HERBAL PRODUCTS AS AN ALTERNATIVE TO ANTIBIOTICS: APPLICATION POSSIBILITIES AND LIMITATIONS

Antimicrobial resistance (AMR) has developed as one of the top 10 global public health threats facing humanity. As the nosocomial bacterial strains are being increasingly resistant to most clinically available antibiotics, there is a constant need for exploration of new substances that could kill them or inhibit their growth, or alternatively inhibit some of their essential virulence factors to counteract the lack of new antibacterials and the rise of antibiotic resistance, plants could represent a potential solution. Plants produce a variety of bioactive secondary metabolites that could be used to fuel the future discovery pipeline. Aim of the present study was to examine inhibitory activity of the supercritical extract of J. communis L. green pseudofructus (7SCO2) against the growth, biofilm production and several virulence factors of significant nosocomial bacterial pathogens. The extract was obtained by fractional extraction with supercritical CO2, and the qualitative and quantitative analysis was performed using the GC-FID/MS method. Clinical isolates of Pseudomonas aeruginosa,Acinetobacter baumannii, Staphylococcus aureus (methicillin-sensitive-MSSA and methicillin- resistant - MRSA), Enterococcus faecalis, and Klebsiella pneumoniae, as well as their antibiotic resistance profiles, were obtained from the Clinical Hospital Centre “Dr Dragiša Mišović Dedinje”. Minimum inhibitory concentrations (MICs) of the 7SCO2 were determined by broth-microdilution method. Examination of the anti-adhesive effect of the extract was carried out using the spectrophotometric method. The pyocyanin production of Pseudomonas aeruginosa was determined by the method described by Rampioni et al. Most significant findings of this study are potent antivirulence activity of the 7SCO2 against P. aeruginosa through the inhibition of pyocyanin production. In addition, the biofilm production of A. baumannii was inhibited by the 7SCO2 in concentration 50 μg/mL. Finally, notable antivirulence activity of the 7SCO2 against E. faecalis and S. aureus was detected, since it significantly inhibited collagen and laminin adhesion of these pathogens.Book of abstract: From biotechnology to human and planetary health XIII congress of microbiologists of Serbia with international participation Mikromed regio 5, ums series 24: 4th – 6th april 2024, Mona Plaza hotel, Belgrade, Serbi

Antimicrobial activity of lozenge with garlic bulb powder

According to the tested antimicrobial activity of constituents and their chemical characteristics, a new formulation of oral antiseptic was made based on garlic bulb powder and its active principles with strong antimicrobial activity against a wide range of bacteria and fungi. The antimicrobial activity of garlic bulb powder, allicin and the lozenge with 15% of garlic powder was tested using broth microdilution method. The tested garlic powder, as well the lozenge, have shown very high antimicrobial activity with MIC 1.25-5.00 mg/ml, and 1.87-7.50 mg/ml, respectively. The major compound, allicin, was highly active at a very low concentration. The minimal inhibitory concentration of allicin was from 6.25-12.50 μg/ml for antibacterial activity and 0.4 μg/ml for antifungal activity. Those concentrations are comparable with concentrations of commercially available antibiotics and fungicides. The formulation of an antiseptic with herbal constituents, high antibacterial and antifungal activity and pleasant taste could be an alternative to classical pharmaceutical oral antiseptics.Na osnovu ispitane antimikrobne aktivnosti komponenata i njihovih hemijskih karakteristika, napravljena je nova formulacija oralnog antiseptika koji kao aktivnu komponentu ima prašak belog luka čiji sastojci pokazuju veoma izraženu aktivnost protiv širokog spektra bakterija i gljive Candida albicans. Antimikrobna aktivnost praška belog luka, alicina i lozengi sa 15% praška belog luka je ispitivana bujon mikrodilucionom metodom. Testiran prašak belog luka, kao i lozenge imaju veoma jaku antimikrobnu aktivnost sa minimalnim inhibitornim koncentracijama (MIC) 1,25-5,00 mg/ml (prašak belog luka) i 1,87-7,50 mg/ml (lozenge). Glavna aktivna komponeta belog luka, alicin, pokazuje antimikrobnu aktivnost u veoma niskim koncentracijama. Minimalne inhibitorne koncentracije alicina se kreću od 6,25-12,5 μg/ml protiv bakterija i 0,4 μg/ml protiv gljivice Candida albicans. Ove koncentracije se mogu uporediti sa koncentracijama komercijalnih antibiotika i fungicida. Naši rezultati su u skladu sa prethodnim ispitivanjima alicina i različitih ekstrakta belog luka, i potvrđuju najvažniju ulogu alicina u antimikrobnoj aktivnosti. Veoma je važna visoka aktivnost ovako formulisanog oralnog preparata protiv gljivice C. albicans koja je čest uzročnik infekcija usne duplje. Formulisan proizvod sa antiseptičkim osobinama karakteriše stanje čvrstog rastvora gde su aktivne supstance molekularno-disperzno ugrađene u obliku dobro rastvornog polimernog matriksa (sorbitola) velike specifične površine. Dobra rastvorljivost polimernog matriksa i velika specifična površina omogućuju zadovoljavajuću brzinu otpuštanja aktivnih principa iz belog luka (alicin). Pored visoke antimikrobne aktivnosti, lozenge poseduju prijatan ukus i osvežavaju dah, pa se mogu koristiti kao prirodni antiseptik u prevenciji i terapiji infekcija sluzokože usta i ždrela. Formulacija antiseptika sa biljnim sastojcima i visokom antibakterijskom i antifungalnom aktivnošću može biti alternativa farmaceutskim oralnim antisepticima.Projekat ministarstva br. 173021, br. 34012 i br. 17303

Comparative Study of the Antimicrobial Activity of Selenium Nanoparticles With Different Surface Chemistry and Structure

Although selenium nanoparticles (SeNPs) have gained attention in the scientific community mostly through investigation of their anticancer activity, a great potential of this nanomaterial was recognized recently regarding its antimicrobial activity. The particle form, size, and surface chemistry have been recognized as crucial parameters determining the interaction of nanomaterials with biological entities. Furthermore, considering a narrow boundary between beneficial and toxic effects for selenium per se, it is clear that investigations of biomedical applications of SeNPs are very demanding and must be done with great precautions. The goal of this work is to evaluate the effects of SeNPs surface chemistry and structure on antimicrobial activity against several common bacterial strains, including Staphylococcus aureus (ATCC 6538), Enterococcus faecalis (ATCC 29212), Bacillus subtilis (ATCC 6633), and Kocuria rhizophila (ATCC 9341), as well as Escherichia coli (ATCC 8739), Salmonella Abony (NCTC 6017), Klebsiella pneumoniae (NCIMB 9111) and Pseudomonas aeruginosa (ATCC 9027), and the standard yeast strain Candida albicans (ATCC 10231). Three types of SeNPs were synthesized by chemical reduction approach using different stabilizers and reducing agents: (i) bovine serum albumin (BSA) + ascorbic acid, (ii) chitosan + ascorbic acid, and (iii) with glucose. A thorough physicochemical characterization of the obtained SeNPs was performed to determine the effects of varying synthesis parameters on their morphology, size, structure, and surface chemistry. All SeNPs were amorphous, with spherical morphology and size in the range 70–300 nm. However, the SeNPs obtained under different synthesis conditions, i.e. by using different stabilizers as well as reducing agents, exhibited different antimicrobial activity as well as cytotoxicity which are crucial for their applications. In this paper, the antimicrobial screening of the selected systems is presented, which was determined by the broth microdilution method, and inhibitory influence on the production of monomicrobial and dual-species biofilm was evaluated. The potential mechanism of action of different systems is proposed. Additionally, the cytotoxicity of SeNPs was examined on the MRC-5 cell line, in the same concentration interval as for antimicrobial testing. It was shown that formulation SeNPs-BSA expressed a significantly lower cytotoxic effect than the other two formulations

NUMERIČKA ANALIZA KONAČNIH HIPOELASTIČNIH CIKLIČNIH DEFORMACIJA SA VELIKIM ROTACIJAMA

Constitutive relations which describe engineering materials behaviour during the finite elastoplastic deformations are usually presented in the form of rates of stresses and strains. One of the possible approaches in the constitutive relations formulation is the additive decomposition of the total deformation rate into its elastic part and its plastic part. The elastic deformation rate contributes to any elastoplastic deformation at any stage. Hence, its exact and well-considered formulation is of particular importance and it has to be properly predicted by the corresponding material law. This is of great importance in particular when deformation cyclic processes are considered, in which case small errors may accumulate, even if the total deformation is small.The implementation of the most frequently used corotational rates, i.e. the Jaumann rate and the Green-Naghdi rate, in the hypo-elastic constitutive relations regarding small and moderate rotations gives accurate results for low number of repeated deformation cycles. With increased number of cycles, however, the implementation of these rates results in different and physically non-admissible material responses. This instability in results is particularly observable during the cyclic deformations with large rotations, which is the main subject of this work. In contrast to the aforementioned objective rates, the results of the logarithmic rate implementation into the hypo-elastic constitutive relations for the case of pure elastic deformation describe a physically stable process.Konstitutivne relacije koje opisuju ponašanje materijala pri konačnim elastoplastičnim deformacijama su najčešće date u formi izvoda napona i deformacija. Jedan od mogućih pristupa u formulaciji ovih konstitutivnih relacija je aditivna dekompozicija ukupnog tenzora brzine deformacije na njegov elastični i plastični deo. Kako je doprinos elastične deformacije prisutan na svakom nivou ukupne elastoplastične  deformacije, tačna i unapred dobro razmotrena formulacija elastičnog dela tenzora brzine deformacije je neophodna. Rešenje ovog problema je primena odgovarajućeg materijalnog zakona u kome glavnu ulogu imaju objektivni izvodi, koji u slučaju konačnih deformacija moraju zameniti materijalni izvod. Izbor odgovarajućeg objektivnog izvoda koji figuriše u konstitutivnoj relaciji ima ključnu ulogu i najvažniji je cilj ovog rada. Ovo može biti od posebne važnosti kada se razmatraju ciklične deformacije, čak i ukoliko su ukupne deformacije male.U slučaju čiste elastične deformacije, implementacijom najčešće korišćenih korotacionih izvoda, t.j. Jaumanovog i Grin-Nagdijevog izvoda, u hipoelastičnim konstitutivnim relacijama pri malim i srednjim rotacijama dobijaju se tačni rezultati, dok je broj ponovljenih deformacionih ciklusa mali. Sa povećanjem broja ciklusa, međutim, implementacija ovih izvoda daje rezultate koji se medjusobno dosta razlikuju, a takođe često opisuju fizički nerealno ponašanje materijala. Ova nestabilnost u rezultatima je posebno uočljiva pri modeliranju cikličnih deformacija pri kojima se javljaju velike rotacije, što je glavni zadatak ovog rada. Suprotno predhodno pomenutim objektivnim izvodima, primena logaritamskog izvoda u hipoelastičnim konstitutivnim relacijama daje rezultate koji u slučaju čiste elastične deformacije opisuju fizički stabilan proces

ALTERNATIVNI PRISTUP KONAČNIM DEFORMACIJAMA

In elastoplasticity formulation constitutive relations are usually given in rate form, i.e. they represent relations between stress rate and strain rate. The adopted constitutive laws have to stay independent in relation to the change of frame of reference, i.e. to stay objective. While the objectivity requirement in a material description is automatically satisfied, in an Eulerian description, especially in the case of large deformations, the objectivity requirement can be violated even for objective quantities. Thus, instead of a material time derivative in the Eulerian description objective time derivatives have to be implemented. In this work the importance of the objective rate implementation in the constitutive relations of finite elastoplasticity is clarified. Likewise, it shows the overview of the most frequently used objective rates nowadays, their advantages and shortcomings, as well as the distinctive features of the recently introduced logarithmic rate.U savremenoj formulaciji elastoplastičnog ponašanja materijala konstitutivne relacije su uglavnom date u formi izvoda, tj. predstavljaju vezu između izvoda napona i izvoda deformacije kako u formulaciji plastičnog tako i elastičnog dela deformacije. Usvojene konstitutivne relacije moraju ostati nezavisne u odnosu na promenu koordinatnog sistema, tj. da ostanu objektivne. Dok je preduslov objektivnosti u materijalnoj deskripciji automatski zadovoljen, u Ojlerovoj deskripciji, posebno u slučaju velikih deformacija, objektivnost može biti narušena čak i za objektivne promenljive. Stoga, umesto materijalnog izvoda, u konstitutivnim relacijama datim u Ojlerovoj deskripciji moraju se implementirati objektivni izvodi. Ovaj rad doprinosi pojašnjenju važnosti implementacije objektivnih izvoda u konstitutivnim relacijama konačne elastoplastičnosti i daje pregled danas najčešće korišćenih objektivnih izvoda, njihovih prednosti i nedostataka, kao i izuzetnih karakteristika nedavno uvedenog logaritamskog izvoda

Synergistic effects of Salvia officinalis L. essential oils and antibiotics against methicillin-resistant Staphylococcus aureus

Infections caused by methicillin-resistant Staphylococcus aureus (MRSA) due to the acquisition of resistance to current antimicrobials pose a serious challenge for therapy, and new measures to treat and prevent this infectious pathogen are of crucial importance. Plant essential oils (EOs) and their constituents are promising agents with antimicrobial properties. The aim of this study was to evaluate the antistaphylococcal effect of essential oils from Salvia officinalis using the broth-microdilution method. Essential oils of S. officinalis were isolated from the same individual, but at different life stages - young and old leaves. The effects of combinations of sub-inhibitory concentrations of oil and different antibiotics were evaluated by the checkerboard method. The results, expressed as the fractional inhibitory concentration (FIC) and index (FICI), indicate that the essential oil isolated from young leaves potentiated the inhibitory effect of antibiotics against tested MRSA strains. [Projekat Ministarstva nauke Republike Srbije, br. 173021

Wild mint (Mentha longifolia) extracts in the production of non-alcoholic beverages

Isolates of medicinal and aromatic herbs are used as additives in non-alcoholic drinks to improve the sensory characteristics and antioxidant potential. The method of drying the plant material, among other factors, has a profound influence on the chemical composition and pharmacological activities of plant extracts. This paper analyzes the effect of the drying technique (I - natural drying, II - in the laboratory oven, III - in low-temperature condensational drier) on the volatile fraction of the wild mint (Mentha longifolia (L.) Hudson) extract, in order to select an extract of the best quality for preparation of non-alcoholic drinks. The volatile profile of the extracts was determined by the GC-FID and GC-MS techniques, the antimicrobial activity by the microdilution technique, the antioxidant activity by the DPPH and FRAP assays, and the sensory acceptance according to the Regulation on quality for refreshing non-alcoholic beverages. The results showed that piperitone was the major component of the volatile fraction extract of the natural drying herb and low-temperature condensational drier herb (53.9% and 61.1%, respectively), while the extract of laboratory oven herb was rich in menthone (35.5%). At the concentrations in the range of 0.8-3.2 mg/mL the extracts better inhibited the Gram (+) bacteria. The beverage to which the extract of naturally dried wild mint was added, showed the antioxidant activity (9.09 +/- 0.17 mu mol Fe2+/mL by FRAP and 14.00 +/- 3.00 mu L/mL by DPPH method) and good sensorial characteristics (concentration of the extract 0.8 g/L)

CHARACTERIZATION OF TEA AQUEOUS EXTRACTS AND THEIR UTILIZATION FOR DYEING AND FUNCTIONALIZING FABRICS OF DIFFERENT CHEMICAL COMPOSITIONS

Green, black, rooibos, and hibiscus tea (GT, BT, RT, and HT) aqueous extracts were prepared and characterized in terms of total flavonoids (TFC) and total phenolic (TPC) contents and antioxidant and antimicrobial activities. BT has the highest, while HT has the lowest TFC (1213 vs. 415 mg l–1), while the extracts’ TPCs (2283 – 7251 mg l–1) decreased in the following order: BT > GT > RT > HT. Their antioxidant activities of 78.1 – 93.1% and 97.8 – 100% were determined according to DPPH and ABTS methods, respectively. BT and especially GT aqueous extracts possessed mild effects against several microorganisms. All examined extracts have an affinity for dyeing wool, cellulose acetate, polyamide, and cotton, which is proven by the color strength values of 1.65–19.12. Wool, polyacrylonitrile, polyester, polyamide, cotton, and cellulose acetate functionalized with GT aqueous extract inhibited the growth of S. aureus and E. coli, while polyacrylonitrile and cotton also inhibited the growth of E. faecalis, and C. albicans, respectively. Wide inhibition zones for S. aureus were observed for fabrics functionalized with BT aqueous extract. Generally, the investigated fabrics showed very high (81.60 – 100%) ABTS radical scavenging ability independent of the extract used. TPCs have good linear correlations with the antioxidant activities of wool and polyacrylonitrile determined by the DPPH method. Fabrics with different chemical compositions dyed and/or functionalized with GT or BT aqueous extracts can be used to produce high-valueadded medical textiles with therapeutic, prophylactic, and protective functions. They can find potential applications in wound treatment, especially in skin wounds that are susceptible to infection with S. aureus. Moreover, wool and cotton functionalized with GT or BT aqueous extract can also be considered for use in disposable medical textiles like bandages and gauze used in the wound-healing process.Supplementary information: [https://technorep.tmf.bg.ac.rs/handle/123456789/6918

Antimicrobial and Cytotoxic Activities of the Sulphur Shelf Medicinal Mushroom, Laetiporus sulphureus (Agaricomycetes), from Serbia

Cyclohexane, dichloromethane, and methanol extracts of the medicinal mushroom Laetiporus sulphureus were tested for their antimicrobial, cytotoxic, and radical scavenging activities. Total polyphenol content was also determined. Regarding the amount of the phenolic compounds in the methanol extract, there were 14.1 +/- 0.6 mg gallic acid/g dry extract and a concentration of 0.66 +/- 0.15 mg/mL resulted in the removal of 50% of the DPPH radicals (half-maximal inhibitory concentration [IC50]) . The average minimum inhibitory concentrations (MICs) against a select panel of microorganisms were between 125 and 250 mu g/mL, and the methanolic extract significantly inhibited the growth of Staphylococcus aureus (MIC, 31.25 mu g/mL). Also, cyclohexane and dichloromethane extracts inhibited the growth of Helicobacter pylori (MIC, 62.5 mu g/mL). Cyclohexane and dichloromethane extracts showed higher antiproliferative action compared with the methanol extract. The lowest IC50 was induced on HeLa cells by dichloromethane extract (IC50,67.20 +/- 5.49 mu g/mL), followed by cyclohexane extract (IC50 75.91 +/- 1.57 mu g/mL). The tested cyclohexane and dichloromethane extracts possessed moderate antibacterial and significant cytotoxic activity against both malignant (HeLa and N87) and healthy (MRC5) cell lines. Methanol extracts exhibited promising anti-Helicobacter activity without cytotoxicity against N87 and MRC5 cell lines