Minimum Microbicidal Concentration Research Articles

Bioactive metabolites from endophytes of African club moss- Selaginella kraussiana (Kunze) A. Braun exhibit broad-spectrum pharmaceutical utilities

The search for potent natural compounds from plant and microbial sources is increasing logarithmically to combat various types of health issues of which multidrug-resistant microbes and problems related to oxidative stress are the prime ones. Novel secondary metabolites from endophytes have always been potent alternatives to contemporary antimicrobials and antioxidants. The present study shows that two potent endophytic fungal isolates Ascochyta medicaginicola SK16 and Phomopsis sp. SK5 synthesises non-proteinaceous, thermostable secondary metabolites with broad-spectrum antimicrobial, antioxidative, and cytotoxic activity. Bioassay-guided fractionation revealed that the Ethyl acetate (EA) extract of the cell-free culture extract (CFCE) of SK5 and SK16 constitutes ten and eleven secondary metabolites of which 2,4, -di tert butyl phenol, aziridine- 1,2-amino ethyl, actinobolin, bactobolin, azulene, menthyl acetate, phenol, p-[2-(methylamino)ethyl], and imidazole components were significant. SK16 exhibited strong antimicrobial activity against seventeen pathogens including Methicillin-resistant Staphylococcus aureus (MRSA), and C. albicans with a minimum microbicidal concentration of 100- 400 µg mL−1. These metabolites disrupt the microbial cell membranes causing lethal leakage of biomacromolecules- nucleic acid, protein, and potassium ions. Enzymes involved in the EMP pathway, TCA cycle, and gluconeogenesis were also blocked. Both the biofilm formation and transition of Candida cells from the yeast-to-hyphal form were inhibited. SK5 metabolites are potent radical scavengers with an IC50 of 34.25 ± 0.87 – 195.21 ± 5.73 µg mL−1 against DPPH, ABTS, FRAP, and H2O2 free radical generators and significantly increased antioxidant parameters in treated peritoneal macrophage cells of male Wistar rats. Also, SK5 metabolites were cytotoxic against breast (T47D), pancreatic (MIA Paca-2), lung (A549) and colon (HCT-116) cancer cells. The present findings suggest that metabolites from endophytes of African club moss hold potent pharmaceutical utilities.

Chemical characterization of Thymus zygis L. (thyme) and Elettaria cardamomum L. (cardamom) essential oils and investigation of their inhibitory potentials against cervicovaginal Escherichia coli isolates

IntroductionThe cervicovaginal microbiota plays a crucial role in women's well-being and reproductive health. This study initially focuses on identifying the chemical components of the essential oils (EOs) from Elettaria cardamomum L. (cardamom) (Ec) and Thymus zygis L. (thyme) (Tz). Subsequently, this study aims to determine the antimicrobial and biofilm inhibitory effects of these EOs against both cervicovaginal mixed cultures and the microbial strains isolated from them. MethodsThe compositions of EOs were determined by GC–MS analysis using an Agilent 7890B GC/5977A Series MSD System. Cervicovaginal samples were obtained from two women presenting complaints of a strong odor and vaginal discharge. Samples were collected from the cervix using a sterile cytobrush, ensuring no contact with the urethra, rectum, or external parts of the vagina. The cytological examination was conducted using Papanicolaou staining. Isolated microorganisms were identified through 16S Ribosomal RNA Gene Sequence Analysis and characterized using antibiogram tests. Antimicrobial tests of the EOs were performed by broth microdilution and disc diffusion methods. Biofilm formation was assessed using a crystal violet binding assay. ResultsThe major components of Ec EO were α-terpinyl acetate (41.95 %) and eucalyptol (28.58 %), whereas Tz EO contained significant amounts of o-cymene (38.76 %), carvacrol (22.66 %), and thymol (20.69 %). Escherichia coli codes OR651248 and OR651249 were isolated from CV 6 and CV 7 mixed cultures, respectively. E. coli OR651248 demonstrated a higher antibiotic resistance level than E. coli OR651249. Biofilm formation by mixed cultures was significantly higher than that by E. coli isolates (P < 0.05). The Ec EO displayed minimal to no effect against both mixed cultures, showing zero inhibition zone, 500 μL/mL minimum inhibitory concentrations (MICs), and 500 μL/mL minimum microbicidal concentrations (MMCs). However, the Tz EO exhibited antimicrobial activity against both mixed cultures and the E. coli isolates, with inhibition zones > 15 mm and MICs/MMCs < 4 μL/mL (P < 0.05). In all microbial cultures, 0.5 MIC of both EOs inhibited biofilm formation by more than 80 %. ConclusionThe Tz EO exhibits promising potential as an antimicrobial and biofilm inhibitory agent for managing cervicovaginal E. coli infections.

Newly synthesized palladium(II) complexes with dialkyl esters of (S,S)-propylenediamine-N,N'-di-(2,2'-di-(4-hydroxy-benzil))acetic acid: in vitro investigation of biological activities and HSA/DNA binding.

The four new ligands, dialkyl esters of (S,S)-propylenediamine-N,N'-di-(2,2'-di-(4-hydroxy-benzil))acetic acid (R2-S,S-pddtyr·2HCl) (R = ethyl (L1), propyl (L2), butyl (L3), and pentyl (L4)) and corresponding palladium(II) complexes have been synthesized and characterized by microanalysis, infrared, 1H NMR and 13C NMR spectroscopy. In vitro cytotoxicity was evaluated using the MTT assay on four tumor cell lines, including mouse mammary (4T1) and colon (CT26), and human mammary (MDA-MD-468) and colon (HCT116), as well as non-tumor mouse mesenchymal stem cells. Using fluorescence spectroscopy were investigated the interactions of new palladium(II) complexes [PdCl2(R2-S,S-pddtyr)]; (R = ethyl (C1), propyl (C2), butyl (C3), and pentyl (C4)) with calf thymus human serum albumin (HSA) and DNA (CT-DNA). The high values of the binding constants, Kb, and the Stern-Volmer quenching constant, KSV, show the good binding of all complexes for HSA and CT-DNA. The mentioned ligands and complexes were also tested on in vitro antimicrobial activity against 11 microorganisms. Testing was performed by the microdilution method, where the minimum inhibitory concentration (MMC) and the minimum microbicidal concentration (MMC) were determined.

Antimicrobial activity of amazon medicinal plants

In recent decades, an increase in resistance of bacteria and fungi to antimicrobials has been observed. Therefore, have each other investigated the antimicrobial potential of plants with medicinal properties. In this context, the Amazon has a high variability of plants with potentially active compounds. Thus, the present study aimed to evaluate the antimicrobial activity of ethanol extracts from Amazonian medicinal plants. Leaves and stems of 19 plant species were dried, crushed and extracted by cold maceration with ethanol. The extracts were dried and solubilized at a concentration of 100 mg mL-1 to done antimicrobial activity assays using the agar diffusion method against gram-positive and gram-negative bacteria, and fungi of the genus Candida. Of the total of 38 extracts analyzed, 14 (36.8%) had antimicrobial activity against at least one of the microorganisms tested. The Brazilnut tree stem extract was active against the highest number of microorganisms, three bacteria (S. aureus, E. coli and K. pneumoniae) and three fungi (C. tropicalis, C. parapsilosis and C. krusei). The mulateiro leaf extract was active against three microorganisms, the saracura-mira stem extract against two, and the other extracts only against one microorganism. K. pneumoniae was the most sensitive microorganism, and the most resistant was C. albicans. The lowest values for minimum inhibitory concentration (MIC) for antibacterial activity were for stone-breaker stem extract against K. pneumoniae (0.048 mg mL-1), and for antifungal activity for Brasilnut tree stem against C. krusei (3.125 mg mL-1), stone-breaker leaf against C. guillermondii (3.125 mg mL-1), and mulateiro leaf against C. tropicalis (3.125 mg mL-1). The lowest values of minimum microbicidal concentration (MMC) were for the extracts of stone-breaker stem against K. pneumoniae (0.192 mg mL-1) and mulateiro leaf against C. tropicalis (3.125 mg mL-1). The tested Amazonian medicinal plants had antimicrobial activity, especially Brazilnut tree, this being the first report for this plant species.

New Facts on the Antimicrobial Essential Oil of Satureja kitaibelii.

The objective of the present study was to assess the difference in antimicrobial activity of Satureja kitaibelii Wierzb. ex Heuff. essential oil at three growth stages. In addition, using statistical and chemometric tools, we tried to explain why the essential oil from a certain vegetation stage shows the highest antimicrobial activity. S. kitaibelii essential oils demonstrated minimum inhibitory concentration values from 160 to 10000 μg mL-1 , and minimum microbicidal concentration values from 630 to 20000 μg mL-1 . Geraniol, borneol, limonene and p-cymene are the dominant compounds of S. kitaibelii essential oil. The most abundant compound, geraniol, possesses antimicrobial activity in a range of MIC values from 40 to 5000 μg mL-1 and MMC values from 80 to 10000 μg mL-1 . The highest activity of essential oil for all tested strains of microorganisms was recorded in November. Results of statistical analysis indicate that the percentage of dominant compounds of essential oils does not affect the antibacterial activity of essential oils. Chemometric analyses leads to the conclusion that borneol, spathulenol, caryophyllene oxide and limonene can be the main contributors to the antibacterial activity of essential oil from November and that their mutual ratio is important. These results may represent a new methodological approach for future research on essential oils.

Chemical composition, antioxidative and antimicrobial activities of essential oil of wild Artemisia annua from Ningxia, China

Artemisia annua is an essential aromatic medicinal plant endemic to China. Here, essential oil was extracted from wild A. annua from Ningxia, China. GC-MS analysis showed that A. annua essential oil was dominated by artemisia ketone, a characteristic compound accounting for 31.26%, followed by eucalyptol (14.89%), camphor (8.69%), myrcene (8.25%) and α-pinene (6.65%). The overall antioxidative potential represented by DPPH and ATBS free radical scavenging rates was weak. The essential oil exhibited good bactericidal activities against Escherichia coli and Staphylococcus aureus and fungicidal activities against Trichophyton rubrum and Epidermophyton floccosum. The minimum inhibitory and microbicidal concentrations were 0.02 mg/mL and 5.12 mg/mL for both bacteria, 0.315% and 2.5% for E. floccosum, and 0.625% and 5% for T. rubrum. The results suggest that A. annua essential oil may be an antimicrobial adjuvant to be applied in pharmaceutical and cosmetic industries.

Synthesis and Characterization of Bioactive Glass and Zinc Oxide Nanoparticles with Enamel Remineralization and Antimicrobial Capabilities.

We investigated the effect of bioactive glass and zinc oxide nanoparticles on enamel remineralization, as well as their antimicrobial effect on cariogenic microbes. This is the first study that investigated the properties of bioactive glass and zinc oxide nanoparticles with mixed materials. Fluoride gel (F), bioactive glass microparticles (µB), bioactive glass nanoparticles (nB), zinc oxide nanoparticles (Z), and a mixed suspension of nB and Z (nBZ) were prepared and characterized by scanning and transmission electron microscopy, zeta potential measurement, X-ray diffraction, and acid buffering capacity testing. Further, we performed a remineralization cycle test of 28 days, and nanoindentation testing was carried out during the immersion period, and then the enamel surfaces were examined using scanning electron microscopy. Additionally, the antimicrobial effects of the sample suspensions were evaluated by measuring their minimum microbicidal concentrations against various cariogenic microbes. Our results revealed that nB had a near-circular shape with an amorphous structure and a considerably large specific surface area due to nanoparticulation. Additionally, nB possessed a rapid acid buffering capacity that was comparable to that of μB. In the remineralization test, faster recovery of mechanical properties was observed on the enamel surface immersed in samples containing bioactive glass nanoparticles (nB and nBZ). After remineralization, demineralized enamel immersed in any of the samples showed a rough and porous surface structure covered with mineralized structures. Furthermore, nBZ exhibited a broad antimicrobial spectrum. These results demonstrated that bioactive glass and zinc oxide nanoparticles have superior demineralization-suppressing and remineralization-promoting effects.

ANTIMICROBIAL ACTION OF PSIDIUM GUAJAVA L. EXTRACT AGAINST ENTEROCOCCUS FAECALIS AND CANDIDA ALBICANS STRAINS: A PILOT STUDY

Endodontic treatment consists of decontamination of the root canal using irrigants like Sodium Hypochlorite (NaOCl). However, some microorganisms resist conventional therapies, causing relapse and secondary infections. Substances with microbicidal power and potential to become new irrigants need to be studied. Thus, the objective of the present study was to evaluate the antimicrobial potential of Psidium guajava L. (guava tree) extract against clinical and standard (ATCC) strains of Enterococcus faecalis and Candida albicans. For this purpose, the extract was produced from the raw material (leaves and shoots) diluted in the hydroethanolic vehicle (EtOH: H2O / 50:50) for subsequent microbiological analysis. The Minimum Inhibitory Concentration (MIC) and Minimum Microbicidal Concentration (MMC) of the plant extract were tested, according to the Clinical and laboratory standards institute (CLSI) guidelines, on four strains: E. faecalis (ATCC and clinic) and C. albicans (ATCC and clinic). The extract of P. guajava did not produce antifungal action on C. albicans, however, it showed microbicidal potential against strains of E. faecalis, showing MIC of 0.20%. This concentration was lower than the MIC of NaOCl which was 0.31%, a solution that is commonly used in dental clinics. In conclusion, the hydroethanolic extract of P. guajava presents bactericidal action against E. faecalis, being a natural product with potential for future studies regarding the development of new endodontic irrigants.

Synthesis, characterization, HSA binding, molecular docking, cytotoxicity study, and antimicrobial activity of new palladium(II) complexes with propylenediamine derivatives of phenylalanine

The four new ligands, propylenediamine derivatives of phenylalanine (R2-S,S-pddbaˑ2HCl; L1-L4) and their palladium(II) complexes (C1-C4) were synthesized and characterized by elemental analysis, infrared, 1H and 13C NMR spectroscopy. The interactions of new palladium(II) complexes with human serum albumin (HSA) were studied by fluorescence spectroscopy. All investigated compounds can be transported to target cells by binding to HSA, but complex C4 interacts most strongly. Molecular docking simulations were applied to comprehend the binding of the complex to the molecular target of HSA. Obtained results are in good correlations with experimental data regarding binding affinity by HSA. In vitro cytotoxicity activities were investigated on four tumor cell lines (mouse mammary (4 T1) and colon (CT26), human mammary (MDA-MD-468) and colon (HCT116)) and mouse mesenchymal stem cells as non-tumor control cells. Cytotoxic capacity was determined by MTT test and according to obtained results ligand L4 stands out as the most active and selective compound and as a good candidate for future in vivo testing. Further examination of the ligand L4 and corresponding complex C4 led to the conclusion that both induced cell death mainly by apoptosis. Ligand L4 facilitated cycle arrest in G0/G1 phase and decreased proliferative capacity of tumor cells. In vitro antimicrobial activity for ligands and corresponding Pd(II) complexes was investigated against eleven microorganisms (eight strains of pathogenic bacteria and three yeast species) using microdilution method. The minimum inhibitory concentration and minimum microbicidal concentration were determined.

Antimicrobial activities, phenolic and flavonoid contents, antioxidant and DNA protection of the internal and outer layers of Allium cepa L. from Iran

Allium cepa L., known as a wild onion in Iran with different high antioxidant and antimicrobial activities in internal and outer layers. The aim of this study was to assess phenolic and flavonoid contents as well as antioxidant and antimicrobial activities of the internal and outer layers of ten Iranian onions (Allium cepa L.) landrace and compare them with three hybrid onions. Results showed that the total phenolic, flavonoid contents and the antioxidant capacity of the onions ranged 18.76–65.25 (mg GAE/g DW), 0.06–1.92 (mg/g DW) and 10.34–40.54%, respectively. The results showed higher total phenolic and flavonoid content as well as antioxidant activity and protection of pBR322 DNA in the outer layer in compare to internal ones due to higher hydroxyl radicals. Based on the results, the present study showed that red onions such as landraces originated from Azarshahr and Nowshahr included the highest quantities of phenolic and flavonoid contents as well as antioxidant activity and DNA protection values. Inhibition zone and minimum inhibitory and minimum microbicidal concentration of internal layer of onion from Kahrizak were significantly different from others (p < 0.05). This research showed the potential of Iranian onions as a natural preservative and good antioxidant.

Evaluation of the antimicrobial activity of silver nanoparticles biosynthesized from the aqueous extract of Schinus terebinthifolius Raddi leaves.

Silver nanoparticles (AgNPs) synthesized from green synthesis using medicinal plants are presented as an option for the development of new antimicrobial agents. In this context, this study aims to evaluate the antimicrobial activity of silver nanoparticles synthesized from the aqueous extract of Schinus terebinthifolius Raddi leaves, popularly known as "aroeira." A 23 factorial design was used to assess the statistical significance of the studied factors, and Box-Behnken design was used to define the optimal conditions for the green synthesis of AgNPs. The studied factors were significant for the synthesis of nanoparticles, and the optimal conditions were pH 9.5, reaction time of 180min, and 10g of S. terebinthifolius Raddi leaves. The samples were characterized using UV-Vis spectroscopy, Fourier transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and dynamic light scattering. Antimicrobial activity was evaluated using the broth microdilution method and through the minimum microbicidal concentration. AgNPs showed greater antimicrobial efficacy compared to the extract, both for bacteria and fungi: bacteriostatic activity against all tested bacteria and bactericidal against Pseudomonas aeruginosa, besides fungistatic action against Candida albicans and Candida glabrata. Finally, the aqueous extract of "aroeira" leaves was effective in the synthesis of AgNPs, with greater antimicrobial potential than the extract.

Phytotoxic, insecticidal, and antimicrobial activities of Ajania tibetica essential oil.

The chemical profile of Ajania tibetica essential oil (EO) and its phytotoxic, insecticidal, and antimicrobial activities were assessed. Monoterpenes (79.05%) and sesquiterpenes (10.33%) were dominant in the EO, with camphor, (+/-)-lavandulol and eucalyptol being the major constituents, representing 55.06% of the total EO. The EO possessed potent phytotoxicity against Poa annua and Medicago sativa starting from 0.5 mg/mL, and when the concentration rose to 5 mg/mL, seed germination of both tested species was 100% suppressed. Ajania tibetica EO displayed significant pesticidal activity against Aphis gossypii with an LC50 value of 17.41 μg/mL; meanwhile, the EO also showed antimicrobial activity against Escherichia coli, Bacillus subtilis, Verticillium dahlia and Aspergillus niger using broth microdilution and disc diffusion methods. For the tested bacterial and fungal strains, the EO exhibited a repressing effect, with minimum inhibitory concentrations (MICs) ranging from 0.3125 to 1.25 mg/mL for bacteria and from 1.25 to 2.5 mg/mL for fungi, whereas the minimum microbicidal concentrations (MMCs) were 5 mg/mL for bacteria and 2.5 mg/mL for fungi. Our study is the first report on the chemical profile as well as the phytotoxicity, insecticidal and antimicrobic activity of A. tibetica EO, indicating its potential value as an alternative synthetic pesticide.

Chemical Composition and Antimicrobial Activity of Essential Oils from Three Mediterranean Plants against Eighteen Pathogenic Bacteria and Fungi.

The chemical composition and antimicrobial activity of essential oils (EOs) obtained from three medicinal plants of the Moroccan flora were evaluated. The chemical composition of EOs of Thymus leptobotrys, Laurus nobilis and Syzygium aromaticum was determined using a gas chromatograph coupled with mass spectrometry. Carvacrol (75.05%) was the main constituent of T. leptobotrys EOs, while 1,8-cineole (31.48%) and eugenol (82.16%) were the predominant components of L. nobilis and S. aromaticum EOs, respectively. The antimicrobial activity of the EOs was evaluated qualitatively and quantitatively against 18 microbial strains pathogenic to humans by using the disc diffusion method, and by measuring the minimum inhibitory concentration (MIC) and minimum microbicidal concentration (MMC). The EOs of T. leptobotrys were the most active against the strains tested, with inhibitory zone values ranging from 7.00 to 45.00 mm, and MIC and MMC values ranging from 0.312 to 80.00 mg/mL. In many cases, these EOs exhibited higher antibacterial and antifungal activities than the chemical compounds ciprofloxacin and fluconazole, respectively. This high antimicrobial activity can be ascribed to their richness in carvacrol. The EOs of T. leptobotrys, L. nobilis, and S. aromaticum could be considered a promising alternative to replace chemical antimicrobials, and a readily available natural source of bioactive compounds.

Optimizing the Culture Medium of Lasiodiplodia sp. to Improve the Yield of Ethyl Acetate Extract as an Antimicrobial Source.

Endophytes often inhabit plant tissues and cause no disease symptoms. Lasiodiplodia is generally considered a pathogenic fungus, but such a genus is capable of producing high-value bioactive molecules, such as enzymes, secondary metabolites including antimicrobials. Therefore, Lasiodiplodia sp. endophyte was cultivated in static mode for 12days and EtOAc extracts were obtained and evaluated against pathogens afterward. Fermentation parameters (glucose, sucrose and NaNO3) were optimized by the factorial design and response surface methodology, as these are powerful tools to provide reliable information about fungal culture conditions and EtOAc extract yields were considered as response variables. Lasiodiplodia growth curve indicated that optimal production of EtOAc extract mass was achieved after 12days of fermentation (284mg 300mL-1 broth), which is in agreement with values obtained from validation tests. Minimum Inhibitory Concentration (MIC) and Minimum Microbicidal Concentration (MMC) essays suggested that the endophyte produce substances presenting antimicrobial and antifungal activities against ATCC Staphylococcus aureus and Candida albicans strains at optimum point under evaluated conditions. MIC values ranged between 50 and 100µgmL-1 for both pathogens, while MMC of C. albicans ranged from 100 to 200µgmL-1, which evidence its fungicidal effect. Furthermore, it was found that the EtOAc extract yield can be increased by optimizing carbon and nitrogen sources in endophyte cultivation, and there was good agreement between predicted and experimental values under optimized conditions. Thus, Lasiodiplodia fungi are promising sources of antimicrobials and changes in carbon and nitrogen sources can improve the yield of secondary metabolites according to the factorial design.

Synthesis, characterization, DNA interactions and biological activity of new palladium(II) complexes with some derivatives of 2-aminothiazoles

Newly palladium(II) complexes (C1, C2) with derivatives of 2-aminothiazoles (L1 = 2-amino-6-methylbenzothiazole, L2 = 2-amino-6-chlorobenzothiazole), general formula [PdL2Cl2] were synthesized and characterized by elemental microanalyses, IR, NMR spectroscopy and X-ray spectroscopy in case of [Pd(L2)2Cl2]. The kinetic of the substitution reactions of complexes and the nucleophiles, such as guanosine-5′-monophosphate (5’-GMP), tripeptide glutathione (GSH) and amino acid L-methionine (L-Met), were studied by stopped-flow technique. The complex C2 was always more reactive, while the order of the reactivity of the nucleophiles, due to the associative mode of the reaction, was L-Met > GSH > 5’-GMP. In order to determine the type of interactions between palladium(II) complexes and calf thymus DNA (CT-DNA), we used electronic absorption spectroscopy, viscosity measurements, and fluorescence spectroscopic studies, while interactions with bovine serum albumin (BSA) were determined only with fluorescence spectroscopic studies. The observed results confirmed that both complexes bound to DNA by groove binding. The significantly strong interaction with BSA, especially for complex C2, was also observed. In vitro cytotoxic activity was evaluated against four tumor cell lines, 4 T1, CT26, MDA-MB-468, HCT116 and mesenchymal stem cells (mMSC). C1 complex showed higher cytotoxic activity against CT26 cell line. Flow cytometry analysis showed that C1 stimulated apoptosis of tumor cells via inhibition of expression of antiapoptotic Bcl-2 molecule and decelerated proliferation by decreasing Cyclin-D and increasing expression of P21. In vitro antimicrobial activity for ligands and corresponding palladium(II) complexes was investigated by microdilution method and minimum inhibitory concentration (MIC) and minimum microbicidal concentration (MMC) were determined. Tested compounds exhibited selective and moderate activity.

Isolation of active antiphytopathogen compound from extracts of Anadenanthera colubrina var. cebil (Griseb.) Altschul

Several microorganisms are responsible for great economic losses in world agriculture. Preventive and treatment methods are applied to avoid contamination of crops by these microorganisms, however, the use of chemical antimicrobials damages health and the environment. Secondary plant metabolites are safe natural sources of antimicrobials for this application. Fabaceae family has its history described in the literature as a potential source for obtaining antimicrobial bioactive. The objective of this work was to isolate bioactive compounds guided by antimicrobial assays against bacteria and fungi in vitro. Organic extracts were prepared by eluotropic series of leaves of Anadenanthera colubrina var. cebil and were tested against six bacteria and six fungi phytopathogenic. The antimicrobial assays of minimum inhibitory concentration (MIC) and minimum microbicidal concentration (MMC) were performed at each purification step that occurred through HPLC-DAD, Flash Chromatography and HPLC-preparative analysis, to confirm the isolation of the bioactive. Through bioguided isolation, the compound p-hydroxybenzoic acid was obtained, which showed activity against the phytobacteria Xanthomonas campestris pv. campestris and Acidovorax citrulli.

Phytochemical Screening, Antimicrobial and Antioxidant Activities of Aloe buettneri, Mitracarpus scaber and Hannoa undulata used in Togolese Cosmetopoeia

Background: Aloe buettneri, Mitracarpus scaber and Hannoa undulata are three plants species used in the Togolese traditional medicine to cure dermatosis. This study aims at assessing their anti-oxidant and anti-microbial activities on acne-developing micro-organisms.&#x0D; Methods: Six micro-organisms including Cutibacterium acnes ATCC 6919, Pseudomonas aeruginosa ATCC 27853; Escherichia coli ATCC 25922; Klebsiella pneumoniae ATCC 700603; Staphylococcus aureus ATCC 29213; and Candida albicans ATCC 35659 were used. Inhibition diameter was assessed using the agar well diffusion method. Minimum inhibitory and minimum microbicidal concentrations have been achieved through the liquid dilution method. Anti-oxidant activities were evaluated by DPPH antiradical scaving and FRAP methods. Phytochemical screening was also realized.&#x0D; Results: All the microorganism’s strains tested, excepted Candida albicans and Escherichia coli, were susceptible to plants extracts at 250 mg/mL in the agar well diffusion assay with inhibition diameters ranging from 12.10 ± 0.07 to 18.20 ± 0.10 mm. The MICs values were comprised between 15.625 mg/mL and 62.5 mg/mL, when MMCs ranged from 31.25 to 125 mg/mL. At the concentration of 500 µg/mL, the scavenging properties on DPPH radicals were 49.20 ± 0.15% for H. undulata, 41.29 ± 0.51% for A. buettneri, 59.57 ± 0.41% for M. scaber and 87.22 ± 0.03% for Quercetin. For FRAP assay, the effective concentration (EC50) of A. buettneri, M. scaber and H. undulata extracts were 977.44 ± 1.13 µg/mL; 267.74 ± 10.13 µg/mL and, 272.54 ± 12.87 µg/mL respectively while quercetin presented the EC50 of 48.63 ± 2.00 µg/mL. The antimicrobial and antioxidant activities of these species might be required to the presence of polyphenols, tannins, flavonoids, triterpenes, saponoside and alkaloids identified by phytochemical screening.&#x0D; Conclusion: The three plants extracts are all potential natural antimicrobial and antioxidant candidates for treating acne vulgaris.&#x0D; Keywords: Aloe buettneri, Mitracarpus scaber, Hannoa undulata, antimicrobial activity, antioxidant activity, phytochemical screening, Acne vulgaris

Synthesis of series of different imidazolidine-2,4-dione derivatives and evaluation of their antimicrobial potential

A series of twenty two different imidazolidine-2,4-dione derivatives, divided according to their structure into five groups, including alkyl, alkenyl or aryl 5,5disubstituted hydantoins, spirohydantoins, and fused bicyclic and tricyclic hydantoins, was synthesized and examined for in vitro antimicrobial activity against 15 strains of bacteria and 4 strains of yeast. The antimicrobial activity was evaluated by the determination of the minimal inhibitory concentration (MIC) and the minimal microbicidal concentration (MMC) using the microdilution method. The assayed compounds exerted moderate antibacterial and weak antifungal activity. The antimicrobial activities were influenced by the structure and concentration of the tested compounds as well as the type of test microorganisms. The fused bicyclic hydantoin derivatives obtained by organoselenium induced intramolecular cyclization exhibited the highest inhibitory activity. The examined hydantoin derivatives seem as drug-like candidate for further evaluation of biological activities.

Grape stalks as a source of antioxidant and antimicrobial substances and their potential application

This research project aimed to analyse the biological potential of aqueous, ethanolic, methanolic, and ethyl acetate extracts of red grape stalks, as well as lyophilised red grape stalks from Krnjevo (Serbia). The concentration of the total phenols and flavonoids, as well as the antioxidant activity of the stalk extracts were measured by means of the spectrophotometric method. In vitro antimicrobial activity of 23 selected species of microorganisms (13 species of bacteria and 10 species of fungi) was evaluated by determining the minimum inhibitory concentration (MIC) and the minimum microbicidal concentration (MMC). The results indicated that the highest concentration of total phenols was measured in the ethyl acetate extract (60.08 mg GAE/g of extract), while the highest total flavonoid concentration was observed in the acetone extract (34.24 mg RUE/g of extract). The tested extracts showed poor antioxidant activity compared to chlorogenic acid. The acetone extract probably showed the strongest antimicrobial activity due to the high concentrations of phenols and flavonoids. The tested extracts showed a better effect on Gram-positive bacteria than on Gram-negative bacteria. Although grape stalks are a by-product in the wine industry, they are a potential source of natural compounds which can be used for a variety of purposes in many fields ranging from the food industry to medicine.

Biological activity of roots and aerial parts of Zinnia peruviana on pathogenic micro-organisms in planktonic state and biofilm forming.

Microbial resistance to antibiotics affects the control of clinical infections and is a growing concern in global public health. One important mechanism whereby micro-organisms acquire resistance is biofilm formation. This context has led to the investigation of new antimicrobial substances from plants popularly used in folk medicine. In this work, we studied the antimicrobial and antibiofilm activity of Zinnia peruviana roots, ziniolide (major root metabolite) and aerial parts against Staphylococcus aureus, Staphylococcus epidermidis, Listeria monocytogenes, Escherichia coli, Pseudomonas aeruginosa and Candida albicans. The minimum inhibitory and minimum microbicidal concentration and inhibition of biofilm production was determined. All Z. peruviana extracts showed antimicrobial activity, but that corresponding to the roots was the most active one. The best inhibitory and microbicidal activity was detected against Gram-positive bacteria (0·039-0·078 mg ml-1 ). The acetonic extract from Z. peruviana leaves showed moderate activity against Gram-positive bacteria (0·625 mg ml-1 ). Acetonic extract of Z. peruviana flowers showed weak activity (1·25-5 mg ml-1 ). All the extracts tested showed inhibition of biofilm formation, as well as the ziniolide, however, roots and flowers extracts showed higher antibiofilm activity particularly against Staphylococcus, Listeria and Candida. The extracts tested may be a promising natural alternative for the control of microbial infections.