Thatyana R. A. Vasconcelos

Fármacos no combate à tuberculose: passado, presente e futuro

Approximately every minute, somewhere in the world four people die from tuberculosis (TB), an infection of Mycobacterium tuberculosis with about 3 million deaths per year. In spite of these problems, unfortunaly, it is about 40 years that a novel drug was last introduced on the market. Due to the rapid spread of multi-drug resistant TB strains, resistant against all major anti-tuberculosis drugs, and the recent resurgence of the incidence of tuberculosis in association with the human immunodeficiency virus (HIV) infection and AIDS, we need urgently the development of new drugs to fight tuberculosis. This is covered in the present article.

Patterns of hydrogen bonding in mono- and di-substituted N-arylpyrazinecarboxamides.

The molecular and supramolecular structures of 18 N-arylpyrazinecarboxamides, Ar NHCO(C(4)H(3)N(2)), have been determined, including the stoichiometric monohydrate of N-(3-methoxyphenyl)pyrazinecarboxamide, and two polymorphs of N-(4-fluorophenyl)pyrazinecarboxamide having Z values of 1 and 4, respectively. The aryl groups were selected to include the geometric isomers for a compact range of substituents, namely methyl, trifluoromethyl, fluoro, chloro, methoxy and nitro groups, which exhibit markedly varied electronic properties and markedly varied behaviour as hydrogen-bond donors and acceptors. However, not all isomers in each group could be structurally investigated. A small number of derivatives containing disubstituted aryl groups have also been included in this study. The crystal structures of the solvent-free carboxamides reported here exhibit a wide range of direction-specific intermolecular forces, including N-H...N, N-H...O, C-H...N and C-H...O hydrogen bonds, and pi...pi stacking interactions, while the structure of N-(3-methoxyphenyl)pyrazinecarboxamide monohydrate also contains O-H...N and O-H...O hydrogen bonds. The resulting supramolecular structures can be zero-, one- or two-dimensional, although no three-dimensional supramolecular aggregation has been observed. In the finite, zero-dimensional structures, pairs of molecules are linked by hydrogen bonds to form cyclic centrosymmetric dimers. The one-dimensional structures include chains formed by the pi-stacking of otherwise isolated molecules, simple chains generated by either C-H...O or C-H...N hydrogen bonds, and hydrogen-bonded chains of rings. The two-dimensional structures include examples of both pi-stacked hydrogen-bonded chains and hydrogen-bonded sheets.

Simple Reduction of Heteroaromatic Esters to Alcohols Using a Sodium Borohydride–Methanol System

Abstract Some heteroaromatic esters were reduced to the corresponding alcohols by using a sodium borohydride–methanol system. The reduction was completed within 0.15–2.0 h in refluxing THF. The alcohol products were isolated after aqueous workup in moderate to excellent yield (48–97%).

Perspectives on the Development of Novel Potentially Active Quinolones Against Tuberculosis and Cancer

Quinolones and its derivatives comprise an important group of heterocyclic compounds that exhibit a wide range of pharmacological properties such as antibacterial, antitumor, antiviral, anti-ischemic, antiparasitic and anxiolytic. Persistent efforts have been made over the years to develop novel congeners with superior biological activities and minimal potential for undesirable side-effects. The present review aims to highlight some recent discoveries on the development of novel quinolone-based compounds with potential antitubercular and anticancer activity.

Nine N-aryl-2-chloronicotinamides: supramolecular structures in one, two and three dimensions

Structures are reported here for eight further substituted N-aryl-2-chloronicotinamides, 2-ClC(5)H(3)NCONHC(6)H(4)X-4. When X = H, compound (I) (C(12)H(9)ClN(2)O), the molecules are linked into sheets by N-H...N, C-H...pi(pyridyl) and C-H...pi(arene) hydrogen bonds. For X = CH(3), compound (II) (C(13)H(11)ClN(2)O, triclinic P1 with Z = 2), the molecules are linked into sheets by N-H...O, C-H...O and C-H...pi(arene) hydrogen bonds. Compound (III), where X = F, crystallizes as a monohydrate (C(12)H(8)ClFN(2)O.H(2)O) and sheets are formed by N-H...O, O-H...O and O-H...N hydrogen bonds and aromatic pi...pi stacking interactions. Crystals of compound (IV), where X = Cl (C(12)H(8)Cl(2)N(2)O, monoclinic P2(1) with Z = 4) exhibit inversion twinning: the molecules are linked by N-H...O hydrogen bonds into four independent chains, linked in pairs by C-H...pi(arene) hydrogen bonds. When X = Br, compound (V) (C(12)H(8)BrClN(2)O), the molecules are linked into sheets by N-H...O and C-H...N hydrogen bonds, while in compound (VI), where X = I (C(12)H(8)ClIN(2)O), the molecules are linked into a three-dimensional framework by N-H...O and C-H...pi(arene) hydrogen bonds and an iodo...N(pyridyl) interaction. For X = CH(3)O, compound (VII) (C(13)H(11)ClN(2)O(2)), the molecules are linked into chains by a single N-H...O hydrogen bond. Compound (VIII) (C(13)H(8)ClN(3)O, triclinic P1 with Z = 2), where X = CN, forms a complex three-dimensional framework by N-H...N, C-H...N and C-H...O hydrogen bonds and two independent aromatic pi...pi stacking interactions.

π-Stacked hydrogen-bonded chains of rings in 2,4-difluoro­benzaldehyde isonicotinoylhydrazone and hydrogen-bonded sheets in 2,3-dichloro­benzaldehyde isonicotinoylhydrazone

The difluorinated ring in 2,4-difluoroxadbenzaldehyde isoxadnicotinoylxadhydrazone, C13H9F2N3O, (I), is disordered over two sets of sites with unequal occupancy. The molxadecules of (I) are linked by a combination of N—H⋯O and C—H⋯O hydrogen bonds into chains of rings, which are linked into sheets by a single π–π stacking interxadaction. In 2,3-dichloroxadbenzaldehyde isonicotinoylhydrazone, C13H9Cl2N3O, (II), the molxadecules are linked by a combination of N—H⋯N, C—H⋯N and C—H⋯O hydrogen bonds into sheets of R44(14) and R44(26) rings.

Four substituted benzohydrazides: hydrogen-bonded structures in one, two and three dimensions

The molecules of 2,6-dichlorobenzohydrazide, C7H6Cl2N2O, are linked into simple chains by a single N-H...O hydrogen bond, while in the isomeric compound 2,4-dichlorobenzohydrazide, the molecules are linked by N-H...N and N-H...O hydrogen bonds into complex sheets comprising an inner polar layer sandwiched between two non-polar layers. In 4-amino-2-chlorobenzohydrazide monohydrate, C7H8ClN3O.H2O, the components are linked into a three-dimensional framework by a combination of O-H...O, O-H...N, N-H...N and N-H...O hydrogen bonds, and in 2-nitrobenzohydrazide, C7H7N3O3, a three-dimensional framework is formed by a combination of N-H...N and N-H...O hydrogen bonds.

First-time Isolation of Flavonoids and Cytotoxic Potential of the Amazonian Shrub Ptychopetalum olacoides Benth

: In the present study three flavonoids, 3- O -methylquercetin ( 1 ), 3,4- O -dimethylquercetin ( 2 ) and 3,7- O -dimethylquercetin ( 3 ) were isolated and characterized for the first time from a methanol extract obtained from the species Ptychopetalum olacoides . The structures of compounds were identified by spectroscopic methods (1D-, 2D-NMR, MS and UV) and confirmed by comparison with the respective literature data. The cytotoxic effect of crude extract was evaluated in vitro against three human cancer cell lines. Results showed a mild cytotoxic activity (IC 50 = 45.16 µg/mL) against breast cancer (MCF-7), however crude extract did not exhibit any cytotoxic effect against normal cell human fibroblast (MRC-5).

CCDC 268198: Experimental Crystal Structure Determination

Related Article: E.L.Fernandes, A.Magalhaes, K.C.Paes, M.V.N.de Souza, T.R.A.Vasconcelos, J.L.Wardell, S.M.S.V.Wardell|2006|J.Chem.Res.||93|

Simple chains in methyl 3,5-dinitro­benzoate, isolated mol­ecules in iso­propyl 3,5-dinitro­benzoate, and a three-dimensional framework containing double and sextuple helices in benzyl 3,5-dinitro­benzoate, all at 120 K

Molecules of methyl 3,5-dinitrobenzoate, C8H6N2O6, are linked into C7 chains by a single nearly linear C-H...O hydrogen bond, but there are no direction-specific interactions in the structure of isopropyl 3,5-dinitrobenzoate, C10H10N2O6. In benzyl 3,5-dinitrobenzoate, C14H10N2O6, the molecules are linked by four independent C-H...O hydrogen bonds into a complex three-dimensional framework structure, in which it is possible to identify simple substructures in the form of cyclic centrosymmetric dimers, double helices and sextuple helices.