Antimicrobial properties of two novel peptides derived from Theobroma cacao osmotin

The osmotin proteins of several plants display antifungal activity, which can play an important role in plant defense against diseases. Thus, this protein can be useful as a source for biotechnological strategies aiming to combat fungal diseases. In this work, we analyzed the antifungal activity of a cacao osmotin-like protein (TcOsm1) and of two osmotin-derived synthetic peptides with antimicrobial features, differing by five amino acids residues at the N-terminus. Antimicrobial tests showed that TcOsm1 expressed in Escherichia coli inhibits the growth of Moniliophthora perniciosa mycelium and Pichia pastoris X-33 in vitro. The TcOsm1-derived peptides, named Osm-pepA (H-RRLDRGGVWNLNVNPGTTGARVWARTK-NH₂), located at R23-K49, and Osm-pepB (H-GGVWNLNVNPGTTGARVWARTK-NH₂), located at G28-K49, inhibited growth of yeasts (Saccharomyces cerevisiae S288C and Pichia pastoris X-33) and spore germination of the phytopathogenic fungi Fusarium f. sp. glycines and Colletotrichum gossypi. Osm-pepA was more efficient than Osm-pepB for S. cerevisiae (MIC = 40 μM and MIC = 127 μM, respectively), as well as for P. pastoris (MIC = 20 μM and MIC = 127 μM, respectively). Furthermore, the peptides presented a biphasic performance, promoting S. cerevisiae growth in doses around 5 μM and inhibiting it at higher doses. The structural model for these peptides showed that the five amino acids residues, RRLDR at Osm-pepA N-terminus, significantly affect the tertiary structure, indicating that this structure is important for the peptide antimicrobial potency. This is the first report of development of antimicrobial peptides from T. cacao. Taken together, the results indicate that the cacao osmotin and its derived peptides, herein studied, are good candidates for developing biotechnological tools aiming to control phytopathogenic fungi.     

A novel cysteine-rich antimicrobial peptide from the mucus of the snail of Achatina fulica

Antimicrobial peptides (AMPs) are important components of the innate immunity. Many antimicrobial peptides have been found from marine mollusks. Little information about AMPs of mollusks living on land is available. A novel cysteine-rich antimicrobial peptide (mytimacin-AF) belonging to the peptide family of mytimacins was purified and characterized from the mucus of the snail of Achatina fulica. Its cDNA was also cloned from the cDNA library. Mytimacin-AF is composed of 80 amino acid residues including 10 cysteines. Mytimacin-AF showed potent antimicrobial activity against Gram-negative and Gram-positive bacteria and the fungus Candida albicans. Among tested microorganisms, it exerted strongest antimicrobial activity against Staphylococcus aureus with a minimal peptide concentration (MIC) of 1.9 μg/ml. Mytimacin-AF had little hemolytic activity against human blood red cells. The current work confirmed the presence of mytimacin-like antimicrobial peptide in land-living mollusks.     

Synthesis,biological evaluation and molecular modeling of 1,3,4-thiadiazol-2-amide derivatives as novel antitubulin agents

A series of 1,3,4-thiadiazol-2-amide derivatives (6a–w) were designed and synthesized as potential inhibitors of tubulin polymerization and as anticancer agents. The in vitro anticancer activities of these compounds were evaluated against three cancer cell lines by the MTT method. Among all the designed compounds, compound 6f exhibited the most potent anticancer activity against A549, MCF-7 and HepG2 cancer cell lines with IC₅₀ values of 0.03 μM, 0.06 μM and 0.05 μM, respectively. Compound 6f also exhibited significant tubulin polymerization inhibitory activity (IC₅₀ = 1.73 μM), which was superior to the positive control. The obtained results, along with a 3D-QSAR study and molecular docking that were used for investigating the probable binding mode, could provide an important basis for further optimization of compound 6f as a novel anticancer agent.     

A family of antimicrobial and immunomodulatory peptides related to the frenatins from skin secretions of the Orinoco lime frog Sphaenorhynchus lacteus (Hylidae)

Peptidomic analysis of norepinephrine-stimulated skin secretions of the Orinoco lime tree frog Sphaenorhynchus lacteus (Hylidae, Hylinae) revealed the presence of three structurally related host-defense peptides with limited sequence similarity to frenatin 2 from Litoria infrafrenata (Hylidae, Pelodryadinae) and frenatin 2D from Discoglossus sardus (Alytidae). Frenatin 2.1S (GLVGTLLGHIGKAILG.NH₂) and frenatin 2.2S (GLVGTLLGHIGKAILS.NH₂) are C-terminally α-amidated but frenatin 2.3S (GLVGTLLGHIGKAILG) is not. Frenatin 2.1S and 2.2S show potent bactericidal activity against clinical isolates of methicillin-resistant Staphylococcus aureus (MRSA) and Staphylococcus epidermidis (MIC ≤16 μM) but are less active against a range of Gram-negative bacteria. Frenatin 2.1S (LC₅₀ = 80 ± 6 μM) and 2.2S (LC₅₀ = 75 ± 5 μM) are cytotoxic against non-small cell lung adenocarcinoma A549 cells but are less hemolytic against human erythrocytes (LC₅₀ = 167 ± 8 μM for frenatin 2.1S and 169 ± 7 μM for 2.2S). Weak antimicrobial and cytotoxic potencies of frenatin 2.3S demonstrate the importance of C-terminal α-amidation for activity. Frenatin 2.1S and 2.2S significantly (P < 0.05) increased production of proinflammatory cytokines IL-1β and IL-23 by lipopolysaccharide (LPS)-stimulated mouse peritoneal macrophages and frenatin 2.1S also enhanced production of TNF-α. Effects on IL-6 production were not significant. Frenatin 2.2S significantly downregulated production of the anti-inflammatory cytokine IL-10 by LPS-stimulated cells. The data support speculation that frenatins act on skin macrophages to produce a cytokine-mediated stimulation of the adaptive immune system in response to invasion by microorganisms. They may represent a template for the design of peptides with therapeutic applications as immunostimulatory agents.     

Derivatives (halogen,nitro and amino) of 8-hydroxyquinoline with highly potent antimicrobial and antioxidant activities

8-Hydroxyquinoline (8HQ) compounds have been reported to possess diverse bioactivities. In recent years, drug repositioning has gained considerable attention in drug discovery and development. Herein, 8HQ (1) and its derivatives (2–9) bearing various substituents (amino, nitro, cyano and halogen) were investigated for their antimicrobial against 27 microorganisms (agar dilution method) and antioxidant (DPPH method) activities. The parent 8HQ (1) exerted a highly potent antimicrobial activity against Gram-positive bacteria including diploid fungi and yeast with MIC values in the range of 3.44–13.78 μM. Moreover, the halogenated 8HQ, especially 7-bromo-8HQ (4) and clioquinol (6), displayed a high antigrowth activity against Gram-negative bacteria compared with the parent compound (1). Apparently, the derivatives with a relatively high safely index, e.g., nitroxoline (2), exhibited strong antibacterial activity against Aeromonas hydrophila (MIC=5.26 μM) and selectively inhibited the growth of P. aeruginosa with the MIC value of 84.14 μM; cloxyquin (3) showed a strong activity against Listseria monocytogenes and Plesiomonas shigelloides with MIC values of 5.57 and 11.14 μM, respectively. Most compounds displayed an antioxidant activity. Specifically, 5-amino-8HQ (8) was shown to be the most potent antioxidant (IC₅₀=8.70 μM) compared with the positive control (α-tocopherol) with IC₅₀ of 13.47 μM. The findings reveal that 8HQ derivatives are potential candidates to be further developed as antimicrobial and antioxidant agents.     

Flavonoids and other bioactive constituents from Ficus thonningii Blume (Moraceae)

Continued interest in the chemistry of Ficus spp. led to the investigation of the figs and the roots of Ficus thonningii Blume. Two new flavonoids, thonningiol (1) and thonningiisoflavone (2) along with nineteen known compounds were isolated. β-Isoluteone (13) was isolated here for the first time from a natural source. Their structures were elucidated on the basis of spectroscopic evidence. Interestingly, thonningiisoflavone (2) and hydroxyalpinumisoflavone (21) showed strong DPPH radical scavenging activity with IC₅₀ = 65.50 μM and 68.20 μM respectively compared to the standard BHA with IC₅₀ = 44.20 μM. The methanolic extract of figs, taxifolin (14), conrauiflavonol (17) and shuterin (19) exhibited moderate antimicrobial activity against six micro-organisms with MIC below 1.5 mg/mL.     

Synthesis and biological activity of new salicylanilide N,N-disubstituted carbamates and thiocarbamates

The development of novel antimicrobial drugs represents a cutting edge research topic. In this study, 20 salicylanilide N,N-disubstituted carbamates and thiocarbamates were designed, synthesised and characterised by IR, ¹H NMR and ¹³C NMR. The compounds were evaluated in vitro as potential antimicrobial agents against Mycobacterium tuberculosis and nontuberculous mycobacteria (Mycobacterium avium and Mycobacterium kansasii) as well as against eight bacterial and fungal strains. Additionally, we investigated the inhibitory effect of these compounds on mycobacterial isocitrate lyase and cellular toxicity. The minimum inhibitory concentrations (MICs) against mycobacteria were from 4 μM for thiocarbamates and from 16 μM for carbamates. Gram-positive bacteria, including methicillin-resistant Staphylococcus aureus, were inhibited with MICs from 0.49 μM by thiocarbamates, whilst Gram-negative bacteria and most of the fungi did not display any significant susceptibility. All (thio)carbamates mildly inhibited isocitrate lyase (up to 22%) at a concentration of 10 μM. The (thio)carbamoylation of the parent salicylanilides led to considerably decreased cytotoxicity and thus improved the selectivity indices (up to 175). These values indicate that some derivatives are attractive candidates for future research.     

Design,expression and characterization of the hybrid antimicrobial peptide LHP7, connected by a flexible linker,against Staphylococcus and Streptococcus

The emergence of bacterial resistance to common antibiotics poses a threat to human health and has rekindled an interest in antimicrobial peptides (AMPs). LHP7, a novel hybrid AMP containing 83 amino acid residues was designed on the basis of the LH28 and plectasin. LHP7 was expressed in Pichia pastoris, the total concentration of secreted protein reached 0.906 g/L after 108 h of methanol induction. Its antimicrobial activity was higher than that of the parent AMPs; the minimal inhibitory concentrations (MICs) of LHP7 against Staphylococcus aureus, Streptococcus pneumoniae and Streptococcus suis were 0.091, 0.023 and 0.18 μM, respectively. The antibacterial activity of LHP7 against clinical MRSA isolates (MICs = 0.73–2.91 μM) was enhanced over that of plectasin. The fractional inhibitory concentration (FIC) indicated a synergistic effect between LHP7 and ampicillin against MRSA (FIC = 0.375), and combinations of LHP7 with gentamicin, rifampin or tetracycline provided evidence of additive effects (FIC = 0.625–1.0). LHP7 exhibited a broad range of pH stability and thermostability, and a hemolytic activity of less than 5% below a concentration of 500 μg/mL. It was resistant to pepsin and papain digestion, but sensitive to trypsin digestion. These results suggest that LHP7 might have potential as a broadly applied and clinically useful antimicrobial agent.     

Synthesis and in vitro antitumor evaluation of primary amine substituted quinazoline linked benzimidazole

By combining the structural features of quinazoline and benzimidazole, new hybrid regioisomeric molecules with substituted primary amines have been synthesized. Evaluation of these molecules over 60 cancer cell line panel has identified three molecules as most potent anticancer agents. Compound 10 showed ten and eleven folds more activity than respective quinazoline and benzimidazole class of compounds with GI₅₀ value of 1.64 μM. Compound 11 (GI₅₀ value of 0.81 μM) showed almost twenty and twenty-two fold more activity than quinazoline and benzimidazole analogue, respectively while compound 12 (GI₅₀ value of 4.52 μM) has four fold more activity than quinazoline and benzimidazole analogue. In vitro evaluation of compound 11 exhibited remarkable anticancer activity towards colon cancer cell lines and prostate cancer cell lines at five dose concentrations with GI₅₀ values of 0.34 and 0.31 μM, respectively.     

Endotoxin-neutralizing activity and mechanism of action of a cationic α-helical antimicrobial octadecapeptide derived from α-amylase of rice

We have previously reported that AmyI-1-18, an octadecapeptide derived from α-amylase (AmyI-1) of rice, is a novel cationic α-helical peptide that exhibited antimicrobial activity against human pathogens, including Porphyromonas gingivalis, Pseudomonas aeruginosa, Propionibacterium acnes, Streptococcus mutans, and Candida albicans. In this study, to further investigate the potential functions of AmyI-1-18, we examined its inhibitory ability against the endotoxic activities of lipopolysaccharides (LPSs, smooth and Rc types) and lipid A from Escherichia coli. AmyI-1-18 inhibited the production of endotoxin-induced nitric oxide (NO), an inflammatory mediator, in mouse macrophages (RAW264) in a concentration-dependent manner. The results of a chromogenic Limulus amebocyte lysate assay illustrated that the ability [50% effective concentration (EC₅₀): 0.17 μM] of AmyI-1-18 to neutralize lipid A was similar to its ability (EC₅₀: 0.26 μM) to neutralize LPS, suggesting that AmyI-1-18 specifically binds to the lipid A moiety of LPS. Surface plasmon resonance analysis of the interaction between AmyI-1-18 and LPS or lipid A also suggested that AmyI-1-18 directly binds to the lipid A moiety of LPS because the dissociation constant (K_D) of AmyI-1-18 with lipid A is 5.6 × 10⁻¹⁰ M, which is similar to that (4.3 × 10⁻¹⁰ M) of AmyI-1-18 with LPS. In addition, AmyI-1-18 could block the binding of LPS-binding protein to LPS, although its ability was less than that of polymyxin B. These results suggest that AmyI-1-18 expressing antimicrobial and endotoxin-neutralizing activities is useful as a safe and potent host defense peptide against pathogenic Gram-negative bacteria in many fields of healthcare.     

Antibacterial and anticancer activity of a series of novel peptides incorporating cyclic tetra-substituted Cα amino acids

Eleven antimicrobial peptides (AMP) based on the incorporation of cyclic tetra substituted C^α amino acids, as well as other unnatural amino acids were designed, synthesized and screened for in vitro activity against 18 strains of bacteria as well as 12 cancer cell lines. The AMPs discussed herein are derived from the following peptide sequence: Ac-GF(X)G(X)B(X)G(X)F(X)G(X)GB(X)BBBB-amide, X = any one of the following residues, A5c, A6c, Tic or Oic and B = any one of the following residues, Arg, Lys, Orn, Dpr or Dab. A diversity of in vitro inhibitory activity was observed for these AMPs. Several analogs exhibited single digit μM activity against drug resistant bacteria including; multiple drug resistant Mycobacterium tuberculosis, extremely drug resistant Mycobacterium tuberculosis and MRSA. The physicochemical properties of the basic amino acid residues incorporated into these AMPs seem to play a major role in defining antibacterial activity. Overall hydrophobicity seems to play a limited role in defining antibacterial activity. The ESKAPE pathogens were used to compare the activity of these AMPs to another family of synthetic AMPs incorporating the unnatural amino acids Tic and Oic. In most cases similarly substituted members of both families exhibited similar inhibitory activity against the ESKAPE pathogens. In specific cases differences in activity as high as 15 fold were observed between analogs. In addition four of these AMPs exhibited promising IC₅₀ (<7.5 μM) values against 12 different and diverse cancer cell lines. Five other AMPs exhibited promising IC₅₀ (<7.5 μM) values against selected cancer cell lines.     

Piscidin 4, a novel member of the piscidin family of antimicrobial peptides

Piscidins are linear, amphipathic, antimicrobial peptides (AMPs) with broad, potent, activity spectrum. Piscidins and other members of the piscidin family appear to comprise the most common group of AMPs in teleost fish. All piscidins and related members of the piscidin family described to date are 18–26 amino acids long. We report here the isolation of a novel 5329.25 Da, 44-residue (FFRHLFRGAKAIFRGARQGXRAHKVVSRYRNRDVPETDNNQEEP) antimicrobial peptide from hybrid striped bass (Morone chrysops female x M. saxatilis male). We have named this peptide “piscidin 4” since it has considerable (to > 65%) N-terminal sequence homology to piscidins 1–3 and this distinctive, 10 to 11-residue, N-terminus is characteristic of piscidins. The native peptide has a modified amino acid at position 20 that, based upon mass spectrometry data, is probably a hydroxylated tryptophan. Synthetic piscidin 4 (with an unmodified tryptophan at position 20) has similar antibacterial activity to that of the native peptide. Piscidin 4 demonstrates potent, broad-spectrum, antibacterial activity against a number of fish and human pathogens, including multi-drug resistant bacteria. Its potent antimicrobial activity suggests that piscidin 4 plays a significant role in the innate defense system of hybrid striped bass.     

Synthesis and antimicrobial activity of polyhalobenzonitrile quinazolin-4(3H)-one derivatives

A novel series of polyhalobenzonitrile quinazolin-4(3H)-one derivatives were synthesized and characterized by NMR, IR, MS, and HRMS spectra. All of the newly prepared compounds were screened for antimicrobial activities against four strains of bacteria (Gram-positive bacterial: Staphylococcus aureus and Bacillus cereus; Gram-negative bacterial: Escherichia coli and Pseudomonas aeruginosa) and one strain of fungi (Candida albicans). Among the synthesized compounds, 5-(dimethylamino)-8-(2,4,5-trichloro-isophthalonitrile) quinazolin-4(3H)-one (7k) exhibited significant activity towards Gram-positive bacterial, Gram-negative bacterial, and the fungi strains. The MIC (0.8–3.3 μg/mL) and MBC (2.6–7.8 μg/mL) for this compound were close to those of nofloxacin, chlorothalonil, and fluconazole, making it the most potent antimicrobial agents in the series.     

Structure activity relationship modelling of milk protein-derived peptides with dipeptidyl peptidase IV (DPP-IV) inhibitory activity

Quantitative structure activity type models were developed in an attempt to predict the key features of peptide sequences having dipeptidyl peptidase IV (DPP-IV) inhibitory activity. The models were then employed to help predict the potential of peptides, which are currently reported in the literature to be present in the intestinal tract of humans following milk/dairy product ingestion, to act as inhibitors of DPP-IV. Two models (z- and v-scale) for short (2–5 amino acid residues) bovine milk peptides, behaving as competitive inhibitors of DPP-IV, were developed. The z- and the v-scale models (p < 0.05, R² of 0.829 and 0.815, respectively) were then applied to 56 milk protein-derived peptides previously reported in the literature to be found in the intestinal tract of humans which possessed a structural feature of DPP-IV inhibitory peptides (P at the N₂ position). Ten of these peptides were synthetized and tested for their in vitro DPP-IV inhibitory properties. There was no agreement between the predicted and experimentally determined DPP-IV half maximal inhibitory concentrations (IC₅₀) for the competitive peptide inhibitors. However, the ranking for DPP-IV inhibitory potency of the competitive peptide inhibitors was conserved. Furthermore, potent in vitro DPP-IV inhibitory activity was observed with two peptides, LPVPQ (IC₅₀ = 43.8 ± 8.8 μM) and IPM (IC₅₀ = 69.5 ± 8.7 μM). Peptides present within the gastrointestinal tract of human may have promise for the development of natural DPP-IV inhibitors for the management of serum glucose.     

Characterization of the host-defense peptides from skin secretions of Merlin's clawed frog Pseudhymenochirus merlini: Insights into phylogenetic relationships among the Pipidae

The family Pipidae comprises the genera Hymenochirus, Pipa, Pseudhymenochirus, Silurana, and Xenopus but phylogenetic relationships within the family are unclear. Peptidomic analysis of norepinephrine-stimulated skin secretions from Pseudhymenochirus merlini Chabanaud, 1920, the single species within the genus Pseudhymenochirus, led to identification of 13 host-defense peptides with antimicrobial activity. Two peptides (hymenochirin-1Pa and -1Pb) show structural similarity to hymenochirin-1B from Hymenochirus boettgeri and eight peptides (hymenochirin-5Pa, -5Pb, -5Pc, -5Pd, -5Pe, -5Pf, 5Pg and -5Ph) are structurally similar to each other and to hymenochirin-5B from H. boettgeri. Two peptides differing by a single amino acid (IKIPSFFRNILKKVGKEAVSLM/I AGALKQS), termed pseudhymenochirin-1Pa and -1Pb, and pseudhymenochirin-2Pa (GIFPIFAKLLGKVIKVASSLISKGRTE) do not resemble host-defense peptides previously isolated from pipid frogs. Hymenochirin-5Pe was the most abundant peptide in the secretions and hymenochirin-1Pa the most potent against Staphylococcus aureus (MIC = 2.5 μM) and Escherichia coli (MIC = 10 μM). The data support a close phylogenetic relationship between Hymenochirus and Pseudhymenochirus that is distinct from the Xenopodinae (Xenopus + Silurana) clade with Pipa sister-group to all other extant pipids.     

Novel pyrazole integrated 1,3,4-oxadiazoles: Synthesis,characterization and antimicrobial evaluation

A novel series of 2-(5-methyl-1,3-diphenyl-1H-pyrazol-4-yl)-5-phenyl-1,3,4-oxadiazoles 7(a–m) were synthesized either by cyclization of N′-benzoyl-5-methyl-1,3-diphenyl-1H-pyrazole-4-carbohydrazide 4a using POCl₃ at 120 °C or by oxidative cyclization of hydrazones derived from various arylaldehyde and (E)-N′-benzylidene-5-methyl-1,3-diphenyl-1H-pyrazole-4-carbohydrazide 5(a–d) using chloramine-T as oxidant. Newly synthesized compounds were characterized by analytical and spectral (IR, ¹H NMR, ¹³C NMR and LC–MS) methods. The synthesized compounds were evaluated for their antimicrobial activity and were compared with standard drugs. The compounds demonstrated potent to weak antimicrobial activity. Among the synthesized compounds, compound 7m emerged as an effective antimicrobial agent, while compounds 7d, 7f, 7i and 7l showed good to moderate activity. The minimum inhibitory concentration of the compounds was in the range of 20–50 μg mL⁻¹ against bacteria and 25–55 μg mL⁻¹ against fungi. The title compounds represent a novel class of potent antimicrobial agents.     

Novel 1,3,4-oxadiazole thioether derivatives targeting thymidylate synthase as dual anticancer/antimicrobial agents

A series of novel 1,3,4-oxadiazole thioether derivatives (compounds 9–44) were designed and synthesized as potential inhibitors of thymidylate synthase (TS) and as anticancer agents. The in vitro anticancer activities of these compounds were evaluated against three cancer cell lines by the MTT method. Among all the designed compounds, compound 18 bearing a nitro substituent exhibited more potent in vitro anticancer activities with IC₅₀ values of 0.7 ± 0.2, 30.0 ± 1.2, 18.3 ± 1.4 μM, respectively, which was superior to the positive control. In the further study, it was identified as the most potent inhibitor against two kinds of TS protein (for human TS and Escherichia coli TS, IC₅₀ values: 0.62 and 0.47 μM, respectively) in the TS inhibition assay in vitro and the most potent antibacterial agents with MIC (minimum inhibitory concentrations) of 1.56–3.13 μg/mL against the tested four bacterial strains. Molecular docking and 3D-QSAR study supported that compound 18 can be selected as dual antitumor/antibacterial candidate in the future study.     

Antimicrobial activity of the toxin VdTX-I from the spider Vitalius dubius (Araneae,Theraphosidae)

BackgroundCurrently there is an urgent need to develop new classes of antimicrobial agents with different mechanisms of action from conventionally antibiotics used for the control of pathogenic microorganisms. The acylpolyamine called VdTX-I was isolated from the venom of the tarantula Vitalius dubius, and first described with activity as an antagonist of nicotinic cholinergic receptors. The main objective of this study was to investigate the antimicrobial activity found in the venom of the spider, with emphasis on the toxin VdTX-I.MethodsAntimicrobial assays were performed in 96 well plates culture against 14 micro-organisms (fungi, yeasts and bacteria), which were tested concentrations from 0.19 to 100 μM of VdTX-I. After qualitative analysis, dose-response curve assays were performed in bacterial kill curve using MTT reagent and hemolytic assay.ResultsThe antimicrobial activity of the VdTX-I toxin was observed in 12 tested species of Candida, Trichosporiun, Staphylococcus and Micrococcus. The toxicity had a dose-response at 3.12 µM – 100 μM in Candida albicans, Candida guillermondii, Micrococcus luteus and Escherichia coli. VdTX-I took about 5 min to inhibit bacterial growth, which was faster than streptomycin. The toxin showed no hemolytic activity between 0.19 and 100 μM. At 2.5 µg/mL of toxin it was observed no growth inhibition against a mammalian cell lineage.ConclusionsThe VdTX-I toxin has a significant antimicrobial activity, with broad spectrum, and is experimentally inert to mammalian blood cells.General SignificanceThis paper explores the antimicrobial potential of the spider toxin VdTX-I, which can provide a new model to design new antimicrobial drugs.     

Inhibition and destruction of Pseudomonas aeruginosa biofilms by antibiotics and antimicrobial peptides

Pseudomonas aeruginosa is one of the major nosocomial pathogen that can causes a wide variety of acute and chronic infections P. aeruginosa is a dreaded bacteria not just because of the high intrinsic and acquired antibiotic resistance rates but also the biofilm formation and production of multiple virulence factors. We investigated the in vitro activities of antibiotics (ceftazidime, tobramycin, ciprofloxacin, doripenem, piperacillin and colistin) and antimicrobial cationic peptides (AMPs; LL-37, CAMA: cecropin(1–7)-melittin A(2–9) amide, melittin, defensin and magainin-II) alone or in combination against biofilms of laboratory strain ATCC 27853 and 4 clinical strains of P. aeruginosa. The minimum inhibitory concentrations (MIC), minimum bactericidal concentration (MBC) and minimum biofilm eradication concentrations (MBEC) were determined by microbroth dilution technique. The MBEC values of antibiotics and AMPs were 80–>5120 and 640–>640 mg/L, respectively. When combined with the LL-37 or CAMA at 1/10× MBEC, the MBEC values of antibiotics that active against biofilms, were decreased up to 8-fold. All of the antibiotics, and AMPs were able to inhibit the attachment of bacteria at the 1/10× MIC and biofilm formation at 1× or 1/10× MIC concentrations. Time killing curve studies showed 3-log₁₀ killing against biofilms in 24 h with almost all studied antibiotics and AMPs. Synergism were seen in most of the studied combinations especially CAMA/LL-37 + ciprofloxacin against at least one or two strains’ biofilms. Since biofilms are not affected the antibiotics at therapeutic concentrations, using a combination of antimicrobial agents including AMPs, or inhibition of biofilm formation by blocking the attachment of bacteria to surfaces might be alternative methods to fight with biofilm associated infections.     

Synthesis,biological evaluation,and molecular docking studies of novel 1,3,4-oxadiazole derivatives possessing benzotriazole moiety as FAK inhibitors with anticancer activity

1,3,4-Oxadiazole derivatives have drawn continuing interest over the years because of their varied biological activities. In order to search for novel anticancer agents, we designed and synthesized a series of new 1,3,4-oxadiazole derivatives containing benzotriazole moiety as potential focal adhesion kinase (FAK) inhibitors. All the synthesized compounds were firstly reported. Among the compounds, compound 4 shows the most potent inhibitory activity against MCF-7 and HT29 cell lines with IC₅₀ values of 5.68 μg/ml and 10.21 μg/ml, respectively. Besides, all the compounds were assayed for FAK inhibitory activity using the TRAP–PCR–ELISA assay. The results showed compound 4 exhibited the most potent FAK inhibitory activity with IC₅₀ values of 1.2 ± 0.3 μM. Docking simulation by positioning compound 4 into the FAK structure active site was performed to explore the possible binding mode. Apoptosis which was analyzed by flow cytometry, demonstrated that compound 4 induced apoptosis against MCF-7 cells. Therefore, compound 4 may be a potential anticancer agent against MCF-7 cancer cell.