Laura Nogueira de Faria Cardoso

Synthesis and antitubercular activity of 7-chloro-4-quinolinylhydrazones derivatives

A series of twenty-one 7-chloro-4-quinolinylhydrazones (3a-u) have been synthesized and evaluated for their in vitro antibacterial activity against Mycobacterium tuberculosis H(37)Rv. The compounds 3f, 3i and 3o were non-cytotoxic and exhibited an important minimum inhibitory concentration (MIC) activity (2.5 microg/mL), which can be compared with that of the first line drugs, ethambutol (3.12 microg/mL) and rifampicin (2.0 microg/mL). These results can be considered an important start point for the rational design of new leads for anti-TB compounds.

Synthesis and Antitubercular Activity of Heteroaromatic Isonicotinoyl and 7-Chloro-4-Quinolinyl Hydrazone Derivatives

Two series of N’(E)-heteroaromatic-isonicotinohydrazide derivatives (3a-f and 4a-b) and 1-(7-chloroquinolin-4-yl)-2-[(heteroaromatic)methylene]hydrazone derivatives (5a-f and 6a-b) have been synthesized and evaluated for their in vitro antibacterial activity against Mycobacterium tuberculosis H37Rv. Several compounds were noncytotoxic and exhibited significant minimum inhibitory concentration (MIC) activity (3.12, 2.50, 1.25, or 0.60 μg/mL), which can be compared to that of the first-line drugs ethambutol (3.12 μg/mL) and rifampicin (2.0 μg/ml). These results can be considered an important starting point for the rational design of new leads for anti-TB compounds.

Synthesis and Antitumoral Evaluation of 7-chloro-4-quinolinylhydrazones Derivatives

A series of twenty-one 7-chloro-4-quinolinylhydrazones derivatives (3a-u) have been synthesized and evaluated for their cytotoxic potential against three cancer cell lines using MTT assay. The compounds 3b, 3e, 3f, 3h, 3j, 3n, 3r and 3u displayed more than 90% of growth inhibition (GI) and they were selected for in vitro anticancer activities evaluation against four human cancer cell lines. These results were expressed as the concentrations that induce 50% inhibition of cell growth (IC50) in μg/mL. Considering that, compounds 3b, 3e, 3h, 3n, 3r and 3u exhibited good cytotoxic activity against at least three cancer cell lines (0.7967-4.200 μg/mL). In general, we observed that the presence of electron-withdrawing groups in the benzene ring is important for the anticancer activity in this series, such as fluorine (3h), chlorine (3b) amd bromine (3e) groups in meta position and nitro group (3r) in para position. These derivatives could be considered interesting start points to develop a new anticancer drug and confirm the potential of chloroquine derivatives as lead compounds in anticancer drug discovery.

Crystal structures of 2-[5-nitrothien-2-yl)- CH=N–NR–CO(CH2)n]thiophene compounds (R = H or Me; n = 0 or 1)

Abstract The crystal structures of four acylhydrazonyl derivatives of thiophene, 2-(ArCH=N–NHCO)- thiophene, (1a), 2-(ArCH=N–NMeCO)-thiophene, (2a), 2-(ArCH=N–NHCOCH2)-thiophene, (3a) and 2-(ArCH= N–NMeCOCH2)-thiophene, (4a) [in each case Ar= 5-nitrothien-2-yl] are reported. The molecular conformations of 1a and 2a are near planar, while those of 3a and 4a exhibit bends at the methylene carbon. Methylations at the hydrazonyl groups in 1a and 3a, to give 2a and 4a, do not result in any significant changes in the molecular conformations. Each of the four molecular conformations possesses a ZC(O)NR/E(C=N) arrangement about the C(O)–NR–N=C(H, aryl) fragment (R=H or Me). The dominant intermolecular interactions in 1a and 3a are N–H···O(carbonyl) hydrogen bonds, with other intermolecular interactions being weaker interactions: C–H···O and N–O···π in 1a and C–H···X (X=O, S, π) and π–π interactions in 3a. In the N-methylated compounds, the intermolecular interactions are restricted to weaker C–H···O hydrogen bonds in 2a and C–H···X (X=O or π) interactions in 4a.

N'-[(1E)-(5-Nitro-furan-2-yl)methyl-idene]thio-phene-2-carbohydrazide: crystal structure and Hirshfeld surface analysis.

The title molecule is curved as seen in the dihedral angle [27.4u2005(2)°] between the outer rings. Supramolecular chains about a 41 screw axis are formed by amide-N—H⋯O(carbonyl) hydrogen bonding.

Substituted 4-alkoxy-7-Cl-quinolines exhibiting π-π stacking.

The molecules of 4-allyloxy-7-chloroquinoline, C(12)H(10)ClNO, (I), 7-chloro-4-methoxyquinoline, C(10)H(8)ClNO, (II), and 7-chloro-4-ethoxyquinoline, C(11)H(10)ClNO, (III), are all planar. In all three structures, π-π interactions between the quinoline ring systems are generated by unit-cell translations along the a axes, irrespective of space group. These structures are the first reported for 4-alkoxyquinolines.

Anti-Mycobacterial Evaluation of 7-Chloro-4-Aminoquinolines and Hologram Quantitative Structure–Activity Relationship (HQSAR) Modeling of Amino–Imino Tautomers

In an ongoing research program for the development of new anti-tuberculosis drugs, we synthesized three series (A, B, and C) of 7-chloro-4-aminoquinolines, which were evaluated in vitro against Mycobacterium tuberculosis (MTB). Now, we report the anti-MTB and cytotoxicity evaluations of a new series, D (D01–D21). Considering the active compounds of series A (A01–A13), B (B01–B13), C (C01–C07), and D (D01–D09), we compose a data set of 42 compounds and carried out hologram quantitative structure–activity relationship (HQSAR) analysis. The amino–imino tautomerism of the 4-aminoquinoline moiety was considered using both amino (I) and imino (II) forms as independent datasets. The best HQSAR model from each dataset was internally validated and both models showed significant statistical indexes. Tautomer I model: leave-one-out (LOO) cross-validated correlation coefficient (q2) = 0.80, squared correlation coefficient (r2) = 0.97, standard error (SE) = 0.12, cross-validated standard error (SEcv) = 0.32. Tautomer II model: q2 = 0.77, r2 = 0.98, SE = 0.10, SEcv = 0.35. Both models were externally validated by predicting the activity values of the corresponding test set, and the tautomer II model, which showed the best external prediction performance, was used to predict the biological activity responses of the compounds that were not evaluated in the anti-MTB trials due to poor solubility, pointing out D21 for further solubility studies to attempt to determine its actual biological activity.

Sodium Chlorite (NaClO2): an Important Reagent in Alcohol and Aldehyde Oxidation and its Application in Total Synthesis of Natural Products

Abstract The oxidation of alcohols is a fundamental transformation in organic synthesis and a large number of reagents have been developed for this purpose. In spite of the different methodologies, the modern organic synthesis still requires more efficient oxidant reagents. In this context, sodium chlorite (NaClO2) has emerged as the chosen reagent. The aim of this review is to highlight sodium chlorite oxidation due to the significance of this reagent nowadays as a very important procedure in the synthesis of natural products and derivatives, accomplished from 2005 to 2010.Abstract The oxidation of alcohols is a fundamental transformation in organic synthesis and a large number of reagents have been developed for this purpose. In spite of the different methodologies, the modern organic synthesis still requires more efficient oxidant reagents. In this context, sodium chlorite (NaClO2) has emerged as the chosen reagent. The aim of this review is to highlight sodium chlorite oxidation due to the significance of this reagent nowadays as a very important procedure in the synthesis of natural products and derivatives, accomplished from 2005 to 2010.