scholarly journals Synthesis and Antibacterial Activity of Cationic Amino Acid-Conjugated Dendrimers Loaded with a Mixture of Two Triterpenoid Acids

Polymers ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 521
Author(s):  
Anna Maria Schito ◽  
Gian Carlo Schito ◽  
Silvana Alfei
Keyword(s):  
Antibacterial Activity ◽  
Amino Acid ◽  
Bacterial Resistance ◽  
Inhibitory Concentration ◽  
Antimicrobial Effect ◽  
Gram Positive ◽  
Cationic Amino Acid ◽  
Gram Positive Bacteria ◽  
Cationic Compounds ◽  
Conjugated Dendrimers

To counteract the growing bacterial resistance, we previously reported the remarkable antimicrobial activity of amino acid-conjugated cationic dendrimers (CDs) against several Gram-negative species, establishing that the cationic lysine was essential for their potency. In this paper, CDs conjugated with lysine and arginine and encapsulating ursolic and oleanolic acids (UOACDs) were assumed to be excellent candidates for developing new antibacterial agents, possibly active against Gram-positive species. Indeed, both the guanidine group of arginine and the two triterpenoid acids are items known for directing antibacterial effects, particularly against Gram-positive bacteria. The cationic dendrimers were obtained by peripheral conjugation with the selected amino acids and by entrapping a physical mixture of the commercial triterpenoid acids. The cationic compounds were characterized and successfully tested against 15 Gram-positive isolates. Interesting minimum inhibitory concentration (MIC) values were obtained for all the dendrimer-drug agents, establishing that the antibacterial activity observed for the UOACDs strongly depended on the density and on the type of the cationic groups of the cationic amino acid-conjugated dendrimers and not on the presence and the release of UOA. Particularly, lysine was critical for potency, while arginine was critical for redirecting activity against Gram-positive species. Especially, a high cationic character, associated with a balanced content of lysine/arginine, produced a remarkable antimicrobial effect (MIC = 0.5–8.7 µM).

scholarly journals Antibacterial Activity of Grepafloxacin

1998 ◽  
Vol 9 (suppl e) ◽  
pp. 4E-9E
Author(s):  
B Wiedemann ◽  
P Heisig
Keyword(s):  
Antibacterial Activity ◽  
Minimum Inhibitory Concentration ◽  
Respiratory Tract Infections ◽  
Inhibitory Concentration ◽  
Gram Positive ◽  
Gram Positive Bacteria ◽  
Pharmacodynamic Profile ◽  
Resistant Mutants ◽  
Tract Infections ◽  
Relative Differences

Grepafloxin has an extremely broad spectrum of activity. Its activity against Gram-positive bacteria exceeds that of currently available quinolones. Grepafloxacin-resistant mutants seem to occur less frequently than ciprofloxacin - or ofloxacin-resistant mutants, and the increase in minimum inhibitory concentration (MIC) against the former mutants is less than that of the latter. This applies only to the relative differences (in dilution steps); the absolute values are similar. Grepafloxacin kills Gram-positive bacteria at concentrations little above the MIC. Its pharmacodynamic profile against pneumococci is promising, favouring use of this drug for respiratory tract infections.

SYNTHESIS OF PIPERINE - PIPERAZINE ANALOGUES AND THEIR ANTIBACTERIAL ACTIVITY

INDIAN DRUGS ◽  
2021 ◽  
Vol 58 (06) ◽  
pp. 30-35
Author(s):  
Naveen K. Kottakki ◽  
◽  
Amperayani K. Rao ◽  
Keyword(s):  
Antibacterial Activity ◽  
Inhibitory Concentration ◽  
Diffusion Method ◽  
Gram Negative Bacteria ◽  
Gram Positive ◽  
Gram Negative ◽  
Gram Positive Bacteria ◽  
Aromatic Nitro ◽  
Heterocyclic Moiety ◽  
Agar Well Diffusion Method

In the current study, a series of piperine – piperazine analogues (5a to 5f) were designed and synthesized. The piperine was isolated from pepper and used for the conjugation with heterocyclic moiety for better biological activity. The piperazine heterocyclic was chosen for conjugation with piperine. The newly synthesized structures were determined by IR, 1H NMR and 13C NMR spectral data. The compounds were examined for their anti‐microbial activity against gram-positive (Bacillus subtilis) and gram-negative (Vibrio cholerae) bacteria using the agar well diffusion method. The newly synthesized compounds exhibited capable activities against V. cholerae and B. subtilis and it showed minimum inhibitory concentration. Among all the synthesized compounds, 5f has the highest activity (26 mm) against gram-positive bacteria and (29mm) against gram-negative bacteria. The remaining compounds showed appreciable antibacterial activity. The enhanced activity of the synthesized compounds may be due to the presence of conjugated amide linkage with the natural product piperine and piperazine heterocyclic molecule. The substituents present on the aromatic (nitro-substituted) ring also influenced the activity of the compound.

scholarly journals PAMAM-dendrimer Enhanced Antibacterial Effect of Vancomycin Hydrochloride Against Gram-Negative Bacteria

2018 ◽  
Vol 22 ◽  
pp. 10-21 ◽  
Author(s):  
Azadeh Serri ◽  
Arash Mahboubi ◽  
Afshin Zarghi ◽  
Hamid Reza Moghimi
Keyword(s):  
Antibacterial Activity ◽  
Inhibitory Concentration ◽  
In Vitro Release ◽  
Pamam Dendrimers ◽  
Dilution Method ◽  
Gram Negative Bacteria ◽  
Gram Positive ◽  
Gram Negative ◽  
Bacterial Membranes ◽  
Gram Positive Bacteria

Purpose: The antibacterial activity of some antibiotics is specific to either Gram-positive or Gram-negative bacteria.  There are different mechanisms behind such insensitivities like inability of antibiotics to permeate through some bacterial membranes, as is the case for vancomycin in Gram-negative bacteria. The present investigation tries to overcome this problem by dendrimers, in order to make Gram-negative bacteria responsive to vancomycin. Methods: The effects of generations 3 (G3) and 5 (G5) polyamidoamine amine-terminated dendrimers (NH2-PAMAM), on the antibacterial activity of vancomycin, were evaluated. Vancomycin-PAMAM dendrimers complexes were prepared and their antibacterial activities were evaluated by determination of their “minimum inhibitory concentration (MIC)”, “minimum bactericidal concentration” and “fractional inhibitory concentration index” values against two Gram-positive and four Gram-negative bacteria, using broth micro-dilution method. The complexation of vancomycin and dendrimers was also assessed by in vitro release studies across dialysis tubing using a developed HPLC method. Results: Results showed that vancomycin solution was effective against Gram-positive bacteria, but, was not effective in Gram-negative ones. Vancomycin-PAMAM dendrimers exhibited significant antibacterial efficacy against Gram-negative bacteria resulting in a decline of vancomycin MIC values by about 2, 2, 4 and 64 times in E. coli, K. pneumonia, S. typhimurium and P. aeruginosa, respectively. Results also showed that enhanced effect by G5 is more than G3. Dendrimers did not affect antibacterial activity of vancomycin in Gram-positive bacteria, as no permeation problem exists here. Conclusions: The present study revealed that both G3 and G5 cationic PAMAM dendrimers are able to make Gram-negative bacteria sensitive to vancomycin, resulting in decline of MIC values up to 64 times, possibly by increasing its permeation through bacterial membrane. These results look promising for broadening the antibacterial spectrum of vancomycin and such a strategy might be used for increasing the overall life of antibiotics.

scholarly journals Antimicrobial activity of omwaprin, a new member of the waprin family of snake venom proteins

2007 ◽  
Vol 402 (1) ◽  
pp. 93-104 ◽  
Author(s):  
Dileep G. Nair ◽  
Bryan G. Fry ◽  
Paul Alewood ◽  
Prakash P. Kumar ◽  
R. Manjunatha Kini
Keyword(s):  
Antibacterial Activity ◽  
Amino Acid ◽  
Snake Venom ◽  
Proteinase Inhibitor ◽  
Whey Acidic Protein ◽  
Acidic Protein ◽  
Gram Positive ◽  
Bacterial Membranes ◽  
Gram Positive Bacteria ◽  
Venom Proteins

We have isolated and characterized omwaprin, a 50-amino-acid cationic protein from the venom of inland taipan (Oxyuranus microlepidotus). It is a new member of the waprin family of snake venom proteins. A synthetic gene was designed and constructed for expressing the recombinant protein in Escherichia coli. Recombinant omwaprin was used for carrying out functional analyses. The protein is non-toxic to Swiss albino mice at doses of up to 10 mg/kg when administered intraperitoneally. However, it shows selective and dose-dependant antibacterial activity against Gram-positive bacteria. The minimum inhibitory doses were in the range 2–10 μg for selected species of bacteria in radial diffusion assays. The antibacterial activity is salt-tolerant up to 350 mM NaCl. However, omwaprin lost its antibacterial activity upon reduction and alkylation of its cysteine residues, or upon deletion of six N-terminal amino acid residues, four of which are positively charged. These observations indicate that the three-dimensional structure constrained by four disulfide bonds and the N-terminal residues are essential for its activity. The mechanism of action is via membrane disruption, as shown by scanning electron microscopy. Importantly, omwaprin lacks haemolytic activity on human erythrocytes. This demonstrates the specificity of omwaprin for bacterial membranes. Unlike other reported WAP (whey acidic protein) domain-containing antibacterial proteins, including elafin, EPPIN (epididymal proteinase inhibitor), SWAM1 and SWAM2 [single WAP (whey acidic protein) motif proteins 1 and 2] and SLPI (secretory leucocyte proteinase inhibitor), omwaprin shows species-specific activity on the Gram-positive bacteria tested.

scholarly journals Synthesis and Antimicrobial Activity of a New Series of Thiazolidine-2,4-diones Carboxamide and Amino Acid Derivatives

Molecules ◽  
2019 ◽  
Vol 25 (1) ◽  
pp. 105 ◽  
Author(s):  
Rakia Abd Alhameed ◽  
Zainab Almarhoon ◽  
Sarah I. Bukhari ◽  
Ayman El-Faham ◽  
Beatriz G. de la Torre ◽  
...  
Keyword(s):  
Antibacterial Activity ◽  
Amino Acid ◽  
Antifungal Activity ◽  
Fungal Isolate ◽  
Amino Acid Derivatives ◽  
Gram Negative Bacteria ◽  
Gram Positive ◽  
Gram Negative ◽  
Gram Positive Bacteria ◽  
Antimicrobial And Antifungal Activity

Novel thiazolidine-2,4-dione carboxamide and amino acid derivatives were synthesized in excellent yield using OxymaPure/N,N′-diisopropylcarbodimide coupling methodology and were characterized by chromatographic and spectrometric methods, and elemental analysis. The antimicrobial and antifungal activity of these derivatives was evaluated against two Gram-positive bacteria (Staphylococcus aureus and Bacillus subtilis), two-Gram negative bacteria (Escherichia coli and Pseudomonas aeruginosa), and one fungal isolate (Candida albicans). Interestingly, several samples demonstrated weak to moderate antibacterial activity against Gram-negative bacteria, as well as antifungal activity. However, only one compound namely, 2-(5-(3-methoxybenzylidene)-2,4-dioxothiazolidin-3-yl)acetic acid, showed antibacterial activity against Gram-positive bacteria, particularly S. aureus.

scholarly journals Covalent Structure and Bioactivity of the Type AII Lantibiotic Salivaricin A2

2017 ◽  
Vol 84 (5) ◽  
Author(s):  
Mengxin Geng ◽  
Frank Austin ◽  
Ronald Shin ◽  
Leif Smith
Keyword(s):  
Amino Acids ◽  
Antibacterial Activity ◽  
Amino Acid ◽  
Amino Acid Residues ◽  
Gram Positive ◽  
Linear Peptide ◽  
Gram Positive Bacteria ◽  
Lipid Ii ◽  
Covalent Structure ◽  
Terminal Amino

ABSTRACTLantibiotics are a class of lanthionine-containing, ribosomally synthesized, and posttranslationally modified peptides (RiPPs) produced by Gram-positive bacteria. Salivaricin A2 belongs to the type AII lantibiotics, which are generally considered to kill Gram-positive bacteria by binding to the cell wall precursor lipid II via a conserved ring A structure. Salivaricin A2 was first reported to be isolated from a probiotic strain,Streptococcus salivariusK12, but the structural and bioactivity characterizations of the antibiotic have remained limited. In this study, salivaricin A2 was purified and its covalent structure was characterized. N-terminal analogues of salivaricin A2 were generated to study the importance for bioactivity of the length and charge of the N-terminal amino acids. Analogue salivaricin A2(3-22) has no antibacterial activity and does not have an antagonistic effect on the native compound. The truncated analogue also lost its ability to bind to lipid II in a thin-layer chromatography (TLC) assay, suggesting that the N-terminal amino acids are important for binding to lipid II. The creation of N-terminal analogues of salivaricin A2 promoted a better understanding of the bioactivity of this antibiotic and further elucidated the structural importance of the N-terminal leader peptide. The antibacterial activity of salivaricin A2 is due not only to the presence of the positively charged N-terminal amino acid residues, but to the length of the N-terminal linear peptide.IMPORTANCEThe amino acid composition of the N-terminal linear peptide of salivaricin A2 is crucial for function. Our study shows that the length of the amino acid residues in the linear peptide is crucial for salivaricin A2 antimicrobial activity. Very few type AII lantibiotic covalent structures have been confirmed. The characterization of the covalent structure of salivaricin A2 provides additional support for the predicted lanthionine and methyl-lanthionine ring formations present in this structural class of lantibiotics. Removal of the N-terminal Lys1 and Arg2 residues from the peptide causes a dramatic shift in the chemical shift values of amino acid residues 7 through 9, suggesting that the N-terminal amino acids contribute to a distinct structural conformer for the linear peptide region. The demonstration that the bioactivity could be partially restored with the substitution of N-terminal alanine residues supports further studies aimed at determining whether new analogues of salivaricin A2 for novel applications can be synthesized.

Antibacterial activity of magnesium oxide nanoparticles prepared by Calcination method

2019 ◽  
Vol 10 (03) ◽  
Author(s):  
Elaf Ayad Kadhem ◽  
Miaad Hamzah Zghair ◽  
Sarah , Hussam H. Tizkam, Shoeb Alahmad Salih Mahdi ◽  
Hussam H. Tizkam ◽  
Shoeb Alahmad
Keyword(s):  
Antibacterial Activity ◽  
Magnesium Oxide ◽  
Diffusion Method ◽  
Oxide Nanoparticles ◽  
Gram Negative Bacteria ◽  
Gram Positive ◽  
Gram Negative ◽  
Gram Positive Bacteria ◽  
Magnesium Oxide Nanoparticles ◽  
Agar Disc

magnesium oxide nanoparticles (MgO NPs) were prepared by simple wet chemical method using different calcination temperatures. The prepared NPs were characterized by Electrostatic Discharge (ESD), Scanning Electron Microscope (SEM) and X-ray Diffraction (XRD). It demonstrates sharp intensive peak with the increase of crystallinty and increase of the size with varying morphologies with respect to increase of calcination temperature. Antibacterial studies were done on gram negative bacteria (E.coli) and gram positive bacteria (S.aureus) by agar disc diffusion method. The zones of inhibitions were found larger for gram positive bacteria than gram negative bacteria, this mean, antibacterial MgO NPs activity more active on gram positive bacteria than gram negative bacteria because of the structural differences. It was found that antibacterial activity of MgO NPs was found it has directly proportional with their concentration.

scholarly journals A novel bis(pyrazolyl)methane compound as a potential agent against Gram-positive bacteria

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Pedro Seguí ◽  
John J. Aguilera-Correa ◽  
Elena Domínguez-Jurado ◽  
Christian M. Sánchez-López ◽  
Ramón Pérez-Tanoira ◽  
...  
Keyword(s):  
Antibacterial Activity ◽  
Inhibitory Effect ◽  
Eukaryotic Cell ◽  
Liver Carcinoma ◽  
Gram Positive ◽  
Minimal Inhibitory Concentrations ◽  
E Coli ◽  
Gram Positive Bacteria ◽  
Therapeutic Compounds ◽  
Toxic Concentrations

AbstractThis study was designed to propose alternative therapeutic compounds to fight against bacterial pathogens. Thus, a library of nitrogen-based compounds bis(triazolyl)methane (1T–7T) and bis(pyrazolyl)methane (1P–11P) was synthesised following previously reported methodologies and their antibacterial activity was tested using the collection strains of Staphylococcus aureus, Enterococcus faecalis, Escherichia coli, and Pseudomonas aeruginosa. Moreover, the novel compound 2P was fully characterized by IR, UV–Vis and NMR spectroscopy. To evaluate antibacterial activity, minimal inhibitory concentrations (MICs), minimal bactericidal concentrations (MBCs), minimum biofilm inhibitory concentrations (MBICs), and minimum biofilm eradication concentrations (MBECs) assays were carried out at different concentrations (2–2000 µg/mL). The MTT assay and Resazurin viability assays were performed in both human liver carcinoma HepG2 and human colorectal adenocarcinoma Caco-2 cell lines at 48 h. Of all the synthesised compounds, 2P had an inhibitory effect on Gram-positive strains, especially against S. aureus. The MIC and MBC of 2P were 62.5 and 2000 µg/mL against S. aureus, and 250 and 2000 µg/mL against E. faecalis, respectively. However, these values were > 2000 µg/mL against E. coli and P. aeruginosa. In addition, the MBICs and MBECs of 2P against S. aureus were 125 and > 2000 µg/mL, respectively, whereas these values were > 2000 µg/mL against E. faecalis, E. coli, and P. aeruginosa. On the other hand, concentrations up to 250 µg/mL of 2P were non-toxic doses for eukaryotic cell cultures. Thus, according to the obtained results, the 2P nitrogen-based compound showed a promising anti-Gram-positive effect (especially against S. aureus) both on planktonic state and biofilm, at non-toxic concentrations.

Preparation of bioactive and antibacterial PMMA-based bone cement by modification with quaternary ammonium and alkoxysilane

2021 ◽  
pp. 088532822110044
Author(s):  
Haiyang Wang ◽  
Toshinari Maeda ◽  
Toshiki Miyazaki
Keyword(s):  
Antibacterial Activity ◽  
Methyl Methacrylate ◽  
Bone Cement ◽  
Setting Time ◽  
Antibacterial Properties ◽  
The Body ◽  
Apatite Formation ◽  
Gram Positive ◽  
E Coli ◽  
Gram Positive Bacteria

Bone cement based on poly(methyl methacrylate) (PMMA) powder and methyl methacrylate (MMA) liquid is a very popular biomaterial used for the fixation of artificial joints. However, there is a risk of this cement loosening from bone because of a lack of bone-bonding bioactivity. Apatite formation in the body environment is a prerequisite for cement bioactivity. Additionally, suppression of infection during implantation is required for bone cements to be successfully introduced into the human body. In this study, we modified PMMA cement with γ-methacryloxypropyltrimetoxysilane and calcium acetate to introduce bioactive properties and 2-( tert-butylamino)ethyl methacrylate (TBAEMA) to provide antibacterial properties. The long-term antibacterial activity is attributed to the copolymerization of TBAEMA and MMA. As the TBAEMA content increased, the setting time increased and the compressive strength decreased. After soaking in simulated body fluid, an apatite layer was detected within 7 days, irrespective of the TBAEMA content. The cement showed better antibacterial activity against Gram-negative E. Coli than Gram-positive bacteria; however, of the Gram-positive bacteria investigated, B. subtilis was more susceptible than S. aureus.

Antimicrobial Activity of Isopteropodine

2005 ◽  
Vol 60 (5-6) ◽  
pp. 385-388 ◽  
Author(s):  
Rubén García ◽  
Cesia Cayunao ◽  
Ronny Bocic ◽  
Nadine Backhouse ◽  
Carla Delporte ◽  
...  
Keyword(s):  
Antimicrobial Activity ◽  
Antibacterial Activity ◽  
Gram Positive ◽  
Uncaria Tomentosa ◽  
Gram Positive Bacteria

Bioassay-directed fractionation for the determination of antimicrobial activity of Uncaria tomentosa, has led to the isolation of isopteropodine (0.3%), a known Uncaria pentacyclic oxindol alkaloid that exhibited antibacterial activity against Gram positive bacteria.

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