation could be applied to further predictions of newly designed trypanosomicidal compounds. 5 5a,b with nitric acid. 23 The reaction of 6a and 6b with the phenols 2a-c or naphthols 2d,e furnished regiospecifically the corresponding 7-aryloxy-quinoline-5,8-dione derivatives 7a-i (24-92% yield).Scheme 2. Synthesis of compounds of series II (7a-i). Reagents and conditions: (i) Br 2 , MeOH, rt, 5 min; (ii) HNO 3 , H 2 SO 4 , 0 °C, 30 min; 23 (iii) K 2 CO 3 , 2a-e, DMF, rt, 3-5 h.Scheme 3. Synthesis of compounds of series III (11a-i). Reagents and conditions: (i) Br 2 , CHCl 3 , rt, 1.5 h; (ii) CrO 3 , H 2 O/AcOH, rt, 2 h; (iii) K 2 CO 3 , DMF, 2a-e, rt, 2 h.