Piper tectoniifolium Kunth: A New Natural Source of the Bioactive Neolignan (-)-Grandisin.

The Piper species are a recognized botanical source of a broad structural diversity of lignans and its derivatives. For the first time, Piper tectoniifolium Kunth is presented as a promising natural source of the bioactive (-)-grandisin. Phytochemical analyses of extracts from its leaves, branches and inflorescences showed the presence of the target compound in large amounts, with leaf extracts found to contain up to 52.78% in its composition. A new HPLC-DAD-UV method was developed and validated to be selective for the identification of (-)-grandisin being sensitive, linear, precise, exact, robust and with a recovery above 90%. The absolute configuration of the molecule was determined by X-ray diffraction. Despite the identification of several enantiomers in plant extracts, the major isolated substance was characterized to be the (-)-grandisin enantiomer. In vascular reactivity tests, it was shown that the grandisin purified from botanical extracts presented an endothelium-dependent vasorelaxant effect with an IC50 of 9.8 ± 1.22 µM and around 80% relaxation at 30 µM. These results suggest that P. tectoniifolium has the potential to serve as a renewable source of grandisin on a large scale and the potential to serve as template for development of new drugs for vascular diseases with emphasis on disorders related to endothelial disfunction.

Structure⁻Activity Relationship of Piplartine and Synthetic Analogues against Schistosoma mansoni and Cytotoxicity to Mammalian Cells.

Schistosomiasis, caused by helminth flatworms of the genus Schistosoma, is an infectious disease mainly associated with poverty that affects millions of people worldwide. Since treatment for this disease relies only on the use of praziquantel, there is an urgent need to identify new antischistosomal drugs. Piplartine is an amide alkaloid found in several Piper species (Piperaceae) that exhibits antischistosomal properties. The aim of this study was to evaluate the structure­function relationship between piplartine and its five synthetic analogues (19A, 1G, 1M, 14B and 6B) against Schistosoma mansoni adult worms, as well as its cytotoxicity to mammalian cells using murine fibroblast (NIH-3T3) and BALB/cN macrophage (J774A.1) cell lines. In addition, density functional theory calculations and in silico analysis were used to predict physicochemical and toxicity parameters. Bioassays revealed that piplartine is active against S. mansoni at low concentrations (5⁻10 µM), but its analogues did not. In contrast, based on 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and flow cytometry assays, piplartine exhibited toxicity in mammalian cells at 785 µM, while its analogues 19A and 6B did not reduce cell viability at the same concentrations. This study demonstrated that piplartine analogues showed less activity against S. mansoni but presented lower toxicity than piplartine.

Anthelmintic, Antibacterial and Cytotoxicity Activity of Imidazole Alkaloids from Pilocarpus microphyllus Leaves.

Pilocarpus microphyllus Stapf ex Wardlew (Rutaceae), popularly known as jaborandi, is a plant native to the northern and northeastern macroregions of Brazil. Several alkaloids from this species have been isolated. There are few reports of antibacterial and anthelmintic activities for these compounds. In this work, we report the antibacterial and anthelmintic activity of five alkaloids found in P. microphyllus leaves, namely, pilosine, epiisopilosine, isopilosine, epiisopiloturine and macaubine. Of these, only anthelmintic activity of one of the compounds has been previously reported. Nuclear magnetic resonance, HPLC and mass spectrometry were combined and used to identify and confirm the structure of the five compounds. As regards the anthelmintic activity, the alkaloids were studied using in vitro assays to evaluate survival time and damaged teguments for Schistosoma mansoni adult worms. We found epiisopilosine to have anthelmintic activity at very low concentrations (3.125 µg mL-1 ); at this concentration, it prevented mating, oviposition, reducing motor activity and altered the tegument of these worms. In contrast, none of the alkaloids showed antibacterial activity. Additionally, alkaloids displayed no cytotoxic effect on vero cells. The potent anthelmintic activity of epiisopilosine indicates the potential of this natural compound as an antiparasitic agent. Copyright © 2017 John Wiley & Sons, Ltd.

Collagen-based silver nanoparticles for biological applications: synthesis and characterization.

BACKGROUND: Type I collagen is an abundant natural polymer with several applications in medicine as matrix to regenerate tissues. Silver nanoparticles is an important nanotechnology material with many utilities in some areas such as medicine, biology and chemistry. The present study focused on the synthesis of silver nanoparticles (AgNPs) stabilized with type I collagen (AgNPcol) to build a nanomaterial with biological utility. Three formulations of AgNPcol were physicochemical characterized, antibacterial activity in vitro and cell viability assays were analyzed. AgNPcol was characterized by means of the following: ultraviolet-visible spectroscopy, dynamic light scattering analysis, Fourier transform infrared spectroscopy, atomic absorption analysis, transmission electron microscopy and of X-ray diffraction analysis. RESULTS: All AgNPcol showed spherical and positive zeta potential. The AgNPcol at a molar ratio of 1:6 showed better characteristics, smaller hydrodynamic diameter (64.34 ± 16.05) and polydispersity index (0.40 ± 0.05), and higher absorbance and silver reduction efficiency (0.645 mM), when compared with the particles prepared in other mixing ratios. Furthermore, these particles showed antimicrobial activity against both Staphylococcus aureus and Escherichia coli and no toxicity to the cells at the examined concentrations. CONCLUSIONS: The resulted particles exhibited favorable characteristics, including the spherical shape, diameter between 64.34 nm and 81.76 nm, positive zeta potential, antibacterial activity, and non-toxicity to the tested cells (OSCC).

Structure-based identification of novel PPAR gamma ligands.

Peroxisome proliferator-activated receptor γ (PPARγ) is a nuclear receptor with an important role in the glucose metabolism and a target for type 2 diabetes mellitus therapy. The recent findings relating the use of the receptor full agonist rosiglitazone and the incidence of myocardial infarction raised concerns regarding whether receptor activation can actually be useful for diabetes management. The discovery of MRL-24 and GQ-16, ligands that can partially activate PPARγ and prevent weight gain and fluid retention, showed that a submaximal receptor activation can be a goal in the development of new ligands for PPARγ. Additionally, two previously described receptor antagonists, SR-202 and BADGE, were also shown to improve insulin sensitivity and decrease TNF-α level, revealing that receptor antagonism may also be an approach to pursue. Here, we used a structure-based approach to screen the subset 'Drugs-Now' of ZINC database. Fifteen ligands were selected after visual inspection and tested for their ability to bind to PPARγ. A benzoimidazol acetate, a bromobenzyl-thio-tetrazol benzoate and a [[2-[(1,3-dioxoinden-2-ylidene)methyl]phenoxy]methyl]benzoate were identified as PPARγ ligands, with IC50 values smaller than 10µM. Molecular dynamic simulations showed that the residues H323, H449, Y327, Y473, K367 and S289 are key structural elements for the molecular recognition of these ligands and the polar arm of PPARγ binding pocket.

2-({1-[2-(Methyl-sulfan-yl)phen-yl]-1H-tetra-zol-5-yl}sulfan-yl)acetic acid.

In the title compound, C10H10N4O2S2, the tetra-zole and benzene rings are almost normal to one another, with a dihedral angle between their planes of 84.33 (9)°. In the crystal, mol-ecules are linked via pairs of bifurcated O-H⋯(N,N) hydrogen bonds, forming inversion dimers with graph-set motif R 4 (4)(12). The dimers are linked by significant π-π inter-actions involving inversion-related tetra-zole rings and inversion-related benzene rings, with centroid-centroid distances of 3.7376 (14) and 3.8444 (15) Å, respectively.

4-{5-[(2-Bromo-benz-yl)sulfan-yl]-1H-tetra-zol-1-yl}benzoic acid.

In the title compound, C15H11BrN4O2S, the tetra-zole ring makes dihedral angles of 45.97 (10) and 75.41 (1)°, respectively, with the benzoyl and bromo-benzene rings while the dihedral angle between the benzene rings is 73.77 (1)°. In the crystal, mol-ecules are linked through O-H⋯ N and C-H⋯ O hydrogen bonds, giving infinite chains in both the [110] and [1-10] directions. These chains are further connected by C-Br⋯π and C-O⋯π inter-actions and also by π-π stacking between tetra-zole rings [centroid-centroid distance = 3.312 (1) Å], generating a three-dimensional network.

µ-Azido-κ(2) N (1):N (1)-µ-chlorido-bis-[(2-chloro-3-dimethyl-amino-1-phenyl-prop-1-en-1-yl-κ(2) C (1),N)palladium(II)] chloro-form monosolvate.

In the binuclear title complex, [Pd2(C11H13ClN)2Cl(N3)]·CHCl3, each Pd(II) atom has a slightly distorted square-planar geometry being coordinated by a C and an N atom of the 2-chloro-3-dimethyl-amino-1-phenyl-propyl ligand, a bridging Cl atom and an N atom of a bridging end-on azide group. There is a short intra-molecular C-H⋯Cl contact in the complex mol-ecule. In the crystal, the chloro-form solvent mol-ecule is linked to the complex via a C-H⋯π inter-action.

(Benzyl isocyanide-κC (1))chlorido(2-chloro-3-dimethyl-amino-1-phenyl-prop-1-en-1-yl-κ(2) C (1),N)palladium(II).

In the title compound, [Pd(C11H13ClN)Cl(C8H7N)], which crystallized in the chiral space group P212121, the Pd(II) atom is coordinated by two C atoms, a Csp(2) atom of the 2-chloro-3-dimethyl-amino-1-phenyl-prop-1-en-1-yl ligand and a Csp atom from the benzyl isocyanide ligand, as well as an N atom of the ligand and a Cl atom, in a square-planar geometry. In the complex, there is a short C-H⋯Cl hydrogen bond and a C-H⋯π inter-action. In the crystal, mol-ecules are linked via C-H⋯Cl hydrogen bonds, forming chains along the a-axis direction.

Potassium morpholine-4-carbodithio-ate monohydrate.

In the ionic title compound, K(+)·C(5)H(8)NOS(2) (-)·H(2)O, the morpholine ring of the morpholine-4-carbodithio-ate anion has a chair conformation. The potassium cation is coordinated by four S and four O atoms in a bipyramidal reversed geometry. In the crystal, the three components are linked, generating infinite two-dimensional networks that lie parallel to the bc plane. These layers are linked via O-H⋯S hydrogen bonds, forming a three-dimensional structure.

Sodium piperidine-1-carbodithio-ate dihydrate.

The asymmetric unit of the title compound, Na(+)·C(6)H(10)NS(2) (-)·2H(2)O, is composed of a sodium cation, a piperidine-dithio-carbamate anion which exhibits positional disorder, and two lattice water mol-ecules. The atoms of the piperidine ring are divided over two sites with occupancy factors of 0.554 (6) and 0.446 (6). In the crystal, the sodium cation (coordination number of 6) and the piperidine-dithio-carbamate anion are linked, forming an infinite two-dimensional network extending parallel to (001). O-H⋯S hydrogen bonds, involving the lattice water mol-ecules, also aid in stabilizing the crystal sructure.

Ammonium piperidine-1-carbodithio-ate.

The title compound, NH(4) (+)·C(6)H(10)NS(2) (-), is composed of an ammonium cation and a piperidine-1-carbodithio-ate anion which exhibits positional disorder. The atoms of the ring have a structural disorder and they are divided into two sites, with occupancy factors of 0.584 and 0.426.. In the crystal, the cation and anion are linked by N-H⋯S hydrogen bonds to form an infinite two-dimensional network.

Morpholin-4-ium morpholine-4-carbo-dithio-ate.

The title compound, C(4)H(10)NO(+)·C(5)H(8)NOS(2) (-), is built up of a morpholinium cation and a dithio-carbamate anion. In the crystal, two structurally independent formula units are linked via N-H⋯S hydrogen bonds, forming an inversion dimer, with graph-set motif R(4) (4)(12).

Tetrazoles as PPARγ ligands: A structural and computational investigation.

Diabetes is an important chronic disease affecting about 10% of the adult population in the US and over 420 million people worldwide, resulting in 1.6 million deaths every year, according to the World Health Organization. The most common type of the disease, type 2 diabetes, can be pharmacologically managed using oral hypoglycemic agents or thiazolidinediones (TZDs), such as pioglitazone, which act by activating the Peroxisome Proliferated-Activated Receptor γ. Despite their beneficial effects in diabetes treatment, TZDs like rosiglitazone and troglitazone were withdrawn due to safety reasons, creating a void in the pharmacological options for the treatment of this important disease. Here, we explored a structure-based approach in the screening for new chemical probes for a deeper investigation of the effects of PPARγ activation. A class of tetrazole compounds was identified and the compounds named T1, T2 and T3 were purchased and evaluated for their ability to interact with the PPARγ ligand binding domain (LBD). The compounds were binders with micromolar range affinity, as determined by their IC50 values. A Monte Carlo simulation of the compound T2 revealed that the tetrazole ring makes favorable interaction with the polar arm of the receptor binding pocket. Finally, the crystal structure of the PPARγ-LBD-T2 complex was solved at 2.3 Å, confirming the binding mode for this compound. The structure also revealed that, when the helix H12 is mispositioned, an alternative binding conformation is observed for the ligand suggesting an H12-dependent binding conformation for the tetrazole compound.

Synthesis, characterization and use of enzyme cashew gum nanoparticles for biosensing applications.

This research reports, for the first time, the immobilization of an enzyme - Rhus vernificera laccase - on cashew gum (CG) nanoparticles (NPs) and its application as a biological layer in the design and development of an electrochemical biosensor. Laccase-CG nanoparticles (LacCG-NPs) were prepared by the nanoprecipitation method and characterized by UV-Vis spectrophotometry, atomic force microscopy, scanning electron microscopy, attenuated total reflectance-Fourier-transform infrared spectroscopy, circular dichroism, cyclic voltammetry, and electrochemical impedance spectroscopy. The average size and stability of the NPs were predicted by DLS and zeta potential. The ATR-FTIR results clearly demonstrated an interaction between -NH and -OH groups to form LacCG-NPs. The average size found for LacCG-NPs was 280 ± 53 nm and a polydispersity index of 0.309 ± 0.08 indicated a good particle size distribution. The zeta potential shows a good colloidal stability. The use of a natural product to prepare the enzymatic nanoparticles, its easy synthesis and the immobilization efficiency should be highlighted. LacCG-NPs were successfully applied as a biolayer in the development of an amperometric biosensor for catechol detection. The resulting device showed a low response time (6 s), good sensitivity (7.86 µA µM-1 cm-2), wide linear range of 2.5 × 10-7-2.0 × 10-4 M, and low detection limit (50 nM).

Antibacterial application of natural and carboxymethylated cashew gum-based silver nanoparticles produced by microwave-assisted synthesis.

This study presents a green synthesis route to silver nanoparticles (AgNPs) stabilized with cashew gum (CG) or carboxymethylated cashew gum (CCG) using microwave-assisted synthesis and evaluates their antibacterial activity. The antimicrobial activity was measured by determining the minimum inhibitory concentration (MIC) with Staphylococcus aureus and Escherichia coli. In both cases of the presence of CG and CCG, it was found that higher pH lead to more efficient conversion of silver nitrate to AgNPs with well dispersed, spherical and stable particles as well as low crystallinity. CCG-capped AgNPs were slightly smaller (137.0 and 96.3 nm) than those coated with non-modified gum (144.7 and 100.9 nm). The samples presented promising antibacterial activity, especially on Gram-negative bacteria, resulting in significant membrane damage on treated bacteria in comparison to the untreated control, observed by atomic force microscopy. Thus, a quick and efficient synthesis route was applied to produce CGAgNPs and CCGAgNPs with antimicrobial potential.

Silver nanoparticle stabilized by hydrolyzed collagen and natural polymers: Synthesis, characterization and antibacterial-antifungal evaluation.

In synthesis of silver nanoparticles (AgNPs), the composition of the stabilizer used can be closely related to the effectiveness of the synthesis and to the shape of the final nanoparticles. Recently, the use of collagen as an effective nanoparticle stabilization agent was reported. In this work, synthesis of silver nanoparticles using mixed capping agents is reported. The capping agents used were cashew gum-hydrolyzed collagen; kappa carrageenan-hydrolyzed collagen, and agar-hydrolyzed collagen. We evaluated antibacterial action against Gram-positive and Gram-negative bacteria, as well as antifungal activity and cytotoxicity. Homogenized mixtures of collagen and aqueous cashew gum, carrageenan or agar respectively were used to produce the nanoparticles AgNPcolCashew, AgNPcolCarr and AgNPcolAgar. AgNP characterization was performed using Uv-vis, XRD, TEM and DLS and the biological activities were assayed using MIC and MBC analyses for both antibacterial and antifungal application. Results showed that the AgNPcollcar sample showed the strongest bacterial inhibition with MIC values of 62.5 and 31.25 µM/mL Ag against E. coli and P. aeruginosa respectively. Interestingly, AgNPcollAgar also presented the lowest cytotoxicity when compared with other AgNPs and AgNO3.

Structure and function of a novel antioxidant peptide from the skin of tropical frogs.

The amphibian skin plays an important role protecting the organism from external harmful factors such as microorganisms or UV radiation. Based on biorational strategies, many studies have investigated the cutaneous secretion of anurans as a source of bioactive molecules. By a peptidomic approach, a novel antioxidant peptide (AOP) with in vitro free radical scavenging ability was isolated from Physalaemus nattereri. The AOP, named antioxidin-I, has a molecular weight [M+H]+ = 1543.69Da and a TWYFITPYIPDK primary amino acid sequence. The gene encoding the antioxidin-I precursor was expressed in the skin tissue of three other Tropical frog species: Phyllomedusa tarsius, P. distincta and Pithecopus rohdei. cDNA sequencing revealed highly homologous regions (signal peptide and acidic region). Mature antioxidin-I has a novel primary sequence with low similarity compared with previously described amphibian's AOPs. Antioxidin-I adopts a random structure even at high concentrations of hydrophobic solvent, it has poor antimicrobial activity and poor performance in free radical scavenging assays in vitro, with the exception of the ORAC assay. However, antioxidin-I presented a low cytotoxicity and suppressed menadione-induced redox imbalance when tested with fibroblast in culture. In addition, it had the capacity to substantially attenuate the hypoxia-induced production of reactive oxygen species when tested in hypoxia exposed living microglial cells, suggesting a potential neuroprotective role for this peptide.

Antiparasitic, structural, pharmacokinetic, and toxicological properties of riparin derivatives.

Schistosomiasis, caused by helminth flatworms of the genus Schistosoma, is one of the most important parasitic diseases in the world, affecting over 200 million people in developing countries. Riparins are natural alkamides found in Aniba riparia (Lauraceae) fruits that possess several pharmacological properties. In this study, we reported the synthesis, characterization and structural analysis of six riparin derivatives (A-F), as well as their schistosomicidal activity against S. mansoni worms together with a biological, pharmacokinetic and toxicological in silico evaluation. Firstly, these compounds were synthesized, purified and characterized by elemental analysis, FT-IR spectroscopy, X-ray diffraction and theoretical calculations to evaluate their stability and conformation. Next, the schistosomicidal activity of the riparins was tested against S. mansoni worms. Bioassays revealed that Riparins E and F were the most active compounds, showing half-maximum inhibitory concentration at low micromolar ranges (IC50 values ~10 µM). Also, confocal laser scanning microscopy studies revealed tegumental damage in parasites after exposition with Riparins B, E and F. Additionally, based on MTT assay, all tested riparins showed no cytotoxic potential toward mammalian cells. Finally, in silico analyses were used to predict the absorption, distribution, metabolism, elimination and toxicity (ADMET) of the compounds. Taken together, the results revealed a promising ADMET profile and suggested that riparins could be starting points for lead optimization programs for natural products with antischistosomal properties.

Self-nanoemulsifying drug-delivery systems improve oral absorption and antischistosomal activity of epiisopiloturine.

AIM: To develop a self-nanoemulsifying drug-delivery system (SNEDDS) able to improve oral absorption of epiisopiloturine (EPI), and test the antischistosomal activity in a mice model. RESULTS: SNEDDS had a nanoscopic size and was able to enhance EPI bioavailability after oral administration, and SNEDDS-EPI (40 mg.kg-1) improved the in vivo antischistosomal activity of EPI, demonstrating that SNEDDS was able to improve the pharmacokinetics of EPI, and to maintain the pharmacodynamic activity against Schistosoma mansoni in vivo. CONCLUSION: Taken together, these results indicate that SNEDDS-EPI is efficient in reducing worm burden in comparison to treatment with the free version of EPI. [Formula: see text].