Characterization of the structural, spectroscopic, nonlinear optical, electronic properties and antioxidant activity of the N-{4’-[(E)-3-(Fluorophenyl)-1-(phenyl)-prop-2-en-1-one]}-acetamide

Antichagasic evaluation, molecular docking and ADMET properties of the chalcone (2E)-3-(2-fluorophenyl)-1-(2-hydroxy- 3,4,6-trimethoxyphenyl)prop-2-en-1-one against Trypanosoma cruzi

Characterized as a neglected disease, Chagas disease is an infection that, in the current scenario, affects about 8 million people per year, with a higher incidence in underdeveloped countries, Chagas is responsible for physiological disabilities that result in impacts that are slightly reflected in world socioeconomic stability. Although treatments are based on drugs such as Benznidazole, the pathology lacks a continuous treatment method with low toxicological incidence. The present study estimates the anti-chagasic activity of the synthetic chalcone CPN2F based on the alignment between in vitro tests and structural classification in silico studies, molecular docking and ADMET studies. The in vitro tests showed a reduction in the protozoan metabolism in host cells (LLC-MK2). At the same time, the molecular docking models evaluate this growth inhibition through the synergistic effect associated with Benznida- zole against validated therapeutic target key stages (Cruzaine TcGAPDH and Trypanothione reductase) of the Trypanosoma cruzi development cycle. The in silico prediction results reveal an alignment between pharmacokinetic attributes, such as renal absorption and release, which allow the preparation of CPN2F as an antichagasic drug with a low incidence of organic toxicity.Communicated by Ramaswamy H. Sarma.

Sulfonamide derived from anacardic acid as potential antichagasic: a theoretical approach based on molecular docking, molecular dynamics, and density functional theory calculations

Chagas disease (CD) is a tropical disease caused by the parasite Trypanosoma cruzi, transmitted by the barber insect. Currently, there are approximately 7 million infected people in the world, and it is estimated that 70 million people could contract this disease. The anacardic acid (AA) showed effectiveness in in silico and in vitro tests. The antichagasic potential of five sulfonamide molecules, derived from anacardic acid, was evaluated from a molecular approach based on the density functional theory (DFT), molecular dynamics (MD), and molecular docking (docking) calculations. Methyl 2-methoxy-6- (8- (methylsulfonamide) octyl) benzoate (SA1); 2-methoxy-6- (8- (phenylsulfonamide) octyl) benzoate (SA2); methyl 2-methoxy-6- (8- (2methylphenyl sulfonamide) octyl) benzoate (SA3); methyl 2-methoxy-6- (8-(methylphenylsulfonamide)octyl)benzoate (SA4); methyl2-(8-(2,5-dimethylphenylsulfonamide)octyl)-6-methoxybenzoate (SA5) were the investigated molecules. The DFT calculations were performed using the B3LYP/6-311+G (d, p) level of theory. The global and local reactivity data showed that SA1 shows the highest molecular reactivity, while SA2 is the most stable derivative. In addition, the structures of investigated molecules were confirmed by the linear correlations higher than 0.98 displayed between the experimental and calculated spectroscopic data (IR and NMR). Molecular docking of the molecules showed a greater prominence for the SA1, SA2, and SA4 molecules in the results of distances of ligand-cruzain. In molecular dynamics, SA2 obtained better stability due to greater interactions with important amino acids of cruzain.

Antioxidant and anticholinesterase activities of amentoflavone isolated from Ouratea fieldingiana (Gardner) Engl. through in vitro and chemical-quantum studies

Ouratea fieldingiana, popularly known as batiputá, is a tree species easily found in the coastal part of northeastern Brazil. Its leaves are rich in biflavonoids, its major compound being amentoflavone. Biflavonoids are well studied due to their high antioxidant capacity. Alzheimer's disease (AD) is a disease characterized by the progressive loss of neurons. Currently, the pharmacological treatment of AD has four drugs: donepezil, galantamine, rivastigmine and memantine. Where these drugs, with the exception of memantine, are inhibitors of acetylcholinesterase, thus inhibiting the enzyme that destroys acetylcholine, thus increasing the availability of this neurotransmitter. This article aims to determine in vitro and in silico the antioxidant and anticholinesterase action of amentoflavone isolated from the leaves of Ouratea fieldingiana. The antioxidant capacity of amentoflavone was evaluated using the DPPH* free radical scavenging method, with an IC₅₀ of 5.73 ± 0.08 µg/mL. The antiradical properties of the molecule were also studied in silico through several HAT, SET-PT and SPLET mechanisms via DFT M06-2X/6-311++G(d,p). It was found that in the hydrogen atom transfer mechanism (HAT) the best trend was obtained as an anti-radical mechanism. Amentoflavone has the ability to inhibit acetylcholinesterase when tested in vitro, having an IC₅₀ of 8.68 ± 0.73 µg/mL, corroborating its effect in the in silico test, presenting four strong covalent hydrogen bonds for having a bond length up to 2.5 Å. Thus, amentoflavone is an important target for further testing against Alzheimer's disease. Communicated by Ramaswamy H. Sarma.

Antiproliferative activity on Trypanosoma cruzi (Y strain) of the triterpene 3β,6β,16β-trihidroxilup-20 (29)-ene isolated from Combretum leprosum

Chagas disease infects approximately seven million people worldwide. Benznidazole is effective only in the acute phase of the disease, with an average cure rate of 80% between acute and recent cases. Therefore, there is an urgent need to find new bioactive substances that can be effective against parasites without causing so many complications to the host. In this study, the triterpene 3β-6β-16β-trihydroxilup-20 (29)-ene (CLF-1) was isolated from Combretum leprosum, and its molecular structure was determined by NMR and infrared spectroscopy. The CLF-1 was also evaluated in vitro and in silico as potential trypanocidal agent against epimastigote and trypomastigote forms of Trypanosoma cruzi (Y strain). The CLF-1 demonstrated good results highlighted by lower IC₅₀ (76.0 ± 8.72 µM, 75.1 ± 11.0 µM, and 70.3 ± 45.4 µM) for epimastigotes at 24, 48 and 72 h, and LC₅₀ (71.6 ± 11.6 µM) for trypomastigotes forms. The molecular docking study shows that the CLF-1 was able to interact with important TcGAPDH residues, suggesting that this natural compound may preferentially exert its effect by compromising the glycolytic pathway in T. cruzi. The ADMET study together with the MTT results indicated that the CLF-1 is well-absorbed in the intestine and has low toxicity. Thus, this work adds new evidence that CLF-1 can potentially be used as a candidate for the development of new options for the treatment of Chagas disease.Communicated by Ramaswamy H. Sarma.

Recent advances in the antioxidant activity and mechanisms of chalcone derivatives: a computational review

In this review, we have reported the antioxidant mechanisms and structure-antioxidant activity relationship of several chalcone derivatives, investigated in the recent past, based on the density functional theory (DFT) calculations, considering free radical scavenging and metal chelation ability. The antioxidant mechanisms include hydrogen atom transfer (HAT), sequential proton loss electron transfer (SPLET), single electron transfer followed by proton transfer (SET-PT), sequential proton loss hydrogen atom transfer (SPLHAT), sequential double proton loss electron transfer (SdPLET), sequential triple proton loss double electron transfer (StPLdET), sequential triple proton loss triple electron transfer (StPLtET), double HAT, double SPLET, double SET-PT, triple HAT, triple SET-PT, triple SPLET, proton-coupled electron transfer (PCET), single electron transfer (SET), radical adduct formation (RAF) and radical adduct formation followed by hydrogen atom abstraction (RAF-HAA). Furthermore, solvent effects have also been considered using different solvation models. The feasibility of scavenging different reactive oxygen and nitrogen species (ROS/RNS) has been discussed considering various factors such as the number and position of hydroxyl as well as methoxy groups present in the antioxidant molecule, stability of the species formed after scavenging reactive species, nature of substituent, steric effects, etc. This review opens new perspectives for designing new compounds with better antioxidant potential.

Current Trends in Computational Quantum Chemistry Studies on Antioxidant Radical Scavenging Activity

The antioxidative nature of chemicals is now routinely studied using computational quantum chemistry. Scientists are constantly proposing new approaches to investigate those methods, and the subject is evolving at a rapid pace. The goal of this review is to collect, consolidate, and present current trends in a clear, methodical, and reference-rich manner. This paper is divided into several sections, each of which corresponds to a different stage of elaborations: preliminary concerns, electronic structure analysis, and general reactivity (thermochemistry and kinetics). The sections are further subdivided based on methodologies used. Concluding remarks and future perspectives are presented based on the remaining elements.

Quantum mechanical, molecular docking, molecular dynamics, ADMET and antiproliferative activity on Trypanosoma cruzi (Y strain) of chalcone (E)-1-(2-hydroxy-3,4,6-trimethoxyphenyl)-3-(3-nitrophenyl)prop-2-en-1-one derived from a natural product

Chagas disease is a leading public health problem. More than 8 million people are affected by the disease, which is endemic in 21 countries in Latin America, generating an average annual cost of 7.2 billion dollars per year. The conventional treatment of Chagas disease is carried out by administering the drug benznidazole (BZN), which has caused numerous adverse reactions. Hence, the search for new, more efficient, and less toxic anti-chagasic agents is essential. Recently, chalcones have been researched to propose new therapies against neglected diseases, mainly Trypanosoma cruzi. The objective of this work was to evaluate for the first time the antiproliferative potential of chalcone derived from the natural product on T. cruzi strain Y. The molecular structure of the chalcone was confirmed by spectrometric data. The toxicity of chalcone in LLC-MK2 cells indicated that a concentration of 514.10 ± 62.40 μM was able to reduce cell viability by 50%. Regarding the effect of chalcone on epimastigote forms, an IC₅₀ value of 46.57 ± 9.81 μM was observed; 45.92 ± 8.42 and 16.32 ± 3.41 μM at times of 24, 48 and 72 hours, respectively. The chalcone was able to eliminate trypomastigote forms at all concentrations tested, except for 31.25 μM, with LC₅₀ values of 117.90 ± 12.60 μM, lower than the reference drug BZN (161.40 ± 31. 80 μM). The mechanism of action may be related to the membrane damage provoked by reduction of the mitochondrial potential. The anti-T. cruzi effect can be assigned through some structural aspects of the chalcone as the nitro group (NO₂) is present, which can be enzymatically reduced forming a nitro radical, and the presence of methoxyl groups in the A ring of the chalcone. In silico studies showed that the chalcone had a higher affinity for cruzain when compared to BZN and the co-crystallized inhibitor KB2, as it presented a more thermodynamically stable complex in the order of -6.9 kcal mol^-1. The pharmacokinetic prediction showed a significant probability of antiprotozoal activity, a good volume of distribution after being absorbed in the intestine, and a low chance of activity in the central nervous system. Therefore, these results suggest that the chalcone can become a potential cruzain enzyme inhibitor with trypanocidal activity.

Potentiating activity of Norfloxacin by synthetic chalcones against NorA overproducing Staphylococcus aureus

Staphylococcus aureus is responsible for a series of infections occurring in both human and animal hosts. S. aureus SA1199B is a strain resistant to hydrophilic fluoroquinolone due to overproduction of the NorA efflux pump that has been used as a microbial model to evaluate if a compound act as efflux pump inhibitor. Finding substances from natural or synthetic origin able to reverse resistance mechanisms like those of efflux pumps is a challenge. The use of Chalcones and their derivatives is of great chemical and pharmacological interest, as they present a simple structure and several pharmacological activities. This study aims to evaluate the antibacterial potential of 4 synthetic chalcones, as well as to evaluate their action in the modulation of Norfloxacin resistance against the strain SA1199B strain. Microdilution assays were performed for evaluation of the antimicrobial activity. For evaluation of the modulating effect on resistance to Norfloxacin or EtBr, MIC values of these compounds were determined in the absence or presence of subinhibitory concentrations used of each chalcone. MICs values of both Norfloxacin and EtBr were significantly reduced in the presence of all tested chalcones, indicating that inhibition of the active efflux of these compounds by NorA could be a possible mechanism of action of the chalcones. These results show that the compounds studied have a high potential as a NorA inhibitor, with the best modulating effect verified for the compound 3. Pharmacokinetic and toxicity predictive studies indicated a high intestinal absorption and good volume of distribution for chalcones by oral administration, activity in the central nervous system and ease to be transported between biological membranes. Emphasizing that analogs 1 and 4 were easily metabolized by CYP3A4 enzyme, constituting a pharmacological active ingredient without toxic risk due to metabolic activation. These chalcones combined with Norfloxacin could be a promise technological strategy to be applied in the treatment of infections caused by S. aureus overproducing NorA.

Caryocar coriaceum Wittm. fruit extracts as Leishmania inhibitors: in-vitro and in-silico approaches

Leishmaniasis is a group of neglected diseases caused by parasites of the Leishmania genus. The treatment of Leishmaniasis represents a great challenge, because the available drugs present high toxicity and none of them is fully effective. Caryocar is a botanical genus rich in phenolic compounds, which leaves extracts have already been described by its antileishmanial action. Thus, we investigated the effect of pulp and peel extracts of the Caryocar coriaceum fruit on promastigote and amastigote forms of Leishmania amazonensis. Both extracts had antipromastigote effect after 24, 48, and 72 h, and this effect was by apoptosis-like process induction, with reactive oxygen species (ROS) production, damage to the mitochondria and plasma membrane, and phosphatidylserine exposure. Knowing that the fruit extracts did not alter the viability of macrophages, we observed that the treatment reduced the infection of these cells. Thereafter, in the in vitro infection context, the extracts showed antioxidant proprieties, by reducing NO, ROS, and MDA levels. Besides, both peel and pulp extracts up-regulated Nrf2/HO-1/Ferritin expression and increase the total iron-bound in infected macrophages, which culminates in a depletion of available iron for L. amazonensis replication. In silico, the molecular modeling experiments showed that the three flavonoids presented in the C. coriaceum extracts can act as synergistic inhibitors of Leishmania proteins, and compete for the active site. Also, there is a preference for rutin at the active site due to its greater interaction binding strength.