Unraveling the Reaction Mechanism of Russell's Viper Venom Factor X Activator: A Paradigm for the Reactivity of Zinc Metalloproteinases?

Snake venom metalloproteinases (SVMPs) are important drug targets against snakebite envenoming, the neglected tropical disease with the highest mortality worldwide. Here, we focus on Russell's viper (Daboia russelii), one of the "big four" snakes of the Indian subcontinent that, together, are responsible for ca. 50,000 fatalities annually. The "Russell's viper venom factor X activator" (RVV-X), a highly toxic metalloproteinase, activates the blood coagulation factor X (FX), leading to the prey's abnormal blood clotting and death. Given its tremendous public health impact, the WHO recognized an urgent need to develop efficient, heat-stable, and affordable-for-all small-molecule inhibitors, for which a deep understanding of the mechanisms of action of snake's principal toxins is fundamental. In this study, we determine the catalytic mechanism of RVV-X by using a density functional theory/molecular mechanics (DFT:MM) methodology to calculate its free energy profile. The results showed that the catalytic process takes place via two steps. The first step involves a nucleophilic attack by an in situ generated hydroxide ion on the substrate carbonyl, yielding an activation barrier of 17.7 kcal·mol-1, while the second step corresponds to protonation of the peptide nitrogen and peptide bond cleavage with an energy barrier of 23.1 kcal·mol-1. Our study shows a unique role played by Zn2+ in catalysis by lowering the pKa of the Zn2+-bound water molecule, enough to permit the swift formation of the hydroxide nucleophile through barrierless deprotonation by the formally much less basic Glu140. Without the Zn2+ cofactor, this step would be rate-limiting.

In Silico and In Vitro Identification of 1,8-Dihydroxy-4,5-dinitroanthraquinone as a New Antibacterial Agent against Staphylococcus aureus and Enterococcus faecalis.

Increasing rates of bacterial resistance to antibiotics are a growing concern worldwide. The search for potential new antibiotics has included several natural products such as anthraquinones. However, comparatively less attention has been given to anthraquinones that exhibit functional groups that are uncommon in nature. In this work, 114 anthraquinones were evaluated using in silico methods to identify inhibitors of the enzyme phosphopantetheine adenylyltransferase (PPAT) of Staphylococcus aureus, Enterococcus faecalis, and Escherichia coli. Virtual screenings based on molecular docking and the pharmacophore model, molecular dynamics simulations, and free energy calculations pointed to 1,8-dihydroxy-4,5-dinitroanthraquinone (DHDNA) as the most promising inhibitor. In addition, these analyses highlighted the contribution of the nitro group to the affinity of this anthraquinone for the nucleotide-binding site of PPAT. Furthermore, DHDNA was active in vitro towards Gram-positive bacteria with minimum inhibitory concentration (MIC) values of 31.25 µg/mL for S. aureus and 62.5 µg/mL for E. faecalis against both antibiotic-resistant isolates and reference strains but was ineffective against E. coli. Experiments on kill-time kinetics indicated that, at the tested concentrations, DHDNA produced bacteriostatic effects on both Gram-positive bacteria. Overall, our results present DHDNA as a potential PPAT inhibitor, showing antibacterial activity against antibiotic-resistant isolates of S. aureus and E. faecalis, findings that point to nitro groups as key to explaining these results.

Changes in antiparasitical activity of gold nanorods according to the chosen synthesis.

Gold nanorods (GNRs) are increasingly being studied for diagnostic and therapeutic purposes. Green synthesis based methods with natural compounds as additives stand out as a hope in terms of better synthesis methodology, with advantages of producing potentially less toxic and, perhaps, biologically active GNRs due to influence of natural additives used during synthesis. Exploring green chemistry using different natural phenolic compounds, the present work reveals different in vitro activity of GNRs evaluated against different parasites that causes skin infectious diseases compared to GNRs produced by convencional seed mediated method. This approach brings advantages in producing active GNRs, with ease calling, less cytotoxic and with a better selectivity index (SI) than GNRs synthesized by conventional seed mediated synthesis, opening new possibilities for therapies. Natural compounds used in green syntheses were gallic acid (GA), resveratrol (RSV) and a purified fraction of the hydroalcoholic extract of Stryphnodendron obovatum. GNRs exhibited great activity against Leishmania braziliensis, and the dermatophytes Tricophyton rubrum, T. interdigitale and Microsporum gypseum. The anti-Leishmania and antidermatophytic activity of GNRs reinforce the applicability of GNRs in biomedical field and the influence of synthesis method in biological activity, showing benefits related to the seedless synthesis with natural compounds. In addition, these preliminary results indicate the possibility of exploring at maximum the physical and chemical properties of GNRs in addition to the biological activity itself, such as the development of topical antiparasitic formulations for association with phototherapy.

Efficacy of photobiomodulation therapy on healing of ionizing irradiated bone: a systematic review of in vivo animal studies.

This systematic review aimed to answer the research focused question: What are the effects of photobiomodulation (PBM) therapy on bone healing after ionizing irradiation in animal models? The EMBASE, LILACS, LIVIVO, PubMed, Scopus, and Web of Science databases, including gray literature, were searched using the following keywords: "Head and Neck Neoplasms"; "Ionizing Radiation"; "Low-Level Light Therapy"; and "Bone regeneration", focusing on the primary studies that assessed the effects of PBM therapy on animal models of irradiated bone. Six studies have met the eligibility criteria and presented an overall regular quality according to the risk of bias assessment tools. All the studies utilized rat animal model and near-infrared laser PBM at low power output setting. Most of the studies showed increased new bone formation, osteocytes, osteoblasts, and vascularization networking, as a result of PBM therapy. However, only one out of the six studies has not shown any differences in bone healing in both lased and non-lased animal groups. Nevertheless, PBM therapy is a potential tool to improve bone healing induced by ionizing radiation. However, due to the scarce number of studies and the great variability of laser parameters and treatment protocols, a clear conclusion cannot be drawn. Hence, extensive preclinical in vivo studies are warranted to ensure these beneficial effects have been addressed prior to translational clinical trials.

Safety and immunogenicity of 17DD attenuated yellow fever vaccine in howler monkeys (Alouatta spp.).

BACKGROUND: Alouatta spp. are highly susceptible to yellow fever (YF) infection and develop an often fatal disease. The threat posed by an outbreak started in 2016 leads us to investigate vaccination as a potential tool in preventing YF in non-human primates (NHP). METHODS: Susceptible howler monkeys were immunized with three different concentrations of the human Brazilian commercial YF17DD vaccine. Post-vaccination viremia/RNAemia, immunogenicity, and safety were characterized. RESULTS: The vaccine did not produce YF clinical manifestations in any of the NHPs. After immunization, all animals seroconverted demonstrating the ability of the YF vaccine to induce humoral response in Alouatta species. CONCLUSIONS: The present work has demonstrated the safe and immunogenic profile of the existing YF 17DD vaccine in howler monkeys. This knowledge may support further studies with other susceptible monkey species and provide a possible solution for controlling epizootics and preventing the devastation of endangered species.

Effects of Orally Administered Resveratrol on TNF, IL-1ß, Leukocyte Phagocytic Activity and Oxidative Burst Function in Horses: A Prospective, Randomized, Double-Blinded, Placebo-Controlled Study.

Resveratrol, a phytophenol, is a commonly used equine nutraceutical supplement touted to exert anti-inflammatory effects. The effect of orally administered resveratrol on tumor necrosis factor (TNF), interleukin-1ß (IL-1ß), leukocyte phagocytic activity or oxidative burst function have not been reported in horses. The objective of this study was to determine the effects of a commercially available, orally administered resveratrol product on innate immune functions in healthy adult horses. Whole blood was collected from 12 horses prior to and following 3 weeks of treatment with either the manufacturer's recommended dose of resveratrol or placebo. Phagocytosis, oxidative burst and pathogen associated molecular pattern (PAMP) motif-stimulated leukocyte production of TNF and IL-1ß were compared pre- and post-treatment between treatment groups. Phagocytosis and oxidative burst capacity were evaluated via flow cytometry. Tumor necrosis factor and IL-1ß were measured using cytotoxicity and ELISA assays, respectively. There were no significant differences in phagocytosis, oxidative burst or stimulated TNF or IL-1ß production between resveratrol and placebo treatment groups. Orally administered resveratrol at a routinely recommended dose for a duration of 3 weeks did not significantly affect phagocytic activity, oxidative burst function or PAMP-stimulated leukocyte cytokine production.

In Vitro Anticoagulant Activity of Mikania laevigata: Deepening the Study of the Possible Interaction Between Guaco and Anticoagulants.

Mikania laevigata, popularly known in Brazil as guaco, is widely used for respiratory disorders. As this plant is rich in coumarins, there is evidence of indications that it may cause bleeding and therefore should not be used concomitantly with anticoagulants. The basis of this information is very theoretical, with no clinical evidence of such contraindication. Thus, the aim of this study was to evaluate the in vitro effect of M. laevigata extract on blood coagulation through prothrombin time (PT) and activated partial thromboplastin time (aPTT) tests, fibrinogen plasma concentration, and the new thrombin generation test, which investigate, with high sensibility, hemostatic changes (CAAE 60904316.6.0000.5149), besides evaluating its qualitative micromolecular composition, providing scientific evidence to support the management of patients taking warfarin. Ethanolic extracts of guaco leaves were incubated with a plasma pool of healthy individuals at concentrations of 1.67, 2.26, and 2.86 mg/mL. The presence of flavonoids, tannins, coumarins, and triterpenes was demonstrated by selective reagents in thin layer chromatography. Benzoylgrandifloric acid, cinnamoylgrandifloric acid, o-coumaric acid, coumarin, and quercetin-3-ß-glucoside were identified by coinjection in ultraperformance liquid chromatography. The extract at all concentrations prolonged TP and aPPT and reduced the potential for endogenous thrombin potential by the thrombin generation test. The control plasma had endogenous thrombin potential = 1465 nM/min, and after the addition of M. laevigata extract (2.26 mg/mL), this value was reduced to 1087 nM/min, indicating a lower generation of thrombin. Related to fibrinogen plasma concentration, concentrations of 2.26 and 2.86 mg/mL were effective in reducing plasma fibrinogen levels. These results allow us to conclude that the guaco extract demonstrated an anticoagulant effect in vitro, possibly interfering with intrinsic, extrinsic, and common coagulation pathways. A discussion on the contribution of the identified substances to the activity is also present.

Effects of tramadol and o-desmethyltramadol on canine innate immune system function.

OBJECTIVE: Tramadol is a commonly used opioid analgesic in dogs, particularly in dogs with a compromised immune system. An opioid may be selected for its immunomodulatory effects. Consequently, the objective of this study was to investigate the effects of tramadol on immune system function by evaluating the effect of tramadol and o-desmethyltramadol (M1) on the function of canine leukocytes in vitro. The hypothesis was that tramadol and M1 would not alter polymorphonuclear leukocyte (PMN) phagocytosis, PMN oxidative burst, or stimulated leukocyte cytokine production capacity of tumor necrosis factor (TNF)-α, interleukin (IL)-6, and IL-10. STUDY DESIGN: In vitro pharmacodynamic study. ANIMALS: Six healthy dogs. METHODS: Blood from six dogs was obtained and incubated with various concentrations of tramadol and M1. Phagocytosis and oxidative burst were assessed using flow cytometry, and lipopolysaccharide (LPS), lipoteichoic acid (LTA) and peptidoglycan (PG)-stimulated leukocyte production of TNF, IL-6, and IL-10 were measured using a canine specific multiplex assay. RESULTS: No differences were detected in phagocytosis or oxidative burst with any drug concentration. Tramadol did not alter leukocyte cytokine production, however, M1 significantly blunted IL-10 production. CONCLUSIONS: Tramadol and its metabolite M1 were sparing to PMN phagocytosis and oxidative burst in dogs in vitro. Tramadol did not alter leukocyte cytokine production, however, M1 blunted IL-10 production at clinically achievable concentrations suggesting that M1 may promote a proinflammatory shift. CLINICAL RELEVANCE: These data suggest that tramadol has minimal effect on phagocytosis and oxidative burst, and may promote a proinflammatory shift. Therefore, tramadol may be an ideal opioid analgesic in dogs at high risk of infection. Further investigation in vivo is warranted.

In vitro acaricidal efficacy of plant extracts from Brazilian flora and isolated substances against Rhipicephalus microplus (Acari: Ixodidae).

The tick Rhipicephalus microplus causes significant losses in livestock cattle and has developed increasing resistance to the primary acaricides that are used to treat these infections. The objective of this study was to identify new biomolecules or isolated substances showing acaricidal activity from plants. Larval packet tests were conducted to evaluate the effects of 11 species of plants and three isolated substances (betulinic acid, eugenol, and nerolidol) on R. microplus. An adult female immersion test was performed with the substance that showed the highest larvicidal activity, which was evaluated for inhibition of reproduction. Tests using Licania tomentosa, Hymenaea stigonocarpa, Hymenaea courbaril, Stryphnodendron obovatum, Jacaranda cuspidifolia, Jacaranda ulei, Struthanthus polyrhizus, Chrysobalanus icaco, Vernonia phosphorea, Duguetia furfuracea, and Simarouba versicolor extracts as well as the isolated substance betulinic acid indicated lower acaricidal effects on R. microplus larvae. The extract displaying the best larvicidal activity was the ethanolic extract from L. tomentosa at a concentration of 60%, resulting in a mortality rate of 40.3%. However, nerolidol and eugenol showed larvicidal activity, which was highest for eugenol. Nerolidol caused a 96.5% mortality rate in the R. microplus larvae at a high concentration of 30%, and eugenol caused 100% mortality at a concentration of 0.3%. In the adult immersion test, 5% eugenol was identified as a good biomolecule for controlling R. microplus, as demonstrated by its high acaricidal activity and inhibition of oviposition.

Immunization with P10 peptide increases specific immunity and protects immunosuppressed BALB/c mice infected with virulent yeasts of Paracoccidioides brasiliensis.

Paracoccidioidomycosis is a systemic granulomatous disease caused by Paracoccidioides spp. A peptide from the major diagnostic antigen gp43, named P10, induces a T-CD4(+) helper-1 immune response in mice and protects against intratracheal challenge with virulent P. brasiliensis. Previously, we evaluated the efficacy of the P10 peptide alone or combined with antifungal drugs in mice immunosuppressed and infected with virulent isolate of P. brasiliensis. In the present work, our data suggest that P10 immunization leads to an effective cellular immune response associated with an enhanced T cell proliferative response. P10-stimulated splenocytes increased nitric oxide (NO) production and induced high levels of IFN-γ, IL-1ß and IL-12. Furthermore, significantly increased concentrations of pro-inflammatory cytokines were also observed in lung homogenates of immunized mice. P10 immunization was followed by minimal fibrosis in response to infection. Combined with antifungal drugs, P10 immunization most significantly improved survival of anergic infected mice. Administration of either itraconazole or sulfamethoxazole/trimethoprim together with P10 immunization resulted in 100 % survival up to 200 days post-infection, whereas untreated mice died within 80 days. Hence, our data show that P10 immunization promotes a strong specific immune response even in immunocompromised hosts and thus P10 treatment represents a powerful adjuvant therapy to chemotherapy.

The effects of co-culturing non-Saccharomyces yeasts with S. cerevisiae on the sugar cane spirit (cachaça) fermentation process.

Twenty non-Saccharomyces strains were previously tested in pure culture for their ability to grow in 12 % ethanol, their ß-glucosidase activity, flocculation, glycerol, ethanol and acetic acid production, fermentation kinetics and their production of volatile compounds. Of these 20 strains, three strains, namely, Pichia anomala UFLA CAF70, P. anomala UFLA CAF119 and Pichia caribbica UFLA CAF733, were evaluated in co-culture with Saccharomyces cerevisiae UFLA CA11. Of the mixed inocula, the mixture of P. caribbica UFLA CAF733 and S. cerevisiae UFLA CA11 gave the highest ethanol concentration (75.37 g/L), the lowest levels of residual glucose (1.14 g/L) and fructose (19.92 g/L), and the highest volumetric productivity (Q (p)) of ethanol. Twenty-three minor volatile compounds were identified in the fermented sugar cane juice. The mixed culture of P. caribbica UFLA CAF733 and S. cerevisiae UFLA CA11 gave the highest concentration of volatile compounds with good sensory descriptors; these compounds included ethyl esters (290.13 µg/L), acetates (715.21 µg/L) and monoterpenic alcohols (195.56 µg/L). This mixed culture also gave the lowest concentration of volatile acids (1774.46 µg/L) and aldehydes (121.10 µg/L). In principal component analysis, the mixed inoculum of UFLA CAF733 and UFLA CA11 was positively characterized by ethyl hexanoate, 2-phenylethanol, linalool, nonanoic acid, ethyl butyrate, phenylethyl acetate, diethylsuccinate, hexanoic acid, and geraniol. In conclusion, we found that clear improvements could be achieved in the fermentation process with mixed, rather than pure, S. cerevisiae culture. The use of the non-Saccharomyces strain P. caribbica UFLA CAF733 in co-culture with S. cerevisiae UFLA CA11 may therefore be an interesting means by which to improve the quality of cachaça.

Alpha-Naphthoflavone as a Novel Scaffold for the Design of Potential Inhibitors of the APH(3')-IIIa Nucleotide-Binding Site of Enterococcus faecalis.

The spread of nosocomial infections caused by antibiotic-resistant Enterococcus faecalis is one of the major threats to global health at present. While aminoglycosides are often used to combat these infections, their effectiveness is reduced by various resistance mechanisms, including aminoglycoside modifying enzymes, and there are currently no drugs to inhibit these enzymes. To address this issue, this study was conducted to identify potential aminoglycoside adjuvants from a database of 462 flavones. The affinity of these molecules with the nucleotide-binding site (NBS) of aminoglycoside phosphotransferase type IIIa of E. faecalis (EfAPH(3')-IIIa) was evaluated, and the five molecules with the highest binding energies were identified. Of these, four were naphthoflavones, suggesting that their backbone could be useful in designing potential inhibitors. The highest-ranked naphthoflavone, 2-phenyl-4H-benzo[h]chromen-4-one, was modified to generate two new derivatives (ANF2OHC and ANF2OHCC) to interact with the NBS similarly to adenine in ATP. These derivatives showed higher binding free energies, better stability in molecular dynamics analysis and superior pharmacokinetic and toxicological profiles compared to the parent molecule. These findings suggest that these alpha-naphthoflavone derivatives are potential inhibitors of EfAPH(3')-IIIa and that this core may be a promising scaffold for developing adjuvants that restore the sensitivity of aminoglycosides.

Antithrombotic potential of Lippia alba: A mechanistic approach.

ETHNOPHARMACOLOGICAL RELEVANCE: Lippia alba (Mill.) N.E.Br. ex Britton & P. Wilson is traditionally used in Brazil as an adjunct in the relief of mild anxiety, as an antispasmodic, and as an antidyspeptic. This medicinal species was included in the Phytotherapeutic Form of the Brazilian Pharmacopeia 2nd edition (2021) and has already been described as the most used medicinal plant in a study with patients from an Anticoagulation Clinic in Brazil. Meanwhile, no studies were found that support the safety of the use of L. alba in patients using anticoagulants, a drug with several safety limitations. AIM OF THE STUDY: Provide scientific evidence to ensure the safety of the concomitant use of L. alba and warfarin and support the management of these patients by evaluating its in vitro anticoagulant effect and chemical composition. And, as a timely complementation, evaluate the potential of this medicinal species in the development of new antithrombotics. METHODS: The chemical profile of L. alba derivatives was analyzed by chromatographic methods such as Ultra-Performance Liquid Chromatography (UPLC) coupled with electrospray ionization mass spectrometry (ESI-MS), qualitative UPLC using Diode-Array Detection, and Thin Layer Chromatography. The anticoagulant activity was evaluated by the innovative Thrombin Generation Assay by Calibrated Automated Thrombogram method and using traditional coagulometric tests: prothrombin time, activated partial thromboplastin time, and plasma fibrinogen measurement. RESULTS: Extracts and fractions prolonged the coagulation time in all the tests and reduced thrombin formation in thrombin generation assay. Coagulation times with the addition of ethanloic extract (2.26 mg/mL) was 17.78s, 46.43s and 14.25s respectively in prothrombin time, activated partial thromboplastin time and fibrinogren plasma measurement. In thrombin generation test, this same extract showed ETP as 323 nM/min compared to control (815 nM/min) with high tissue factor and 582 nM/min compared to control (1147 nM/min) using low tissue factor. Presence of flavonoids, phenylpropanoids, and triterpenes were confirmed by chromatographic methods and 13 compounds were identified by UPLC-ESI-MS. Based on these results and on the scientific literature, it is possible to propose that phenylpropanoids and flavonoids are related to the anticoagulant activity observed. CONCLUSION: The results demonstrate the in vitro anticoagulant activity of L. alba, probably due to the activation of intrinsic and extrinsic pathways. It is concluded, then, that there is a potential for interaction, which needs to be further studied, between L. alba and warfarin. Also, this medicinal species shows a great potential for use in the development of new antithrombotics.

Chemical characterization, antinociceptive and anti-inflammatory effect of Lippia lacunosa, a species used by the Bandeirantes.

ETHNOPHARMACOLOGICAL RELEVANCE: Lippia lacunosa Mart. & Schauer is an endemic plant from the Serra do Espinhaço mountain range located on the Atlantic plateau, Brazil. It is known as "chá de pedestre" and "rosmaninho" in folk medicine. This species has a characteristic mango aroma and is widely used by the population for flu, colds, sinus infections, coughing, relaxing baths, and foot baths after long walks. It is often confused with and, therefore, used interchangeably with L. rotundifolia and L. pseudothea. AIM OF THE STUDY: This study aimed to increase scientific knowledge on the ethnopharmacological use of Lippia lacunosa through the evaluation of the micromolecular composition and anti-inflammatory and antinociceptive activities of the hexane and ethanolic extracts, essential oil, and fractions in mice. MATERIALS AND METHODS: The chemical profile of L. lacunosa extracts and fractions were obtained by chromatographic methods such as Ultra-Performance Liquid Chromatography (UPLC), Gas Chromatography (GC), Column Chromatography (CC), and Thin Layer Chromatography (TLC). Carrageenan-induced paw edema was used to investigate the anti-inflammatory activity in mice. Mechanical allodynia induced by carrageenan and hot plate tests were employed to evaluate the antinociceptive activity. RESULTS: The main constituents found in the essential oil were the monoterpenes myrcene (13.81%), linalool (6.84%), ipsenone (21.2%), and myrcenone (25.44%); and sesquiterpenes elemol (7.30%) and spathulenol (3.15%). The chromatograph fractionation of essential oil yielded a fraction rich in the main compounds (F33), ipsenone and mircenone. In experimental models of paw edema and mechanical allodynia induced by carrageenan (600 µg, 30 µL, i.pl.), the administration of hexane extract, essential oil (50 or 100 mg/kg, p.o.) or majority fraction (10 mg/kg, p.o.) reduced paw edema. The ethanolic extract (100 mg/kg) reduced mechanical allodynia only in the 2 nd h of evaluation. On the other hand, the hexane extract (50 or 100 mg/kg) and essential oil (100 mg/kg), as well as the majority fraction (10 mg/kg), reduced mechanical allodynia throughout the evaluation period. The hexane extract, essential oil, and majority fraction F33 also reduced the heat-induced nociceptive response. Also, majority fraction F33 did not affect the time mice spent in the rota-rod apparatus. CONCLUSIONS: The elucidation of the composition of the essential oil and the demonstration of the activity of L. lacunosa in experimental models of acute inflammation and also in models of nociceptive and inflammatory pain can help to increase knowledge on the ancient ethnopharmacological use by the Bandeirantes, aiming at the evaluation of the species as a candidate for herbal medicine or phytopharmaceutical in the treatment of patients with inflammatory and painful conditions.

Catalytically Active Snake Venom PLA2 Enzymes: An Overview of Its Elusive Mechanisms of Reaction.

Snake venom-secreted phospholipase A2 (svPLA2) enzymes, both catalytically active and inactive, are a central component in envenoming. These are responsible for disrupting the cell membrane's integrity, inducing a wide range of pharmacological effects, such as the necrosis of the bitten limb, cardiorespiratory arrest, edema, and anticoagulation. Although extensively characterized, the reaction mechanisms of enzymatic svPLA2 are still to be thoroughly understood. This review presents and analyses the most plausible reaction mechanisms for svPLA2, such as the "single-water mechanism" or the "assisted-water mechanism" initially proposed for the homologous human PLA2. All of the mechanistic possibilities are characterized by a highly conserved Asp/His/water triad and a Ca2+ cofactor. The extraordinary increase in activity induced by binding to a lipid-water interface, known as "interfacial activation," critical for the PLA2s activity, is also discussed. Finally, a potential catalytic mechanism for the postulated noncatalytic PLA2-like proteins is anticipated.

Virtual screening, optimization and molecular dynamics analyses highlighting a pyrrolo[1,2-a]quinazoline derivative as a potential inhibitor of DNA gyrase B of Mycobacterium tuberculosis.

Tuberculosis is a disease that remains a significant threat to public health worldwide, and this is mainly due to the selection of strains increasingly resistant to Mycobacterium tuberculosis, its causative agent. One of the validated targets for the development of new antibiotics is DNA gyrase. This enzyme is a type II topoisomerase responsible for regulating DNA topology and, as it is essential in bacteria. Thus, to contribute to the search for new molecules with potential to act as competitive inhibitors at the active site of M. tuberculosis DNA gyrase B, the present work explored a dataset of 20,098 natural products that were filtered using the FAF-Drugs4 server to obtain a total of 5462 structures that were subsequently used in virtual screenings. The consensus score analysis between LeDock and Auto-Dock Vina software showed that ZINC000040309506 (pyrrolo[1,2-a]quinazoline derivative) exhibit the best binding energy with the enzyme. In addition, its subsequent optimization generated the derivative described as PQPNN, which show better binding energy in docking analysis, more stability in molecular dynamics simulations and improved pharmacokinetic and toxicological profiles, compared to the parent compound. Taken together, the pyrrolo[1,2-a]quinazoline derivative described for the first time in the present work shows promising potential to inhibit DNA gyrase B of M. tuberculosis.

An In-Silico Evaluation of Anthraquinones as Potential Inhibitors of DNA Gyrase B of Mycobacterium tuberculosis.

The World Health Organization reported that tuberculosis remains on the list of the top ten threats to public health worldwide. Among the main causes is the limited effectiveness of treatments due to the emergence of resistant strains of Mycobacterium tuberculosis. One of the main drug targets studied to combat M. tuberculosis is DNA gyrase, the only enzyme responsible for regulating DNA topology in this specie and considered essential in all bacteria. In this context, the present work tested the ability of 2824 anthraquinones retrieved from the PubChem database to act as competitive inhibitors through interaction with the ATP-binding pocket of DNA gyrase B of M. tuberculosis. Virtual screening results based on molecular docking identified 7122772 (N-(2-hydroxyethyl)-9,10-dioxoanthracene-2-sulfonamide) as the best-scored ligand. From this anthraquinone, a new derivative was designed harbouring an aminotriazole moiety, which exhibited higher binding energy calculated by molecular docking scoring and free energy calculation from molecular dynamics simulations. In addition, in these last analyses, this ligand showed to be stable in complex with the enzyme and further predictions indicated a low probability of cytotoxic and off-target effects, as well as an acceptable pharmacokinetic profile. Taken together, the presented results show a new synthetically accessible anthraquinone with promising potential to inhibit the GyrB of M. tuberculosis.

Effect of honey and propolis, compared to acyclovir, against Herpes Simplex Virus (HSV)-induced lesions: A systematic review and meta-analysis.

ETHNOPHARMACOLOGICAL RELEVANCE: Apitherapy is a branch of traditional medicine that uses bee products to manage numerous diseases. In this context, the antiherpetic effect of these bee products has been demonstrated in some studies with some controversial results. AIM OF THE STUDY: Thus, we conducted a systematic review and meta-analysis to compare the effectiveness of honey and propolis with acyclovir, the reference drug, in the treatment of cold sores and genital herpes. MATERIALS AND METHODS: The selection of eligible studies was conducted through the search in Pubmed/MEDLINE, Scopus, Cochrane Library, LILACS, and Electronic Scientific Library. RESULTS: The search yielded 147 articles, of which nine were considered eligible for analysis. The analysis of these studies showed that the healing property of propolis is superior to that obtained for acyclovir (95% CI: 2.70 to 8.25; p = 0.0001). Furthermore, honey also presented a better healing effect than acyclovir against Herpes simplex virus-induced wounds (95% CI: 3.58 to -0.19; p = 0.03), inducing complete re-epithelization of herpetic lesions after 8 days, while for acyclovir, the healing time average was 9 days. It also provoked a similar reduction of pain caused by herpetic compared to acyclovir (95% CI: 2.27 to -0.42; p = 0.18). CONCLUSIONS: Overall, these results confirm the use of honey and propolis as potent antiherpetic agents.

Costus spiralis extract restores kidney function in cisplatin-induced nephrotoxicity model: Ethnopharmacological use, chemical and toxicological investigation.

ETHNOPHARMACOLOGICAL RELEVANCE: Costus spiralis (Jacq.). Roscoe (Costaceae) is traditionally used in Brazil for the treatment of kidney diseases such as pyelonephritis, urethra inflammation, kidney stones, and inflammatory conditions. There are reports of its use by Brazilian Indians since the 17th century when it was known as "pacocatinga." Currently, the use of the Costus species in Brazil is widespread, which was evidenced by the inclusion of the genus in the Brazilian National List of Medicinal Plants of Interest to the Unified Health System (RENISUS). AIM OF THE STUDY: This study aimed to confirm the ethnopharmacological use of Costus spiralis in the treatment of kidney diseases, toxicity study using animal models, and the phytochemistry of the species. MATERIALS AND METHODS: The chemical profile of Costus spiralis leaves extract (CSLE) was obtained for the hydroethanolic extract by ultra-performance liquid chromatography coupled to a mass spectrometer and ultraviolet detector with diode array (UPLC-UV/DAD-ESI-MS). The acute oral toxicity of the extract was predicted using the neutral red uptake cytotoxicity assay. Wistar rats were used in a model in vivo for confirmation of acute oral toxicity (2000 mg/kg p.o. for 14 days.) and determination of the effect on a cisplatin-induced nephrotoxicity model. RESULTS: The analysis by UPLC-UV/DAD-ESI-MS showed that the chemical composition of the extract is mostly di-glycosylated flavones of apigenin. In the extract were identified the flavones vicenin II and schaftoside. The quantification of total flavonoids by spectrometry showed 0.880%. CSLE proved to be safe for acute oral administration (2000 mg/kg) with an IC50 value of 222.9 µg/mL and predicted oral toxic dose of 523.82 µg/mL in a neutral red uptake cytotoxicity assay. The absence of death allows the classification of the extract in class 5 according to OECD 423 guidelines and therefore it can be considered as a high acute safety product, which is highly relevant, considering the wide popular use of the species. In the cisplatin-induced nephrotoxicity model, C. spiralis extract (5, 15, and 30 mg/kg) significantly improved renal function, reversing almost completely the effects on plasma creatinine levels and creatinine clearance (p < 0.001). CONCLUSIONS: This study demonstrates that oral administration of Costus spiralis extract leaves is safe and effective in restoring the renal function in rats in a cisplatin-induced nephrotoxicity. It is suggested that the observed activity is related to the flavonoids present. This hypothesis should be confirmed, and the participation of other secondary metabolites should be investigated in the future.

Anticoagulant and antiplatelet activity of aqueous extracts of Citrus sinensis and Lippia alba : interactions and potential for the development of antithrombotics.

Citrus sinensis and Lippia alba are herbal medicines widely used in the form of tea (infusion, decoction), which ethanolic extracts have already shown great anticoagulant activity in vitro . For this reason, they seem to be excellent candidates for the development of new antithrombotics and also have the potential to interact with them. The aim of this study was to evaluate the activity of aqueous extracts in blood coagulation and platelet aggregation, in addition to analysing the micromolecular composition of these species. Thrombin generation test (TGT) by the Calibrated Automated Thrombogram method and Platelet Aggregation Test by turbidimetry were performed to evaluate the biological activities, while the chemical composition was qualitatively evaluated using high-performance liquid chromatography. Aqueous extracts were elaborated according to the folk use. All extracts were effective in reducing thrombin formation in TGT. Infusion of L. alba and infusion and decoction of C. sinensis at a concentration of 0.6 mg/ml significantly reduced platelet aggregation induced by ADP, and only the decoction of L. alba at the same concentration was able to significantly reduce collagen-induced platelet aggregation. The presence of phenylpropanoids and flavonoids in C. sinensis and L. alba extracts was verified. Furthermore, hesperidin was identified in C. sinensis through coinjection. C. sinensis and L. alba are rich in phenolics and demonstrated an in-vitro effect on important processes of haemostasis (blood coagulation, platelet agreggation), corroborating the potential of C. sinensis and L. alba for the development of antithrombotics and interact with them.