Letters in Drug Design & Discovery - Volume 15, Issue 3, 2018

Background: In recent years, the multi-drug resistance of bacteria and fungi strains has become a worldwide problem. The incidence of fungal and bacterial infections is experiencing a serious growth and the microorganisms have developed several new mechanisms of antibiotic resistance. Methods: Antimicrobial peptides (AMPs) constitute one of the well-known barrier defense systems of plants. They have been isolated from roots, seeds, flowers, stems and leaves of a wide variety of species and have activities towards phytopathogens, as well as against human pathogens. AMPs are often cationic peptides able to interact with the membrane through penetration or dissolving the biofilms. Results and Conclusion: In this paper, we report the synthesis of several arginine and lysine-rich peptides and their evaluation as antimicrobial agents.

Background: The marine macroalgae are very diverse group of benthonic photosynthetic organisms. These organisms are a source of a high variety of phytocompounds useful to the human kind, demonstrating several applications in the human and animal nutrition, in the pharmaceutical, cosmetic, food and biotechnological industries. Several bioactivities were reported, as antioxidant, anti-inflammatory, immune-modulatory, antiviral and antimicrobial, indicating the huge pharmacological potential of this group. Gracilaria cervicornis (Turner) J. Agardh, (Gracilariaceae) is a red macroalgae which is studied less for its pharmacological applications, mainly against multi-resistant bacteria. Objective: The objective of this work was to determine the Minimal Inhibitory Concentration (MIC) and the antibiotic-modulatory effect of the dichloromethane/methanol extract of G. cervicornis (DEMGC) against standard and multi-drug resistant clinical isolates (MDRs). Methods: The MIC of the antibiotics (aminoglycosides) were determined alone or in association with ECG by the microdilution method. The assays were performed in triplicate and the results were statistically analyzed using the geometric mean. Results: The ECG did not demonstrate a clinically relevant antibacterial effect (MIC ≥1024 μg/mL), however, when in association with gentamicin, ECG potentiated significantly the antibiotic effect against the MDR strains of Pseudomonas aeruginosa 10 and Escherichia coli 06 (p<0.001), indicating a synergism. Conclusion: These results indicated that products from G. cervicornis can be used to combat the bacterial drug multi-resistance, being a source of new drugs or formulations of antibiotics.

Background: Hyptis pectinata (Lamiaceae) is commonly known as ‘sambacaita’ and ‘canudinho’ in Brazil. In folk medicine, this plant is used to treat rhinopharyngitis, nasal congestion, certain skin diseases, gastric disorders, fever and bacterial infections. The present study aimed to study the phytoconstituents from the H. pectinata essential oil. Methods: The chemical composition of the essential oil from the leaves of H. pectinata was determined by GC-MS, the major component which was isolated and characterized by spectroscopic methods (NMR 1D/2D and IR). Thermoanalytical techniques (TG/DTG and DSC) were used to verify the thermal properties of calamusenone. Results: In GC-MS results, 25 compounds were identified. The essential oil contained mainly sesquiterpenes (92.09%), with calamusenone (62.61%). The potential of calamusenone for scavenging peroxyl radicals, quench hydroxyl radicals, and superoxide anions and reducing the formation of nitric oxide radicles indicates that this compound shows antioxidant capacity according to assay and the tested concentration. Conclusion: Together, the results conclude that the identified compounds could contribute to treat various ailments and diseases induced by oxidative stress.

Background: Metal-based antimicrobial agents have recently been identified as an alternate therapy for the treatment of infectious diseases. This investigation relates to one-pot solventfree preparation of some new transition metal complexes of omeprazole (OMP), followed by their characterization and in vitro applications as anti-Helicobacter pylori agents and urease inhibitors. Methods: The complexes were characterized by elemental analyzer, IR, Powder X-Ray diffraction, 1H-NMR,13C-NMR and mass spectrometric and thermal methods, which elucidated that the complexes have the general formula [ML] X where M 149; Zn, Ni, Cu and X149; CH3COO– and [ML] X. H2O, where M 149; Co, X149; CH3COO–. The complexes exhibited antibacterial activity against selected strains of Gram +ve and Gram –ve bacteria including Staphylococcus aureus (ATCC 29213), S. epidermidis (ATCC 12228), Escherichia coli (ATCC 12435), Proteus vulgaris (NCTC 4175), Pseudomonas aeruginosa (ATCC 49189) and fifteen local isolates and two reference strains of H. pylori. Zinc omeprazole (Zn-OMP), cobalt omeprazole (Co-OMP) and copper omeprazole (Cu- OMP), all exhibited potent and selective anti-H. pylori activity in the range of 1.0-16 μgmL-1, 8.0- 64 μgmL-1and 32-128 μgmL-1, respectively. Results: However, all of the complexes showed mild anti-bacterial activity against rest of the tested strains. Amoxicillin (break points of 1≤) was used as a reference standard. Zn-OMP was found to be equally effective against the antibiotic-resistant and antibiotic-susceptible strains of H. pylori, whereas Co-OMP and Cu-OMP exhibited mixed trends. Urease inhibition was evaluated by using the urease isolated from H. pylori reference. Zn-OMP was found to be the most potent urease inhibitor followed by Cu-OMP and then Co-OMP. Lineweaver-Burk plots were used to determine Michaelis Menten constant for elucidating the mechanism of inhibition. Conclusion: The results of the present work revealed that the devised mechano-chemical method can be explored as an environment-friendly route for the synthesis of metal based anti- H. plyori drugs.

Background: In the current study, we evaluate the possible in vitro hepatoprotective and antioxidant activity of Asphodeline lutea (L.) Rchb. dry root extract (ALE), and isolated from the same extract 2-acetyl-1,8-dimethoxy-3-methylnaphthalene (1). The potential of the main root compounds, chrysophanol (2) and caffeic acid (3), was studied as well. A model of non-enzyme lipid peroxidation (LPO) in isolated liver microsomes was induced by iron-ascorbic acid (Fe2+/AA) mixture and assessed by the quantity of malondialdehyde (MDA) – an LPO product. The incubation of the microsomes with ALE (1 mg/ml) and 1-3 (100 μg/ml) resulted in a significant decrease in MDA production, compared to the Fe2+/AA incubated samples with 23% (ALE), 61 % (1), 62% (3), while classical hepatoprotector silymarin decreased the parameter with 64 %. Methods: Studied compounds showed some toxicity in isolated rat hepatocytes discerned by increased LDH leakage and MDA quantity, decreased cell viability and reduced glutathione (GSH) levels compared to the control (non-treated hepatocytes). Results: The antioxidant and hepatoprotective potential of 1-3 was observed in vitro against carbon tetrachloride (CCl4)-induced toxicity, where they normalize all the examined parameters perturbated by CCl4 administration. The effects of 1 are lower than 3 and silymarin, but were better than those of 2. Conclusion: On the basis of these results, we discuss a bidirectional potential of the assayed parameters that might be explained with naphthalene transformation in cytochrom P450-dependent oxidation by CYP3A. The lack of metabolism and bioactivation of CCl4 could explain the cytoprotective effects of 1-3. The pro-oxidant effects of 1 and 2, in in vitro models, could be due to naphthalene and anthraquinone bioactivation pathways involving toxic metabolites.

Background: Silybum marianum (L.) Gaertn (Milk thistle) is a medicinal herb fraught with flavonolignans known as silymarin. Methods: We investigated and compared in vitro effects of commercial silibinin (mixture of two diastereomers, silybin A and silybin B) and milk thistle flavonolignans on the kinetic parameters and activities of aldehyde oxidase (AO) and xanthine oxidase (XO) of rat liver. Samples of milk thistle seeds were collected from different locations in Iran and their silymarin extract (contained silibinin flavonolignans) were extracted and quantified. Partially purified hepatic AO and XO were prepared from liver homogenates of rats. AO and XO activities were spectrophotometrically determined in the presence of silibinin (10, 50 and 100 μM) and silymarin extracts (10, 50 and 100 μg/ml) using phenanthridine and xanthine as substrates, respectively. Silymarin extract (100 μg/ml) and silibinin (100 μM) were able to inhibit the rat hepatic XO activities by 65 ± 4 and 70 ± 1%, respectively. Furthermore, the AO activity was reduced to 62 ± 1 and 70 ± 3% in the presence of silymarin extracts and silibinin, respectively. Results and Conclusion: Kinetic studies indicated that AO is inhibited by silibinin in an uncompetitive manner, whereas this flavonolignan was found as a mixed inhibitor of the XO activity. However, compared to the menadione (an AO inhibitor) and allopurinol (the XO inhibitor), silibinin and silymarin extracts had a lower inhibitory effect.

Background: In this investigation, we aimed to purify and elucidate compounds from Spatoglossum asperum J. Agardh (Dictyotaceae). Moreover, general toxicity, anti-proliferative, antibacterial and antioxidant properties of crude extracts were studied. Methods: The extract was isolated by petroleum ether (PE), dichloromethane (DCM) and methanol (MeOH) using Soxhlet. The PE and DCM extracts were subjected to vacuum liquid chromatography (VLC) and elution was done by n-hexane and ethyl acetate mixtures. Collected fractions were analyzed by gas chromatography/mass spectroscopy (GC/MS). The fraction of PE (eluted by ethyl acetate: hexane (8:92) mixture) was subjected to column chromatography (CC) using a gradient mixture of ethyl acetate and chloroform mixture and compound (1) and (2) were purified. The structures of the isolated compounds were elucidated on the basis of extensive spectroscopic analyses including UV, 1D and 2D NMR spectra. The antioxidant activity of all extracts was assessed using the DPPH method and anti-proliferative activity was evaluated by MTT assay. Brine shrimp lethality assay (BSLA) was also used to determine the general toxicity of extracts. NMR data and facts retrieved from literature showed that compound (1) and (2) were caulerpin and trioleoylglycerol, respectively. Results and Conclusion: All crude extracts showed weak cytotoxic activity against L5178Y mouse lymphoma cells compared with podophyllotoxin. Finally, GC/MS analysis showed that tocopherol (11.44%), fucosterol (11.6%) and isoaromadendrene epoxide (7.83%) were the most abundant components in PE extract and stigmas-5-3 ol (20.22%), isoaromadendrene epoxide (22.01%) and tocopherol (4%) were the major compounds in DCM extract. Conclusively, our results showed that Spatoglossum asperum is a hopeful source for the different bioactive sterols including fucosterol and tocopherol.

Background: The work describes the voltammetric determination of mercury(II), copper( II), lead(II), cadmium(II), zinc(II) by square wave anodic stripping voltammetry (SWASV) in herbal medicines. Methods: The voltammetric measurements were carried out using a conventional three electrode cell and two working electrodes, a gold electrode (GE) and a stationary hanging mercury drop electrode (HMDE). The analytical procedure was verified on the standard reference materials Spinach Leaves NIST-SRM 1570a, Tomato Leaves NIST-SRM 1573a and Apple Leaves NIST-SRM 1515. For all the elements, precision as repeatability, expressed as relative standard deviation (sr) was of the order of 4-6 %, while authenticity, expressed as relative error (e) was generally of the order of 5-8 %. Once set up on the standard reference materials, the analytical procedure was applied to commercial herbal medicine samples, and a critical comparison with spectroscopic measurements was done to evaluate the analytical performance. Results and Conclusion: Results are also processed by Principal Components Analysis (PCA), which provides very easy-to-read graphic outputs evidencing the influence of herbs prewashing on the content of risky elements. The correlation matrix is also obtained, allowing to study correlation between elements or methods.

Background: Many studies have shown the benefits deriving from plants secondary metabolites to human health also for the prevention of several diseases associated to oxidative stress including cancer, cardiovascular diseases and diabetes mellitus. Nowadays there is a high attention on plant secondary metabolites and analytical techniques related to their identification and characterization. Conclusion: This review aims to report analytical procedures, instrumental configurations, and extraction approaches devoted to secondary metabolites analyses. In this direction, an introduction to secondary metabolites is made with emphasis on their formation, biological and pharmaceutical roles. Extraction, characterization and analytical procedures are described in the second part of this review, while a comparison of the analytical techniques will be discussed in the third part. This review could provide a better understanding of the analytical procedure and techniques for secondary metabolites and their applications in the scientific and industrial areas including food, food supplements, cosmetic, and pharmaceutical, especially related to quality control analyses and to chemical fingerprint elucidation, all in order to standardize these plant-derived extracts before in vitro and in vivo studies.

Background: Neurodegenerative, neurological and mental disorders, as well as substance abuse have a worldwide high incidence rate, becoming relevant factors that contribute to premature morbidity and mortality. Dopamine is well known to be involved in these pathologies. The key focus in the search for new drugs, that alleviate or cure these diseases, is pursuing the design of compounds with both efficacy and fewer adverse effects in order to obtain novel agents capable of restoring the homeostasis in the CNS of dopaminergic neurotransmission and counteracting some of neurodegenerative and neuropsychiatric diseases, such as Parkinson's disease, schizophrenia, Huntington's chorea and drug addictions. Methods: the compounds 11,12H-dihydronaphthalene[1,2-b] quinoline 2a and 9-methoxy-11,12Hdihydronaphthalene [1,2-b] quinoline 2b were designed and synthesized. The organic synthesis was performed according to the outlined synthesis strategies, together with a pharmacological evaluation of the male Sprague-Dawley rats. Results: Compound structures were confirmed by 1H, 13C, DEPT and HETCOR NMR. Pharmacological testing and computational studies validated the asserted medicinal-chemical approach for their design, showing compound 2a acting as an atypical dopamine antagonist. Conclusion: The study showed that compound 2a has an atypical antagonistic action on the central dopaminergic system. These pharmacological and computational-theoretical results support the suitability of the medicinal chemical approach in the design of this compound.

Background: Respiratory syncytial virus (RSV) is a major cause of acute lower respiratory- tract infections (ALRI) in young children, elderly and high-risk adults and results in considerable hospitalizations. The fusions of RSV were proved to be a potent target in combating virus. Methods: A series of newly reported isoindol-5-ones derivatives as RSV fusion inhibitors was studied via in silico methodologies 3D-QSAR (CoMFA and CoMSIA) to explore compounds with better activity. Internal and external cross-validation techniques were investigated. Results: Satisfactory CoMFA model (q2=0.542, r2=0.908) and CoMSIA model (q2=0.563, r2=0.874) were obtained. The external validation indicated that CoMFA and CoMSIA models possessed high predictive powers with Q2 F2 values of 0.734 and 0.701, respectively. The contour maps shows the bulky, and hydrogen bond acceptor groups at R2 position are essential to improve the antivirus activity. The minor and hydrophobic groups such as ether bond at para-position or metaposition of substituent group R1 may increase their activities. Conclusion: The plots of CoMFA and CoMISA provided information of the structure–activity relationship and revealed the chemical features affecting the antivirus activity. These results expand our understanding of RSV fusion inhibitors and could be helpful in rationally designing of new analogs with more potent inhibitory activities.

Introduction: Stryphnodendron rotundifolium Mart. is a native specie of the “Cerrado” area of Northeast Brazil and is used in traditional communities for the treatment of inflammation, infection, gastritis and other diseases. Objective: We evaluated the gastroprotective effect of the hydroalcoholic extract of Stryphnodendron rotundifolium Mart. (HESR) in animal models of classic gastric lesions, the mechanism of action and its effect on intestinal motility. Methods: Phytochemical prospecting is a procedure by qualitative and HPLC-DAD method. The in vivo assay was evaluated by classical methods of gastric lesion and intestinal motility. Results: HESR showed a significant gastroprotective effect without altering the intestinal motility of mice. Furthermore, the effect of HESR was significantly reduced in mice pretreated with L-NAME and endogenous prostaglandins, the respective inhibitors of nitric oxide synthase and prostaglandin activation. Conclusion: The data provides evidence to show that HESR provides gastroprotection against gastric damage induced by ethanol, acidified ethanol and indomethacin. The mechanism away showed involvement of endogenous prostaglandins, nitric oxide release, the activation of TRPV1 receptor and ATP-sensitive K+ channels and significant action in the reduction of intestinal motility. This result represents a promising source of natural pharmacological therapies or treatments of gastric diseases.

Introduction: Astronium fraxinifolium (Anarcadiaceae) is used in folk medicine in inflammation diseases. This study evaluates the chemical profile as well as antioxidant, antimicrobial, gastroprotective and wound healing activities of the hydroalcoholic extract of Astronium fraxinifolium bark (HAAF). Material and Methods: Phytochemical screening and high-performance liquid chromatography (HPLC). The antioxidant activity was determined by DPPH (2,2- diphenyl, 1-picrihidrazila) and FRAP (ferric fraction reductive) methods. The gastroprotective activity was evaluated against HAAF to classical models of acute gastric: absolute ethanol, acidified ethanol and Indomethacin (50, 100 and 200mg/kg/orally) and physical barrier mechanism (50mg/kg/orally, intraperitoneally), used Swiss mice (Mus musculus). The healing activity of HAAF was identified from tissue shrinkage rate in the control. The antimicrobial activity was observed from the Minimum Inhibitory Concentration method (MIC) and modulation associated with antibiotics (amikacin, gentamicin, benzylpenicilin, imipinem + cilastatin sodium, cephalothin, oxalacina and ampicillin) and antifungals (amphotericin B, nystatin, mebendazole and benzoilmetronidazol). Results: Phytochemical prospection of Chromatography (HPLC) quantified gallic acid (4.25 %), chlorogenic acid (2.11%), caffeic acid (0.73%), rutin (0.08 %) and quercetin (0.29%). Measurement of total flavonoids (0.034 g of quercetin) and phenols (0.538 g of gallic acid) gram of extract showed significant amount. HAAF showed significant antioxidant potential in DPPH and FRAP assays. The MIC did not show clinically relevant activity (≥1024 μg/mL). HAAF displayed gastroprotective different doses (50, 100 and 200 mg/Kg) and Healing activity (100 mg/g). Conclusion: The results obtained in this study provide biological evidence of the antioxidant potential, gastroprotective and wound healing effect of the species.