antimicrobial activity

Holarrhena pubescens is used traditionally for treating several infectious and inflammatory disorders with no scientific evidence. The present study was designed to evaluate the antimicrobial and free radical scavenging properties of different fractions of ethanolic extract of H. pubescens seeds. Furthermore, the potential of the fractions of the plant extract in treating acute and chronic inflammation through in vitro and in vivo experiments was also evaluated.

The successive fractions of ethanolic extract of H. pubescens seeds, including petroleum ether (HPF), chloroform (HCF), and methanol (HMF) fractions were subjected to in vitro study to evaluate the properties to eradicate the microorganisms using disc diffusion method and to scavenge oxidants in the DPPH method. The HCF was further used in an anti-inflammatory activity study by inhibition of bovine serum albumin denaturation assay and an in vivo study to evaluate the effect of the drug in a chronic inflammatory condition by adjuvant-induced arthritis in a rats’ model.

HCF showed the most potent effect among all the test drugs. The fraction showed a broad-spectrum antimicrobial effect and 80.35 ± 0.46% free radical scavenging effect (IC50 value = 28.41 ± 0.33 µg/mL) in the antioxidant study. Further, HCF showed an anti-inflammatory effect with 68.37 ± 1.11% inhibition of denaturation of albumin and 75.16% (0.38 ± 0.16 mL, P<0.05) inhibition of rat paw edema in the in vivo study.

The study exhibited the antimicrobial, antioxidant and anti-inflammatory potentials of the fractions of ethanolic extract of H. pubescens seeds.

The discovery of novel therapies and the provenance of antimicrobial medication are critically important, as antimicrobial resistance is becoming more common because of the presence and continuous evolution of antimicrobial-resistant organisms. Studies regarding synergy in medicinal plant extracts with antimicrobials have emerged as a novel and important research field. The synergy itself can serve as a beneficial tactic to strengthen and replenish antimicrobial medications that are currently less effective in clinical settings when treating microbial infections that are multi-resistant. The current work is a web-based search performed using PubMed, which covered studies that were published over more than a 25-year period, specifically between 1997 and July 2024, and assessed the potential for synergy between plant extracts and conventionally prescribed antimicrobial medications. The findings of the current review held great promise for the development of novel plant-based remedies combined with clinical-in-use antimicrobial medications to be exceptionally successful in treating severe infections that are resistant to antimicrobial treatments alone.

 In this research, a novel series of heterocyclic compounds containing pyrazoline nuclei was synthesized in two steps.

In the first step, chalcones were prepared using the Claisen-Schmidt reaction between substituted benzaldehydes and acetophenone derivatives. In the second step, the chalcones were cyclized under acidic conditions with hydrazine derivatives to produce pyrazolines. All compounds were characterized through physical, chromatographic, spectroscopic, and elemental analyses, and their antibacterial properties were tested using seven microorganisms. The minimum inhibitory concentrations of all compounds were determined using the broth dilution method.

Among them, compound 2f (4-(1, 5-diphenyl-4, 5-dihydro-1H-pyrazol-3-yl) phenol) exhibited the highest antibacterial and antifungal activity, making it the most potent compound in the series.

 These results indicate that increasing the polarity of the compounds enhanced their efficacy against Gram-positive strains, whereas derivatives containing at least one methoxy group in their structure suppressed Gram-negative growth.

The primary aim was to analyze Phagnalon saxatile essential oils at the three vegetative stages, exploring their chemical composition. Additionally, antimicrobial activity was assessed during these developmental phases. The essential oils extracted from the three phenological stages were examined using gas chromatography coupled with mass spectrometry. Their antimicrobial properties were evaluated on nine reference strains using the minimum inhibitory concentration (MIC) method. This method determines the lowest concentration of the antimicrobial substance that prevents visible growth of the microorganisms in a series of dilutions. The oil yield rate varied with the stage of development, with the highest concentration recorded at 0.08% (w/w) during the growth phase. Chemical analysis of the essential oils using GC and GC-MS revealed the presence of 112 different compounds. Significant variations were noted in the main classes of compounds. Notably, hydrocarbon monoterpenes showed a significant increase from 7.4% at the beginning of the vegetative cycle to 66.6% during the flowering period. In contrast, non-oxygenated compounds decreased significantly from 49.6% to 15.0% and non-oxygenated hydrocarbons decreased from 7.5% to 2.6%. During the early vegetative cycle, the essential oil of P. saxatile showed a more marked antimicrobial activity against the nine bacterial strains. In contrast, at the beginning of flowering and full flowering, the essential oils exhibited less significant antimicrobial activity. Analyses of P. saxatile essential oils throughout its development cycle have shown promising bactericidal properties. These results could be utilized for the development of new drugs in the pharmaceutical field.

It has been shown that strains of the genus Enterococcus isolated from donkey milk from different regions of the Republic of Armenia have antimicrobial activity, synthesize different polysaccharides and produce disaccharide polymers (glucose and galactose). The quantitative synthesis of polysaccharides (8-15%) depends on the composition of the nutrient medium, temperature and growing time.

Species identification of LAB strains was confirmed by 16S rDNA gene sequencing method using universal primers LAB strains. The methods used for extraction, purification and detection of exopolysaccharides are based on the method of Sørensen et al. (2022). The antibacterial activity of EPS was investigated by agar diffusion assay. Determination of the immunostimulating property was carried out using the ELISA method.

The antimicrobial activity of the polysaccharide and antimicrobial protein-like fractions of the genus Enterococcus strains depends on its concentration, time of interaction with the test culture, and the species of the pathogenic bacteria.

The obtained results were shown that strains isolated from fermented donkey milk that are capable of synthesizing two substances of different nature with high antimicrobial properties during the growth process are promising for further research and application for their use as probiotics and biopreparations in pharmaceuticals.

The rise of multi-drug-resistant bacteria seriously threatens human health. Some microorganisms can produce new antimicrobials that have effects on multidrug-resistant bacteria. On the other hand, halophilic bacteria show promise in producing novel bioactive antimicrobial compounds that could benefit drug development. This study aims to investigate the antimicrobial properties of halophilic bacteria recently isolated in soil samples from Shushtar City, Khuzestan Province, Iran.

In this research, saline soil samples were collected from the salty areas around Shushtar City. The soil sample was then cultured in an enriched culture medium, and in order to isolate the halophilic bacteria, they were cultured in a solid medium. The microorganisms were examined for the production of antimicrobial agents using the agar well diffusion method. Subsequently, the halophilic bacteria were identified through molecular analysis of the 16S rRNA method. The phylogenetic tree was constructed using Mega software through the neighbor-joining method.

Twenty-two strains were isolated in this study. Strain E1, identified as Alkalihalobacillus sp, displayed antimicrobial activity against Enterococcus faecalis. The MIC and MBC of the Alkalihalobacillus extracts against Enterococcus faecalis were determined to be 25 µg/mL

This research highlights the potential therapeutic and preventive advantages of Alkalihalobacillus sp. extracts as antibacterial agents. This research report, for the first time,reveals that isolated Alkalihalobacillus in Iran has the ability to produce antimicrobial agents.The discovery and isolation of beneficial bacteria from natural sources could have significantimplications for future pharmaceutical and industrial applications.

Due to the increasing resistance of pathogenic bacteria to common antibiotics, researchers are looking for antimicrobial agents of plant origin as alternative drugs.

This study aimed to investigate the antimicrobial activity and pigmentation of the extract of the Rhazya stricta plant against human bacteria.

The minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC) in six concentrations were evaluated by the dilution method in a liquid medium on the determined bacteria. The pink color of the plant extract was assessed using ELISA.

The results of the diameter of the inhibition zone showed that the maximum diameter of the inhibition zone for ethyl acetate (2 mm), aqueous (7 mm), ethanolic (8 mm), methanolic (9 mm), and hydroalcoholic (10 mm) extracts was against Staphylococcus aureus . The smallest diameter of the inhibition zone was related to the ethyl acetate extract of R.stricta against methicillin-resistant strains of Staphylococcus aureus (MRSA) (2 mm), while the largest diameter of the inhibition zone was related to the methanolic extract of R.stricta (8 mm).

The results of the study showed that different medicinal plant solvents inhibit the growth of pathogenic bacteria at different concentrations, which can be used in the treatment of infections caused by these bacteria. Additionally, this medicinal plant can be used in the dyeing industry due to its pigmentation properties.

The aim of this study was to investigate the antimicrobial properties and pigmentation effects of several medicinal plants on antibiotic-resistant Salmonella typhimurium .

Medicinal plant extracts were prepared using ethanol as a solvent, and the antimicrobial activity was assessed by measuring the diameter of the inhibition zones using the microdilution method. The pigmentation effect of the plant extracts, indicated by pink coloration, was evaluated using an ELISA reader.

The findings showed that the maximum inhibition zone diameter for Nannorrhops ritchiana ethanolic extract was 8 mm, while the minimum was 1 mm. For Ficus religiosa leaves, the maximum inhibition zone was 15 mm, and the minimum was 2 mm. The inhibition zone for musk ranged from 1 mm (minimum) to 18 mm (maximum). Capparis spinosa L. fruits exhibited an inhibition zone diameter of 15 mm.

The results indicate that medicinal plants possess significant inhibitory effects against Salmonella typhimurium and can be considered potential treatments for infections caused by this bacterium.

Chronic bacterial diarrheas are common intestinal infections that have been treated with antibiotics for many years. However, the excessive use of antibiotics has led to the development of resistance in the bacteria that cause these infections. As a result, there has been growing interest in using probiotics with antibacterial effects and a greater ability to survive stomach acidity to help control antibiotic-resistant bacteria.

In the current study, the antimicrobial activity of Bacillus coagulans (a probiotic bacterium) against four different enteric pathogens ( Escherichia coli , Salmonella typhi , Shigella flexneri , and Bacillus cereus ), which play a significant role in the prevalence of bacterial diarrhea, has been investigated.

The antimicrobial effect of the cell-free supernatant of Bacillus coagulans against pathogens ( E. coli , S. typhi , Sh. flexneri , and B. cereus ) was studied using agar well-diffusion, agar disc-diffusion, as well as minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) methods. In the MIC test, the concentrations of B. coagulans cell-free supernatant examined were 100, 50, 25, 12.5, 6.25, and 3.1 µg per mL. Each bacterial strain was tested in four replicates.

The antimicrobial activity of B. coagulans supernatant was not observed in either the agar well-diffusion or agar disc-diffusion results. However, MIC results showed that different concentrations of B. coagulans supernatant significantly inhibit the growth of E. coli (MIC = 25 µg/mL, P < 0.0001), S. typhi (MIC = 50 μg/mL, P < 0.0001), S. flexneri (MIC = 3.1 μg/mL, P < 0.0001), and B. cereus (MIC = 100 µg/mL, P < 0.0001).

The MBC results showed that the minimum inhibitory concentration of the supernatant had no bactericidal effects and did not completely prevent the growth of all four pathogens. Although the MIC results indicated the antibacterial activity of B. coagulans against all four pathogens, further studies are required to draw more accurate conclusions.

Application of the nanomaterials to preparing X-ray shields and successfully treating multiresistant microorganisms has attracted great attention in modern life. This study aimed to prepare flexible silicone-based matrices containing Bi2O3, PbO, or Bi2O3/PbO nanoparticles and select a cost-effective, cytocompatible, and antibacterial/antifungal X-ray shield in clinical radiography. In this experimental study, we prepared the nanoparticles by the modified biosynthesis method and fabricated the X-ray shields containing 20 wt% of the nanoparticles. The X-ray attenuation percentage and Half Value Layer (HVL) of the shields were investigated for the photon energies in the range of 40-100 kVp in clinical radiography. The antibacterial/antifungal activities of the shields were evaluated using a colony count method for the gram-negative (Escherichia coli), and gram-positive (Enterococcus faecalis) bacteria, and Candida albicans fungus. The shield toxicity was investigated on A549 cells. The highest X-ray attenuation percentage and the lowest HVL were obtained using the shield containing Bi2O3 nanoparticles. Although all shields displayed antimicrobial activity, the shield containing Bi2O3/PbO nanoparticles showed the most effective reduction in the colony counts. Both X-ray shields containing nano Bi2O3 and Bi2O3/PbO demonstrated high cytocompatibility on A549 cells at a concentration as high as 500 µg/ml. The shield with PbO nanoparticles was also cytocompatible at a concentration of 50 µg/ml.   The best X-ray attenuation performance is attributed to the silicone-based matrix with nano Bi2O3; however, the flexible shield with Bi2O3/PbO nanoparticles can be cost-effective and cytocompatible with the best antibacterial/antifungal properties.

In recent years, research has focused on the isolation of new bacterial strains with diverse and beneficially biological activities. This study investigated stability (under various acid concentrations, various bile-salt concentrations, cholesterol absorption ability and surface hydrophobicity) and antagonistic, antioxidant and immune activities of Lactobacillus acidophilus strain ABC240 isolated from traditional yogurts.

Strain was identified using polymerase chain reaction technique. Its viability was assessed under acidic conditions (pH values of 3, 4 and 5) and in presence of bile salts (concentrations of 0.3, 0.5 and 0.7%). Additionally, antimicrobial activity was assessed through well diffusion and disc diffusion methods. Antioxidant capacity was assessed using ABTS (2,2-azino-bis-3-ethylbenzothiazoline-6-sulfonic acid) and DPPH (2,2-diphenyl-1-picrylhydrazyl) assays. This study analyzed the microbial cell surface hydrophobicity, cholesterol absorption ability and safety parameters, including antibiotic sensitivity, hemolytic activity, DNase activity and biogenic amine production.

Results demonstrated high stability of this strain against various concentrations of acid (pH values of 3, 4 and 5) and bile salts (0.3, 0.5 and 0.7%). Ability of Lactobacillus acidophilus strain ABC240 to absorb cholesterol included 43.60% ±0.66 and its cell surface hydrophobicity was assessed at 50.49% ±0.63. The antimicrobial potential assessments revealed strong activity against several bacterial species. Furthermore, antioxidant activities, assessed using DPPH and ABTS methods, were detected as 44.69% ±0.89 and 49.80% ±0.79, respectively, indicating the bacterial high potential in inhibiting free radicals. Antibiotic sensitivity assay showed a non-growth zone diameter ranging from 13.20 mm ±0.55 (vancomycin) to 24.50 mm ±0.66 (chloramphenicol). Lactobacillus acidophilus strain ABC240 showed no hemolytic or DNase activity and did not produce biogenic amines.

In conclusion, Lactobacillus acidophilus strain ABC240 can be introduced as a new probiotic strain with biological and functional characteristics appropriate for use in the food industry.

The escalating incidence of foodborne diseases caused by pathogenic bacteria presents a substantial global health concern. Microbial spoilage of food not only shortens product shelf life but also increases the risk of foodborne diseases. According to the World Health Organization, one in ten people worldwide falls ill after consuming contaminated food. While foodborne diseases are preventable, the implementation of effective strategies to control and prevent these illnesses remains a critical global challenge. The unique properties of both organic and inorganic nanoparticles have attracted significant attention in the food industry due to their potential to enhance nutritional, safety, and quality attributes of food products. A majority of foodborne infections are attributed to pathogens such as Salmonella, Listeria, Escherichia coli, Clostridium, and Campylobacter. Silver and silver-based compounds have been shown to exhibit potent antimicrobial activity against a broad spectrum of bacteria. The current body of knowledge regarding the application of silver nanoparticles for the elimination of foodborne pathogens is expanding rapidly, providing opportunities to explore their mechanisms of action, benefits, and limitations. This perspective aims to identify novel strategies for reducing the burden of foodborne diseases by critically evaluating the potential of silver nanoparticles. Furthermore, the potential health implications of silver nanoparticles for human consumption will be discussed to inform the development of effective policies for public health.

Moringa oleifera is a traditional South Indian medicinal plant and an excellent source of antioxidants.

To evaluate the antimicrobial potential of copper nanoparticles (CuONPs) derived from Moringa oleifera pods against urinary tract-infecting microbes.

Phyto constituents of the Moringa oleifera pod were screened. CuONPs were synthesized from Moringa oleifera pod, and it was characterized using UV-visible spectroscopy, FTIR, and SEM. Antioxidant activity of CuONPs was also determined. CuONPs discs at 50, 75, and 100 µg/ml were prepared and tested for antimicrobial action against Escherichia coli, Enterococcus faecalis, Klebsiella pneumonia, Streptococcus aureus, and Candida albicans. The integrity of the E.coli was assayed by determining the lactate dehydrogenase activity.

GCMS analysis revealed the presence of Di-n-Octyl Phthalate and 2, 2-diethoxy Propane presence in the Moringa oleifera pod. Antioxidant assay revealed the free radical scavenging property of CuONPs. UV- VIS confirmed the synthesis of CuONPs by showing the λ Vmax at 220nm. SEM analysis revealed the CuONPs size in 40 to 160nm. The FTIR analysis exhibited the presence of OH and C = C groups in the CuONPs. The klebsiella pneumoniae was the most susceptible strain for CuONPs, followed by Escherichia coli and Candida albicans. E. coli showed a significant LDH activity at high concentration of CuONPs.

The CuONPs synthesized from the Moringa oleifera pod exhibited significant antimicrobial activity against the microbes.

The use of nanotechnology in various biomedical and pharmaceutical fields is expanding rapidly.

The aim of this study was to synthesize zinc nanoparticles using Hibiscus sabdariffa plant extract and investigate their antimicrobial properties.

In this experimental study, the aqueous extract of sour tea was mixed with a 0.1 M zinc sulfate solution at a 1:1 ratio and allowed to react for 15 minutes at room temperature to produce nanoparticles. The synthesis of zinc oxide nanoparticles was confirmed using spectrophotometric methods, measuring the average diameter of nanoparticles, X-ray diffraction, and scanning electron microscopy (SEM). The minimum inhibitory concentration (MIC) of the zinc oxide nanoparticles was then measured against standard strains.

The results showed that the largest inhibition zone diameter was observed at a concentration of 1024 μg/mL against Listeria monocytogenes , while the smallest inhibition zone was observed against Aeromonas hydrophila . At a concentration of 512 μg/mL, an inhibition zone of 10 mm was developed against two strains: Vibrio cholerae and Escherichia coli .

Based on the results of this study, zinc oxide nanoparticles, along with the sour tea aqueous extract and zinc sulfate, exhibited antibacterial properties. However, the most pronounced antimicrobial effects were observed with the zinc oxide nanoparticles.

The purpose of this study was to synthesize copper oxide nanoparticles (CuO NPs), cobalt oxide nanoparticles (Co3O4 NPs), and CuO-Co3O4 nano system using Moringa stenopetala plant leaf extract. These nanoparticles were specifically developed for their antioxidant and antibacterial properties.

The nanoparticles were synthesized by a green synthesis approach using M. stenopetala leaf extract. Comprehensive characterization using spectroscopic techniques such as X-ray diffraction (XRD), UV-visible spectroscopy, scanning electron microscopy (SEM), Fourier transform infrared (FT-IR), and thermogravimetric analysis (TGA) was executed.

UV-Vis analysis revealed an energy bandgap of 3.32 eV for CuO NPs, 3.36 eV for Co3O4 NPs, and 3.66 eV for CuO-Co3O4 nano system. XRD analysis revealed that CuO NPs have a monoclinic crystal structure with an average crystallite size of 11.59 nm, whereas Co3O4 NPs have a cubic crystal structure with an average crystallite size of 12.25 nm. The CuO-Co3O4 nano system exhibited an average crystal size of 9.53 nm. The SEM images showed inhomogeneous composition and large granular particles of CuO NPs, inhomogeneous cubic shape and size with encapsulation and hydrogen bonding aggregation of Co3O4 NPs, and particle heterogeneity. The CuO-Co3O4 nano system. FT-IR analysis confirmed the presence of bioactive molecules such as flavonoids, tannins, terpenoids, steroids, glycosides, saponins, and phenols that actively participate in the synthesis process.

The synthesized CuO-Co3O4 nano system showed superior inhibitory effects against the selected bacterial strains compared to CuO NPs and Co3O4 NPs. Furthermore, they showed excellent antioxidant activity. These results highlight the significant potential of CuO-Co3O4 nano system for a wide range of applications due to their remarkable bacterial inhibition and radical scavenging properties.

The resistance of microorganisms, which is quickly expanding is the most serious problem of commercial antibiotics. Thus, it seems necessary to study and know about new antimicrobial agents. Candida glabrata is the second most common cause of candidiasis after Candida albicans. Resistance to azole antifungal drugs, especially fluconazole, has been repeatedly reported in fungal infections caused by C. glabrata. As a result, the treatment of this type of fungal infection has faced many problems, and high mortality in high-risk patients admitted to the hospital, especially immunocompromised patients, has been reported many times.

This survey aimed at investigating the antimicrobial properties of lemon peel pineapple peels, and fruit extracts on some oral pathogens such as Streptococcus salivarius, Lactobacillus casei, C. albicans, and C. glabrata in vitro.

 In this study the soaking method was used to obtain the extracts of the selected plants, and the well method in agar was utilized to check their antimicrobial properties.

The results indicated that the lemon peel extract with a minimal inhibitory concentration (MIC) of 1.56 mg/mL and pineapple fruit extract with a MIC of 50 mg/mL had the strongest and weakest antimicrobial properties on C. glabrata, respectively. In addition, the lemon peel extract had high antimicrobial properties on S. salivarius, with a MIC of 6.25 mg/mL. Pineapple peel and fruit extracts demonstrated moderate antimicrobial properties on L. casei with a MIC of 25 mg/mL.

Taking into account the antimicrobial properties of lemon and pineapple and their in vivo antimicrobial properties it may be possible to apply them as natural antimicrobial factors in the treatment of oral and dental infections and other infectious diseases.