Browsing by Subject "antimicrobial"

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  • Noman, Omar M.; Herqash, Rashed N.; Shahat, Abdelaaty A.; Ahamad, Syed Rizwan; Mechchate, Hamza; Almoqbil, Abdulaziz N.; Alqahtani, Ali S. (2022)
    Centaurea is one of the most important genera within the family Asteraceae. An investigation of the phytochemical composition of Centaurea bruguieriana using Gas-Chromatography coupled to Mass spectrometry (GC-MS) was performed. Antimicrobial activity was evaluated using the minimum inhibitory concentration method (MIC) and validated by molecular docking for the major compounds of the most active fraction (1,10-di-epi-cubenol and methyl 8-oxooctanoate) of C. bruguieriana against three bacterial receptors (TyrRS, DNA gyrase, and dihydrofolate reductase (DHFR)). Evaluation of antioxidant activity was conducted using 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2 '-azino-bis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) assays. High-performance liquid chromatography (HPLC) was used to identify and quantify the contents of major compounds from ethyl acetate fraction (luteolin 7-O-glucoside, chlorogenic acid, kaempferol and isorhamnetin). The antimicrobial activity test showed that the chloroform fraction was more active against all microbial strains. The results of the molecular docking of two major compounds from chloroform fraction showed that good affinities were made between 1,10-di-epi-cubenol and the three selected receptors (TyrRs: -6.0 Kcal/mol against -8.2 Kcal/mol obtained with clorobiocin (standard); DNA gyrase: -6.6 Kcal/mol against -9.1 Kcal/mole obtained with clorobiocin; DHFR: -7.4 Kcal/mol against -6.3 Kcal/mol obtained with SCHEMBL2181345 Standard). Antioxidant evaluation showed that the ethyl acetate fraction was the most active fraction in DPPH (IC50 49.4 mu g/mL) and ABTS (IC50 52.8 mu g/mL) models. HPLC results showed the contents of luteolin 7-O-glucoside (7.4 mu g/mg), and chlorogenic acid (3.2 mu g/mg). Our study demonstrated that C. bruguierana is a promising source of bioactive compounds.
  • Joraholmen, May Wenche; Johannessen, Mona; Gravningen, Kirsten; Puolakkainen, Mirja; Acharya, Ganesh; Basnet, Purusotam; Skalko-Basnet, Natasa (2020)
    Chlamydia trachomatis is the most common cause of bacterial sexually transmitted infections and causes serious reproductive tract complications among women. The limitations of existing oral antibiotics and treatment of antimicrobial resistance require alternative treatment options. We are proposing, for the first time, the natural polyphenol resveratrol (RES) in an advanced delivery system comprising liposomes incorporated in chitosan hydrogel, for the localized treatment of C. trachomatis infection. Both free RES and RES liposomes-in-hydrogel inhibited the propagation of C. trachomatis in a concentration-dependent manner, assessed by the commonly used in vitro model comprising McCoy cells. However, for lower concentrations, the anti-chlamydial effect of RES was enhanced when incorporated into a liposomes-in-hydrogel delivery system, with inhibition of 78% and 94% for 1.5 and 3 mu g/mL RES, respectively for RES liposomes-in-hydrogel, compared to 43% and 72%, respectively, for free RES. Furthermore, RES liposomes-in-hydrogel exhibited strong anti-inflammatory activity in vitro, in a concentration-dependent inhibition of nitric oxide production in the LPS-induced macrophages (RAW 264.7). The combination of a natural substance exhibiting multi-targeted pharmacological properties, and a delivery system that provides enhanced activity as well as applicability for vaginal administration, could be a promising option for the localized treatment of C. trachomatis infection.
  • Huttunen, Sanna; Toivanen, Marko; Liu, Cheng-Hai; Tikkanen-Kaukanen, Carina Alexandra (2016)
    New methods against bacterial infections are needed due to antibiotic resistance and lack of effective vaccines. Antiadhesion therapy is a modern approach in preventing bacterial attachment to host cells. In our previous studies we have shown that berry polyphenolic fractions have binding inhibition activity against serious human pathogen Neisseria meningitidis. In this study new binding inhibitor against N. meningitidis was searched from a Chinese herbal medicine, Salvianolic acid B (SA-B), which is an active polyphenol isolated from the radix Salviae miltiorrhizae. Inhibition of meningococcal pili binding to bovine thyroglobulin, (reference glycoprotein for meningococcal binding), and to human epithelial cells (HEC-1B) was tested. SA-B inhibited pili binding to bovine thyroglobulin totally at the concentration of 0.3 mg/mL, and to HEC-1B cells at the concentration of 0.5 mg/mL. 50 % binding inhibition activity to bovine thyroglobulin was achieved with 0.6 µg/mL. Antimicrobial activity of SA-B against N. meningitidis was found only in relatively high concentrations. For comparison polyphenol macromolecular complexes isolated from Fructus Momordica (Momordica grosvenori Swingle) and wolfberry (Lycium barbarum L.) had only slight or none binding inhibitory effects. Our results indicate that SA-B may have potential in preventing infections by inhibiting meningococcal binding to host cells. New methods against bacterial infections are needed due to antibiotic resistance and lack of effective vaccines. Antiadhesion therapy is a modern approach in preventing bacterial attachment to host cells. In our previous studies we have shown that berry polyphenolic fractions have binding inhibition activity against serious human pathogen Neisseria meningitidis. In this study new binding inhibitor against N. meningitidis was searched from a Chinese herbal medicine, Salvianolic acid B (SA-B), which is an active polyphenol isolated from the radix Salviae miltiorrhizae. Inhibition of meningococcal pili binding to bovine thyroglobulin, (reference glycoprotein for meningococcal binding), and to human epithelial cells (HEC-1B) was tested. SA-B inhibited pili binding to bovine thyroglobulin totally at the concentration of 0.3 mg/mL, and to HEC-1B cells at the concentration of 0.5 mg/mL. 50 % binding inhibition activity to bovine thyroglobulin was achieved with 0.6 µg/mL. Antimicrobial activity of SA-B against N. meningitidis was found only in relatively high concentrations. For comparison polyphenol macromolecular complexes isolated from Fructus Momordica (Momordica grosvenori Swingle) and wolfberry (Lycium barbarum L.) had only slight or none binding inhibitory effects. Our results indicate that SA-B may have potential in preventing infections by inhibiting meningococcal binding to host cells.
  • Miettinen, Ilkka (Helsingfors universitet, 2016)
    Multi-drug tolerance is a phenomenon, in which microorganisms normally susceptible to an antimicrobial agent are able to withstand a treatment via phenotypic alteration. The tolerance is conveyed by a microbial subpopulation that is in a non-replicative and metabolically inactive state also known as persistence. Through this kind of dormancy, the subpopulation may survive an otherwise appropriate course of antimicrobials, since the majority of the drugs target cellular division or metabolism. Upon the reduction of the surrounding antimicrobial concentration the multi-drug tolerant cells - persisters - become resuscitated thus allowing repopulation. As opposed to the more widely acknowledged challenge of antimicrobial resistance, the offspring of the specialist survivor cells are genetically identical to the susceptible majority. Persisters are especially abundant in biofilms, a microbial lifestyle characterized by aggregated microcolonies that are covered in a self-produced slimy matrix known as extracellular polymeric substance (EPS). Partly owning to this protective matrix, biofilms are inherently somewhat tolerant to antimicrobial chemotherapy. Moreover, microbes confined in a biofilm are additionally protected against the components of the host immune system. Conversely, it is assumed that persisters in planktonic, i.e. freely floating state, are easily cleared out by white blood cells. Combined, the immune evasive properties of biofilms and the remarkable multi-drug tolerance of persisters give rise to recalcitrant infections that are immensely difficult to eradicate. The described phenomenon constitutes crucially to the major healthcare challenge of chronic, treatment-resistant infections. Tuberculosis, cystic fibrosis lung disorder, bacterial endocarditis and infections related to indwelling medical devices are only a few examples of such problems. Despite the need for antimicrobials with anti-persister efficacy, no such therapeutics is available and very few are being investigated - one important factor being the lack of relevant drug discovery platforms. Therefore, the aim of this study was to develop an anti-persister assay and to carry out a pilot screening of natural product derived bioactive compounds. Based on the notion that persisters are enriched in bacterial cultures that have reached the stationary phase of growth, a persister model was designed using Staphylococcus aureus ATCC 25923 as the test strain. The bacteria were grown in liquid cultures until they reached the stationary phase and subsequent experimentation was carried out to confirm the tolerant state. After the stationary phase persister model was validated, a small pilot screening of natural products was undertaken in the hope of finding novel anti-persister activity. Mitomycin C, a cytotoxic drug with an existing anti-cancer indication was assigned as the positive control compound because of its previously established anti-persister activity. Since it is common for all of the persister-related diseases that the target microorganisms reside within a protective biofilm, an additional assay based on biofilm regrowth was designed to characterize the hit compounds on a more clinically relevant platform. The persister model culture was shown to be tolerant to conventional antibiotics. The re-induction of metabolic activity by diluting into fresh medium recovered the antimicrobial susceptibility expectedly. A total of 4 compounds were identified as anti-persister hits in the pilot screening campaign. Chromomycin A3, dehydroabietic acid, mithramycin A and oleanolic acid were all able to reduce the viable bacterial count in the stationary phase persister model more than 2 logarithmic units at 100 µM. Mithramycin A was the most potent, reducing the viability over 6 log units. The model compound mitomycin C reduced the viable counts 5.49 (± 0.96) logarithmic units. Out of the 4 hits, dehydroabietic acid was selected for the biofilm relapse assay because of its favourable biocompatibility properties. It reduced regrowth for the treated biofilms by 4 logarithmic.
  • Andersson, Maria; Salo, Johanna; Lipponen, Olli; Salonen, Pauliina; Viljanen, Martti; Ojamo, Heikki; Mikkola, Raimo; Sistonen, Esko; Gasik, Michael; Teplova, Vera V; Salin , Mikko; Salkinoja-Salonen, Mirja Sinikka (Sisäilmayhdistys, 2014)
    Raportti / Sisäilmayhdistys
    Antimikrobisia biosideja ja muita bioreaktiivisia kemikaaleja sisältyy rakennus tuotteisiin ja käytetään rakennusten ylläpidossa, huollossa, siivouksessa ja (home)saneerauksessa. Käytetyt aineet ovat pääosin pitkävaikutteisia biosideja, jotka sisätiloissa käytettyinä kertyvät muodostaen tilojen käyttäjille pysyvän kemiallisen rasitteen, koska mekanismit (luonnonvalo, sade, tuuli, biohajottavat mikrobit, jotka niitä hävittäisivät, puuttuvat. Selvitimme kokeellisesti ja kirjallisuudesta näiden kemikaalien: 1) antimikrobista tehoa terveyshaitallisiksi tunnettuihin, toksiineja tuottaviin mikrobilajeihin; 2) herkistävyyttä ja muita vaikutuksia ihmisen ja muiden lämminveristen soluihin; 3) tekijöitä, jotka vaikuttavat mikrobien haitta-aine päästöihin ja läpäisevyyteen rakennuksessa.