Saccharomyces cerevisiae DNA repair pathways involved in repair of lesions induced by mixed ternary mononuclear Cu(II) complexes based on valproic acid with 1,10-phenanthroline or 2,2'- bipyridine ligands.

The sodium valproate has been largely used as an anti-epilepsy drug and, recently, as a putative drug in cancer therapy. However, the treatment with sodium valproate has some adverse effects. In this sense, more effective and secure complexes than sodium valproate should be explored in searching for new active drugs. This study aims to evaluate the cytotoxicity of sodium valproate, mixed ternary mononuclear Cu(II) complexes based on valproic acid (VA) with 1,10-phenanthroline (Phen) or 2,2'- bipyridine (Bipy) ligands - [Cu2(Valp)4], [Cu(Valp)2Phen] and [Cu(Valp)2Bipy] - in yeast Saccharomyces cerevisiae, proficient or deficient in different repair pathways, such as base excision repair (BER), nucleotide excision repair (NER), translesion synthesis (TLS), DNA postreplication repair (PRR), homologous recombination (HR) and non-homologous end-joining (NHEJ). The results indicated that the Cu(II) complexes have higher cytotoxicity than sodium valproate in the following order: [Cu(Valp)2Phen] > [Cu(Valp)2Bipy] > [Cu2(Valp)4] > sodium valproate. The treatment with Cu(II) complexes and sodium valproate induced mutations in S. cerevisiae. The data indicated that yeast strains deficient in BER (Ogg1p), NER (complex Rad1p-Rad10p) or TLS (Rev1p, Rev3p and Rad30p) proteins are associated with increased sensitivity to sodium valproate. The BER mutants (ogg1Δ, apn1Δ, rad27Δ, ntg1Δ and ntg2Δ) showed increased sensitivity to Cu(II) complexes. DNA damage induced by the complexes requires proteins from NER (Rad1p and Rad10p), TLS (Rev1p, Rev3p and Rad30p), PRR (Rad6 and Rad18p) and HR (Rad52p and Rad50p) for efficient repair. Therefore, Cu(II) complexes display enhanced cytotoxicity when compared to the sodium valproate and induce distinct DNA lesions, indicating a potential application as cytotoxic agents.

Synthesis, chemical characterization and DNA interaction study of new diclofenac and ibuprofen zinc (II)-nicotinamide ternary complexes as cyclooxygenase inhibitor prototypes.

In the search for new drugs, strategies such as bioisosterism have been evidenced, in which the modification of molecules is already known to be active. Thus, metal complexes of known drugs have been highlighted, with examples of significant improvements in therapeutic efficacy. In this way, this work aimed at the synthesis of new zinc complexes with nonsteroidal anti-inflammatory drugs (NSAIDs), as well as the chemical characterization and the previous toxicity by cytotoxicity with Artemia salina, and evaluating the ability of these compounds to interact with DNA. As result, two new zinc II ternary complexes containing the NSAIDs diclofenac (Diclof) and ibuprofen (Ibup) and nicotinamide neutral linker (Nic) were obtained by the two-step solvent metal-ligand complexation method. Molecular structures were determined by NMR, FTIR, HR-MS, UV-Vis and X-ray diffraction, which demonstrated that both complexes are binuclear systems of general formula [Zn2(R-COO-)4(Nic)2]. Plasmidial DNA breakdown capacities were evaluated by producing single and double breaks (DNA FII and FIII) from plasmid incubation with complex solutions in the concentration range 0 to 400 µmol·L-1 in experiments with the presence and absence of light. Both experiments did not show significant differences (P ≤ 0.05) in induced DNA cleavage activity between the maximum study concentrations (400 µmol·L-1) and the negative controls for both complexes. The types of complex 1 and 2 interactions with the secondary DNA structure were determined by titrating a CT-DNA solution with complex solutions and monitored by circular dichroism spectrometry. The results showed that both complexes interact with the grooves of the secondary structure of CT-DNA by electrostatic attraction, but without evidence of alteration in the primary structure. Acute toxicity tests against Artemia salina showed that both complexes did not produce lethality >10% of the population up to a maximum concentration of 1200 µg·mL-1 within an exposure interval of 24 h. Thus, two new compounds were synthesized, characterized and had their previous toxicities determined. These compounds are promising new drugs, with the next step being evaluations of their activity.

Brazilian red propolis: Chemical composition and antibacterial activity determined using bioguided fractionation.

The indiscriminate use of antibiotics is causing an increase in bacterial resistance, complicating therapeutic planning. In this context, natural products have emerged as major providers of bioactive compounds. This work performs a bioguided study of Brazilian red propolis to identify compounds with antibacterial potential and to evaluate their cytotoxicity against non-tumour cells. Using bioguided fractionation performed with the hydroalcoholic extract of red propolis from Alagoas, it was possible to obtain subfractions with remarkable bacteriostatic activity compared with the precursor fractions. The SC2 subfraction was highlighted and showed the best results with minimal inhibitory concentrations (MICs) of 56.75, 28.37, 454.00, and 227.00 µg mL-1 against Staphylococcus aureus, Bacillus subtilis, Escherichia coli, and Pseudomonas aeruginosa, respectively. However, this study also revealed a cytotoxic effect against the non-tumour Vero cell line. Furthermore, through chemical analyses using high resolution mass spectrometry, high performance liquid chromatography with UV detection, and gas chromatography coupled to mass spectrometry, we verified the presence of important marker compounds in the fractions and extracts, including formononetin (m/z 267.0663), biochanin A (m/z 283.0601), and liquiritigenin (m/z 255.0655). The results obtained in this study suggest an important antibacterial potential of red propolis subfractions. In this context, the bioguided fractionation has been a useful process, due to its ability to isolate and concentrate active compounds in a logical and rational way.

Teratogenic and anticonvulsant effects of zinc and copper valproate complexes in zebrafish.

Valproic acid (VPA) is an antiepileptic drug (AED) that has the broadest spectrum across all types of seizures and epileptic syndromes. Unfortunately, approximately 30% of epileptic patients are refractory to the classical AED. Metal ions have been frequently incorporated into pharmaceuticals for therapeutic or diagnostic purposes and research. In this preliminary study, we assess the embryo toxicity and the anticonvulsant activity of 4 novel metallodrugs, with Zn+2 and Cu+2, a derivative of valproic acid and the N-donor ligand in an adult zebrafish epileptic seizure model induced by pentylenetetrazole. The most toxic complex was [Cu(Valp)2Bipy], in which the LC50 was 0.22 µM at 48 h post fertilization (HPF) and 0.12 µM at 96 HPF, followed by [Zn(Valp)2Bipy] (LC50 = 10 µM). These same metallodrugs ([Cu(Valp)2Bipy] 10 mM/kg and [Zn(Valp)2Bipy] 30 mM and 100 mM/kg) displayed superior activity, thus reducing the seizure intensity by approximately 20 times compared to sodium valproate (175 mM/kg). Overall, [Cu(Valp)2Bipy] showed the best anticonvulsant effects. However, because of the toxicity of copper, [Zn(Valp)2Bipy] is considered the most promising anticonvulsant for future studies.

Cephalotaxus Alkaloids.

Cephalotaxus alkaloids represent a family of plant secondary metabolites known for 60 years. Significant activity against leukemia in mice was demonstrated for extracts of Cephalotaxus. Cephalotaxine (CET) (1), the major alkaloid of this series was isolated from Cephalotaxus drupacea species by Paudler in 1963. The subsequent discovery of promising antitumor activity among new Cephalotaxus derivatives reported by Chinese, Japanese, and American teams triggered extensive structure elucidation and biological studies in this family. The structural feature of this cephalotaxane family relies mainly on its tetracyclic alkaloid backbone, which comprises an azaspiranic 1-azaspiro[4.4]nonane unit (rings C and D) and a benzazepine ring system (rings A and B), which is linked by its C3 alcohol function to a chiral oxygenated side chain by a carboxylic function alpha to a tetrasubstituted carbon center. The botanical distribution of these alkaloids is limited to the Cephalotaxus genus (Cephalotaxaceae). The scope of biological activities of the Cephalotaxus alkaloids is mainly centered on the antileukemic activity of homoharringtonine (HHT) (2), which in particular demonstrated marked benefits in the treatment of orphan myeloid leukemia and was approved as soon as 2009 by European Medicine Agency and by US Food and Drug Administration in 2012. Its exact mechanism of action was partly elucidated and it was early recognized that HHT (2) inhibited protein synthesis at the level of the ribosome machinery. Interestingly, after a latency period of two decades, the topic of Cephalotaxus alkaloids reemerged as a prolific source of new natural structures. To date, more than 70 compounds have been identified and characterized. Synthetic studies also regained attention during the past two decades, and numerous methodologies were developed to access the first semisynthetic HHT (2) of high purity suitable for clinical studies, and then high grade enantiomerically pure CET (1), HHT (2), and analogs.

Fishing Anti-Inflammatories from Known Drugs: In Silico Repurposing, Design, Synthesis and Biological Evaluation of Bisacodyl Analogues.

Herein is described in silico repositioning, design, synthesis, biological evaluation and structure-activity relationship (SAR) of an original class of anti-inflammatory agents based on a polyaromatic pharmacophore structurally related to bisacodyl (BSL) drug used in therapeutic as laxative. We describe the potential of TOMOCOMD-CARDD methods to find out new anti-inflammatory drug-like agents from a diverse series of compounds using the total and local atom based bilinear indices as molecular descriptors. The models obtained were validated by biological studies, identifying BSL as the first anti-inflammatory lead-like using in silico repurposing from commercially available drugs. Several biological in vitro and in vivo assays were performed in order to understand its mechanism of action. A set of analogues of BSL was prepared using low-cost synthetic procedures and further biologically investigated in zebrafish models. Compound 5c and 7e exhibited the best antiinflammatory activities and represent new promising anti-inflammatory agents for further preclinical development.

Synthesisand Biological Evaluationof New Substituted Hantzsch Thiazole Derivatives from Environmentally Benign One-Pot Synthesis Using Silica Supported Tungstosilisic Acid as Reusable Catalyst.

An efficient and green method has been developed for the synthesis of new substituted Hantzsch thiazole derivatives in 79%-90% yield, via the one-pot multi-component procedure, by the reaction of 3-(bromoacetyl)-4-hydroxy-6-methyl-2H-pyran-2-one, thiourea and substituted benzaldehydes in the presence of silica supported tungstosilisic acid, as a reusable catalyst, under conventional heating or under ultrasonic irradiation. The catalyst is recoverable by a simple filtration and can be reused in the subsequent reactions. Most of the thiazoles exhibited significant antibacterial activity compared toamoxicillin and ciprofloxacin as positive controls. In addition, the new compounds showed moderate to good antioxidant (DPPH) radical scavenging activity.

Tricyclic Sesquiterpenes from Marine Origin.

The structure elucidation, biosynthesis, and biological activity of marine carbotricyclic sesquiterpene compounds are reviewed from the pioneering results to the end of 2015. Their total syntheses with a particular emphasis on the first syntheses, enantiomeric versions, and syntheses that led to the revision of structures or stereochemistries are summarized. Overall, 284 tricyclic compounds are classified into fused, bridged, and miscellaneous structures based on 54 different skeletal types. Tricyclic sesquiterpenes constitute an important group of natural products. Their structural diversity and biological activities have generated further interest in the field of drug discovery research, although the exact mechanisms of action of these species are not well known. Furthermore, these tricyclic structures, according to their chemical complexity, are a source of inspiration for chemists in the field of total synthesis for the development of innovative methodologies.

First enantioselective total synthesis and configurational assignments of suberosenone and suberosanone as potential antitumor agents.

The first enantioselective total syntheses of two marine sesquiterpenes (1R)-suberosenone and (1R)-suberosanone are achieved leading to revision of the AC of natural (1S)-suberosanone. Key elements of the synthesis include hyperbaric asymmetric Michael addition and highly efficient silver trifluoroacetate mediated α-alkylation for the formation of ring A.

Synthesis, structural analysis and anticonvulsant activity of a ternary Cu(II) mononuclear complex containing 1,10-phenanthroline and the leading antiepileptic drug valproic acid.

The synthesis and characterization of the binary complex of copper(II) with the antiepileptic drug valproic acid sodium salt (Valp) and the related ternary complex with 1,10-phenanthroline (phen) are reported, as well as the anticonvulsant properties of the latter. The characterization was carried out by means of elemental analyses, infrared (IR), UV-visible (UV-vis) spectrophotometry and Electron Paramagnetic Resonance (EPR). The X-ray crystal structure of the mononuclear complex bis(2-propylpentanoate)(1,10-phenanthroline)copper(II) [Cu(Valp)(2)phen] is showed for the first time. It crystallized in C2/c space group with unit cell dimensions of a = 14.939(1) A, b = 19.280(1) A, c = 9.726(1) A, beta = 97.27(2) degrees , V = 2778.8(4) A(3) and Z = 8. The carboxylates bond in an asymmetric chelating mode and the copper atom adopts a highly distorted octahedral coordination, characterized by the sum of the angles of 365.9 degrees around Cu(II) and its nearest atoms in the CuN(2)O(2) + O(2) chromophore instead of the expected 360 degrees for a basal square planar geometry found in most Cu(II) complexes. Molecules assemble three by three through slipped pi-pi stacking of the aromatic phen with respectively 3.519 and 3.527 A distances, in a head-to-tail arrangement. Studies of the anticonvulsant properties of this bioligand chelate evidenced its lack of efficacy in preventing MES-induced seizures. Interestingly, complex 4 protected mice against the Minimal Clonic seizures at doses that do not cause Rotorod toxicity, with an ED(50) documenting very potent anticonvulsant activity in this model of seizure, a particularly useful pharmacological profile of activity for the treatment of Petit Mal seizures.

Functionalization of single-wall carbon nanotubes by tandem high-pressure/Cr(CO)6 activation of Diels-Alder cycloaddition.

An original method to induce Diels-Alder cycloadditions on carbon nanotubes is reported. The process is based on the double activation of the nanotube surface by combining high pressure and Cr(CO)6. This allows the efficient functionalization of carbon nanotubes by electron-rich dienes.

Crystallographic/experimental electron density characterizations and reactions with nucleophiles of beta-enaminonitriles possessing a pyrrolobenzazepine core.

In connection with a total synthesis of cephalotaxine (1a), we have examined the addition of various nucleophilic reagents to [ABC] subunits 2 and 7 possessing a pyrrolobenzazepine core. In fact, this reaction implicates invariably the carbonyl group of 2. Regarding the reaction of 7 with nucleophiles, the most striking aspect is the complete lack of reactivity of the enaminonitrile moiety. For instance, the condensation of 7 with methylmagnesium bromide involves exclusively the cleavage of the dioxole ring, yielding regioisomers 9 and 10. With the aim of understanding the unexpected reactivity of 2 and 7 toward nucleophiles, crystallographic studies of 2 and 7 and an experimental electron density determination of 7 were carried out. The marked reactivity of the carbonyl group of 2 was interpreted by invoking the weakness of the amide resonance, due to a pronounced delocalization of the N(9) lone pair over the enaminonitrile moiety. The electron density study of 7 reveals this electron delocalization along the enaminonitrile fragment, highlighted and quantified through the bond geometries, topological indicators, and atomic charges, a phenomenon that is responsible for the failure of the addition of nucleophilic species.