Green synthesis of silver nanoparticles using Arbutus andrachne leaf extract and its antimicrobial activity

Purpose: To synthesize silver nanoparticles (AgNPs) of Arbutus andrachne leaf water extract (LE) and to evaluate the antimicrobial activity of both LE and AgNPs. Methods: The synthesized AgNPs were characterized using the following techniques: ultraviolet-visible spectroscopy (UV-vis), Fourier transform infrared spectroscopy (FT-IR), transmission electron microscopy (TEM), thermal gravimetric analysis (TGA), X-ray diffraction (XRD) analysis, and analysis of particle size (PS) and zeta potential (ZP). The antimicrobial activities of LE and NPs were assessed by Kirby-Bauer disc diffusion (DD) and broth microdilution (MD) methods according to the recommendations of the Clinical and Laboratory Standards Institute (CLSI). LE and AgNPs were examined against fresh cultures of four Gram-positive and five Gram-negative bacteria, and three yeast strains. Results: AgNPs were successfully synthesized and characterized using Arbutus andrachne LE. The AgNPs showed moderate antibacterial activity against Staphylococcus aureus ATCC 6538p, S. epidermidis ATCC 12228, Escherichia coli ATCC 29998, Klebsiella pnemoniae ATCC 13883 and Pseudomonas aeruginosa ATCC 27853, and also antifungal activity against Candida albicans ATCC 10239 and C. krusei ATCC 6258. Conclusions: Due to the potent activity of AgNPs against Gram-positive and Gram-negative bacteria, and yeast strains, it is suggested that AgNPs are potential broad spectrum antimicrobial agents.

Antimicrobial activity of the essential oils of Dittrichia viscosa subsp viscosa on Helicobacter pylori

Dittrichia viscosa subsp. viscosa (Compositae) is found on edges, wood clearings and in waste places of the Iberian Peninsula. Aerial parts of D. viscosa were collected at flowering phase in September-October 2001 around Lisbon, Portugal and the essential oils isolated by hydro-distillation for 4 h using a Clevenger-type apparatus. The oils were analyzed by gas chromatography and gas chromatography-mass spectrometry. Preliminary examination of the essential oils allowed the identification of 32 components. Only four components reached percentages over 5%: fokienol (11.8%), T-muurorol (7.9%), (E)-nerolidol (5.5%) and delta-cadinene (5.0%). The essential oils were tested against Helicobacterpylori and Listeria monocytogenes. Essential oils did not have antimicrobial activity against L. monocytogenes. The essential oil at 0.88 to 22.22 mu g.ml(-1) did not inhibit the growth of H. pylori, affected the growth slightly at 44.40 mu g.ml(-1), and completely inhibited the growth at 88.80 to 133.20 mu g.ml(-1) Results show that use of D. viscosa essential oil in the treatment of gastric disorders caused by H. pylori can be effective.

Synthesis and antimicrobial activity of some 2- Piperidinomethylamino-4-(7-H/substituted coumarin-3-yl)- 6-chlorosubstitutedphenyl pyrimidines

Purpose: To prepare and evaluate some 2-piperidinomethylamino-4-(7-H/substitutedcoumarin-3-yl)-6- chlorosubstitutedphenyl pyrimidines as antimicrobial agents. Methods: Some 2-piperidinomethylamino-4-(7-H/substitutedcoumarin-3-yl)-6-chlorosubstitutedphenyl pyrimidines were prepared by reacting 2-amino-4-(7-H/substitutedcoumarin-3-yl)-6- (chlorosubstitutedphenyl) pyrimidines with piperidine and formaldehyde. The chemical structures of the synthesized compounds were elucidated by Fourier transform infrared (FTIR), 1H-nuclear magnetic resonance (1H-NMR), mass spectrometry and elemental analysis. These compounds were investigated for their antimicrobial activity against ten bacteria and five fungi by serial plate dilution method using standard drugs, namely, ofloxacin and ketoconazole, respectively, and their minimum inhibitory concentrations (MICs) were also determined. Results: A total of eighteen new compounds (1a-18a) were synthesized. Compound 6a (MIC = 50 μg/mL; p < 0.05 or less) displayed the highest activity against S. aureus , E. faecalis , Staphylococcus epidermidis , B. subtilis , and B. cereus . Compound 6a further showed good activity (MIC = 25 μg/mL; p < 0.05 or less) against E. coli ; P. aeruginosa K. pneumonia , B. bronchiseptica , and P. vulgaris . Compounds 6a (MIC = 25 μg/mL; p < 0.0001) and 17a (MIC = 25 μg/mL; p < 0.0001) displayed very good activity against C. albicans , A. niger , A. flavus , M. purpureous , and P. citrinum , respectively. Analysis of structure-activity relationship revealed that the presence of bromo group at 7-postion of the coumarin moiety along with the 4-chlorophenyl group at position-6 of the pyrimidine ring is critical for antimicrobial activity against Gram-positive bacteria, Gram negative bacteria and fungi. Conclusion: The synthesized 2-piperidino derivatives are better antifungal and antibacterial agents than the earlier reported 2-morpholino derivatives, but require further investigations against other microbial strains to ascertain their broad spectrum antimicrobial activity.

Investigation of the enhanced antimicrobial activity of combination dry powder inhaler formulations of lactoferrin

The airways of most people with cystic fibrosis are colonized with biofilms of the Gram-negative, opportunistic pathogen Pseudomonas aeruginosa. Delivery of antibiotics directly to the lung in the form of dry powder aerosols offers the potential to achieve high local concentrations directly to the biofilms. Unfortunately, current aerosolised antibiotic regimes are unable to efficiently eradicate these biofilms from the airways. We investigated the ability of the innate antimicrobial, lactoferrin, to enhance the activity of two aminoglycoside antibiotics (tobramycin and gentamicin) against biofilms of P. aeruginosa strain PAO1. Biofilms were prepared in 96 well polystyrene plates. Combinations of the antibiotics and various lactoferrin preparations were spray dried. The bacterial cell viability of the various spray dried combinations was determined. Iron-free lactoferrin (apo lactoferrin) induced a 3-log reduction in the killing of planktonic cell by the aminoglycoside antibiotics (p < 0.01) and also reduced both the formation and persistence of P. aeruginosa biofilms (p < 0.01). Combinations of lactoferrin and an aminoglycoside displays potential as an effective new therapeutic strategy in the treatment of P. aeruginosa biofilms infections such as those typical of the CF lungs.

Draft genome sequence of Lactobacillus crispatus EM-LC1, an isolate with antimicrobial activity cultured from an elderly subject

Here we report the 1.86-Mb draft genome sequence of Lactobacillus crispatus EM-LC1, a fecal isolate with antimicrobial activity. This genome sequence is expected to provide insights into the antimicrobial activity of L. crispatus and improve our knowledge of its potential probiotic traits.

Antimicrobial activity of Brazilian propolis extracts for Staphylococcus aureus of sheep and goats mastitis origin

Twenty-four S. aureus isolates were analysed. From those, 22 were isolated from milk of goats and sheep with clinical and subclinical mastitis, from the region of Vale do São Francisco in the Brazilian Sertão and S. aureus ATCC 25923 plus a MRSA strain were added. Alcoholic extracts were produced from several batches of green, red and brown propolis consisting of 300 g of raw propolis in 700 mL of 70 % ethanol. Four genes related to antimicrobial resistance were assessed: blaZ that determines the resistance to β-lactam antibiotics, and genes icaA, icaD and bap that influence the production of biofilm. For the tests of susceptibility to different types of propolis the microdilution method was used, in triplicate, and dilutions between 0.003672 and 15% were tested, 70 % ethanol consisted of a negative control. The gene blaZ was found in 15 isolates; icaA gene was present in 3 isolates, icaD gene in 2 and bap gene was detected in 6 isolates. All the propolis tested exhibited antimicrobial activity, ranging from 44 to 100 % of susceptible isolates depending on different propolis batches. According to the results of this experiment the green and red propolis appear to have better antimicrobial activity than the brown variety.

Antimicrobial activity of essential oil from some Verbenaceae and Asteraceae from Brazilian Cerrado.

2016

Lawsonia Inermis-mediated Synthesis Of Silver Nanoparticles: Activity Against Human Pathogenic Fungi And Bacteria With Special Reference To Formulation Of An Antimicrobial Nanogel.

Lawsonia inermis mediated synthesis of silver nanoparticles (Ag-NPs) and its efficacy against Candida albicans, Microsporum canis, Propioniabacterium acne and Trichophyton mentagrophytes is reported. A two-step mechanism has been proposed for bioreduction and formation of an intermediate complex leading to the synthesis of capped nanoparticles was developed. In addition, antimicrobial gel for M. canis and T. mentagrophytes was also formulated. Ag-NPs were synthesized by challenging the leaft extract of L. inermis with 1 mM AgNO₃. The Ag-NPs were characterized by Ultraviolet-Visible (UV-Vis) spectrophotometer and Fourier transform infrared spectroscopy (FTIR). Transmission electron microscopy (TEM), nanoparticle tracking and analysis sytem (NTA) and zeta potential was measured to detect the size of Ag-NPs. The antimicrobial activity of Ag-NPs was evaluated by disc diffusion method against the test organisms. Thus these Ag-NPs may prove as a better candidate drug due to their biogenic nature. Moreover, Ag-NPs may be an answer to the drug-resistant microorganisms.

Antimicrobial and Cytotoxic Activity of Fruit Extract from Syzygium cumini (L.) Skeels

The aim of the present study was to evaluate the antimicrobial and cytotoxic activity of the ethanolic extract of S. cumini according to the Clinical and Laboratory Standards Institute reference method (with modifications), determining the minimal inhibitory and lethal concentration. Activity against Gram-positive (Staphylococcus aureus and S. epidermidis), Gram-negative (Pseudomonas aeruginosa) and yeast of Candida sp and Cryptococcus neoformans was evaluated. The effects of the fruit extract were examined in hamster cells ovaries in concentrations ranging from 1250.0 a 4.9 mu g/ml, measuring the reduction of the tetrazolium salt 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulphophenyl)-2H-tetrazolium. The extract showed both bactericidal and fungicidal activity among the various microorganisms tested and the MIC ranging from 7.8 to 250 mu g/ml. The MIC, MBC and MFC should values that were similar for all the microorganisms. Cytotoxicity index of the dried extract corresponded to the concentration of 400 mu g/ml. The extract could potentially be used in topical antimicrobial products. Thus, the activity of extract was potent to bacteria and mainly to non-albicans species and C. neoformans.

Synthesis, Antimicrobial and Antiproliferative Activity of Novel Silver(I) Tris(pyrazolyl)methanesulfonateand 1,3,5-Triaza-7-phosphadamantane Complexes

Five new silver(I) complexes of formulas [Ag(Tpms)] (1), [Ag(Tpms)-(PPh3)] (2), [Ag(Tpms)(PCy3)] (3), [Ag(PTA)][BF4] (4), and [Ag(Tpms)(PTA)] (5) {Tpms = tris(pyrazol-1-yl)methanesulfonate, PPh3 = triphenylphosphane, PCy3 = tricyclohexylphosphane, PTA = 1,3,5-triaza-7-phosphaadamantane) have been synthesized and fully characterized by elemental analyses, H-1, C-13, and P-31 NMR, electrospray ionization mass spectrometry (ESI-MS), and IR spectroscopic techniques. The single crystal X-ray diffraction study of 3 shows the Tpms ligand acting in the N-3-facially coordinating mode, while in 2 and 5 a N2O-coordination is found, with the SO3 group bonded to silver and a pendant free pyrazolyl ring. Features of the tilting in the coordinated pyrazolyl rings in these cases suggest that this inequivalence is related with the cone angles of the phosphanes. A detailed study of antimycobacterial and antiproliferative properties of all compounds has been carried out. They were screened for their in vitro antimicrobial activities against the standard strains Enterococcus faecalis (ATCC 29922), Staphylococcus aureus (ATCC 25923), Streptococcus pneumoniae (ATCC 49619), Streptococcus pyogenes (SF37), Streptococcus sanguinis (SK36), Streptococcus mutans (UA1S9), Escherichia coli (ATCC 25922), and the fungus Candida albicans (ATCC 24443). Complexes 1-5 have been found to display effective antimicrobial activity against the series of bacteria and fungi, and some of them are potential candidates for antiseptic or disinfectant drugs. Interaction of Ag complexes with deoxyribonucleic acid (DNA) has been studied by fluorescence spectroscopic techniques, using ethidium bromide (EB) as a fluorescence probe of DNA. The decrease in the fluorescence of DNA EB system on addition of Ag complexes shows that the fluorescence quenching of DNA EB complex occurs and compound 3 is particularly active. Complexes 1-5 exhibit pronounced antiproliferative activity against human malignant melanoma (A375) with an activity often higher than that of AgNO3, which has been used as a control, following the same order of activity inhibition on DNA, i.e., 3 > 2 > 1 > 5 > AgNO3 >> 4.

Propolis: anti-Staphylococcus aureus activity and synergism with antimicrobial drugs

Propolis is a natural resinous substance collected by bees from tree exudates and secretions. Its antimicrobial activity has been investigated and inhibitory action on Staphylococcus aureus growth was evaluated. The in vitro synergism between ethanolic extract of propolis (EEP) and antimicrobial drugs by two susceptibility tests (Kirby and Bauer and E-Test) on 25 S. aureus strains was evaluated. Petri dishes with sub-inhibitory concentrations of EEP were incubated with 13 drugs using Kirby and Bauer method and synergism between EEP and five drugs [choramphenicol (CLO), gentamicin (GEN), netilmicin (NET), tetracycline (TET), and vancomycin (VAN)] was observed. Nine drugs were assayed by the E-test method and five of them exhibited a synergism [CLO, GEN, NET, TET, and clindamycin (CLI)]. The results demonstrated the synergism between EEP and antimicrobial drugs, especially those agents that interfere on bacterial protein synthesis.

In vitro antiviral activity of antimicrobial peptides against herpes simplex virus 1, adenovirus, and rotavirus

Peptides with broad-spectrum antimicrobial activity, known as antimicrobial peptides, have been isolated from distinct organisms. This paper describes the in vitro evaluation of the cytotoxicity and antiviral activity of nine peptides with different structures and origins against herpes simplex virus type 1, human adenovirus respiratory strain, and rotavirus SA11. Most of the evaluated peptides presented antiviral activity but they were only active near cytotoxic concentrations. Nevertheless, these results seem promising, and further modifications on the peptide's structures may improve their selectivity and reduce their cytotoxicity.

Antimicrobial and antileishmanial activity of essential oil from the leaves of Annona foetida (Annonaceae)

bicyclogermacrene (35.12%), (E)-caryophyllene (14.19%) and α-copaene (8.19%). The antimicrobial and antileishmanial activities were investigated. The oil showed potent antimicrobial activity against Candida albicans and Rhodococcus equi. The oil also showed significant antileishmanial activity, giving the best results against Leishmania guyanensis. A preliminary cytotoxicity assay for this oil was carried out on hamster and mice (Balb/c) peritoneal macrophages. The results obtained were similar to pentamidine and considered not to be cytotoxic to macrophages.

Study of the mechanism of action of anoplin, a helical antimicrobial decapeptide with ion channel-like activity, and the role of the amidated C-terminus

Anoplin, an antimicrobial, helical decapeptide from wasp venom, looses its biological activities by mere deamidation of its C-terminus. Secondary structure determination, by circular dichroism spectroscopy in amphipathic environments, and lytic activity in zwitterionic and anionic vesicles showed quite similar results for the amidated and the carboxylated forms of the peptide. The deamidation of the C-terminus introduced a negative charge at an all-positive charged peptide, causing a loss of amphipathicity, as indicated by molecular dynamics simulations in TFE/water mixtures and this subtle modification in a peptide`s primary structure disturbed the interaction with bilayers and biological membranes. Although being poorly lytic, the amidated form, but not the carboxylated, presented ion channel-like activity on anionic bilayers with a well-defined conductance step; at approximately the same concentration it showed antimicrobial activity. The pores remain open at trans-negative potentials, preferentially conducting cations, and this situation is equivalent to the interaction of the peptide with bacterial membranes that also maintain a high negative potential inside. Copyright (C) 2007 European Peptide Society and John Wiley & Sons, Ltd.

Antimicrobial and Cytotoxic Activity of Fruit Extract from Syzygium cumini (L.) Skeels

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)