Browsing by Subject "ANTIBACTERIAL ACTIVITY"

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  • Metsämuuronen, Sari; Sirén, Heli (2019)
    Phenolics and extracted phenolic compounds of Scots pine (Pinus sylvestris) and Norway spruce (Picea abies) show antibacterial activity against several bacteria. The majority of phenolic compounds are stilbenes, flavonoids, proanthocyanidins, phenolic acids, and lignans that are biosynthesized in the wood through the phenylpropanoid pathway. In Scots pine (P. sylvestris), the most abundant phenolic and antibacterial compounds are pinosylvin-type stilbenes and flavonol- and dihydroflavonol-type flavonoids, such as kaempferol, quercetin, and taxifolin and their derivatives. In Norway spruce (P. abies) on the other hand, the main stilbene is resveratrol and the major flavonoids are quercetin and myricetin. In general, when the results from the literature regarding the activities of flavonoid glycosides and their aglycones against a total of twenty-one microorganisms are summarized, it was found that phenolic glycosides are less active than the corresponding aglycones, although a number of exceptions are also known. The aglycones in plants respond to various kinds of biotic stress. Synergistic effects between aglycones and their glycosides have been observed. Minimum inhibition concentrations of below 10 mg L−1 against bacteria have been reported for gallic acid, apigenin, and several methylated and acylated flavonols present in these industrially important trees. In general, the phenolic compounds are more active against Gram-positive bacteria, but apigenin is reported to exhibit strong activity against Gram-negative bacteria. The present review lists some of the biosynthesis pathways for the antibacterial phenolic metabolites found in Scots pine (P. sylvestris) and Norway spruce (P. abies). The antimicrobial activity of the compounds is collected and compared to gather information about the most effective secondary metabolites.
  • Kanerva, Mikko; Matrenichev, Vsevolod; Layek, Rama; Takala, Timo M.; Laurikainen, Pekka; Sarlin, Essi; Elert, Anna Maria; Yudin, Vladimir; Seitsonen, Jani; Ruokolainen, Janne; Saris, Per (2020)
    The quantitative difference in the antibacterial response was measured for pine rosin and propolis against Staphylococcus aureus ATCC 12598. The activity was studied for fibrous networks that form entirely bio-based cellulose-acetate (CA) materials. The analysis considers the effects of bacterial input, additive dosage, solvent type, variation in preparation, as well as the effect of storage time. Based on the results, the electrospun network structure is dependent on the solvent and the concentration of rosin and propolis. Both rosin and propolis improved the cellulose acetate solution processability, yet they formed beads at high concentrations. Rosin and propolis created strong antibacterial properties when these material systems were immersed in the liquid for 24 h at room temperature. The response remained visible for a minimum of two months. The electrospun networks of water and DMAc solvent systems with 1 to 5 wt% rosin content were clearly more efficient (i.e., decrease of 4 to 6 logs in colony forming units per mL) than the propolis networks, even after two months. This efficiency is likely due to the high content of abietic acids present in the rosin, which is based on the Fourier transform infrared spectra. The results of the additional analysis and cell cultivation with dermal fibroblast cells indicated an impairing effect on skin tissue by the rosin at a 1 wt% concentration compared to the pure CA fibers.
  • Jakopin, Ziga; Ilas, Janez; Barancokova, Michaela; Brvar, Matjaz; Tammela, Paivi; Dolenc, Marija Sollner; Tomasic, Tihomir; Kikelj, Danijel (2017)
    DNA gyrase and topoisomerase IV are type IIa topoisomerases that are essential bacterial enzymes required to oversee the topological state of DNA during transcription and replication processes. Their ATPase domains, GyrB and ParE, respectively, are recognized as viable targets for small molecule inhibitors, however, no synthetic or natural product GyrB/ParE inhibitors have so far reached the clinic for use as novel antibacterial agents, except for novobiocin which was withdrawn from the market. In the present study, a series of substituted oxadiazoles have been designed and synthesized as potential DNA gyrase inhibitors. Structure-based optimization resulted in the identification of compound 35, displaying an IC50 of 1.2 mu M for Escherichia coli DNA gyrase, while also exhibiting a balanced low micromolar inhibition of E. coli topoisomerase IV and of the respective Staphylococcus aureus homologues. The most promising inhibitors identified from each series were ultimately evaluated against selected Grampositive and Gram-negative bacterial strains, of which compound 35 inhibited Enterococcus faecalis with a MIC90 of 75 mu M. Our study thus provides further insight into the structural requirements of substituted oxadiazoles for dual inhibition of DNA gyrase and topoisomerase IV. (C) 2017 Elsevier Masson SAS. All rights reserved.
  • Talon, Emma; Lampi, Anna-Maija; Vargas, Maria; Chiralt, Amparo; Jouppila, Kirsi; Gonzalez-Martinez, Chelo (2019)
    The encapsulation of eugenol (E) by spray-drying using whey protein (WP) or soy lecithin (LE) and maltodextrin in combination with oleic acid (OA) and chitosan (CH) was analysed in order to obtain antioxidant and antimicrobial powders for food applications. Formulations with only WP or LE showed higher encapsulation efficiencies (EE) (95-98%) and antibacterial effect against E. coli and L. innocua due to their greater E load. Incorporation of OA or CH promoted lower EE, which negatively affected the antimicrobial and antioxidant activities of the powders. Furthermore, the addition of CH implied less thermal protection against the E losses. The eugenol release was not notably affected by pH or polarity of the food simulant, but the release rate significantly decreased when incorporating OA and CH. The E-LE formulations better retained the eugenol than E-WP powders when heated above 200 degrees C, this being relevant for the powder inclusion in thermally treated products.
  • Skok, Žiga; Barančoková, Michaela; Benek, Ondřej; Cruz, Cristina Durante; Tammela, Päivi; Tomašič, Tihomir; Zidar, Nace; Mašič, Lucija Peterlin; Zega, Anamarija; Stevenson, Clare E. M.; Mundy, Julia E. A.; Lawson, David M.; Maxwell, Anthony; Kikelj, Danijel; Ilaš, Janez (2020)
    We designed and synthesized a series of inhibitors of the bacterial enzymes DNA gyrase and DNA topoisomerase IV, based on our recently published benzothiazole-based inhibitor bearing an oxalyl moiety. To improve the antibacterial activity and retain potent enzymatic activity, we systematically explored the chemical space. Several strategies of modification were followed: varying substituents on the pyrrole carboxamide moiety, alteration of the central scaffold, including variation of substitution position and, most importantly, modification of the oxalyl moiety. Compounds with acidic, basic, and neutral properties were synthesized. To understand the mechanism of action and binding mode, we have obtained a crystal structure of compound 16a, bearing a primary amino group, in complex with the N-terminal domain of E. coli gyrase B (24 kDa) (PDB: 6YD9). Compound 15a, with a low molecular weight of 383 Da, potent inhibitory activity on E. coli gyrase (IC50 = 9.5 nM), potent antibacterial activity on E. faecalis (MIC = 3.13 mu M), and efflux impaired E. coli strain (MIC = 0.78 mu M), is an important contribution for the development of novel gyrase and topoisomerase IV inhibitors in Gram-negative bacteria.
  • Fyhrquist, Pia; Salih, Enass Y. A.; Helenius, Satu; Laakso, Into; Julkunen-Tiitto, Riitta (2020)
    Combretum padoidesEngl. & Diels,C. psidioidesWelv. andC. zeyheriSond. are used for the treatment of infections and tuberculosis related symptoms in African traditional medicine. In order to verify these uses, extracts were screened for their growth inhibitory effects againstM. smegmatisATCC 14468. Ultra-high pressure liquid chromatography coupled to quadrupole time-of-flight mass spectrometry (UHPLC/QTOF-MS) and GC-MS were used to investigate the polyphenolic composition in the active extracts. The lowest minimum inhibitory concentration (MIC), 625 mu g/mL, was shown by a methanol extract of the stem bark ofC. psidioides. A butanol extract ofC. psidioidesgave large inhibition zone diameters (IZD 21 mm) and inhibited 84% of the mycobacterial growth at 312 mu g/mL. Combretastatin B-2 and dihydrostilbene derivatives were present in the methanol extract ofC. psidioides, whereas the butanol extract of this species contained punicalagin, corilagin, and sanguiin H-4. Methanol and butanol extracts of the stem bark ofC. padoidesgave large inhibition zone diameters (IZD 26.5 mm) and MIC values of 1250 and 2500 mu g/mL, respectively.C. padoidescontained an ellagitannin with a mass identical to punicalagin ([M-H](-)1083.0587) and a corilagin like derivative ([M-H](-)633.0750) as well as ellagic acid arabinoside and methyl ellagic acid xyloside. A butanol extract of the roots ofC. zeyherishowed mild antimycobacterial activity and contained a gallotannin atm/z[M-H](-)647.0894 as the main compound along with punicalagin and three unknown ellagitannins atm/z[M-H](-)763.0788, 765.0566, and 817.4212. Our results indicate that the studied species ofCombretumcontain phenolic and polyphenolic compounds with possible potential as leads for antimycobacterial drugs or as adjuvants for conventional anti-TB drugs.
  • Guillaume, O.; Perez-Tanoira, R.; Fortelny, R.; Redl, H.; Moriarty, T. F.; Richards, R. G.; Eglin, D.; Puchner, A. Petter (2018)
    The incidence of mesh-related infection after abdominal wall hernia repair is low, generally between 1 and 4%; however, worldwide, this corresponds to tens of thousands of difficult cases to treat annually. Adopting best practices in prevention is one of the keys to reduce the incidence of mesh-related infection. Once the infection is established, however, only a limited number of options are available that provides an efficient and successful treatment outcome. Over the past few years, there has been a tremendous amount of research dedicated to the functionalization of prosthetic meshes with antimicrobial properties, with some receiving regulatory approval and are currently available for clinical use. In this context, it is important to review the clinical importance of mesh infection, its risk factors, prophylaxis and pathogenicity. In addition, we give an overview of the main functionalization approaches that have been applied on meshes to confer anti-bacterial protection, the respective benefits and limitations, and finally some relevant future directions. (C) 2018 Elsevier Ltd. All rights reserved.
  • Nilsson, Sofia; Henschel, Henning; Scotti, Gianmario; Haapala, Markus; Kiriazis, Alexandros; Boije af Gennäs, Gustav; Kotiaho, Tapio; Yli-Kauhaluoma, Jari (2019)
    We have identified the most likely reaction mechanism for oxidizing heptafulvenes to the corresponding tropones by experimental and theoretical investigations. The experimental studies were done by coupling a three-dimensional printed miniaturized reactor with an integrated electrospray ionization needle to a mass spectrometer. Using the experimentally observed ions as a basis, nine alternative reaction pathways were investigated with density functional theory calculations. The lowest energy reaction pathway starts with the formation of an epoxide that is opened upon the addition of a second equivalent of the oxidizing species meta-chloroperoxybenzoic acid. The adduct formed then undergoes a Criegee-like rearrangement to yield a positively charged hemiketal, which on deprotonation dissociates into acetone resembles a Hock-like rearrangement. and tropone. Overall, the reaction mechanism resembles a Hock-like rearrangement.
  • Munsch-Alatossava, Patricia; Jääskeläinen, Susanna; Alatossava, Tapani; Gauchi, Jean-Pierrre (2017)
    Antibiotic resistance has been noted to be a major and increasing human health issue. Cold storage of raw milk promotes the thriving of psychrotrophic/psychrotolerant bacteria, which are well known for their ability to produce enzymes that are frequently heat stable. However, these bacteria also carry antibiotic resistance (AR) features. In places, where no cold chain facilities are available and despite existing recommendations numerous adulterants, including antibiotics, are added to raw milk. Previously, N-2 gas flushing showed real potential for hindering bacterial growth in raw milk at a storage temperature ranging from 6 to 25 degrees C. Here, the ability of N-2 gas (N) to tackle antibiotic-resistant bacteria was tested and compared to that of the activated lactoperoxidase system (HT) for three raw milk samples that were stored at 6 degrees C for 7 days. To that end, the mesophiles and psychrotrophs that were resistant to gentamycin (G), ceftazidime (Ce), levofloxacin (L), and trimethoprim-sulfamethoxazole (TS) were enumerated. For the log(10) ratio (which is defined as the bacterial counts from a certain condition divided by the counts on the corresponding control), classical Analyses of Variance (ANOVA) was performed, followed by a mean comparison with the Ryan-Einot-Gabriel-Welsch multiple range test (REGWQ). If the storage "time" factor was the major determinant of the recorded effects, cold storage alone or in combination with HT or with N promoted a sample-dependent response in consideration of the AR levels. The efficiency of N in limiting the increase in AR was highest for fresh raw milk and was judged to be equivalent to that of HT for one sample and superior to that of HT for the two other samples; moreover, compared to HT, N seemed to favor a more diverse community at 6 degrees C that was less heavily loaded with antibiotic multi-resistance features. Our results imply that N-2 gas flushing could strengthen cold storage of raw milk by tackling the bacterial spoilage potential while simultaneously hindering the increase of bacteria carrying antibiotic resistance/multi-resistance features.
  • Aly, Ashraf A.; El-Sheref, Essmat M.; Brown, Alan B.; Braese, Stefan; Nieger, Martin; Abdelhafez, El-Shinnaa M. N. (2019)
    A new one pot reaction of substituted thiosemicarbazides with 2-bromoacetophenone and carbonyl compounds gave 2-hydrazonothiazoles in good yields. The structures of the isolated compounds were corroborated by NMR, IR, mass spectra and elemental analyses in addition to X-ray structure determination. [GRAPHICS] .
  • Vaara, Martti (2019)
    Polymyxins (polymyxin B (PMB) and polymyxin E (colistin)) are cyclic lipodecapeptide antibiotics, highly basic due to five free amino groups, and rapidly bactericidal against Gram-negative bacteria, such as the majority of Enterobacteriaceae as well as Acinetobacter baumannii and Pseudomonas aeruginosa. Their clinical use was abandoned in the 1960s because of nephrotoxicity and because better-tolerated drugs belonging to other antibiotic classes were introduced. Now, due to the global dissemination of extremely-drug resistant Gram-negative bacterial strains, polymyxins have resurged as the last-line drugs against those strains. Novel derivatives that are less toxic and/or more effective at tolerable doses are currently under preclinical development and their properties have recently been described in several extensive reviews. Other derivatives lack any direct bactericidal activity but damage the outermost permeability barrier, the outer membrane, of the target bacteria and make it more permeable to many other antibiotics. This review describes the properties of three thus far best-characterized permeabilizer derivatives, i.e., the classic permeabilizer polymyxin B nonapeptide (PMBN), NAB7061, and SPR741/NAB741, a compound that recently successfully passed the clinical phase 1. Also, a few other permeabilizer compounds are brought up.
  • Soleymaniha, Mohammadreza; Shahbazi, Mohammad-Ali; Rafieerad, Ali Reza; Maleki, Aziz; Amiri, Ahmad (2019)
    MXene nanosheets have emerged as biocompatible transition metal structures, which illustrate desirable performance for various applications due to their unique structural, physicochemical, and compositional features. MXenes are currently expanding their usage territory from mechanical, optical, chemical, and electronic fields toward biomedical areas. This is mainly originated from their large surface area and strong absorbance in near-infrared region, which in combination with their facile surface functionalization with various polymers or nanoparticles, make them promising nanoplatforms for drug delivery, cancer therapy, precise biosensing and bioimaging. The facile surface modification of the MXenes can mediate the better in vivo performance of them through reduced toxicity, enhanced colloidal stability, and extended circulation within the body. Herein, the synthesis and state-of-the-art progresses of MXene nanosheets designed for biomedical applications, including structural- and dose-dependent antimicrobial activity, photothermal therapy, drug delivery, and implants are emphasized. Furthermore, biosensing applications are highlighted and a comprehensive discussion on photoacoustic imaging, magnetic resonance imaging, computed tomography imaging, and optical imaging of MXenes is presented. The challenges and future opportunities of applying MXene nanomaterials in the area of biomedicine are also discussed.
  • Ferro, Claudio; Florindo, Helena; Santos, Hélder A. (2021)
    Selenium (Se) is an essential element to human health that can be obtained in nature through several sources. In the human body, it is incorporated into selenocysteine, an amino acid used to synthesize several selenoproteins, which have an active center usually dependent on the presence of Se. Although Se shows several beneficial properties in human health, it has also a narrow therapeutic window, and therefore the excessive intake of inorganic and organic Se-based compounds often leads to toxicity. Nanoparticles based on Se (SeNPs) are less toxic than inorganic and organic Se. They are both biocompatible and capable of effectively delivering combinations of payloads to specific cells following their functionalization with active targeting ligands. Herein, the main origin of Se intake, its role on the human body, and its primary biomedical applications are revised. Particular focus will be given to the main therapeutic targets that are explored for SeNPs in cancer therapies, discussing the different functionalization methodologies used to improve SeNPs stability, while enabling the extensive delivery of drug-loaded SeNP to tumor sites, thus avoiding off-target effects.
  • Durcik, Martina; Tammela, Päivi Sirpa Marjaana; Barančoková, Michaela; Tomašič, Tihomir; Ilaš, Janez; Kikelj, Danijel; Zidar, Nace (2018)
    ATP-competitive inhibitors of DNA gyrase and topoisomerase IV are among the most interesting classes of antibacterial drugs that are unrepresented in the antibacterial pipeline. We developed 32 new N-phenylpyrrolamides and evaluated them against DNA gyrase and topoisomerase IV from E.coli and Staphylococcus aureus. Antibacterial activities were studied against Gram-positive and Gram-negative bacterial strains. The most potent compound displayed an IC50 of 47 nm against E.coli DNA gyrase, and a minimum inhibitory concentration (MIC) of 12.5 mu m against the Gram-positive Enterococcus faecalis. Some compounds displayed good antibacterial activities against an efflux-pump-deficient E.coli strain (MIC=6.25 mu m) and against wild-type E.coli in the presence of efflux pump inhibitor PA beta N (MIC=3.13 mu m). Here we describe new findings regarding the structure-activity relationships of N-phenylpyrrolamide DNA gyrase B inhibitors and investigate the factors that are important for the antibacterial activity of this class of compounds.
  • Manner, Suvi; Skogman, Malena; Goeres, Darla; Vuorela, Pia; Fallarero, Adyary (2013)
  • Salih, Enass Y.A.; Julkunen-Tiitto, Riitta; Lampi, Anna-Maija; Kanninen, Markku; Luukkanen, Olavi; Sipi, Marketta; Lehtonen, Mari; Vuorela, Heikki; Fyhrquist, Pia (2018)
    AbstractEthnopharmacological relevance Terminalia laxiflora Engl. & Diels, (Sudanese Arabic name: Darout الدروت) and Terminalia brownii Fresen (Sudanese Arabic name: Alshaf ألشاف) (Combretaceae) are used in Sudanese traditional folk medicine and in other African countries for treatment of infectious diseases, TB and its symptoms, such as cough, bronchitis and chest pain. Aim of study Because of the frequent use of T. laxiflora and T. brownii in African traditional medicine and due to the absence of studies regarding their antimycobacterial potential there was a need to screen extracts of T. laxiflora and T. brownii for their growth inhibitory potential and to study the chemical composition and compounds in growth inhibitory extracts. Materials and methods The plant species were collected in Sudan (Blue Nile Forest, Ed Damazin Forestry areas) and selected according to their uses in traditional medicine for the treatment of bacterial infections, including TB. Eighty extracts and fractions of the stem bark, stem wood, roots, leaves and fruits of T. laxiflora and T. brownii and nine pure compounds present in the active extracts were screened against Mycobacterium smegmatis ATCC 14468 using agar diffusion and microplate dilution methods. Inhibition zones and MIC values were estimated and compared to rifampicin. HPLC-UV/DAD, GC/MS and UHPLC/Q-TOF MS were employed to identify the compounds in the growth inhibitory extracts. Results The roots of T. laxiflora and T. brownii gave the best antimycobacterial effects (IZ 22–27 mm) against Mycobacterium smegmatis. The lowest MIC of 625 µg/ml was observed for an acetone extract of the root of T. laxiflora followed by methanol and ethyl acetate extracts, both giving MIC values of 1250 µg/ml. Sephadex LH-20 column chromatography purification of T. brownii roots resulted in low MIC values of 62.5 µg/ml and 125 µg/ml for acetone and ethanol fractions, respectively, compared to 5000 µg/ml for the crude methanol extract. Methyl (S)-flavogallonate is suggested to be the main active compound in the Sephadex LH- 20 acetone fraction, while ellagic acid xyloside and methyl ellagic acid xyloside are suggested to give good antimycobacterial activity in the Sephadex LH-20 ethanol fraction. RP-18 TLC purifications of an ethyl acetate extract of T. laxiflora roots resulted in the enrichment of punicalagin in one of the fractions (Fr5). This fraction gave a five times smaller MIC (500 µg/ml) than the crude ethyl acetate extract (2500 µg/ml) and this improved activity is suggested to be mostly due to punicalagin. 1,18-octadec-9-ene-dioate, stigmast-4-en-3-one, 5α-stigmastan-3,6-dione, triacontanol, sitostenone and β-sitosterol were found in antimycobacterial hexane extracts of the stem bark of both studied species. Of these compounds, 1,18-octadec-9-ene-dioate, stigmast-4-en-3-one, 5α-stigmastan-3,6-dione, triacontanol, sitostenone have not been previously identified in T. brownii and T. laxiflora. Moreover, both plant species contained friedelin, betulinic acid, β-amyrine and two unknown oleanane-type triterpenoids. Of the listed compounds, friedelin, triacontanol and sitostenone gave a MIC of 250 µg/ml against M. smegmatis, whereas stigmasterol and β-sitosterol gave MIC values of 500 µg/ml. Conclusions Our results show that T. laxiflora and T. brownii contain antimycobacterial compounds of diverse polarities and support the traditional uses of various parts of T. laxiflora and T.brownii as decoctions for treatment of tuberculosis. Further investigations are warranted to explore additional (new) antimycobacterial compounds in the active extracts of T. laxiflora and T. brownii.