Comparative metabolic profiling by 1H-NMR spectroscopy analysis reveals the adaptation of S. mansoni from its host to in vitro culture conditions: a pilot study with ex vivo and GSH-supplemented medium-cultured parasites.

Schistosomiasis is a neglected tropical disease caused by parasitic flatworms (blood fluke) of the genus Schistosoma. Parasites acquire most nutrients for their development and sustainment within the definitive host either by ingestion into the gut or across the body surface. Over the years, the best conditions for long-term maintenance of parasites in vitro have been thoroughly established. In our hands, 1H-NMR spectroscopy represents a powerful tool to characterize the metabolic changes in S. mansoni in response to culturing condition perturbations. In order to compare the metabolic fingerprint of ex vivo and parasites cultured in vitro with or without the supplement of reduced glutathione, we conducted a pilot study applying the 1H-NMR spectroscopy-based metabolomics. We obtained new insight into specific metabolic pathways modulated under these different experimental conditions.

Personalized Metabolic Profile by Synergic Use of NMR and HRMS.

A new strategy that takes advantage of the synergism between NMR and UHPLC-HRMS yields accurate concentrations of a high number of compounds in biofluids to delineate a personalized metabolic profile (SYNHMET). Metabolite identification and quantification by this method result in a higher accuracy compared to the use of the two techniques separately, even in urine, one of the most challenging biofluids to characterize due to its complexity and variability. We quantified a total of 165 metabolites in the urine of healthy subjects, patients with chronic cystitis, and patients with bladder cancer, with a minimum number of missing values. This result was achieved without the use of analytical standards and calibration curves. A patient's personalized profile can be mapped out from the final dataset's concentrations by comparing them with known normal ranges. This detailed picture has potential applications in clinical practice to monitor a patient's health status and disease progression.

Drug effects on metabolic profiles of Schistosoma mansoni adult male parasites detected by 1H-NMR spectroscopy.

Schistosomiasis is one of the most devastating neglected tropical parasitic diseases caused by trematodes of the genus Schistosoma. Praziquantel (PZQ) is today the only drug used in humans and animals for the treatment of schistosomiasis but unfortunately it is poorly effective on larval and juvenile stages of the parasite. Therefore, it is urgent the discovery of new drug targets and compounds. We have recently showed that the anti-anginal drug perhexiline maleate (PHX) is very active on multiple developmental stages of Schistosoma mansoni in vitro. It is well known that PHX impacts the lipid metabolism in mammals, but the final target on schistosomes still remains unknown. The aim of this study was to evaluate the ability of 1H nuclear magnetic resonance (NMR) spectroscopy in revealing metabolic perturbations due to PHX treatment of S. mansoni adult male worms. The effects of PHX were compared with the ones induced by vehicle and gambogic acid, in order to detect different metabolic profiles and specificity of the PHX action. Remarkably a list of metabolites associated to PHX-treatment was identified with enrichment in several connected metabolic pathways including also the Kennedy pathway mediating the glycerophospholipid metabolism. Our study represents the first 1H-NMR metabolomic approach to characterize the response of S. mansoni to drug treatment. The obtained "metabolic fingerprint" associated to PHX treatment could represent a strategy for displaying cellular metabolic changes for any given drug and to compare compounds targeting similar or distinct biochemical pathways.

KuQuinones Equilibria Assessment for Biomedical Applications.

A small library of pentacyclic quinoid compounds, called KuQuinones (KuQs), has been prepared through a one-pot reaction. KuQuinones complex structure is made up by two naphthoquinone units connected by a five-membered ring. Due to KuQs structural features, keto-enol tautomerization in solution likely occurs, leading to the generation of four different species, i.e., the enol, the enolate, the external enol and the diquinoid species. The interchange among KuQ tautomers leads to substantial spectral variations of the dye depending on the experimental conditions used. The comprehension of tautomeric equilibria of this new class of quinoid compounds is strongly required in order to explain their behavior in solution and in biological environment. UV-vis, 1H NMR spectroscopies, and DFT calculations resulted appropriate tools to understand the nature of the prevalent KuQuinone species in solution. Moreover, due to the structural similarity of KuQuinones with camptothecin (CPT), a largely used anticancer agent, KuQs have been tested against Cisplatin-resistant SKOV3 and SW480 cancer cell lines. Results highlighted that KuQs are highly active toward the analyzed cell lines and almost nontoxic for healthy cell, indicating a high specific activity.

A Highly Emissive Water-Soluble Phosphorus Corrole.

The synthesis, spectroscopic, and optical properties of the water-soluble phosphorus complex of a 2-sulfonato-10-(4-sulfonatophenyl)-5,15-dimesitylcorrole have been investigated. The compound was prepared by adopting a novel strategy for the corrole sulfonation, leading to the regioselective isomer in an almost quantitative yield. The phosphorus coordination has a key role in determining the corrole substitution pattern, limiting the formation of poly-substituted species, which affected the reaction of the corrole free base. The resulting complex shows excellent optical properties in terms of emission quantum yield, also in polar protic solvents, including water. 31 P NMR spectroscopy in CD3 OD indicates that the P sulfonate complex has been isolated in a hexacoordinated geometry with two different ligands (L1=-OH, L2=-OCH3 ), and it is prone to axial ligand exchange with methanol, with no evidence of intermediate pentacoordinated species. The morphological characterization of thin layers of the P corrole deposited onto an Au(111) surface showed that the addition of an intermediate layer of reduced graphene oxide allows for a better control of corrole aggregation, inducing also transformation of the Au(111) reconstructed surface.

5,10,15-Triferrocenylcorrole Complexes.

Complexes of 5,10,15-triferrocenylcorrole were synthesized from the crude free-base corrole product obtained by the reaction of ferrocenyl aldehyde and pyrrole. Direct formation of the complex in this manner leads to an increase of the reaction yield by protecting the corrole ring toward oxidative decomposition. The procedure was successful and gave the expected product in the case of the copper and triphenylphosphinecobalt complexes, but an unexpected result was obtained in the case of the nickel derivative, where metal insertion led to a ring opening of the macrocycle at the 5 position, giving as a final product a linear tetrapyrrole nickel complex bearing two ferrocenyl groups. The purified 5,10,15-triferrocenylcorrole complexes have been fully characterized by a combination of spectroscopic methods, electrochemistry, spectroelectrochemistry, and density functional theory calculations. Copper derivatives of 10-monoferrocenyl- and 5,15-diferrocenylcorrole were prepared to investigate how the number and position of the ferrocenyl groups influenced the spectroscopic and electrochemical properties of the resulting complexes. A complete assignment of resonances in the (1)H and (13)C NMR spectra was performed for the cobalt and nickel complexes, and detailed electrochemical characterization was carried out to provide additional insight into the degree of communication between the meso-ferrocenyl groups on the conjugated macrocycle and the central metal ion of the ferrocenylcorrole derivatives.

New example of hemiporphycene formation from the corrole ring expansion.

The reaction of 5,10,15-tris(4-tert-butylphenyl)corrole with 2,3-bis(bromomethyl)-5,6-dicyanopyrazine provides a new example of corrole ring expansion to a hemiporphycene derivative. The ring expansion is regioselective, with insertion of the pyrazine derivative at the 5-position of the corrole ring, affording the corresponding 5-hemiporphycene. Different macrocyclic products accompany formation of the 5-hemiporphycene, depending on the reaction experimental conditions. Br-substitued 5-hemiporphycenes and the 2-Br substituted corrole were obtained in 1,2,4-trichlorobenzene, while in refluxing toluene traces of an inner core substituted corrole were observed together with a significant amount of the unreacted corrole. These results provide an important indication of the reaction pathway. The coordination behavior of the 5-hemiporphycene, together with detailed electrochemical characterization of the free-base and some metal complexes, provides evidence for the reactivity of the peripheral pyrazino group.

A small organic compound enhances the religation reaction of human topoisomerase I and identifies crucial elements for the religation mechanism.

The different steps of the human Top1 (topoisomerase I) catalytic cycle have been analysed in the presence of a pentacyclic-diquinoid synthetic compound. The experiments indicate that it efficiently inhibits the cleavage step of the enzyme reaction, fitting well into the catalytic site. Surprisingly the compound, when incubated with the binary topoisomerase-DNA cleaved complex, helps the enzyme to remove itself from the cleaved DNA and close the DNA gap, increasing the religation rate. The compound also induces the religation of the stalled enzyme-CPT (camptothecin)-DNA ternary complex. Analysis of the molecule docked over the binary complex, together with its chemical properties, suggests that the religation enhancement is due to the presence on the compound of two oxygen atoms that act as hydrogen acceptors. This property facilitates the deprotonation of the 5' DNA end, suggesting that this is the limiting step in the topoisomerase religation mechanism.

Unexpected one-pot synthesis of highly conjugated pentacyclic diquinoid compounds.

A new class of pentacyclic diquinoid compounds has been synthesized with a facile one-pot reaction of two molecules of 2-hydroxynaphthoquinone and 1-bromoalkanes in the presence of ferrocene. These molecules were isolated as enol tautomers that exhibit intramolecular hydrogen bond and extended electronic conjugation as proved by the intense absorption spectrum with a broad band between 400 and 600 nm. The spectroscopic and electrochemical characterization of this new class of compounds has been performed. One of the synthesized diquinoid derivatives showed a significant cytotoxicity with IC(50) values of 25-50 µM against Cisplatin-Resistant SKOV3 and colon carcinoma SW480 cell lines. The results of our study provide a valuable tool to a one-pot synthesis of highly conjugated polyquinones, analogous to important biological systems, with significant antitumoral activity.