Rational Approach toward COVID-19's Main Protease Inhibitors: A Hierarchical Biochemoinformatics Analysis.

This study investigated the potential of selected compounds as inhibitors of SARS-CoV-2 Mpro through pharmacokinetic and toxicological analyses, molecular docking, and molecular dynamics simulations. In silico molecular docking simulations revealed promising ligands with favorable binding affinities for Mpro, ranging from -6.2 to -9.5 kcal/mol. Moreover, molecular dynamics simulations demonstrated the stability of protein-ligand complexes over 200 ns, maintaining protein secondary structures. MM-PBSA analysis revealed favorable interactions between ligands and Mpro, with negative binding energy values. Hydrogen bond formation capacity during molecular dynamics was confirmed, indicating consistent interactions with Mpro catalytic residues. Based on these findings, selected ligands show promise for future studies in developing COVID-19 treatments.

Toxic profile of marinobufagin from poisonous Amazon toads and antitumoral effects on human colorectal carcinomas.

ETHNOPHARMACOLOGICAL RELEVANCE: South Americans natives have extensively used the toad "kururu" to reduce/treat skin infections, cutaneous lesions and sores. They release secretions rich in bufadienolides, polyhydroxy steroids with well-documented cardiotonic and antiproliferative actions, but in vivo antitumoral evaluations in mammals are rare, and toxicological safety has been left in second place. AIMS OF THE STUDY: This investigation used in silico, in vitro and in vivo tools to evaluate acute and subacute toxic effects of marinobufagin and the anticancer action in tumor-bearing mice models. MATERIALS AND METHODS: Initially, in silico toxic predictions were performed, followed by in vitro assays using human and murine normal and tumor lines. Next, acute and subacute studies on mice investigated the behavior, hematological and intestinal transit profile and antitumoral activity of marinobufagin in sarcoma 180- and HCT-116 colorectal carcinoma-transplanted mice for 7 and 15 days, respectively. Ex vivo and in vivo cytogenetic assays in Sarcoma 180 and bone marrow cells and histopathological examinations were also executed. RESULTS: In silico studies revealed ecotoxicological effects on crustaceans (Daphnia sp.), fishes (Pimephales promelas and Oryzias latipes), and algae. A 24-h marinobufagin-induced acute toxicity included signals of central activity, mainly (vocal frenzy, absence of body tonus, increased ventilation, ataxia, and equilibrium loss), and convulsions and death at 10 mg/kg. The bufadienolide presented effective in vitro cytotoxic action on human lines of colorectal carcinomas in a similar way to ouabain and tumor reduction in marinobufagin-treated SCID-bearing HCT-116 heterotopic xenografts. Animals under subacute nonlethal doses exhibited a decrease in creatinine clearance with normal levels of blood urea, probably as a result of a marinobufagin-induced renal perfusion fall. Nevertheless, only minor morphological side effects were identified in kidneys, livers, hearts and lungs. CONCLUSIONS: Marinobufagin has in vitro and in vivo anticancer action on colorectal carcinoma and mild and reversible alterations in key metabolic organs without direct chemotherapy-induced gastrointestinal effects at subacute exposure, but it causes acute ataxia, equilibrium loss, convulsions and death at higher acute exposure.

Nanoparticles Obtained from Zein for Encapsulation of Mesalazine.

We encapsulated MSZ in zein nanoparticles (NP-ZN) using a desolvation method followed by drying in a mini spray dryer. These nanoparticles exhibited a size of 266.6 ± 52 nm, IPD of 0.14 ± 1.1 and zeta potential of -36.4 ± 1.5 mV, suggesting colloidal stability. Quantification using HPLC showed a drug-loaded of 43.8 µg/mg. SEM demonstrated a spherical morphology with a size variation from 220 to 400 nm. A FTIR analysis did not show drug spectra in the NPs in relation to the physical mixture, which suggests drug encapsulation without changing its chemical structure. A TGA analysis showed thermal stability up to 300 °C. In vitro release studies demonstrated gastroresistance and a sustained drug release at pH 7.4 (97.67 ± 0.32%) in 120 h. The kinetic model used for the release of MSZ from the NP-ZN in a pH 1.2 medium was the Fickian diffusion, in a pH 6.8 medium it was the Peppas-Sahlin model with the polymeric relaxation mechanism and in a pH 7.4 medium it was the Korsmeyer-Peppas model with the Fickian release mechanism, or "Case I". An in vitro cytotoxicity study in the CT26.WT cell line showed no basal cytotoxicity up to 500 µg/mL. The NP-ZN showed to be a promising vector for the sustained release of MSZ in the colon by oral route.

Cecropia pachystachya Trécul: identification, isolation of secondary metabolites, in silico study of toxicological evaluation and interaction with the enzymes 5-LOX and α-1-antitrypsin.

Cecropia pachystachya Tréc., popularly known as embaúba, belongs to the Cecropiaceae family and is used by the native population in the treatment of bronchitis, asthma, high blood pressure, fever, and as a diuretic. The pharmacological actions including anti-inflammatory, antioxidant, cardiotonic and sedative were previously reported. The objective of this study was to (1) isolate and identify bioactive compounds extracted from the ethanolic extract of C. pachystachya roots (ERCP), as well as (2) verify the affinity of these metabolites with the enzymes 5-lipoxygenase (5-LOX) and α-1-antitrypsin through in silico tests. Isolation and/or identification were performed using GC-MS, HPLC, Infrared (IR), and nuclear magnetic resonance (NMR) techniques. After isolation and identification of the active compounds, these substances were subjected to the in silico investigation that proceeded by performing PreADMET simulations and molecular docking calculations. The bioactive compounds identified were 1-(+)-ascorbic acid 2,6-dihexadecanoate, ethyl hexadecanoate, ethyl (9E,12E)-octadec-9,12-dienoate, ethyl (Z)-octadec-9-enoate and ethyl octadecanoate by GC-MS; chlorogenic acid, catechin, epicatechin, syringaldehyde by HPLC; ß-sitosterol, sitostenone, beccaridiol, tormentic acid, lupeol, α- and ß-amyrin by classical chromatography, IR, 1H and 13C NMR techniques. The ADMET (absorption, distribution, metabolism, excretion, and toxicity) properties were determined for each bioactive compound. Tormentic acid demonstrated a greater affinity for 5-LOX enzyme while sitostenone demonstrated a higher affinity for the α-1-antitrypsin enzyme. Our findings demonstrated a diverse range of secondary metabolites isolated from C. pachystachya that showed relevant interactions with the enzymes 5-LOX and α-1-antitrypsin. Thus, "embaúba" may be employed in in vivo experimental studies as a form of alternative treatment for chronic lung diseases.Abbreviations: ADT: Autodock Tools; BBB: Blood-brain barrier; CaCo2: Human colonic adenocarcinoma cells; CC: Classic/open Column; TLC: Thin Layer Chromatography; CD40: Differentiation Cluster 40; CENAUREMN: Centro Nordestino de Aplicação e Uso da Ressonância Magnética Nuclear; GC-MS: Gas Chromatography coupled to mass spectrometry; HPLC: High-Perfomance Liquid Chromatography; CYP2C9, CYP2C19, CYP2D6 and CYP3A4: Cytochrome P450 isoenzymes; COPD: Chronic Obstructive Pulmonary Disease; DRX-500: X-Ray Diffraction - 500; ERCP: Ethanolic extract of the roots of C. pachystachya; FAPEPI: Fundação de Amparo à Pesquisa do Piauí; HIA: Human Intestinal Absorption; IR: Infrared; Ki: Inhibition constant; 5-LOX: 5-Lipoxygenase; mM: miliMolar; nM: nanoMolar; OECD423: acute toxic class method; PDB: Protein Data Bank; P-gP: P-glycoprotein; PM2,5: Small inhalable particles 2,5; PPB: Plasm Protein Binding; PreADMET: Prediction Absorption, Distribution, Metabolization, Excretion and Toxicity; NMR: Nuclear Magnetic Resonance; +S9: with metabolic activation; -S9: no metabolic activation; SisGen: Sistema Nacional de Gestão de Patrimônio Genético e do Conhecimento Tradicional Associado; RT: Retention time; TA100: Ames test with TA100 cells line; TA1535: Ames test with cells of the TA1535 cell line; UESPI: State University of Piauí; V79: lung fibroblast cells; ΔG: Gibbs free energy (Kcal/mol); µM: microMolar.

Samanea tubulosa Benth. (Fabaceae): Antinociceptive effect on acute pain in mice: K+ATP channel and opioid activity.

Samanea tubulosa Benth. it has been widely used in traditional medicine to treat inflammatory processes. The present study aimed to investigate the antinociceptive effect and mechanism of action of the fractions obtained from the Samanea tubulosa pods in mice. The antinociceptive activity was evaluated in formalin, capsaicin and glutamate tests and the. The possible mechanisms of action involved in the antinociceptive effect of the hexane and ethyl acetate fraction in the opioid system, also the the K + ATP channels and the L-arigine pathways of nitric oxide were evaluated. The chemical characterization analysis revealed in the hexane fraction the presence of triterpenes such as lupenone and lupeol. In the glutamate test, the hexane and ethyl acetate fractions showed antinociceptive activity at the dose of 12.5 and 25 mg kg-1. The antinociception produced by the hexane and ethyl acetate fractions was significantly reversed by naloxone, indicating that the fractions act through the opioid pathway. Antinociceptive response of the ethyl acetate fraction was blocked by glibenclamide, indicating that this fraction acts via the K + ATP channels activation. It is concluded that the fractions under study exert antinociceptive activity possibly related to the opioid route and through K+ ATP channels activation.

Diffuse Large B-Cell Lymphoma - Rare Presentation.

Teaching Point: Subcutaneous nodules sparing the dermis and without extracutaneous involvement is a rare presentation of the diffuse large B-cell lymphoma.

Comparative study of composition of methanolic extracts of the paratoid gland secretions (PGS) of Rhinella jimi (cururu toad) from northeastern Brazil: Gender, seasonality and geographic occurrence.

Toads belonging to the Bufonidae family have a pair of paratoid glands that store highly toxic a biological secretion with varied chemical composition, that act as a chemical defense against microbial infections and predators. The paratoid gland secretion (PGS) of bufonids is rich in bioactive steroids, alkaloids, proteins, bufadienolides and bufotoxins. In the present investigation we performed a systematic analysis of the chemical profile of PGS obtained from the Bufonidae toad Rhinella jimi ("Cururu" toad) collected at three different regions of Piauí state, Northeastern Brazil. Our aim was to investigate the PGS variation related to the season of animals collection, geographic distribution and gender of the animals. The methanolic extracts of PGS were analyzed by UPLC-QToF-MS/MS. Principal component analysis (PCA) were applied to the data set obtained by the UPLC-QToF-MS/MS analyses. Among 23 compounds identified, dehydrobufotenine, suberoyl arginine, 3-(N-suberoyl-argininyl) telocinobufagin, 3-(N-suberoyl-argininyl) marinobufagin, telocinobufagin, marinobufagin and 3-(N-suberoyl-argininyl) bufalin were detected in all PGS. Minimal variations in the composition of paratoid secretions of R. jimi were observed related to distinct geographical and seasonal parameters. R. jimi female animals presented the most diverse chemical composition in its PGS. With this comparative study, unprecedented for the species, it was possible to observe that the secretions of the paratoid glands produced by R. jimi from different regions of the state of Piauí, at different times of the year, presented consistent chemical composition, with discrete particularities in the number and nature chemistry of its constituents.

Identification of Potential Antiviral Inhibitors from Hydroxychloroquine and 1,2,4,5-Tetraoxanes Analogues and Investigation of the Mechanism of Action in SARS-CoV-2.

This study aimed to identify potential inhibitors and investigate the mechanism of action on SARS-CoV-2 ACE2 receptors using a molecular modeling study and theoretical determination of biological activity. Hydroxychloroquine was used as a pivot structure and antimalarial analogues of 1,2,4,5 tetraoxanes were used for the construction and evaluation of pharmacophoric models. The pharmacophore-based virtual screening was performed on the Molport® database (~7.9 million compounds) and obtained 313 structures. Additionally, a pharmacokinetic study was developed, obtaining 174 structures with 99% confidence for human intestinal absorption and penetration into the blood-brain barrier (BBB); posteriorly, a study of toxicological properties was realized. Toxicological predictions showed that the selected molecules do not present a risk of hepatotoxicity, carcinogenicity, mutagenicity, and skin irritation. Only 54 structures were selected for molecular docking studies, and five structures showed binding affinity (ΔG) values satisfactory for ACE2 receptors (PDB 6M0J), in which the molecule MolPort-007-913-111 had the best ΔG value of -8.540 Kcal/mol, followed by MolPort-002-693-933 with ΔG = -8.440 Kcal/mol. Theoretical determination of biological activity was realized for 54 structures, and five molecules showed potential protease inhibitors. Additionally, we investigated the Mpro receptor (6M0K) for the five structures via molecular docking, and we confirmed the possible interaction with the target. In parallel, we selected the TopsHits 9 with antiviral potential that evaluated synthetic accessibility for future synthesis studies and in vivo and in vitro tests.

Interobserver variability in MRI measurements of mesorectal invasion depth in rectal cancer.

PROPOSE: To assess the interobserver variability in MRI measurements of mesorectal invasion depth (MID) in rectal adenocarcinomas primarily staged as T3, by determining the level of interobserver agreement in the differentiation of individual T3 substages and of T3a-b vs. T3c-d disease, between readers with different levels of expertise. METHODS: A retrospective analysis of 60 patients classified by MRI as having T3 rectal cancers was performed. Each patient underwent MR examination in a 1.5 T machine and the standard imaging protocol included a high-resolution axial T2-weighted sequence in which the measurements were determined by independent radiologists (readers A and B, with 15 years and 1 year of experience, respectively). The rectum was further divided into quadrants and each reader selected the quadrant where the measurement was taken. The patients were grouped according to the MID (T3a < 1 mm; T3b 1-5 mm; T3c > 5-15 mm; T3d > 15 mm) and the interobserver reliability was tested using Cohen's kappa. RESULTS: Population included 40 males and 20 females with a median age of 65.9 years. Interobserver agreement on individual substage differentiation (T3 a, b, c and d) was moderate (K = 0.428) and in the quadrant evaluation the level of agreement was also moderate (K = 0.414). Nevertheless, the interobserver reliability for the differentiation between stages T3a-b vs. T3c-d was substantial (K = 0.697). CONCLUSIONS: There is no considerable interobserver variability when distinguishing T3a-b from T3c-d tumors, regardless of the quadrant where the MID is measured. Therefore, assessment of MID, for that purpose, is a reproducible MR parameter, irrespectively of the readers' experience.

Purinergic signaling: A new front-line determinant of resistance and susceptibility in leishmaniasis.

Leishmaniasis is a neglected tropical disease that causes several clinical manifestations. Parasites of the genus Leishmania cause this disease. Spread across five continents, leishmaniasis is a particular public health problem in developing countries. Leishmania infects phagocytic cells such as macrophages, where it induces adenosine triphosphate (ATP) release at the time of infection. ATP activates purinergic receptors in the cell membranes of infected cells and promotes parasite control by inducing leukotriene B4 release and NLRP3 inflammasome activation. Moreover, uridine triphosphate induces ATP release, exacerbating the immune response. However, ATP may also undergo catalysis by ectonucleotidases present in the parasite membrane, generating adenosine, which activates P1 receptors and induces the production of anti-inflammatory molecules such as prostaglandin E2 and IL-10. These mechanisms culminate in Leishmania's survival. Thus, how Leishmania handles extracellular nucleotides and the activation of purinergic receptors determines the control or the dissemination of the disease.

Four new cycloartane-type triterpenoids from the leaves of Combretum mellifluum Eichler: assessment of their antioxidant and antileishmanial activities.

The beneficial pharmacological actions including antioxidant effects as an antileishmanial, antibacterial, antifungal, antidiabetic, anti-inflammatory, antitumor, antiviral, and analgesic of compounds isolated from Combretum mellifluum Eichler (Combretaceae) are well established. The aim of the present study was to determine the phytochemistry as well as assess the antioxidant and antileishmanial activities of the leaves from Combretum mellifluum Eichler (Combretaceae). Analysis of ethanolic extract resulted in isolation and identification of two epimeric mixtures of four previously unknown cycloartane-type triterpenoids, methyl quadrangularate M and methyl 24-epiquadrangularate M, and 2α,3ß,24ß-trihydroxy-cycloart-25-ene and 2α, 3ß, 24α-trihydroxy-cycloart-25-ene, and eight known compounds. Their structures were using one-dimensional nuclear magnetic resonance (1D NMR), 2D NMR and high-resolution electrospray ionization mass spectroscopy (HRESIMS) analysis. Further, the extract and fractions were tested for antioxidant potential. The ethyl acetate and aqueous fractions demonstrated the highest antioxidant activity against 2,2-dipheny-1-picrylhydrazl (DPPH) free radicals, which correlated directly with total flavonoid content. All extracts and fractions from C. mellifluum Eichler were assessed for antileishmanial activity. The supernatant fraction exhibited highest potential, inhibiting the growth of Leishmania amazonensis with IC50 value 31.29 µg/ml. Our findings provide information on the chemical composition of C. mellifluum and the potential beneficial therapeutic usefulness as an antioxidant agent in various diseases.

Successful long-term use of pioglitazone in Berardinelli-Seip lipodystrophy-associated diabetes.

SUMMARY: Berardinelli-Seip congenital lipodystrophy (BSCL) is a rare autosomal recessive disease, characterized by the absence of subcutaneous adipose tissue, leptin deficiency and severe metabolic complications, such as insulin resistance, diabetes mellitus, and dyslipidemia. The most common mutation occurs in BCSL2 which encodes seipin, a protein involved in adipogenesis. We report a patient with BSCL who was diagnosed with diabetes at 11 years old. He was started on metformin 1000 mg twice daily, which lowered glycated hemoglobin (HbA1c) to less than 7%. Four months later, HbA1c raised above 7.5%, indicating secondary failure to metformin. Therefore, we added the peroxisome proliferator-activated receptor-gamma (PPARG) agonist, pioglitazone. Since then and for the last 5 years his HbA1c has been within the normal range. These findings indicate that pioglitazone should be considered as a valid alternative in the treatment of diabetes in BSCL patients. To the best of our knowledge, this is the first specific report of successful long-term treatment with pioglitazone in a patient with BSCL. LEARNING POINTS: Berardinelli-Seip congenital lipodystrophy (BSCL) is a recessive genetic disorder associated with severe insulin resistance and early onset diabetes, usually around puberty. Failure of oral antidiabetic medication occurs within the first years of treatment in BSCL patients. When failure to achieve metabolic control with metformin occurs, pioglitazone may be a safe option, lowering insulin resistance and improving both the metabolic control and lipodystrophic phenotype. Herein we show that pioglitazone can be a safe and efficient alternative in the long-term treatment of BSCL patients with diabetes.

Protein methyltransferase 7 deficiency in Leishmania major increases neutrophil associated pathology in murine model.

Leishmania major is the main causative agent of cutaneous leishmaniasis in the Old World. In Leishmania parasites, the lack of transcriptional control is mostly compensated by post-transcriptional mechanisms. Methylation of arginine is a conserved post-translational modification executed by Protein Arginine Methyltransferase (PRMTs). The genome from L. major encodes five PRMT homologs, including the cytosolic protein associated with several RNA-binding proteins, LmjPRMT7. It has been previously reported that LmjPRMT7 could impact parasite infectivity. In addition, a more recent work has clearly shown the importance of LmjPRMT7 in RNA-binding capacity and protein stability of methylation targets, demonstrating the role of this enzyme as an important epigenetic regulator of mRNA metabolism. In this study, we unveil the impact of PRMT7-mediated methylation on parasite development and virulence. Our data reveals that higher levels of LmjPRMT7 can impair parasite pathogenicity, and that deletion of this enzyme rescues the pathogenic phenotype of an attenuated strain of L. major. Interestingly, lesion formation caused by LmjPRMT7 knockout parasites is associated with an exacerbated inflammatory reaction in the tissue correlated with an excessive neutrophil recruitment. Moreover, the absence of LmjPRMT7 also impairs parasite development within the sand fly vector Phlebotomus duboscqi. Finally, a transcriptome analysis shed light onto possible genes affected by depletion of this enzyme. Taken together, this study highlights how post-transcriptional regulation can affect different aspects of the parasite biology.

Phytochemical profile and ethnopharmacological applications of Lecythidaceae: An overview.

ETHNOPHARMACOLOGICAL RELEVANCE: The family Lecythidaceae has about 25 genera and 400 identified species, which are distributed especially in the pantropical region, mostly found in the tropics of Central and South America, Southeast Asia and Africa. The third most abundant family in Amazonian forests and the genus Eschweilera, with the large number of species in Lecythidaceae. AIM OF THE REVIEW: The present review compiles information since the 1934s about of ethnopharmacology, and chemical constituents of species of Lecythidaceae, as well as a summary of the bioactivities shown by the extracts, fractions, and secondary metabolites. MATERIALS AND METHODS: All relevant information on ethnopharmacology, and chemical constituents of species of Lecythidaceae were gathered from electronic databases including Web of Science, Science Direct, Elsevier, ResearchGate, and Google Scholar. Information was also obtained from local books, PhD. and MSc. Dissertations. RESULTS: The phytochemical diversity of the family was demonstrated with 180 different metabolites that have been reported from 25 species, most of them being triterpenes or flavonoids. The pharmacological studies carried out with the extracts, fractions and compounds showed promising antibacterial, antifungal, anti-inflammatory, antinociceptive, cytotoxic and antioxidant activities. CONCLUSION: The present review provides an insight into ethnopharmacology, phytochemistry and pharmacology of species of Lecythidaceae. Based on the pharmacological studies it has been found that different plant species of Lecythidaceae possess a wide range of bioactivities such as anti-arthritic, anti-inflammatory, antileishmanial, antibacterial and antifungal. These activities are due to the presence of bioactive compounds including triterpenoids and their glycosides derivatives, flavonoids, steroids, sesquiterpenoids, alkaloids, and other compounds. However, there are many plants, which have not been assessed pharmacologically and hence warrant further studies.

Cytotoxicity potential of chemical constituents isolated and derivatised from Rhinella marina venom.

Chemical compounds from skin secretions from toads of Bufonidae family have been long-studied. In the search for new molecules with pharmacological action, the 3ß-OH groups of bufadienolides are commonly derivatised using acetyl groups. This work described the isolation and/or structural elucidation of isolated and derivatised compounds from the venom of the Brazilian anuran Rhinella marina, and their evaluation in in vitro assays. In the methanolic extract of the R. marina venom, compound cholesterol (1) was isolated from the CRV-52 fraction by classic column chromatography, dehydrobufotenine (2) by Sephadex LH-20 from the CRV-28 fraction, and a mix of suberoyl arginine (3) and compound 2 was obtained from the CRV-6-33 fraction. The compounds marinobufagin (4), telocionbufagin (5) and bufalin (6) were isolated by classic column chromatography, followed by separation via HPLC in the CRV-70 fraction, and the compound marinobufotoxin (9) was isolated by classic column chromatography in the CRV-6 fraction, here being isolated for the first time in R. marina specimens. Compounds 4 and 5 were submitted for acetylation with acetic anhydride, in the presence of pyridine and 4-dimethyilaminopiridine (DMAP), in order to obtain the compounds 3-acetyl-marinobufagin (7) and 3-acetyl-telocinobufogin (8). The isolated and derivatised compounds were identified by 1H and 13C NMR, and their molecular mass confirmed by mass spectrometry. All compounds (except 1 and 3) were tested in cytotoxic assays by the MTT method and presented cytotoxic potential against human cancer cell lines, as well as against non-tumoral human embryonic kidney HEK-293 cells. With the exception of compound 2, all molecules presented IC50 values < 4 µM, and none caused hemolysis of human erythrocytes, demonstrating a promising cytotoxic potential of natural and chemically-modified bufadienolides. This study presents a detailed contribution of bioactive chemicals from Brazilian Amazon Rhinella species, and indicates promising areas for further studies and pharmaceutical investments.

Dehydrobufotenin extracted from the Amazonian toad Rhinella marina (Anura: Bufonidae) as a prototype molecule for the development of antiplasmodial drugs.

BACKGROUND: The resistance against antimalarial drugs represents a global challenge in the fight and control of malaria. The Brazilian biodiversity can be an important tool for research and development of new medicinal products. In this context, toxinology is a multidisciplinary approach on the development of new drugs, including the isolation, purification, and evaluation of the pharmacological activities of natural toxins. The present study aimed to evaluate the cytotoxicity, as well as the antimalarial activity in silico and in vitro of four compounds isolated from Rhinella marina venom as potential oral drug prototypes. METHODS: Four compounds were challenged against 35 target proteins from P. falciparum and screened to evaluate their physicochemical properties using docking assay in Brazilian Malaria Molecular Targets (BraMMT) software and in silico assay in OCTOPUS® software. The in vitro antimalarial activity of the compounds against the 3D7 Plasmodium falciparum clones were assessed using the SYBR Green I based assay (IC50). For the cytotoxic tests, the LD50 was determined in human pulmonary fibroblast cell line using the [3(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] (MTT) assay. RESULTS: All compounds presented a ligand-receptor interaction with ten Plasmodium falciparum-related protein targets, as well as antimalarial activity against chloroquine resistant strain (IC50 = 3.44 µM to 19.11 µM). Three of them (dehydrobufotenine, marinobufagin, and bufalin) showed adequate conditions for oral drug prototypes, with satisfactory prediction of absorption, permeability, and absence of toxicity. In the cell viability assay, only dehydrobufotenin was selective for the parasite. CONCLUSIONS: Dehydrobufotenin revealed to be a potential oral drug prototype presenting adequate antimalarial activity and absence of cytotoxicity, therefore should be subjected to further studies.

Phytochemical screening, phenolic and flavonoid contents, antioxidant and cytogenotoxicity activities of Combretum leprosum Mart. (Combretaceae).

Combretum leprosum Mart. (Combretaceae), a shrub popularly known as mofumbo, is used in folk medicine for treatment of uterine bleeding, pertussis, gastric pain, and as a sedative. The aim of this study was to (1) determine the phytochemical profile,(2) identify chemical constituents and (3) examine antioxidant and cytogenotoxic activity of ethanolic extracts and fractions of stem bark and leaves. The plant material (leaf and stem bark) was submitted to extraction with ethanol, followed by partition using hexane, chloroform, and ethyl acetate. It was possible to identify and quantify the epicatechin in the ethanolic stem bark extract (0.065 mg/g extract) and rutin in the leaf extract (3.33 mg/g extract). Based upon in vitro tests a significant relationship was noted between findings from antioxidant tests and levels of total phenolic and flavonoid. Comparing all samples (extracts and fractions), the ethyl acetate fractions of stem bark (411.40 ± 15.38 GAE/g) and leaves (225.49 ± 9.47 GAE/g) exhibited higher phenolic content, whereas hexanic fraction of stem bark (124.28 ± 56 mg/g sample) and ethyl acetate fraction of leaves (238.91 ± 1.73 mg/g sample) demonstrated a higher content of flavonoids. Among the antioxidant tests, the intermediate fraction of stem bark (28.5 ± 0.60 µg/ml) and ethyl acetate fraction of leaves (40 ± 0.56 µg/ml) displayed a higher % inhibition of free radical DPPH activity, whereas intermediate fraction of stem bark (27.5 ± 0.9 µg/ml) and hydromethanol fraction of leaves (81 ± 1.4 µg/ml) demonstrated inhibition of the free radical ABTS. In biological tests (Allium cepa and micronucleus in peripheral blood), data showed that none of the tested concentrations of ethanolic extracts of leaves and stem bark produced significant cytotoxicity, genotoxicity, and mutagenic activity.Abbreviations AA%: percentage of antioxidant activity; ABTS: 2,2'-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid); CEUA: Ethics Committee in the Use of Animals; TLC: Thin Layer Chromatography; DNA: deoxyribonucleic acid; DPPH: 1,1-diphenyl-2-picrylhydrazyl; ROS: Reactive oxygen species; EEB: ethanol extract of the stem bark; HFB: Hexanic fraction of stem bark; IFB: Intermediate fraction of stem bark; CFB: Chloroform fraction of stem bark; EAFB: Ethyl acetate fraction of stem bark; HMFB: Hydromethanol fraction of the stem bark; EEL: Ethanol extract from leaves; HFL: Hexane fraction of leaves; CFL: Chloroform fraction of leaves; EAFL: Ethyl acetate fraction of leaves; HMFL: Hydromethanol fraction of leaves; GAE: Gallic Acid Equivalent; IC50: 50% inhibition concentration; HCOOH: Formic acid; HCl: hydrochloric acid; HPLC: High-performance liquid chromatography; MN: micronucleus; WHO: World Health Organization; UFLC: Ultra-Fast Liquid Chromatography; UESPI: State University of Piauí.

Proteins from Rhinella jimi parotoid gland secretion: A comprehensive analytical approach.

Toad skin secretions are sources of complex mixtures of bioactive compounds, such as proteins and peptides. Rhinella jimi species is a common toad in the Brazilian northeast, considered by only a few known studies. The experimental design was applied to optimize the protein extraction method from R. jimi parotoid gland secretions. The optimum condition was using 100 mmol L-1 Tris-HCl buffer pH 7.2 under vortexing for 5 min. The FTIR analysis combined with PCA revealed high-protein purity of the extracts, confirming the success of the proposed extraction method. The total protein concentration by the Bradford method was 102.4 and 66.5 mg g-1 on toad poisons from Teresina and Picos, respectively. The comparative proteomic analysis using HPLC-SEC-DAD and 1D SDS-PAGE revealed significant differences in protein abundance. HMW biomolecules showed greater abundance in toads from Teresina, while LMW protein species were more abundant in toads from Picos. The significant difference in amphibian proteome can be attributed to the edaphoclimatic conditions of their habitat. The cytotoxicity of the protein extract from Teresina was higher on the tumor cell lines 4T1 and CT26.WT. These new findings are fundamental for future studies the on identity and biological activity of biomolecules from this noble sample.

Cenostigma macrophyllum Tul. var. acuminata Teles Freire Fraction Leaves Stimulate Gastric Healing in Rats and Human Cell Cultures.

Cenostigma macrophyllum Tul. var. acuminata Teles Freire (Leguminosae-Caesalpinioideae) is a medicinal plant traditionally used for treatment of gastric ulcer. This study evaluated the ulcer-healing activity of the hydroalcoholic fraction of C. macrophyllum Tul. var. acuminata Teles Freire leaves (Cm-FHA) and the tea of the leaves of C. macrophyllum (Cm-tea), as well as the possible action of Cm-FHA, through in vitro models. Leaves of C. macrophyllum were dried and powdered to obtain the Cm-FHA. Subsequently, the Cm-FHA was characterized phytochemically and biologically. Besides, Cm-tea was prepared. The gastric healing effects of Cm-tea and Cm-FHA were analyzed using the model of acetic acid-induced gastric ulcer in rats. The human gastric adenocarcinoma (AGS) cell line was employed as an in vitro model. Cm-tea promoted a protective effect against gastric ulcers induced by absolute ethanol. Cm-FHA or Cm-tea (100 mg/kg/7 days) exhibited a significant healing effect on ulcers induced by acetic acid. In the histological analysis, gastric mucosa treated with Cm-FHA or Cm-tea advanced restoration of the mucosal epithelium. In vitro, lower concentrations of Cm-FHA stimulated cell proliferation in the BrdU assay and cell migration. Cm-tea and Cm-FHA present a significant gastric healing effect in in vivo and in vitro models.