The Brazilian octocoral Phyllogorgia dilatata as a source of cytotoxic compounds.

The extensive marine biodiversity has proved to be a promising source of substances with biomedical potential. In this study, the cytotoxicity of the Brazilian octocoral Phyllogorgia dilatata (Gorgoniidae) was evaluated against two tumor cell lines and three bacterial strains. The methanol/dichloromethane crude extract presented no antibacterial activity up to the highest concentration tested (512 µg/mL), however it revealed a noteworthy antiproliferative effect against HCT-116 (80%) and MCF-7 (54%) cell lines at 50 µg/mL. Therefore, guided by the cytotoxic activity, a multistep chemical fractionation of the extract provided the subfraction 5 (PDPH2-5) with IC50 values of 3.18 and 17.80 µg/mL against HCT-116 and MCF-7, respectively. The LC-HRMS/MS analysis of PDPH2-5 showed ions of m/z 219.1742 and 219.1743, characterized as (E,E) and (Z,E) germacrone, after a LC-DAD-SPE/NMR analysis of the hexanic fraction and comparisons of NMR data with the literature. Previously reported assessments to the cytotoxic activity of the (E,E)-diastereoisomer disclosed higher IC50 values than that obtained for the PDPH2-5 fraction, suggesting, herein, a potentiated effect of the diastereoisomeric mixture. Such remark encourage further bioactivity studies with stereoisomer mixtures and reduce the urge for compound isolation.

Quinoline: An Attractive Scaffold in Drug Design.

Quinoline and its derivatives comprise an important group of heterocyclic compounds that exhibits a wide range of pharmacological properties such as antibacterial, antiviral, anticancer, antiparasitic, anti-Alzheimer and anticholesterol. The quinoline nucleus is found in the structure of many drugs and rational design in medicinal chemistry for the discovery of novel bioactive molecules. Persistent efforts have been made over the years to develop novel congeners with superior biological activities and minimal potential for undesirable side effects. This review highlights some discoveries on the development of quinoline-based compounds in recent years (2013-2019), focusing on their biological activities, including anticancer, antitubercular, antimalarial, anti-ZIKV, anti-DENV, anti- Leishmania and anti-Alzheimer's disease.

Cytotoxicity and selectiveness of Brazilian Piper species towards oral carcinoma cells.

BACKGROUND: Oral squamous cell carcinoma (OSCC) is one of the ten most common types of cancer worldwide. Plants of the genusPiper are used in traditional medicine to treat cancer, and they have a vast diversity of phytochemicals with cytotoxic potential. Purpose and Study Design: In this work, we analyzed the cytotoxic and selective potential of extracts and semipurified fractions of Piper mollicomum (PM), Piper truncatum (PT), Piper cernuum (PC), Piper arboreum (PA), and Piper cabralanum (PCa) using three different OSCC cell lines (SCC4, SCC9 and SCC25), and we measured their in vivo toxicities and conducted chemical analyses of their active fractions. RESULTS: The dichloromethane fractions of the crude methanolic extracts of the leaves of PM(-L-D), PC(-L-D) and PCa(-L-D) exhibited notable IC50 values of 94.2, 47.2 and 47.5 µg/mL, respectively, and all three of these extracts were more active than carboplatin (172.3 µg/mL). The most selective fraction was PC-L-D, which exhibited SI > 4.5; less than 5% hemolysis; and no significant alterations in in vivo acute toxicology. The major constituents in active fractions were lignans (PC-L-D and PCa-L-D) and chromenes (PM-L-D). CONCLUSION: PC-L-D demonstrated great potential for further development as an anticancer drug and could be the key to developing more effective and less toxic therapies against oral cancer.

Crystal structures and Hirshfeld surfaces of two 1,3-benzoxa-thiol-2-one derivatives.

The crystal structures of 6-meth-oxy-1,3-benzoxa-thiol-2-one, C9H8O3S, (I), and 2-oxo-1,3-benzoxa-thiol-6-yl acetate, C9H6O4S, (II), are described. Compound (I) is almost planar (r.m.s. deviation for the non-H atoms = 0.011 Å), whereas (II) shows a substantial twist between the fused-ring system and the acetate substituent [dihedral angle = 74.42 (3)°]. For both structures, the bond distances in the heterocyclic ring suggest that little if any conjugation occurs. In the crystal of (I), C-H⋯O hydrogen bonds link the mol-ecules into [1-11] chains incorporating alternating R22(8) and R22(12) inversion dimers. The extended structure of (II) features C(7) [201] chains linked by C-H⋯O hydrogen bonds, with further C-H⋯O bonds and weak π-π stacking inter-actions connecting the chains into a three-dimensional network. Hirshfeld fingerprint analyses for (I) and (II) are presented and discussed.

Evaluation of 1,3-benzoxathiol-2-one Derivatives as Potential Antifungal Agents.

BACKGROUND: Over the last few years, fungal infections have emerged as a worrisome global public health problem. Candidiasis is a disease caused by Candida species and has been a problem worldwide mainly for immunosuppressed patients. Lately, the resistant strains and side effects have been reported as important issues for treating Candidiasis, which have to be solved by identifying new drugs. OBJECTIVE: The goal of this work was to synthesize a series of 1,3-benzoxathiol-2-one derivatives, XYbenzo[ d][1,3]oxathiol-2-ones, and evaluate their antifungal activity against five Candida species. METHODS: In vitro antifungal screening test and minimum inhibitory concentration determination were performed according to CLSI protocols using ketoconazole as the reference drug. The cytotoxicity of the most active compounds was evaluated by hemolysis and MTT (Vero cells) assays. RESULTS: Compounds 2 (XY = 6-hydroxy-5-nitro, MIC = 4-32 µg/mL) and 7 (XY = 6-acetoxy-5-nitro, MIC =16-64 µg/mL) showed good results when compared with current antifungals in CLSI values (MIC = 0.04-250 µg/mL). These compounds exhibited a safer cytotoxicity as well as a lower hemolytic profile than ketoconazole. CONCLUSION: Overall, the in vitro results pointed to the potential of compounds 2 and 7 as new antifungal prototypes to be further explored.

Synthesis and anticancer activity of (E)-2-benzothiazole hydrazones.

Benzothiazole hydrazones have been synthesized and evaluated for their in vitro antiproliferative activity against three human cancer cell lines: HL-60 (leukemia), MDAMB-435 (breast) and HCT-8 (colon). The good cytotoxicity for the three cancer cell lines and theoretical profile of compounds 3o and 3p pointed them as promising lead molecules for anticancer drug design.

Antibacterial activity of thioetherhydroxyethylsulfonamide derivatives.

Thioetherhydroxyethylsulfonamide derivatives were synthesized and evaluated for their in vitro antibacterial activity against Escherichia coli (ATCC 25922), Pseudomonas aeruginosa (ATCC 27853) and Staphylococcus aureus (ATCC 25923). Results have shown that compounds 8c and 9e display potent activity (MIC = 0.125 µg/mL) against E. coli when compared with the standard drug sulfamethoxazole (SMZ, MIC < 0.5 µg/mL) for this same strain. All the new compounds were fully identified and characterized by NMR ((1)H and (13)C) and X-ray crystallography (for compound 8c). This class of compounds can be considered as a good starting point for the development of new lead molecules in the fight against multi-drug bacterial resistance.

tert-Butyl N-[3-hy-droxy-1-phenyl-4-(pyrimidin-2-ylsulfan-yl)butan-2-yl]carbamate monohydrate.

In the title hydrate, C(19)H(25)N(3)O(3)S·H(2)O, the configuration at each chiral centre in the organic mol-ecule is S, with the hy-droxy and carbamate substituents being anti [O-C-C-N torsion angle = -179.3 (3)°]. The thio-pyrimidyl and carbamate residues lie to one side of the pseudo-mirror plane defined by the C(5)S backbone of the mol-ecule; this plane approximately bis-ects the benzene ring at the 1- and 4-C atoms. The dihedral angle formed between the terminal rings is 5.06 (18)°. In the crystal, supra-molecular tubes aligned along the b axis are found: these are sustained by a combination of O-H⋯O, O-H⋯N and N-H⋯O hydrogen bonds.

N-{(2S)-3-Hy-droxy-4-[(5-methyl-1,3,4-thia-diazol-2-yl)sulfan-yl]-1-phenyl-2-but-yl}-4-methyl-benzene-sulfonamide.

The thia-diazoyl and sulfonyl-benzene rings in the title compound, C(20)H(23)N(3)O(3)S(3), are aligned to the same side of the mol-ecule, forming a twisted 'U' shape [dihedral angle = 77.6 (5)°]. The benzyl-benzene ring is orientated in the opposite direction from the mol-ecule but projects approximately along the same axis as the other rings [dihedral angle between benzene rings = 28.2 (5)°] so that, overall, the mol-ecule has a flattened shape. The hy-droxy and amine groups are almost syn which enables the formation of inter-molecular hy-droxy-OH⋯N(thia-diazo-yl) and amine-H⋯O(sulfon-yl) hydrogen bonds leading to a supra-molecular chain aligned along the a axis.

Synthesis and antimalarial activity of thioetherhydroxyethylsulfonamides, potential aspartyl protease inhibitors, Part 3.

A series of novel thioetherhydroxyethylsulfonamide derivatives has been synthesized from the coupling of intermediates 3-amino-4-phenyl-1-thioetherazine-butan-2-oles 6,7 with arenesulfonyl chlorides in good yields. Characterizations of products were achieved by NMR techniques and specifically for compound 8e by X-ray crystallography. Preliminary results of antimalarial activity in vitro against the Plasmodium falciparum W2 clone (chloroquine resistant and mefloquine sensitive) showed moderate activity for hydroxyethylsulfonamide 8f. In addition, none of the compounds tested showed cytotoxicity at high concentration tested against HepG2 and BGM cell lines.

Synthesis and anticancer activities of some novel 2-(benzo[d]thiazol-2-yl)-8-substituted-2H-pyrazolo[4,3-c]quinolin-3(5H)-ones.

A series of 2-(benzo[d]thiazol-2-yl)-8-substituted-2H-pyrazolo[4,3-c]quinolin-3(5H)-ones (3a-g) have been synthesized and evaluated for their in vitro antiproliferative activities against four human cancer cell lines: MDA-MB-435 (breast), HL-60 (leukemia), HCT-8 (colon) and SF-295 (central nervous system). The results showed that the compounds 3b (2-(benzo[d]thiazol-2-yl)-8-methyl-2H-pyrazolo[4,3-c]quinolin-3(5H)-one) and 3c (2-(benzo[d]thiazol-2-yl)-8-bromo-2H-pyrazolo[4,3-c]quinolin-3(5H)-one) exhibited good cytotoxicity for three cell lines with IC(50) values lower than 5 µg/mL. Analysis of theoretical toxicity risks have shown medium tumorigenic and irritant risks related to 3b and 3c in contrast to doxorubicin, the positive control.

Synthesis and antitubercular activity of novel Schiff bases derived from d-mannitol.

Six Schiff base derivatives of d-mannitol, 1,6-dideoxy-1,6-bis-{[(E)-arylmethylidene]amino}-d-mannitol (6: aryl=XC(6)H(4): X=o-, m- and p- Cl or NO(2)), have been synthesized and evaluated for their in vitro antibacterial activity against Mycobacterium tuberculosis H(37)Rv using the Alamar Blue susceptibility test and the activity expressed as the minimum inhibitory concentration (MIC) in microg/mL. All three nitro derivatives exhibit significant activities: activities of (6d: X=o-NO(2)), (6e: X=m-NO(2)) and (6f: X=p-NO(2)) are 12.5, 25.0 and 25.0microg/mL, respectively. When compared with first line drugs, such as ethambutol, they can be considered as a good starting point to develop new lead compounds for the treatment of multidrug-resistant tuberculosis. Characterization of the new compounds 6 is generally achieved spectroscopically. The structure of compound 3 has been confirmed by X-ray crystallography.

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.

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.

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.

A three-dimensional framework of pi-stacked hydrogen-bonded chains in benzyl 4-chloro-3-nitrobenzoate, and chains of hydrogen-bonded rings in benzyl 4-nitrobenzoate, redetermined at 120 K.

Benzyl 4-chloro-3-nitrobenzoate, C14H10ClNO4, crystallizes with Z' = 2 in the space group P-1. The molecules are linked by three independent C-H...O hydrogen bonds into chains of edge-fused R(4)4 (26) and R(4)4 (34) rings, and these chains are linked into a three-dimensional framework structure by aromatic pi-pi stacking interactions. In benzyl 4-nitrobenzoate, C14H11NO4, the molecules are linked by two independent C-H...O hydrogen bonds into chains containing two types of R(2)2 (10) ring.

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.

pi-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-difluorobenzaldehyde isonicotinoylhydrazone, C13H9F2N3O, (I), is disordered over two sets of sites with unequal occupancy. The molecules 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 pi-pi stacking interaction. In 2,3-dichlorobenzaldehyde isonicotinoylhydrazone, C13H9Cl2N3O, (II), the molecules are linked by a combination of N-H...N, C-H...N and C-H...O hydrogen bonds into sheets of R(4)(4)(14) and R(4)(4)(26) rings.

Supramolecular structures of three isomeric 2-chloro-N-(nitrophenyl)nicotinamides.

Molecules of 2-chloro-N-(2-nitrophenyl)nicotinamide, C12H8ClN3O3, are linked by two C-H...O hydrogen bonds into a chain of edge-fused R(2)(2) (14) and (4)(4) (24) rings. In 2-chloro-N-(3-nitrophenyl)nicotinamide monohydrate, C12H8ClN3O3.H2O, the molecules are linked by a combination of N-H...O, O-H...O and O-H...N hydrogen bonds into a chain of edge-fused rings containing two distinct types of R(4)(4) (16) ring. In 2-chloro-N-(4-nitrophenyl)nicotinamide, C12H8ClN3O3, which crystallizes with Z' = 2 in space group P2(1)/n, the molecules are linked by two N-H...N hydrogen bonds into simple C(2)(2) (12) chains.