Evaluation of inhibitory effects of citric and tartaric acids and their combination on the growth of Trichophyton mentagrophytes, Aspergillus fumigatus, Candida albicans, and Malassezia furfur

Incorporating versus coating antimicrobials for polymethyl methacrylate: A systematic review

STATEMENT OF PROBLEM

Incorporating and coating with antimicrobials are techniques that can confer antimicrobial action on polymethyl methacrylate (PMMA) denture bases, which can accumulate microorganisms and promote oral and systemic disease.

PURPOSE

The purpose of this systematic review was to answer the question: "Do techniques for incorporating and coating antimicrobial agents in PMMA promote antimicrobial action?"

MATERIAL AND METHODS

The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) checklist guidelines were followed, and the SCOPUS, PubMed/Medline, EMBASE, and Science Direct databases searched. The studies were selected in 2 stages, reading the titles and abstracts and then reading the selected studies in full. The risk of bias was analyzed by adapting the quasi-experimental studies tool by the Joanna Briggs Institute (JBI).

RESULTS

A total of 970 articles were found in the databases; 71 were duplicates and, after reading the abstracts, 38 were selected for full reading. From these, 6 were excluded because they did not fulfill the inclusion criteria, and 32 studies were included in this review. Autopolymerizing, heat- polymerizing, and light-polymerizing resins were evaluated, with the incorporating technique prevailing over the coating, but both techniques effectively promoted antimicrobial activity.

CONCLUSIONS

Incorporating and coating antimicrobial agents are effective methods of promoting antimicrobial activity in PMMA. Combining the 2 methods led to increased antimicrobial activity compared with each individually.

Inhibiting pathogenicity of vaginal Candida albicans by lactic acid bacteria and MS analysis of their extracellular compounds

Maintaining healthy vaginal microflora post-puberty is critical. In this study we explore the potential of vaginal lactic acid bacteria (LAB) and their extracellular metabolites against the pathogenicity of Candida albicans. The probiotic culture free supernatant (PCFS) from Lactobacillus crispatus, L. gasseri, and L. vaginalis exhibit an inhibitory effect on budding, hyphae, and biofilm formation of C. albicans. LGPCFS manifested the best potential among the LAB PCFS, inhibiting budding for 24 h and restricting hyphae formation post-stimulation. LGPCFS also pre-eminently inhibited biofilm formation. Furthermore, L. gasseri itself grew under RPMI 1640 stimulation suppressing the biofilm formation of C. albicans. The PCFS from the LAB downregulated the hyphal genes of C. albicans, inhibiting the yeast transformation to fungi. Hyphal cell wall proteins HWP1, ALS3, ECE1, and HYR1 and transcription factors BCR1 and CPH1 were downregulated by the metabolites from LAB. Finally, the extracellular metabolome of the LAB was studied by LC-MS/MS analysis. L.gasseri produced the highest antifungal compounds and antibiotics, supporting its best activity against C. albicans. Vaginal LAB and their extracellular metabolites perpetuate C. albicans at an avirulent state. The metabolites produced by these LAB in vitro have been identified, and can be further exploited as a preventive measure against vaginal candidiasis.

Whole-transcriptome analysis reveals mechanisms underlying antibacterial activity and biofilm inhibition by a malic acid combination (MAC) in Pseudomonas aeruginosa

Background

Pseudomonas aeruginosa is a highly prevalent bacterial species known for its ability to cause various infections and its remarkable adaptability and biofilm-forming capabilities. In earlier work, we conducted research involving the screening of 33 metabolites obtained from a commercial source against two prevalent bacterial strains, Escherichia coli and Staphylococcus aureus. Through screening assays, we discovered a novel malic acid combination (MAC) consisting of malic acid, citric acid, glycine, and hippuric acid, which displayed significant inhibitory effects. However, the precise underlying mechanism and the potential impact of the MAC on bacterial biofilm formation remain unknown and warrant further investigation.

Methods

To determine the antibacterial effectiveness of the MAC against Pseudomonas aeruginosa, we conducted minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) assays. Transmission electron microscopy (TEM) and scanning electron microscopy (SEM) techniques were employed to observe bacterial morphology and biofilm formation. We further performed a biofilm inhibition assay to assess the effect of the MAC on biofilm formation. Whole-transcriptome sequencing and bioinformatics analysis were employed to elucidate the antibacterial mechanism of the MAC. Additionally, the expression levels of differentially expressed genes were validated using the real-time PCR approach.

Results

Our findings demonstrated the antibacterial activity of the MAC against P. aeruginosa. SEM analysis revealed that the MAC can induce morphological changes in bacterial cells. The biofilm assay showed that the MAC could reduce biofilm formation. Whole-transcriptome analysis revealed 1093 differentially expressed genes consisting of 659 upregulated genes and 434 downregulated genes, in response to the MAC treatment. Mechanistically, the MAC inhibited P. aeruginosa growth by targeting metabolic processes, secretion system, signal transduction, and cell membrane functions, thereby potentially compromising the survival of this human pathogen. This study provides valuable insights into the antibacterial and antibiofilm activities of the MAC, a synergistic and cost-effective malic acid combination, which holds promise as a potential therapeutic drug cocktail for treating human infectious diseases in the future.

Susceptibility of emetic and enterotoxigenic Bacillus cereus grown at high temperature to disinfectants

The prevalence of emetic strains in food products is rare; however, infection with these may be fatal to the vulnerable population. Bacterial control of the emetic Bacillus cereus strains is still unclear. This study aimed to assess the influence of high temperature on the disinfection of emetic and enterotoxigenic B. cereus. Emetic B. cereus strains survived up to 50 °C; the lag time and maximum growth rate were higher at 42 °C than those at 30 °C. Compared to enterotoxigenic B. cereus, all emetic food strains showed higher minimum inhibitory concentrations and minimum bactericidal concentrations for sodium hypochlorite and citric acid. The disinfectant susceptibility of the emetic B. cereus OS-05 strain incubated at a higher temperature did not increase and was maintained at the highest MBC value. In all emetic B. cereus strains, enterotoxin gene expression was upregulated at 42 °C and 45 °C. Increased ces gene expression was also found in emetic B. cereus strains GP-15 and OS-05, with upregulation of 128- and 820-fold at 42 °C. Thus, emetic B. cereus grown at high temperatures may resist common disinfectants of the food industry. The findings may help control B. cereus in food or the food processing industry.

Citrous Lime-A Functional Reductive Booster for Oil-Mediated Green Synthesis of Bioactive Silver Nanospheres for Healthcare Clothing Applications and Their Eco-Mapping with SDGs

Silver nanoparticles (Ag-NPs) are most effective against pathogens and have widely been studied as antibacterial agents in commodity clothing, medical textile, and other hygiene products. However, prolonged utilization of silver and rapid mutation in bacterium stains has made them resistant to conventional silver agents. On the other hand, strict compliance against excessive utilization of toxic reagents and the current sustainability drive is forcing material synthesis toward green routes with extended functionality. In this study, we proposed an unprecedented chemical-free green synthesis of bioactive Ag-NPs without the incorporation of any chemicals. Cinnamon essential oil (ECO) was used as a bio-reducing agent with and without the mediation of lime extract. A rapid reaction completion with better shape and size control was observed in the vicinity of lime extract when incorporated into the reaction medium. The interaction of natural metabolites and citrus compounds with nanoparticles was established using Fourier transform infrared spectroscopy (FTIR) and Raman spectroscopy. The application of as-prepared nanoparticles on textiles encompasses extended bioactivity to treated fabric with infused easy-care performance. To the best of our knowledge, this is the first reported instance of utilizing bioactive silver nanoparticles as a functional finish, both as an antimicrobial and as for easy care in the absolute absence of toxic chemicals. The easy-care performance of fabric treated with lime-mediated nanoparticles was found to be 141^O, which is around 26% better than bare cotton without any significant loss in fabric strength. Furthermore, to enlighten the sustainability of the process, the development traits were mapped with the United Nations Sustainable Development Goals (SDGs), which show significant influence on SDGs 3, 8, 9, and 14. With the effective suspension of microorganisms, added functionality, and eco-mapping with SDGs with the chemical-free synthesis of nanoparticles, widespread utilization can be found in various healthcare and hygiene products along with the fulfillment of sustainability needs.

Antifungal Effect of Metabolites from a New Strain Lactiplantibacillus Plantarum LPP703 Isolated from Naturally Fermented Yak Yogurt

The antifungal effect of metabolites produced by a new strain of Lactiplantibacillus (Lpb.) plantarum LPP703, isolated from naturally fermented yak yogurt, was investigated. The results showed that Lpb. plantarum LPP703 significantly inhibited four fungal species, including Penicillium sp., Rhizopus delemar, Aspergillus flavus, and Aspergillus niger. The metabolites produced after 20 h of Lpb. plantarum LPP703 fermentation showed the highest antifungal activity against Penicillium sp. Compared with the control group, the Lpb. plantarum LPP703 metabolites-treated Penicillium sp. spores were stained red by propidium iodide, indicating that the cell membrane of the fungal spores was damaged. Moreover, the antifungal effect of the Lpb. plantarum LPP703 metabolites on Penicillium sp. was not changed after heating or treatment with various proteases, but showed a sharp decrease when the pH value was regulated to 5.0 or above. The oleamide, trans-cinnamic acid, and citric acid were the three most abundant in the Lpb. plantarum LPP703 metabolites. Molecular docking predicated that the oleamide interacted with the active site of lanosterol 14-alpha-demethylase (CYP51, a crucial enzyme for fungal membrane integrity) through hydrogen bonds and had the lowest docking score, representing the strongest binding affinity to CYP51. Taken together, the metabolites from a new strain of Lpb. plantarum, LPP703, had potent antifungal activity against Penicillium sp., which might be associated with the damage of the active ingredient to fungal membrane integrity. This study indicated that Lpb. plantarum LPP703 and its metabolites might act as biological control agents to prevent fungal growth in the food industry.

Conversion of fungicide cyprodinil to salts with organic acids: preparation, characterization, advantages

BACKGROUND

As an effective strategy to improve the basic properties of drugs, salt formation was less used in the field of pesticides than the medicine field. It is worth trying to improve the inherent shortcomings of cyprodinil (high K_ow values; polymorphism) in this way to enhance its practicality.

RESULTS

Eight cyprodinil salts (CYP-Salts) were prepared. The properties of CYP-Salts, including solubility in various solvents, polymorphic behavior, soil absorption, photolysis in aquatic water, in vitro fungicidal activity and curative activity, were assessed. It was observed that compared with those of cyprodinil, CYP-Salts had lower soil adsorption, while also having lower log K_ow values and could be more easily photodegraded in water. That is, CYP-Salts have lower impacts on water bodies and aquatic organisms than cyprodinil. Three CYP-Salts showed higher in vitro antifungal activities and curative activity. CYP-Salts have enhanced practicality, as they could avoid possible agglomeration caused by recrystallization.

CONCLUSION

Salt forming enhanced the properties of Cyprodinil in many aspects. CYP-Salts may potentially become a better substitute for cyprodinil. This study offers a more economical and effective strategy to prepare better alternatives to existing fungicides. © 2022 Society of Chemical Industry.

Antihypertensive Potential of Tartaric Acid and Exploration of Underlying Mechanistic Pathways

Tartaric acid is capable of balancing blood pressure. It is the main constituent of antihypertensive agents (grapes and wine) and has not been scientifically explored as an antihypertensive remedy. This study aimed to investigate the antihypertensive effect of a low-dose tartaric acid in vivo and explore underlying mechanisms in vitro. Intravenous administration of tartaric acid at the dose of 50 µg/kg caused a % fall in mean arterial pressure (MAP) in normotensive and hypertensive rats [51.5 ± 1.7 and 63.5 ± 2.9% mmHg]. This hypotensive effect was partially inhibited by atropine (1 mg/kg) and _L-NAME (100 µg/kg) pretreatment. In hypertensive rats, oral administration of tartaric acid (.1, .5, 1, 5, and 10 mg/kg) for 2 weeks resulted in 65 ± 7.3 mmHg MAP at 10 mg/kg. This antihypertensive effect was comparable to the orally administered verapamil (10 mg/kg) for 2 weeks which caused a decrease in MAP 60.4 ± 3.8 mmHg. Tartaric acid relaxed phenylephrine (PE) and High K⁺-induced contractions with EC₅₀ values of .157 (.043-.2) and 1.93 (.07-2) µg/mL in vitro. This endothelium-dependent relaxation was inhibited with atropine (1 µM) and _L-NAME (10 µM) pretreatment. Tartaric acid also suppressed phenylephrine contractions in Ca⁺² free/EGTA medium and on voltage-dependent calcium channels, causing the concentration–response curves toward right. Tartaric acid induced negative inotropic and chronotropic effects with EC₅₀ values of .26 (.14-.4) and .60 (.2-.8) in rat atria. It showed its effect by complete blockade against atropine and partially in propranolol pretreatment. These findings provide scientific basis to low-dose tartaric acid as an antihypertensive and vasodilatory remedy through muscarinic receptor-linked nitric oxide (NO) pathway and Ca⁺² channel antagonist.

A Novel Endophytic Trichoderma longibrachiatum WKA55 With Biologically Active Metabolites for Promoting Germination and Reducing Mycotoxinogenic Fungi of Peanut

Plant residuals comprise the natural habitat of the plant pathogen; therefore, attention is currently focusing on biological-based bioprocessing of biomass residuals into benefit substances. The current study focused on the biodegradation of peanut plant residual (PNR) into citric acid (CA) through a mathematical modeling strategy. Novel endophytic Trichoderma longibrachiatum WKA55 (GenBank accession number: MZ014020.1), having lytic (cellulase, protease, and polygalacturonase) activity, and tricalcium phosphate (TCP) solubilization ability were isolated from peanut seeds and used during the fermentation process. As reported by HPLC, the maximum CA (5505.1 μg/g PNR) was obtained after 9 days in the presence of 15.49 mg TCP, and 15.68 mg glucose. GC–MS analysis showed other bioactive metabolites in the filtrate of the fermented PNR. Practically, the crude product (40%) fully inhibited (100%) the growth and spore germination of three mycotoxinogenic fungi. On peanuts, it improved the seed germination (91%), seedling features, and vigor index (70.45%) with a reduction of abnormal seedlings (9.33%). The current study presents the fundamentals for large-scale production in the industry for the sustainable development of PNR biomass as a natural source of bioactive metabolites, and safe consumption of lignocellulosic-proteinaceous biomass, as well. T. longibrachiatum WKA55 was also introduced as a novel CA producer specified on PNR. Application of the resulting metabolite is encouraged on a large scale.

Extraction and characterisation of bioactive proteins from Pongamia pinnata and their conversion into bioproducts for food packaging applications

In this research, proteins were obtained from Pongamia pinnata oil meal and subsequently converted into films and compression molded into various packaging products. Films with a maximum tensile strength of 1.9 MPa were obtained when 15% citric acid was used as the crosslinker. Minimum swelling of 120% was seen in 20% citric acid crosslinked film whereas the uncrosslinked films readily disintegrated in water. The protein films had excellent antioxidant properties with an IC50 value of 14.6 µg/ml compared to 26.9 µg/ml for the standard ascorbic acid. The pongamia protein-based bioproducts showed good activity against Bacillus cereus and Aspergillus niger. Unique properties, low cost, and large availability make pongamia proteins an ideal biopolymer for the development of green and sustainable materials and bioproducts.

Lactobacillus plantarum strain HT-W104-B1: potential bacterium isolated from Malaysian fermented foods for control of the dermatophyte Trichophyton rubrum

The objective was to screen and evaluate the anti-fungal activity of lactic acid bacteria (LABs) isolated from Malaysian fermented foods against two Trichophyton species. A total of 66 LAB strains were screened using dual culture assays. This showed that four LAB strains were very effective in inhibiting growth of T. rubrum but not T. interdigitale. More detailed studies with Lactobacillus plantarum strain HT-W104-B1 showed that the supernatant was mainly responsible for inhibiting the growth of T. rubrum. The minimum inhibitory concentration (MIC), inhibitory concentration, the 50% growth inhibition (IC₅₀) and minimum fungicide concentration (MFC) were 20 mg/mL, 14 mg/mL and 30 mg/mL, respectively. A total of six metabolites were found in the supernatant, with the two major metabolites being L-lactic acid (19.1 mg/g cell dry weight (CDW)) and acetic acid (2.2 mg/g CDW). A comparative study on keratin agar media showed that the natural mixture in the supernatants predominantly contained L-lactic and acetic acid, and this significantly controlled the growth of T. rubrum. The pure two individual compounds were less effective. Potential exists for application of the natural mixture of compounds for the treatment of skin infection by T. rubrum.

Scrutinising the relationship between major physiological and compositional changes during 'Merrill O'Henry' peach growth with brown rot susceptibility

In the present work, the major physiological and compositional changes occurring during 'Merrill O'Henry' peach growth and its relationship with susceptibility to three strains of Monilinia spp. at 49, 77, 126 and 160 days after full bloom were explored. Results of disease incidence indicated wide differences among phenological stages, being 49 and 126 days after full bloom the moment when peaches showed significantly lower susceptibility to brown rot (40 and 23% of rotten fruit, respectively, for strain ML8L). Variation in brown rot susceptibility among different growth stages was also strain-dependent. Lower fruit susceptibility to ML8L at 49 and 126 was accompanied by noticeable changes in the fruit ethylene and respiration patterns, and also in sugars and organic acids content. By employing a partial least squares regression model, a strong negative relationship between citric acid, and a positive association of ethylene with peach susceptibility to Monilinia spp. at diverse phenological stages were observed. The results obtained herein highlight that the content of certain compounds such as citrate, malate and sucrose; the respiratory activity and the fruit ethylene production may mediate in a coordinated manner the fruit resistance to Monilinia spp. at different phenological stages of peach fruit.

Onychomycosis Unresponsive to Antifungals: Etiology and Treatment with a New Direct Technique

Aims and Objectives:

The aim of this study was to identify the fungal agents causing onychomycosis that were unresponsive to antifungal treatment and to treat these cases by placing under-nail cushions with a mild keratolytic to clear the fungus-invaded tissue.

Materials and Methods:

Fungal agents were identified by the matrix-assisted laser desorption/ionization time of flight (MALDI-TOF) technique.

Results:

Nine patients had Aspergillus spp. (7 Aspergillus niger, 2 Aspergillus flavus); four had Candida species and one had Trichophyton rubrum. All patients were free of infection at the end of treatment.

Conclusion:

As per the results, we may state that onychomycosis that is unresponsive to treatment in immunocompetent patients seems to be mostly associated with molds. Direct application of a mild keratolytic to the fungus-invaded part, e.g., the nail plate and/or nail bed and removal of fungal elements may provide a successful treatment outcome.

Reduction of Candida albicans biofilm formation by coating polymethyl methacrylate denture bases with a photopolymerized film

STATEMENT OF PROBLEM

As Candida albicans biofilm formation is associated with severe local and systemic infections in denture-wearing patients, its prevention or reduction becomes an essential factor in the health of this population.

PURPOSE

The purpose of this in vitro study was to investigate whether 2 photopolymerized coatings of poly(acrylic acid) (PAA) and poly(itaconic acid) (PIA) can effectively reduce the adhesion of C albicans on denture base acrylic resin surfaces.

MATERIAL AND METHODS

The surface of the polymethyl methacrylate (PMMA) denture base was modified through photopolymerization of a thin film of PAA or PIA. The polymeric coatings were characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), contact angle goniometry (CA), and surface roughness measurement (Ra). For biological evaluation, the coated PMMA surfaces were tested in a C albicans biofilm dynamic formation model, observed by confocal laser scanning microscopy (CLSM), and quantified by the number of colony-forming units (CFUs). The cytotoxicity of the polymeric coatings was also evaluated by using a lactic dehydrogenase-based (LDH) test. For statistical analysis, ANOVA and the nonparametric Kruskal-Wallis test were used (α=.05).

RESULTS

The PMMA resin base surfaces coated with PAA and PIA had an inhibitory effect on C albicans growth, the wettability of the coated surface, and the average roughness. The PAA and PIA coatings had no statistically significant cytotoxic effect on periodontal ligament fibroblasts.

CONCLUSIONS

PMMA acrylic resin base material was superficially modified through the incorporation of carboxylic acid groups by using PAA and PIA coatings that reduced the adherence of C albicans biofilm by 90%.

A comprehensive analysis of the Lactuca sativa, L. transcriptome during different stages of the compatible interaction with Rhizoctonia solani

The leafy green vegetable Lactuca sativa, L. is susceptible to the soil-born fungus Rhizoctonia solani AG1-IB. In a previous study, we reported on the transcriptional response of R. solani AG1-IB (isolate 7/3/14) during the interspecies interaction with L. sativa cv. Tizian by means of RNA sequencing. Here we present the L. sativa transcriptome and metabolome from the same experimental approach. Three distinct interaction zones were sampled and compared to a blank (non-inoculated) sample: symptomless zone 1, zone 2 showing light brown discoloration, and a dark brown zone 3 characterized by necrotic lesions. Throughout the interaction, we observed a massive reprogramming of the L. sativa transcriptome, with 9231 unique genes matching the threshold criteria for differential expression. The lettuce transcriptome of the light brown zone 2 presents the most dissimilar profile compared to the uninoculated zone 4, marking the main stage of interaction. Transcripts putatively encoding several essential proteins that are involved in maintaining jasmonic acid and auxin homeostasis were found to be negatively regulated. These and other indicator transcripts mark a potentially inadequate defence response, leading to a compatible interaction. KEGG pathway mapping and GC-MS metabolome data revealed large changes in amino acid, lignin and hemicellulose related pathways and related metabolites.

Rapid screening and quantification of major organic acids in citrus fruits and their bioactivity studies

Organic acids (OAs) are small non-volatile molecules with widespread usage in processed foods, feeds and instant beverages. The prime aim of this study was to explore major OAs in local citrus fruits (Citrus limetta, Citrus aurantifolia, Citrus nobilis, Citrus karna, Citrus medica, Citrus ichangensis and Citrus aurantium) and assessment of their bioactivities. A RP-HPLC-DAD method was developed using buffer free solvent system for rapid detection and quantification of major OAs from citrus fruits and derived products. Method validation studies showed good linear calibration curve (0.985-0.998) for all OAs. The values of %RSD ranged between 0.0001-1.129 and 0.142-1.941 for interday and intraday variability respectively. The limit of detection and limit of quantification values for different OAs were ranged between 1.5-12 and 5-40 µg mL^-1. The juice of above mentioned citrus fruit cultivars were assessed for OAs, total phenolics, free radical scavenging antioxidants and their antimicrobial potential against selected bacterial and fungal strains. The results showed variable contents of phenolics [0.28 ± 0.001-1.17 ± 0.014 mg (GAE) mL^-1] and antioxidant compounds (1.26 ± 0.009-2.84 ± 0.006 mg of trolox equivalents mL^-1) in all juice samples besides significant antifungal activity against C. albicans and A. niger strains. However, in case of antibacterial activity, only C. aurantifolia showed inhibitory effects against selected strains. It was found that citrus fruits have immense potential for their utilization as economic source of natural OAs and development of value added products, beverages and bio-preservatives.

Synthesis and fungistatic activity of aryl aldoxime derivatives

OBJECTIVE

The antifungal activity of 13 arylaldoxime ester and ether derivatives was tested against 4 dermatophytes Trichophyton mentagrophytes (TM), Microsporum canis (MC); M. cookei, and M. gypseum.

MATERIALS AND METHODS

Structures of all new compounds prepared from aryl aldehydes were established by spectral means. The tests were performed on the Sabouraud Dextrose Agar (SDA) substrate. The sensitivity of the dermatophyte strains towards oxime derivatives was established by determining MIC and MFC values.

RESULTS

The tested compounds showed a moderate fungicidal activity reaching 100% inhibition rate at 1% concentration. The activity against M. canis of 4 derivatives was higher than the activity of a reference drug clotrimazole.

CONCLUSION

A novel group of biologically active compounds was introduced. Simple aldoxime derivatives can be developed into a new class of antifungals.