Minimum Inhibitory Concentration (MIC) And Minimum Bactericidal/fungicidal Concentration Research Articles

Antibacterial and Antifungal Activities of Cimbopogon winterianus and Origanum syriacum Extracts and Essential Oils against Uropathogenic Bacteria and Foodborne Fungal Isolates.

This study focused on testing the antibacterial and antifungal activity of Origanum syriacum (O. syriacum) and Cimbopogon winterianus (C. winterianus) extracts and their essential oils (EOs). The bacteria were isolated from urine samples and identified by a VITEK assay, and the fungi were isolated from spoiled food samples and further identified by MALDI-TOF. The susceptibility of the microbial isolates was assessed by determining the bacteriostatic and bactericidal/fungicidal effects by the minimum inhibitory concentration (MIC) and minimum bactericidal/fungicidal concentration (MBC/MFC) broth microdilution assay and time-kill test. The antibiofilm activities were assessed by the antibiofilm screening assays. The bacterial isolates included three Gram-negative isolates (Escherichia coli, Klebsiella pneumonia, and Citrobacter freundii) and two Gram-positive isolates (Staphylococcus aureus and Streptococcus intermedius). The fungal isolates included Candida albicans and Aspergillus niger. The O. syriacum and C. winterianus extracts exhibited bacteriostatic and fungistatic activities (MIC 1.25-2.5 mg/mL for the bacterial isolates and 2.5-5 mg/mL for the fungal isolates). However, their EOs exhibited bactericidal (MBC 5-20%) and fungicidal (MFC 1.25-10%) activities, meaning that the EOs had a better antimicrobial potential than the extracts. The antibiofilm activities of the mentioned extracts and their EOs were relatively weak. The O. syriacum extract inhibited S. aureus, S. intermedius, and K. pneumonia biofilms at a concentration of 0.3125 mg/mL and C. albicans and A. niger biofilms at 0.625 mg/mL. No antibiofilm activity was recorded for C. winterianus extract. In addition, the packaging of grapes with C. winterianus extract preserved them for about 40 days. The results reflect the significant antimicrobial activity of O. syriacum and C. winterianus extracts and their EOs, thus suggesting their potential in food packaging and preservation.

Chemical Composition and Antimicrobial Activity of Essential Oils and Hydrosols from Oregano, Sage and Pennyroyal against Oral Pathogens

In this study, the chemical composition of essential oils (EOs) extracted from Origanum vulgare ssp. hirtum Lamiaceae, (oregano), Salvia officinalis Lamiaceae (sage), Mentha pulegium Lamiaceae (pennyroyal), and respective hydrosols (HSs) has been investigated by Gas Chromatography–Mass Spectrometry (GC-MS). The antimicrobial activity was assessed against two oral pathogens: Gram-positive bacterium Streptococcus mutans and the fungus Candida albicans by determination of Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal/Fungicidal concentration (MBC/MFC). Three-fold diluted solutions were dispensed into each well of a 96-well microtiter plate and, after incubation, MIC was determined by visual monitoring. The MBC/MFC was determined by transferring a small quantity of sample contained in each replicate well of the microtiter plates to appropriate culture media using a microplate replicator. The EOs of the tested herbs showed antimicrobial properties, especially the EO oil of O. vulgare, which exerted the highest antimicrobial activity. HSs of S. officinalis and M. pulegium exerted no antimicrobial activity, in contrast to oregano HS, which displayed strong antimicrobial activity. In all cases, a higher number of compounds were detected in EOs than in the corresponding HSs. The major compounds of sage EO were detected to be α-thujone (25.1%), 1,8-cineole (15.8%) and β-pinene (10.0%), while the HS was characterized by the presence of 1,8-cineole (32.6%), borneol (22.6%) and α-thujone (22.4%). Pennyroyal EO and HS consists mainly of pulegone (62.1 and 50.6%, respectively). Carvacrol was the major component present in EO (63%) and HS (97.3%) of oregano, probably contributing to the antimicrobial activity. Further research is needed in order to elucidate the antimicrobial mechanisms of specific compounds present in essential oils and hydrosols of Lamiaceae grown in Greece against oral pathogens.

In vitro antimicrobial and antibiofilm screening of eighteen Iranian medicinal plants

BackgroundNatural products are one of the best candidates for controlling drug-resistant pathogens, the advantages of which include low production costs and low side effects. In this study, as potential antimicrobials, the anti-bacterial and antibiofilm activities of several Iranian native medicinal plants were screened.MethodsThe antibacterial/antifungal and anti-biofilm activities of 18 medicinal plants including Reseda lutea L., Nepeta sintenisii Bunge., Stachys turcomanica Trautv., Stachys lavandulifolia Vahl, Diarthron antoninae (Pobed.) Kit Tan., Ziziphora clinopodioides Lam., Euphorbia kopetdaghi Prokh, Euphorbia serpens Kunth., Hymenocrater calycinus Benth., Scutellaria pinnatifida A.Ham., Viola tricolor L., Hypericum helianthemoides (Spach) Boiss., Hypericum scabrum L., Convolvulus lineatus L., Scabiosa rotata M.Bieb Greuter & Burdet, Delphinium semibarbatum Bien. Ex Boiss., Glycyrrhiza triphylla Fisch. & C.A.Mey., and Ziziphus jujuba Mill., against two Gram-positive bacteria, Staphylococcus aureus, Bacillus cereus, as well as two Gram-negative bacteria, Pseudomonas aeruginosa, Escherichia coli; and Candida albicans as a fungal strain, were evaluated. The minimum inhibitory concentration (MIC) and minimum bactericidal/fungicidal concentration (MBC/MFC) values of the extracts against tested microorganisms were reported and we investigated their effect on the biofilm inhibition of Pseudomonas aeruginosa PAO1, Staphylococcus epidermis, Staphylococcus aureus and Streptococcus mutans. In addition, the effect of the extracts on the eradication of the biofilms of these bacteria was evaluated.ResultsIn this study, H. scabrum was found to exhibit potentially significant activity against Gram-positive bacteria with the MIC range of 6.25–25 µg/mL. This extract also showed a significant effect on inhibiting the biofilm of S. aureus, S. mutans, and S. epidermidis and eradicating the biofilm of S. epidermidis DSMZ 3270. In addition, Hymenocrater calycinus root extract had moderate antibacterial activity against B. cereus with the MIC and MBC 62.5 µg/mL, respectively.ConclusionsThe results of this study showed that the root extracts of two plants, Hypericum scabrum and Hymenocrater calycinus, had antimicrobial and anti-biofilm effects. Based on the observed anti-biofilm effects, these two plants may be considered in future studies to find responsible antimicrobial compounds.

Antimicrobial photodynamic therapy against a dual-species cariogenic biofilm using a ruthenium-loaded resin-based dental material

BackgroundStreptococcus mutans and Candida albicans are associated with caries recurrence. Therefore, this study evaluated the combination of a Ru(II)-loaded resin-based dental material (RDM) and antimicrobial photodynamic therapy (aPDT) against a dual-species biofilm of S. mutans and C. albicans. MethodsAn aPDT protocol was established evaluating Ru(II)'s photocatalytic activity and antimicrobial potential under blue LED irradiation (440–460 nm, 22.55 mW/cm2) at different energy densities (0.00, 6.25, 20.25, 40.50 J/cm2). This evaluation involved singlet oxygen quantification and determination of minimum inhibitory concentration (MIC) and minimum bactericidal/fungicidal concentration (MBC/MFC). The biofilm was grown (72 h) on resin disks prepared with Ru(II)-doped RDM (0.00, 0.56, or 1.12 %) and samples were exposed to aPDT or dark conditions. The biofilm was then harvested to analyze cell viability (CFU counts) and formation of soluble and insoluble exopolysaccharides. ResultsThe photocatalytic activity of Ru(II) was concentration and energy density dependent (p < 0.05), and MIC/MBC values were reduced for the microorganisms after LED irradiation (40.5 J/cm2); therefor, this energy density was chosen for aPDT. Although incorporation of Ru(II) into RDM reduced the biofilm growth compared to Ru(II)-free RDM for both species in dark conditions (p < 0.05), aPDT combined with an Ru(II)-loaded RDM (0.56 or 1.12 %) potentialized CFU reductions (p < 0.05). Conversely, only 1.12 % Ru(II) with LED irradiation showed lower levels of both soluble and insoluble exopolysaccharides compared to Ru(II)-free samples in dark conditions (p < 0.05). ConclusionsWhen the Ru(II)-loaded RDM was associated with blue LED, aPDT reduced cell viability and lower soluble and insoluble exopolysaccharides were found in the cariogenic dual-species biofilm.

Ceragenin-mediated disruption of Pseudomonas aeruginosa biofilms.

Microbial biofilms, as a hallmark of cystic fibrosis (CF) lung disease and other chronic infections, remain a desirable target for antimicrobial therapy. These biopolymer-based viscoelastic structures protect pathogenic organisms from immune responses and antibiotics. Consequently, treatments directed at disrupting biofilms represent a promising strategy for combating biofilm-associated infections. In CF patients, the viscoelasticity of biofilms is determined mainly by their polymicrobial nature and species-specific traits, such as Pseudomonas aeruginosa filamentous (Pf) bacteriophages. Therefore, we examined the impact of microbicidal ceragenins (CSAs) supported by mucolytic agents-DNase I and poly-aspartic acid (pASP), on the viability and viscoelasticity of mono- and bispecies biofilms formed by Pf-positive and Pf-negative P. aeruginosa strains co-cultured with Staphylococcus aureus or Candida albicans. The in vitro antimicrobial activity of ceragenins against P. aeruginosa in mono- and dual-species cultures was assessed by determining minimum inhibitory concentration (MIC) and minimum bactericidal/fungicidal concentration (MBC/MFC). Inhibition of P. aeruginosa mono- and dual-species biofilms formation by ceragenins alone and in combination with DNase I or poly-aspartic acid (pASP) was estimated by the crystal violet assay. Additionally, the viability of the biofilms was measured by colony-forming unit (CFU) counting. Finally, the biofilms' viscoelastic properties characterized by shear storage (G') and loss moduli (G"), were analyzed with a rotational rheometer. Our results demonstrated that ceragenin CSA-13 inhibits biofilm formation and increases its fluidity regardless of the Pf-profile and species composition; however, the Pf-positive biofilms are characterized by elevated viscosity and elasticity parameters. Due to its microbicidal and viscoelasticity-modifying properties, CSA-13 displays therapeutic potential in biofilm-associated infections, especially when combined with mucolytic agents.

Development of a Novel Peptide with Antimicrobial and Mineralising Properties for Caries Management.

The purpose of the study is to develop a novel peptide for caries management. Gallic-Acid-Polyphemusin-I (GAPI) was synthesised by grafting Polyphemusin I (PI) and gallic acid (GA). Biocompatibility was evaluated using a Cell Counting Kit-8 Assay. Antimicrobial properties were assessed using minimum inhibitory concentration (MIC) and minimum bactericidal/fungicidal concentration (MBC/MFC). The bacterial and fungal morphology after GAPI treatment was investigated using transmission electron microscopy (TEM). The architecture of a consortium biofilm consisting of Streptococcus mutans, Lacticaseibacillus casei and Candida albicans was evaluated using scanning electron microscopy (SEM) and confocal laser scanning microscopy. The growth kinetics of the biofilm was examined using a propidium monoazide-quantitative polymerase chain reaction. The surface and calcium-to-phosphorus molar ratio of GAPI-treated enamel after pH cycling were examined with SEM and energy-dispersive X-ray spectroscopy. Enamel crystal characteristics were analysed using X-ray diffraction. Lesion depths representing the enamel's mineral loss were assessed using micro-computed tomography. The MIC of GAPI against S. mutans, L. casei and C. albicans were 40 μM, 40 μM and 20 μM, respectively. GAPI destroyed the biofilm's three-dimensional structure and inhibited the growth of the biofilm. SEM showed that enamel treated with GAPI had a relatively smooth surface compared to that treated with water. The calcium-to-phosphorus molar ratio of enamel treated with GAPI was higher than that of the control. The lesion depths and mineral loss of the GAPI-treated enamel were less than the control. The crystallinity of the GAPI-treated enamel was higher than the control. This study developed a biocompatible, mineralising and antimicrobial peptide GAPI, which may have potential as an anti-caries agent.

Chemical Composition and Antimicrobial Properties of Honey Bee Venom.

Due to its great medical and pharmaceutical importance, honey bee venom is considered to be well characterized both chemically and in terms of biomedical activity. However, this study shows that our knowledge of the composition and antimicrobial properties of Apis mellifera venom is incomplete. In this work, the composition of volatile and extractive components of dry and fresh bee venom (BV) was determined by GC-MS, as well as antimicrobial activity against seven types of pathogenic microorganisms. One-hundred and forty-nine organic C1-C19 compounds of different classes were found in the volatile secretions of the studied BV samples. One-hundred and fifty-two organic C2-C36 compounds were registered in ether extracts, and 201 compounds were identified in methanol extracts. More than half of these compounds are new to BV. In microbiological tests involving four species of pathogenic Gram-positive and two species of Gram-negative bacteria, as well as one species of pathogenic fungi, the values of the minimum inhibitory concentration (MIC) and minimum bactericidal/fungicidal concentration (MBC/MFC) were determined for samples of dry BV, as well as ether and methanol extracts from it. Gram-positive bacteria show the greatest sensitivity to the action of all tested drugs. The minimum MIC values for Gram-positive bacteria in the range of 0.12-7.63 ng mL-1 were recorded for whole BV, while for the methanol extract they were 0.49-125 ng mL-1. The ether extracts had a weaker effect on the tested bacteria (MIC values 31.25-500 ng mL-1). Interestingly, Escherichia coli was more sensitive (MIC 7.63-500 ng mL-1) to the action of bee venom compared to Pseudomonas aeruginosa (MIC ≥ 500 ng mL-1). The results of the tests carried out indicate that the antimicrobial effect of BV is associated with the presence of not only peptides, such as melittin, but also low molecular weight metabolites.

Phytochemical analysis and antibacterial/antifungal activity of the essential oil of Phlomis olivieri Benth in Iran.

Phlomis olivieri Benth. is an aromatic plant endemic to Iran belonging to the Lamiaceae family. It is used to treat pain, stomach ache and common cold in Iranian traditional medicine. P. olivieri also has valuable biological properties including antioxidant, antimicrobial and analgesic ones. This was the first study designed to assess the quality, quantity and antimicrobial activity of Phlomis olivieri Benth. essential oil (POEO). Samples were randomly collected from flowering twigs of this species in three locations between Azeran and Kamoo in Kashan, Iran at peak flowering in June 2019. Water distillation extraction was used to obtain the POEO the quantity of which was calculated by weight. Gas chromatography coupled to mass spectrometry (GC/MS) was also used for POEO qualitative analysis, which revealed its chemical compounds and their percentages. Antimicrobial activity of POEO was also determined using the agar well diffusion method. Minimum inhibitory concentration (MIC) and minimum bactericidal/fungicidal concentration (MBC/MFC) were also measured using the broth microdilution method. The results of the quantitative and qualitative analysis showed that the POEO yield was ~ 0.2292% and its main chemical compounds included the sesquiterpenes germacrene D (26.43%), β-caryophyllene (20.72%), elixene (6.58%), β-trans-farnesene (6.17%), β-Cyclogermacrane (5.04%), germacrene B (4.73%), α-humulene (4.22%), and monoterpene α-pinene (3.22%). The agar diffusion method demonstrated the highest antimicrobial activity of POEO (MIC ~ 14.50mm) was against the Gram-positive species Streptococcus pyogenes. The POEO also showed the strongest inhibitory and lethal activity against the gram-negative bacterial species Pseudomonas aeruginosa (MIC < 62.50μg/mL) and S. paratyphi-A (MIC < 62.50μg/mL and MBC = 125μg/mL), and fungal species Candida albicans (MIC and MBC = 250μg/mL) as compared to control-positive antibiotics. Therefore, POEO is a valuable natural alternative rich in sesquiterpenes with strong antimicrobial and antifungal activities against some fungal and bacterial strains. It can also be used in the pharmaceutical, food and cosmetic industries.

In vitro antibacterial and antifungal activities of extracts and fractions of leaves of Ricinus communis Linn against selected pathogens.

IntroductionInfectious disease impacts are reduced due to the development of antimicrobial agents. However, the effectiveness of antimicrobial agents is reduced over time because of the emergence of antimicrobial resistance. To overcome these problems, scholars have been searching for alternative medicines. Ricinus communis is used as a traditional treatment for bovine mastitis, wound infection, and other medicinal purposes.ObjectiveThe objective of the present study was to further evaluate the antimicrobial activities of R. communis leaf extracts and fractions.Methods R. communis leaves were macerated in methanol and acetone. The methanol extract showed better antimicrobial activity and subjected to further fractionation via increasing polarity of solvents (n‐hexane, chloroform, ethyl acetate, and aqueous). Test microorganisms included in the study were six laboratory reference bacteria (Escherichia coli, Staphylococcus aureus, Streptococcus agalactiae, Kleibsella pneumoniae, Pseudomonas aeruginosa and Streptococcus pyogenes), two clinical isolate bacteria (E. coli and S. aureus), and Candida albicans. The agar well diffusion method was employed to determine antimicrobial activity. The minimum inhibitory concentrations (MIC) and minimum bactericidal/fungicidal concentrations (MBC/MFC) were determined through broth microdilution.ResultsThe results indicated that the best antimicrobial activity for ethyl acetate fraction ranged from 14.67 mm (clinical E. coli) to 20.33 mm (S. aureus) at 400 mg/ml, however, n‐hexane exhibited the lowest antimicrobial activity. Among the tested fractions, ethyl acetate fraction showed the lowest MIC values ranged from 1.5625 mg/ml (S. aureus) to 16.67 mg/ml (Candida albicans). The ethyl acetate fraction showed bactericidal activity against all tested microorganisms.ConclusionHence, ethyl acetate fraction of crude methanol extract exhibited the best antimicrobial activity.

Assessment of Microbiological Quality and Efficacy of Gbogbonise Epa Ijebu Herbal Remedy on Some Uropathogens

Background: Gbogbonise Epa Ijebu is a commercially sold native concoction in South-West, Nigeria, with the potential of curing many ailments as claimed by the manufacturer and vendors. This study investigated the antimicrobial quality and efficacy of Gbogbonise Epa Ijebu. Materials and Methods: A total of 20 samples of the herbal remedy were purchased from local vendors in Ilishan-Remo Community of Ogun State, Nigeria and were assessed for their microbiological quality using standard microbiological methods. Also, the efficacy of the herbal remedy was tested against some selected uropathogens using the Punch-hole agar diffusion method. Data generated were analyzed using the Instant GraphPad software package and P value &lt;0.05 was considered statistically significant. Results: The outcome of the study shows that half (50%) of the herbal remedy samples examined were sterile, while the other half (50%) were contaminated with a microbial count of &lt;10 CFU/mL. The microbial isolates recovered from the herbal remedy include: Staphylococcus aureus (8.3%), Coagulase negative Staphylococcus (75%) and Microsporium spp (16.7%). Assessment of the antimicrobial potential of the herbal remedy show that the test herbal remedy had strong inhibitory activity against Staphylococcus aureus (17±0.6 mm), Escherichia coli (16.3±0.3 mm), Pseudomonas aeruginosa (16.3±0.3 mm), Klebsiella pneumoniae (15±0.6 mm) and Proteus mirabilis (14±0.8 mm), except Candida albican, at a concentration of 200 mg/mL. The combined herbal solution and standard drug gave higher zone diameter of inhibition: Klebsiella pneumoniae (25±0.6 mm), Pseudomonas aeruginosa (24±0.6 mm), Staphylococcus aureus (23.7±0.3 mm), Escherichia coli (23.3±0.3 mm) and Candida albican (15±0.6mm), except Proteus mirabilis. The Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal/Fungicidal Concentration (MBC/MFC) of the herbal remedy for all the test isolates (except Candida albican) was 100mg/mL and 200mg/mL, respectively. The result of the phytochemical screening showed the presence of alkaloids, anthraquinones, cardiac glycosides, flavonoids, saponins and tannins, while steroids and resins were absent. Conclusion: The outcome of this study further strengthens the claim of efficacy made by the manufacturer and vendors of the herbal remedy. However, more attention should be given to quality preparations, packaging and storage in view of the general safety of the consumers.

A novel dual-action antimicrobial peptide for caries management

ObjectivesTo develop a novel dual-action peptide with antimicrobial and mineralising properties. MethodsA novel peptide, namely GA-KR12, was synthesised through grafting gallic acid to KR12. The secondary structure of GA-KR12 was evaluated by circular dichroism spectroscopy. The stability was evaluated by high-performance liquid chromatography. The cytotoxicity was evaluated by a mitochondrial dehydrogenase activity assay. The antimicrobial properties against common cariogenic species were evaluated by minimum inhibitory concentration (MIC) and minimum bactericidal/fungicidal concentration (MBC/MFC). The morphology of cariogenic species was analysed by transmission electron microscope (TEM). To assess the mineralising effect of GA-KR12 on enamel, the lesion depths, mineral loss, surface morphology, calcium-to-phosphorus ratio and crystal characteristics were determined using micro-computed tomography, scanning electron microscopy (SEM) and energy dispersive spectroscopy X-ray diffraction, respectively. ResultsGA-KR12 did not exhibit cytotoxicity against HGF. Around 82% of the GA-KR12 remained in human saliva at 37°C for 1 h. The MIC and MBC/MFC against the tested species were 10-320 μM and 20-1,280 μM, respectively. GA-KR12 induced remarkable morphological defects in the tested species. The enamel treated with GA-KR12 had smaller lesion depths (p < 0.001), less mineral loss (p < 0.001) and higher calcium-to-phosphorus molar ratios (p < 0.001) than those in the enamel treated with water. SEM showed a well-organised prism pattern in enamel treated with GA-KR12. X-ray diffraction revealed that the hydroxyapatite on the enamel treated with GA-KR12 was better crystalised. ConclusionsThis study developed a biocompatible and stable peptide which inhibited the growth of cariogenic species and mineralised the enamel caries. Clinical significanceThe novel dual-action peptide, GA-KR12, is potential applicable in the management of caries.

Origanum vulgare L. essential oil effects on microbial pathogens causing vaginitis

Multidrug resistance of human isolates of bacteria that cause vaginal infections is one of most recent topics in scientific investigations along with the search for novel antimicrobial drugs originating from nature. Monitoring of antimicrobial activity of traditionally used herbal essential oils may give us basic perspective and directions for future studies design. Antimicrobial activity of commercial essential oil (EO) of Origanum vulgare against human clinical isolates of bacteria and Candida was determined by microdilution method, obtaining minimum inhibitory concentration (MIC) and minimum bactericidal/fungicidal concentration (MBC/MFC) (CLSI protocol). Both investigated strains of Candida as well as all bacterial strains, except P. aeruginosa, showed susceptibility to investigated EO. The most susceptible strain was Gram positive S. aureus1 strain unlike S. aureus2 which indicates strain specificity. Both Gram negative E. coli isolates (E. coli1 and E. coli2) showed resistance to all tested antibiotics in this study, and susceptibility to oregano EO at 12.5 ?l/ml. GC/MS analysis identified a total of 35 components (96.13%) in commercial oregano EO, with the most dominant phenol carvacrol (64.12%). Our data suggest that oregano EO possess potent antimicrobial activity and that human vaginal isolates shows strain specificity in antimicrobial susceptibility.

Susceptibility of bacterial and fungal isolates to spices commonly used in Ghana

Spices are used as flavoring agents, preservatives and colorants; also in medicine, religion, tradition and magic in parts of the world. This work was designed to test the susceptibility of the clinical isolates - Salmonella sp., Klebsiella sp., Staphylococcus aureus (S. aureus), Escherichia. coli (E. coli) and Candida albicans to the single spices and their combinations. Twenty single spices and their combinations were extracted with ethanol, and zones of inhibition (ZOI), minimum inhibitory concentrations (MIC) and minimum bactericidal/fungicidal concentrations (MBC/MFC) determined by Agar Well Diffusion and Dilution Tube Methods respectively. The microbes showed various susceptibilities to the spices compared to the controls, all at a concentration of 100 µg/ml, with the highest effect by the spice combinations. All the five isolates showed the highest susceptibility towards Cloves and Negro pepper together followed by Guinea and Ashanti peppers, then Rosemary and Aniseed. Even though all the single spices were effective against Klebsiella sp., none of them showed susceptibility towards E. coli. The MIC for the combined spices was dominant at 125 µg/ml, whiles MIC for the single spices ranged between 250 and 1000 µg/ml. Analysis of variance (P<0.05) between the single spices and their combinations recorded 0.4587, 0.0094 and 0.0012 for ZOI, MIC and MBC/MFC respectively. The resulting susceptibilities of the microbes to the combined spices over their single counterparts suggest a better synergy and food hygiene effect when their right selection, pairing and quantities are determined, and could be useful for the development of antimicrobial products against persistent human infections.

Chemical composition and antimicrobial activity of fruit essential oils of Myrica gale, a neglected non-wood forest product

The study aimed to establish the chemical composition of fruit essential oils of M. gale and test their activities against the selected pathogenic bacteria (Staphylococcus aureus, Escherichia coli, Acinetobacter baumannii), yeasts (Candida albicans, C. parapsilosis), fungi (Aspergillus fumigatus, A. flavus) and dermatophytes (Trichophyton rubrum, T. mentagrophytes). Fruit samples from natural (Western Lithuania) and anthropogenic (Eastern Lithuania) M. gale populations were studied separately. Essential oils were isolated from dried fruits by hydrodistillation and analysed by GC/FID and GC/MS methods; enantiomeric composition of α-pinene was established by chiral-phase capillary GC. Minimum inhibitory concentration (MIC) and minimum bactericidal/fungicidal concentration (MBC/MFC) of essential oils were determined using the broth microdilution method. Plants from the natural population with a humid marine climate accumulated significantly higher amounts of fruit essential oils (3.34±0.05%) than those from the anthropogenic population with a more continental climate (2.71±0.22%). In total, 39 volatiles including α-pinene (23.52–27.17%), 1,8-cineole (17.19–18.84%) and α-phellandrene (9.47–10.03%) as main compounds were identified. Chiral analysis demonstrated that (1S)-(–)-α-pinene prevailed over (1R)-(+)-α-pinene and amounted to 94.09–95.28% of all fraction of this monoterpene. The antimicrobial study in vitro indicated that C. parapsilosis, dermatophytes and Aspergillus fungi were more susceptible to fruit essential oils of M. gale, whereas E. coli and C. albicans were weakly inhibited even at the highest essential oil concentration. The strongest growth-inhibitory and bactericidal effect of sweet gale essential oil was established on S. aureus. This could be attributed to the major essential oil compounds with known antimicrobial activity, such as α-pinene, 1,8-cineole and a-phellandrene.&#x0D; Keywords: Myrica gale; essential oil; chemical compounds; terpenes; enantiomers; antimicrobial.

Synthesis and Characterization of Novel Azole Functionalized Poly(glycidyl methacrylate)s for Antibacterial and Anticandidal Activity.

Presently, rise in the infectious diseases and subsequent development of drug resistance, is a global threat to human health. However, much efforts are being made by scientists, to develop novel antimicrobials, and also to improve the efficacy of available drugs, in order to combat the lifethreatening infections. Synthesis and characterization of azole functional polymer systems for antimicrobial applications. Poly(glycidyl methacrylate) (PGMA), was produced by free radical polymerization of the monomer, glycidyl methacrylate (GMA). Different azole functional PGMAs were produced, through chemical modification with imidazole (Im), 1H-1,2,4-triazole (Tri) and 3-amino-1,2,4-triazole (ATri), to get PGMA-Imi, PGMA-Tri and PGMA-ATri, respectively. The structure was confirmed by Fourier transform infrared spectroscopy (FT-IR), thermal properties were investigated by Thermogravimetric Analysis (TGA), and surface morphology was studied by scanning electron microscopy (SEM). Newly synthesized derivatives were further explored, for their antibacterial and anticandidal activities. All the three synthesized and characterized derivatives, displayed a significant activity against the tested microorganisms. The minimum inhibitory concentration (MIC) and minimum bactericidal/fungicidal concentration (MBC/MFC), recorded against Staphylococcus aureus (S. aureus), was 0.5 &1mg/ml for PGMA-Imi, followed by PGMA-ATri & PGMA-Tri, respectively, followed by E. coli with, 1 & 2 mg/ml, 4 & 8 mg/ml, 4& 8 mg/ml, respectively, whereas the maximum MIC & MFC was recorded against C. albicans i.e., 8 & 16 mg/ml, 4 & 8 mg/ml ,4 & 8 mg/ml for PGMA-ATri, PGMA-Tri, PGMA-Imi, respectively. In the present work, we report on the state-of-the-art, azole functional polymer systems for antimicrobial applications. These findings suggest that the synthesized azole functional polymer films have antimicrobial properties, which could be potential candidates for coating applications in the biomedical and wastewater treatment field.

In-vitro Screening of Antimicrobial Activities of Ocimum gratissimum on Clinical Isolates

This study was undertaken to evaluate the antimicrobial activities of crude ethanol and methanol extracts of the leaves of Ocimum gratissimum L. (scent leaf) on Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, Staphylococcus auerus and Candida albicans.The antimicrobial activities were carried out using agar well diffusion method. The Minimum inhibitory concentration (MIC) and minimum bactericidal/fungicidal concentration (MBC/MFC) of the plant extracts on the test isolates were determined by the agar dilution method. Ciprofloxacin and fluconazole (positive controls) were used in comparison with crude extract of O. gratissimum leaves and also, Dimethyl sulfoxide (DMSO) was used as the negative control. The ethanolic extract of O. gratissimum showed antibacterial activity with the mean inhibitory zone diameter of 3 -7mm against S. auerus, 2 mm against E. coli, 2 – 12 mm against K. pneumoniae, 2 mm against P.aeruginosa. Ethanol and methanol crude extracts of O. gratissimum leaves showed no effect on C.albicans. O. gratissimum extracts showed the lower antimicrobial activity than the commercially available antibiotics (ciprofloxacin and fluconazole). The minimum Inhibitory Concentration and Minimum Bactericidal Concentration of the extracts on the test organisms also increased in the following order; methanol &lt; ethanol. Hence, this extract could only serve as antibacterial agent in the management of bacterial infection because it has no antifungal activities on Candida isolates used in this study.

Manganese (II) and Cobalt (II) Acetylacetonates as Antimicrobial Agents

Mn(II) and Co(II) complexes were prepared by reaction of the metal chlorides with acetylacetone in ammonical aqueous medium. The metal complexes were prepared in order to investigate their antimicrobial activity on some selected pathogens. The characterisation of the complexes was on the basis of various spectroscopic techniques like infrared and ultraviolet studies. The compounds were subjected to antimicrobial activity screening using serial broth dilution method. Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal/Fungicidal Concentration (MBC/MFC) were determined. Mn(II) complex has shown significantly both antibacterial and antifungal activity with a MIC of 1.25 μg/mL while Co(II) complex was noticeable for antifungal activity at the same concentration. Whereas Mn(II) acetylacetonate is a more potent bactericide while Co(II) acetylacetonate is a more potent fungicide, both with MBC/MFC value of 2.5 μg/mL. Antimicrobial agent of the ligand has enhanced on complexation with Mn(II) and Co(II) ions. Though, the potency of the prepared antibiotics on the tested microbes is less compared to the standard drugs (Ciprofloxacin and Fulcin).

Phytochemical Screening and Antimicrobial Activity of Terminalia catappa L. Leaf Extract Against Potential Pathogens of Animals

The challenge of antimicrobial resistance prompted exploration of therapeutic products from medicinal plants. This study evaluated the antimicrobial activity of T. catappa leaf extract against Staphylococcus aureus, Bacillus cereus, Bordetella bronchiseptica, Pasteurella multocida, Candida albicans, and Microsporum canis. Different concentrations were used to establish the minimum inhibitory concentration (MIC) and minimum bactericidal/fungicidal concentration (MBC/MFC) of the plant extract. The extract demonstrated a broad antimicrobial spectrum by inhibiting both gram-positive and gram-negative bacteria at MIC range of 5,000 to 10,000 µg/mL. C. albicans was inhibited at 78.12 µg/mL and M. canis at 312.5 µg/mL. The MIC-MBC ratios and the MIC-MFC ratios indicate that T. catappa leaf extract has bactericidal action, fungicidal action to M. canis, and fungistatic action to C. albicans. Tannins, saponins and alkaloids were detected from the extract, which may be responsible for the antimicrobial activities of the plant.

Phytochemical investigation and antimicrobial appraisal of Parrotiopsis jacquemontiana (Decne) Rehder

BackgroundParrotiopsis jacquemontiana (Decne) Rehder. is locally used for skin infections and in wound healing. In this study we have evaluated methanol extract of its leaves and derived fractions against the clinical multi-drug resistant bacterial strains.MethodsP. jacquemontiana leaves powder extracted with 95% methanol (PJM) and fractionated in escalating polarity of solvents; n-hexane (PJH), chloroform (PJC), ethyl acetate (PJE), n-butanol (PJB) and the remaining as aqueous fraction (PJA). Clinical as well as environmental 19 bacterial strains and 8 fungal strains were screened for minimum inhibitory concentration (MIC) and minimum bactericidal/fungicidal concentration (MBC/MFC). Preliminary phytochemical investigation for various phytochemical classes was also carried out.ResultsPJM contained the coumarins, phenols, flavonoids, tannins, alkaloids, glycosides, saponins, sterols, phlobatannins, steroids, phytosterols, triterpenoids, acids, quinones, proteins, vitamin C, betacyanins, oils and resins while anthraquinones, phytosteroids, carbohydrates and anthocyanins were not detected. Disc diffusion assay (1 mg/disc) indicated the sensitivity of all the MDR strains of bacteria with PJM, PJE and PJB, while no inhibition was recorded with PJA. PJH and PJC inhibited the growth of all the strains of Staphylococcus aureus, Pseudomonas aeruginosa and Coagulase negative staphylococci used in this study. Maximum zone of inhibition (35.5 ± 1.32 mm) was obtained with PJM against Staphylococcus lugdenesis MDR (6197). Comparatively lower MIC (8-64 μg/ml) and MBC (32-256 μg/ml) values were recorded for PJM and PJE. In case of fungal strains only PJM, PJE and PJB markedly inhibited the growth and lower MIC (8-128 μg/ml) and MFC (32-512 μg/ml) values were determined for PJM and PJE.ConclusionThe remarkable inhibition of various bacterial and fungal strains at low doses of the extract/fractions suggested the strong antibacterial, antifungal and anti-candidal potential of P. jacquemontiana leaves.

Chemical compounds and antimicrobial activity of petitgrain (Citrus aurantium L. var. amara) essential oil

Summary Introduction: Due to its low cost and easy availability on the market, the petitgrain oil is commonly used in food, cosmetics, and aromatherapy. Objective: The examination of chemical composition and antibacterial activity of commercial petitgrain oil. Methods: Identification of chemical components of the petitgrain oil was performed by gas chromatography (GC). The minimum inhibitory concentrations (MIC) and minimum bactericidal/fungicidal concentrations (MBC/MFC) were determined using macrodilution method for the reference strains of bacteria and fungi. Results: Twenty components were identified. The petitgrain oil contained mostly oxygenated monoterpene hydrocarbons (98.01%), and the main components included linalyl acetate (48.06%) and linalool (26.88%). The MIC/MBC of the petitgrain oil for bacteria was in the range of 0.63-5.0/1.25-5.0 mg/ml and for fungi in the range of 1.25-40/5.0-80 mg/ml. Conclusion: The petitgrain oil had higher antibacterial activity than antifungal activity. Bacillus subtilis among the tested bacteria and Aspergillus niger and Penicillium expansum among the fungi were found to be highly inhibited by the petitgrain oil.