Anti-Mayaro virus activity of a hydroethanolic extract from Fridericia chica (Bonpl.) L. G. Lohmann leaves.

ETHNOPHARMACOLOGICAL RELEVANCE: Mayaro fever is a neglected tropical disease. The region of the most significant circulation of the Mayaro virus (MAYV) is the Amazon rainforest, situated in remote areas that are difficult to access and where medicine is scarce. Thus, the regional population uses plants as an alternative for the treatment of various diseases. Fridericia chica is an endemic plant of tropical regions used in traditional medicine to treat fever, malaise, inflammation, and infectious diseases such as hepatitis B. However, its antiviral activity is poorly understood. AIM OF THE STUDY: This study aimed to investigate the anti-MAYV activity of the hydroethanolic extract of the leaves of Fridericia chica (HEFc) in mammalian cells and its possible mechanism of action. MATERIALS AND METHODS: The antiviral activity of HEFc was studied using Vero cell lines against MAYV. The cytotoxicity and antiviral activity of the extract were evaluated by the 3-(4, 5- dimethyl-2-thiazolyl)-2, 5-diphenyl-2H-tetrazolium bromide (MTT) assay. The overall antiviral activity was confirmed by the plaque forming units (PFU) method. Then, the effects of HEFc on MAYV multiplication kinetics, virus adsorption, penetration, and post-penetration, and its virucidal activity were determined in Vero cells using standard experimental procedures. RESULTS: HEFc exerted a effect against viral infection in Vero cells at a non-cytotoxic concentration, and no virion was detected in the supernatant in a dose-dependent and selective manner. HEFc inhibited MAYV in the early and late stages of the viral multiplication cycle. The extract showed significant virucidal activity at low concentrations and did not affect adsorption or viral internalization stages. In addition, HEFc reduced virions at all post-infection times investigated. CONCLUSIONS: HEFc has good antiviral activity against MAYV, acting directly on the viral particles. This plant extract possesses an excellent and promising potential for developing effective herbal antiviral drugs.

A 3-alkylpyridine-bearing alkaloid exhibits potent antimicrobial activity against methicillin-resistant Staphylococcus aureus (MRSA) with no detectable resistance.

Staphylococcus aureus is a Gram-positive bacterium responsible for a wide variety of infectious diseases, and its methicillin-resistant isolates pose a serious worldwide public health risk. New drugs are urgently needed for the treatment of methicillin-resistant Staphylococcus aureus (MRSA) infections. Here, we evaluated the antibacterial activity of five 3-alkyl-pyridinic analogs against MRSA and, of these compounds, compound 6 showed promising antibacterial activity against Staphylococcus with minimum inhibitory concentration (MIC) ranging from 0.98 to 3.9 µgmL-¹ . In addition, it exhibited a rapid bactericidal action, with complete elimination of MRSA after 6 h of incubation at 15.6 µgmL-¹ . Compound 6 had the ability to damage the bacterial membrane and induce cell lysis and, due to its action on the membrane, showed low resistance induction potential in vitro. In the combination study, compound 6 revealed an additive effect (FICI = 1) with vancomycin and ofloxacin and ciprofloxacin (FICI = 0.75) against MRSA, reducing the effective concentration of this antibiotic two-fold. The anti-staphylococcal activity of compound 6 was stable in the presence of different concentrations of NaCl (50, 200, and 400 µM), trypsin ( 1:500, 1:250) and under a variety of pH values (4, 5, 6, and 8); however, its binding to plasmatic proteins (i.e., albumin) was substantial. The previous exposure of MRSA to the compound was able to reduce the formation of bacterial biofilm and reduce the biomass of mature biofilms. Compound 6 showed low selectivity in vitro for MRSA USA 300 when compared to eukaryotic cells (epithelial, fibroblast, and red blood cells).

Antifungal activity of a novel 3-Alkylpyridine analog derived from Marine sponge alkaloids.

Candida spp. is considered an important cause of healthcare-associated infections worldwide. Currently, the emergence and spread of resistant Candida isolates are being increasingly reported, making the development of new agents urgently needed. In this study, we showed the in vitro anti-Candida activity of seven synthetic 3-alkylpyridine alkaloid analogs. Among them, alkaloid 1 presented a potent antifungal effect, which was independent of its capacity of binding with the fungal membrane ergosterol or cell wall. Analog 1 showed fungistatic and fungicidal effects against C. albicans (MIC 7.8 µg/mL and MFC 62.5 µg/mL), C. glabrata, C. krusei (MIC and MFC 31.2 µg/mL), and C. tropicalis (MIC 31.2 µg/mL and MFC 125 µg/mL). The time kill-curve study showed that compound 1 has a potent fungicidal effect in vitro, eliminating C. albicans cells. Furthermore, an in vitro synergistic effect with ketoconazole was observed for compound 1. This compound also eliminated the yeast-to-hypha transition. However, it showed high cytotoxicity against mammalian cells. Taken together, these findings support the use of compound 1 as a prototype to develop new anti-Candida agents, but molecular modifications should be done to minimize the high cytotoxicity obtained.

Identification of a Potential Zika Virus Inhibitor Targeting NS5 Methyltransferase Using Virtual Screening and Molecular Dynamics Simulations.

The NS5 methyltransferase (MTase) has been reported as an attractive molecular target for antivirals discovery against the Zika virus (ZIKV). Here, we report structure-based virtual screening of 42 390 structures from the Development Therapeutics Program (DTP) AIDS Antiviral Screen Database. Among the docked compounds, ZINC1652386 stood out due to its high affinity for MTase in comparison to the cocrystallized ligand MS2042, which interacts with the Asp146 residue in the MTase binding site by hydrogen bonding. Subsequent molecular dynamics simulations predicted that this compound forms a stable complex with MTase within 50 ns. Thus, ZINC1652386 may represent a promising ZIKV methyltransferase inhibitor.

Antifungal Activity Directed Toward the Cell Wall by 2-Cyclohexylidenhydrazo- 4-Phenyl-Thiazole Against Candida albicans.

BACKGROUND: The increasing incidence of invasive forms of candidiasis and resistance to antifungal therapy leads us to seek new and more effective antifungal compounds. OBJECTIVE: To investigate the antifungal activity and toxicity as well as to evaluate the potential targets of 2- cyclohexylidenhydrazo-4-phenyl-thiazole (CPT) in Candida albicans. METHODS: The antifungal activity of CPT against the survival of C. albicans was investigated in Caenorhabditis elegans. Additionally, we determined the effect of CPT on the inhibition of C. albicans adhesion capacity to buccal epithelial cells (BECs), the toxicity of CPT in mammalian cells, and the potential targets of CPT in C. albicans. RESULTS: CPT exhibited a minimum inhibitory concentration (MIC) value of 0.4-1.9 µg/mL. Furthermore, CPT at high concentrations (>60 x MIC) showed no or low toxicity in HepG2 cells and <1% haemolysis in human erythrocytes. In addition, CPT decreased the adhesion capacity of yeasts to the BECs and prolonged the survival of C. elegans infected with C. albicans. Analysis of CPT-treated cells showed that their cell wall was thinner than that of untreated cells, especially the glucan layer. We found that there was a significantly lower quantity of 1,3-ß-D-glucan present in CPT-treated cells than that in untreated cells. Assays performed on several mutant strains showed that the MIC value of CPT was high for its antifungal activity on yeasts with defective 1,3-ß-glucan synthase. CONCLUSION: In conclusion, CPT appears to target the cell wall of C. albicans, exhibits low toxicity in mammalian cells, and prolongs the survival of C. elegans infected with C. albicans.

Synthesis and Evaluation of the in vitro Antimicrobial Activity of Triazoles, Morpholines and Thiosemicarbazones.

BACKGROUND: Microbial infections is a global public health problem. The aim of this work was to synthesize and evaluate the antimicrobial activity of novel triazoles, morpholines and thiosemicarbazones. METHODS: Compounds were synthesized using 2,4-Dihydroxyacetophenone and 4-hydroxybenzaldehyde as starting materials. The antimicrobial activity of these compounds against bacteria and yeast was evaluated by the broth microdilution method. RESULTS: The proposed route for synthesis gave high to moderate yields, moreover these compounds were successfully characterized by 1H NMR, 13C NMR and LC-MS. Antimicrobial testing indicated that the thiosemicarbazone and morphine derivatives had the best antimicrobial activity against the microorganisms tested with minimum inhibitory concentrations (MIC) between 0.29 and 5.30 µM. Thiosemicarbazone derivative (12) was able to inhibit the growth of C. tropicalis, with minimum fungicidal concentration (MFC) of 0.55 µM. In addition, this compound was active against E. coli, S. aureus and S. epidermidis, with MIC values ranging from 0.29 to 1.11 µM. Moreover, the morpholine derivative (15) had an MIC value of 0.83 µM against C. albicans and E. coli. CONCLUSION: We have efficiently synthesized a series of eleven novel triazoles, thiosemicarbazones and morpholine derivatives using 2,4-Dihydroxyacetophenone and 4-hydroxybenzaldehyde as starting materials. Thiosemicarbazone derivative (12) showed promising antifungal and antibacterial activity and these findings suggest that this compound can be used as scaffolds to design new antimicrobial drugs.

Design, synthesis, biological activity and structure-activity relationship studies of chalcone derivatives as potential anti-Candida agents.

Vulvovaginal candidiasis (VVC) affects millions of women around the world every year. Candida albicans is the most frequently isolated pathogen in women and its rapid ability to develop resistance to first and second line therapies has boosted the search for new and effective antifungal agents. In this study, we show the in vitro anti-Candida activity of fifteen synthetic chalcone analogs and their antifungal potential in an in vivo model of VVC. Chalcone 12 showed potent antifungal effects, being able to inhibit the growth of Candida spp. at a concentration of 15.6 µg mL-1. In addition, mechanism of action studies have indicated the ergosterol fungal membrane as the target of this compound. Despite a considerable antifungal activity, the chalcone 12 showed high cytotoxicity in kidney cells lineages. Moreover, this compound was able to reduce Candida-associated virulence, impairing yeast-hyphal transition in C. albicans. An in vivo model of VVC showed that chalcone 12 significantly reduces the fungal load. Taken together, these findings showed that the chalcone 12 is a potent anti-Candida agent in vitro beyond of contribute to improve the fungal infection in a model of CVV. However, it showed low selectivity and high toxicity, suggesting molecular modifications to minimize these proprieties.

Antibacterial activity of Lamiaceae plant extracts in clinical isolates of multidrug-resistant bacteria.

The antibacterial activity of plant extracts of the Lamiaceae family was evaluated against clinical isolates of multi-resistant Gram-negative bacteria by broth microdilution technique. Promising results were obtained considering that all extracts were active for at least two bacterial species with MIC ranging from 0.5 to 2.0 mg/mL.

Volatile compounds of Lamiaceae exhibit a synergistic antibacterial activity with streptomycin

Bacterial infections cause thousands of deaths in the world every year. In most cases, infections are more serious because the patient is already weakened, and often, the bacteria are already resistant to the antibiotics used. Counterparting this negative scenario, the interest in medicinal plants as an alternative to the synthetic antimicrobial drugs is blossoming worldwide. In the present work, we identified the volatile compounds of ethanol extracts of Melissa officinalis, Mentha sp., Ocimum basilicum, Plectranthus barbatus, and Rosmarinus officinalis by gas chromatography/mass spectrometry (GC/MS). Also was evaluated antimicrobial activity of ethanol extracts against 6 bacteria of clinical interest, and was tested the interaction of these extracts with a commercial antibiotic streptomycin. Phytol was a compound identified in all extracts by GC/MS, being majoritary component in Plectranthus barbatus and Rosmarinus officinalis. The Gram-positive bacteria were more sensitive to ethanol extracts, and Plectranthus barbatus and Rosmarinus officinalis were the most active extracts. Ethanol extracts exhibited a synergetic effect with streptomycin. These results encourage additional studies, in order to evaluate the possibilities of using ethanol extracts of Lamiaceae family as natural source for antibacterial activity.

Volatile compounds of Lamiaceae exhibit a synergistic antibacterial activity with streptomycin.

Bacterial infections cause thousands of deaths in the world every year. In most cases, infections are more serious because the patient is already weakened, and often, the bacteria are already resistant to the antibiotics used. Counterparting this negative scenario, the interest in medicinal plants as an alternative to the synthetic antimicrobial drugs is blossoming worldwide. In the present work, we identified the volatile compounds of ethanol extracts of Melissa officinalis, Mentha sp., Ocimum basilicum, Plectranthus barbatus, and Rosmarinus officinalis by gas chromatography/mass spectrometry (GC/MS). Also was evaluated antimicrobial activity of ethanol extracts against 6 bacteria of clinical interest, and was tested the interaction of these extracts with a commercial antibiotic streptomycin. Phytol was a compound identified in all extracts by GC/MS, being majoritary component in Plectranthus barbatus and Rosmarinus officinalis. The Gram-positive bacteria were more sensitive to ethanol extracts, and Plectranthus barbatus and Rosmarinus officinalis were the most active extracts. Ethanol extracts exhibited a synergetic effect with streptomycin. These results encourage additional studies, in order to evaluate the possibilities of using ethanol extracts of Lamiaceae family as natural source for antibacterial activity.

Passatempo virus, a vaccinia virus strain, Brazil.

Passatempo virus was isolated during a zoonotic outbreak. Biologic features and molecular characterization of hemagglutinin, thymidine kinase, and vaccinia growth factor genes suggested a vaccinia virus infection, which strengthens the idea of the reemergence and circulation of vaccinia virus in Brazil. Molecular polymorphisms indicated that Passatempo virus is a different isolate.