Combining esters of para-hydroxy benzoic acid (parabens) to achieve increased antimicrobial activity

Necrophages and necrophiles: a review of their antibacterial defenses and biotechnological potential

With antibiotic resistance on the rise, there is an urgent need for new antibacterial drugs and products to treat or prevent infection. Many such products in current use, for example human and veterinary antibiotics and antimicrobial food preservatives, were discovered and developed from nature. Natural selection acts on all living organisms and the presence of bacterial competitors or pathogens in an environment can favor the evolution of antibacterial adaptations. In this review, we ask if vultures, blow flies and other carrion users might be a good starting point for antibacterial discovery based on the selection pressure they are under from bacterial disease. Dietary details are catalogued for over 600 of these species, bacterial pathogens associated with the diets are described, and an overview of the antibacterial defenses contributing to disease protection is given. Biotechnological applications for these defenses are then discussed, together with challenges facing developers and possible solutions. Examples include use of (a) the antimicrobial peptide (AMP) gene sarcotoxin IA to improve crop resistance to bacterial disease, (b) peptide antibiotics such as serrawettin W2 as antibacterial drug leads, (c) lectins for targeted drug delivery, (d) bioconversion-generated chitin as an antibacterial biomaterial, (e) bacteriocins as antibacterial food preservatives and (f) mutualistic microbiota bacteria as alternatives to antibiotics in animal feed. We show that carrion users encounter a diverse range of bacterial pathogens through their diets and interactions, have evolved many antibacterial defenses, and are a promising source of genes, molecules, and microbes for medical, agricultural, and food industry product development.

Assessment of Endocrine Disruptor Exposure in Hospital Professionals Using Hair and Urine Analyses: An Awareness Campaign

BACKGROUND

In 2021, French public authorities initiated the fourth National Environmental Health Plan to prevent environment-related health risks. This plan primarily focuses on the sensitization of health professionals and health care institutions. Endocrine disruptors (EDs) are environmental factors associated with several adverse health effects, such as reproductive disorders, obesity, and cancer. This study aimed to conduct an awareness campaign among professionals at a general hospital center on the risks related to EDs.

METHODS

Hospital professionals were directly involved in this study, and urine and hair samples were collected to determine bisphenol and paraben exposure levels. Analyses were performed using validated liquid chromatography-tandem mass spectrometry methods, enabling the simultaneous determination of bisphenols and parabens. A questionnaire on lifestyle habits was distributed to assess its relationship with the exposure profiles. Nineteen professionals were recruited for the study.

RESULTS

Bisphenol A was detected in 95% of the urine samples, and the chlorinated derivatives of bisphenol A were between 16% and 63%. parabens showed detection frequencies between 37% and 100%, and methylparaben was quantified at an average concentration of 0.45 ± 0.46 ng/mL. In hair samples, bisphenols A, F, and S were detected at 95%-100%, chlorinated derivatives of bisphenol A were detected at 37%-68%, and parabens were detected at 100%.

CONCLUSIONS

This awareness campaign may encourage health care institutions to adopt a policy of reducing endocrine disruptor exposure among their patients and professionals, who could be educated regarding the risks associated with EDs. Conducting a multicenter study to refine the results herein and establish a dynamic to prevent endocrine disruptor and environmental risks in health care systems would be valuable.

Synthesis and its biological activity of carboxymethyl hemicellulose p-hydroxybenzoate (P-CMHC)

Hemicellulose extracted from ecalyptus APMP pulping waste liquor and undergoes etherification modification to produce carboxymethyl hemicellulose (CMHC). Subsequently, CMHC undergoes esterification reaction with p-hydroxybenzoic acid to synthesize a novel polysaccharide-based preservative known as carboxymethyl hemicellulose p-hydroxybenzoate (P-CMHC). The synthesis conditions of P-CMHC were optimized using the response surface methodology, resulting in an optimal esterification condition that achieved a degree of substitution of 0.232. P-CMHC exhibits excellent antioxidant activity, including 2,2-diphenyl-1-picrylhydrazyl (DPPH) and hydroxyl radical scavenging activities. Additionally, it demonstrates favorable hygroscopic and moisturizing properties. Thiazole blue (MTT) experiments evaluating cell proliferation rate indicate that P-CMHC possesses negligible cytotoxicity, making it a promising, safe, and healthy preservative. Consequently, it can be considered as a new material for applications in the fields of biomedicine, food, and cosmetics.

Solvent-free enzymatic synthesis and evaluation of vanillyl propionate as an effective and biocompatible preservative

Preservatives are chemicals added to protect products against microbial spoilage, and thus are indispensable for pharmaceuticals, cosmetics, and foods. Due to growing concerns about human health and environments in conventional chemical preservatives, many companies have been seeking safe and effective alternatives that can be produced through environment-friendly processes. In this work, in order to develop effective and safe preservatives from plants, we attempt solvent-free lipase-catalyzed transesterification of vanillyl alcohol with ethyl propionate for the first time. The reaction product, vanillyl propionate was efficiently obtained in a high yield. Unlike vanillyl alcohol and ethyl propionate, vanillyl propionate showed antimicrobial activity. The minimal inhibitory concentration test showed that it exhibited high and broad antimicrobial activity against all the tested microorganisms (Gram-negative and Gram-positive bacteria, yeasts, and molds), which was overall comparable to that of propyl paraben, which is one of the most effective preservatives. It was also found to have even higher antioxidant capacity and biocompatibility with human cells than propyl paraben. Vanillyl propionate, which is a plant-based preservative produced through a green bioprocess, is expected to be successfully applied to various industries thanks to its high antimicrobial and antioxidant effect, and high biocompatibility.

Health safety of parabens evaluated by selected in vitro methods

Seven selected parabens (4 allowed, 3 banned in cosmetics) were tested in order to confirm and expand historical data on their toxicological properties and safety. The aim was to apply novel in vitro methods, which have been sufficiently technically and scientifically validated for the purposes of toxicological testing of chemicals. The study included several toxicological endpoints such as skin/eye irritation, skin sensitization, endocrine disruption and genotoxicity. The battery of selected methods comprised regulatory accepted EpiDerm™ skin model (OECD TG 439); EpiOcular™ corneal model (OECD TG 492) and scientifically valid test method HET-CAM (DB-ALM Protocol No. 47); in chemico test DPRA (OECD TG 442C); in vitro test LuSens (OECD TG 442D) and in vitro test h-CLAT (OECD TG 442E); Ames MPF™ (Xenometrix) and XenoScreen YES/YAS (Xenometrix). Overall, none of the 4 allowed parabens exhibited skin/eye irritation or genotoxicity. However, all allowed parabens in cosmetics were predicted as samples with potentially sensitizing properties in the LuSens and h-CLAT test methods, but not confirmed by DPRA. Endocrine disruption was recorded only at high concentrations, whereas methyl paraben and ethyl paraben exhibited the lowest activity. This study confirmed the safety of use of the allowed parabens in the highest recommended concentrations in cosmetics or pharmaceuticals.

Embryonic exposure to butylparaben and propylparaben induced developmental toxicity and triggered anxiety-like neurobehavioral response associated with oxidative stress and apoptosis in the head of zebrafish larvae

Parabens are synthetic antimicrobial compounds used as a preservative for extending the shelf life of food, pharmaceutical and cosmetic products. The alkyl chain length of the paraben esters positively correlates with their antimicrobial property. Hence, long-chain paraben esters, namely butylparaben and propylparaben, are used in combination as they have better solubility and antimicrobial efficacy. Extensive use of parabens has now resulted in the ubiquitous presence of these compounds in various human and environmental matrices. During early life, exposure to environmental contaminants is known to cause oxidative-stress mediated apoptosis in developing organs. The brain being one of the high oxygen-consuming, metabolically active and lipid-rich organ, it is primarily susceptible to reactive oxygen species (ROS) and lipid peroxidation (LP) induced neuronal cell death. The primary cause for the impairment in cognitive and emotional neurobehvioural outcomes in neurodegenerative disease was found to be associated with neuronal apoptosis. The present study aimed to study butylparaben and propylparaben's effect on zebrafish during early embryonic stages. Besides this, the association between alteration in anxiety-like neurobehavioral response with oxidative stress and antioxidant status in head region was also studied. The study results showed variation in the toxic signature left by butylparaben and propylparaben on developmental parameters such as hatching rate, survival and non-lethal malformations in a time-dependent manner. Data from the light-dark preference test showed embryonic exposure to butylparaben and propylparaben to trigger anxiety-like behavior in zebrafish larvae. In addition, a significant increase in intracellular ROS and LP levels correlated with suppressed antioxidant enzymes: superoxide dismutases (SOD), catalases (CAT), Glutathione peroxidase (GPx), glutathione S-transferase (GST), and Glutathione (GSH) activity in the head region of the zebrafish larvae. Acetylcholinesterase (AChE) activity was also suppressed in the exposed groups, along with increased nitric oxide production. The overall observations show increased oxidative stress indices correlating with upregulated expression of apoptotic cells in a dose-dependent manner. Collectively, our findings reveal butylparaben and propylparaben as an anxiogenic neuroactive compound capable of inducing anxiety-like behavior through a mechanism involving oxidative-stress-induced apoptosis in the head of zebrafish larvae, which suggests a potential hazard to the early life of zebrafish and this can be extrapolated to human health as well.

Food-inspired innovations to improve the stability of active pharmaceutical ingredients

Food-processing and pharmaceutical industries share a lot of stability issues against the same physical, chemical, and microbiological phenomena. They also share some solutions to improve the stability as the use of preservatives and packaging. Ecological concerns lead to the development of tremendous innovations in food. Some of these innovations could also be beneficial in the pharmaceutical domain. The objective of this review is to evaluate the potential application of these findings in the pharmaceutical field and the main limits in terms of toxicity, environmental, economic and regulatory issues. The principal factors influencing the shelf-life were highlighted through the description of the stability studies usually performed in the pharmaceutical industry (according to European guidelines). To counter those factors, different solutions are currently available as preservatives and specific packaging. They were described and debated with an overview of recent food innovations in each field. The limits of the current solutions in the pharmaceutical field and the innovation in the food field have inspired a critical pharmaceutical outlook. The active and intelligent packaging for active pharmaceutical ingredients of the future is imagined.

The potential implications of estrogenic and antioxidant-dependent activities of high doses of methyl paraben on MCF7 breast cancer cells

Methyl paraben (MP) is an endocrine-disrupting compound that possesses estrogenic properties and contributes to an aberrant burden of estrogen signaling in the human breast and subsequently increasing the risks for the development of breast cancer. The exact exposure, as well as the safe concentrations, are variable among daily products. The present study addresses the effects of exposure to escalated concentrations of MP on the proliferation of MCF-7 breast cancer cells in addition to exploring its other mechanisms of action. The study involved exposure of cultured MCF-7 breast cancer cells to seven MP concentrations, ranging from 40 to 800 µM for 5 days. Cell viability, apoptosis, and proliferation were respectively assessed using crystal violet test, flow cytometric analysis, and quantitative real-time polymerase chain reaction for Ki-67 expression. The estradiol (E2) secretion and oxidative stress were also assessed and analyzed in correlation to MP's proliferation and cytotoxicity potentials. The results showed that the maximum proliferative concentration of MP was 800 µM. At a concentration of 40 μM and higher, MP induced increased expression of Ki-67, denoting enhanced proliferation of the cells in monolayer culture. A positive correlation between the detrimental oxidative stress effect of MP's tested concentrations, cell proliferation, and viability was demonstrated (p < 0.05). Our results indicated that MP at high doses induced sustained cell proliferation due to E2 secretion as well as its antioxidant activity. Accordingly, it was concluded that high and unpredicted exposure to MP might carry a carcinogenic hazard on estrogen receptor-positive breast cancer cells.

The implication of parabens in cosmetics and cosmeceuticals: advantages and limitations

Cosmetics, cosmeceuticals, and variable healthcare products used parabens, among other excipients, for their preservative and antimicrobial activities. Paraben derivatives exhibit distinguished physiochemical properties that enable them to be compatible with the formulation of cosmetic agents in different dosage forms. In addition to their potency and efficacy, parabens are economically efficient as they have low manufacturing costs. Despite the desirable characteristics, the safety of parabens use is controversial after detecting these chemicals in various biological tissues after repetitive and long-term use of formulations containing them. The use of parabens drew public health attention after scientific reports linked skin exposure to parabens with health issues, in particular, breast cancer. In response, worldwide authorities set regulations for the allowance concentrations of paraben to be used in variable cosmetic products.

Perinatal Environmental Health Education Intervention to Reduce Exposure to Endocrine Disruptors: The PREVED Project

Environmental health promotion interventions may reduce endocrine disruptor (ED) exposure. The PREVED (PREgnancy, preVention, Endocrine Disruptors) project was developed to improve knowledge, to enhance risk perception, and to change exposure behavior. Our objective was to present the phases of the PREVED project using the RE-AIM method. PREVED intervention consisted of three workshops during pregnancy. Reach, adoption, and implementation phases were assessed with qualitative studies. Efficacy study consisted of a three-arm randomized controlled trial (RCT) on 268 pregnant women: (i) control group (leaflet), (ii) intervention group in neutral location, (iii) intervention group in contextualized location. The main outcome was the percentage evolution of participants who reported consuming canned food. Secondary outcomes were evolution of psycho-social scores, evolution of ED presence in urine, and ED presence in colostrum. The intervention adoption was centered on upper-privileged women, but implementation assessment showed that key features (highly practical intervention) seemed to be carried out and had initiated some behavior changes. A total of 268 pregnant women participated in the intervention and 230 in a randomized controlled trial (control group: 86 and intervention groups: 172). We found no significant differences in consumption of canned food and in percentage of women having a decrease of bisphenol A or parabens in urine, but we found a significant increase in the evolution of risk perception score and overall psychosocial score in intervention groups (respectively: +15.73 control versus +21.03 intervention, p = 0.003 and +12.39 versus +16.20, p = 0.02). We found a significant difference in percentage of women with butylparaben detection between control group and intervention groups (13% versus 3%, p = 0.03). PREVED intervention is the first intervention research dedicated to perinatal environmental health education in France. By sharing know-how/experience in a positive non-alarmist approach, it improved risk perception, which is key to behavior change, aiming to reduce perinatal ED exposure. Including women in precarious situations remains a major issue.

Controversy around parabens: Alternative strategies for preservative use in cosmetics and personal care products

Parabens usage as preservatives in cosmetics and personal care products have been debated among scientists and consumers. Parabens are easy to production, effective and cheap, but its safety status remains controversial. Other popular cosmetics preservatives are formaldehyde, triclosan, methylisothiazolinone, methylchloroisothiazolinone, phenoxyethanol, benzyl alcohol and sodium benzoate. Although their high antimicrobial effectiveness, they also exhibit some adverse health effects. Lately, scientists have shown that natural substances such as essential oils and plant extracts present antimicrobial potential. However, their use in cosmetic is a challenge. The present review article is a comprehensive summary of the available methods to prevent microbial contamination of cosmetics and personal care products, which can allow reducing the use of parabens in these products.

Coiled molecularly imprinted polymer layer open-tubular capillary tube for detection of parabens in personal care and cosmetic products

Personal care and cosmetic products (PCPs) are the primary exposure pathway of humans to parabens and their safety has become a public concern. However, sample pretreatment of PCPs is a great challenge due to their complexities and diversity. In this study, epoxide modified molecularly imprinted polymers (MIPs) were synthesized using ethylparaben as a template, methacrylic acid and isobutyl vinyl ether as co-monomers and glycidilmethacrylate as a post-modified monomer. MIP layer open-tubular tubes were prepared by modifying branched polyethylenimine and then grafting MIPs onto the inner surface of Teflon capillary tubes. The tube was coiled to effectively increase mass transfer and coupled to an HPLC-UV system for parabens detection in PCPs. Matrix interference was significantly decreased while efficient enrichment and recoveries were obtained. Under optimized conditions, the linear range for parabens detection was 0.5-600 ng mL^-1 with detection limits of 0.2 to 0.3 ng mL^-1. The system was used to study the contents of parabens in popular PCPs. The concentrations of parabens in 108 PCPs ranged from <0.5 ng g^-1 to 2856 μg g^-1 with geometric mean of 250.3 μg g^-1. Almost all of the products contained at least one kind of parabens; methyl paraben (geometric mean: 182.9 μg g^-1) and n-propyl paraben (geometric mean: 42.5 μg g^-1) were the predominant compounds had been found in the samples. This method could be useful for human exposure assessment towards parabens.

Screening of preservatives and evaluation of sterilized cellulose nanofibers for toxicity studies

OBJECTIVES

The aim of this study is to establish a sterilization method for cellulose nanofibers (CNFs) dispersions that uses multiple preservatives with different hydrophilicities without affecting the physical and chemical properties of CNFs, and to provide useful information for sample preparation in future toxicity study of CNFs.

METHODS

Various preservatives were added to the phosphorylated CNF dispersions, endotoxin level and the numbers of bacteria and fungi in the CNF dispersion were analyzed. The pH values and viscosity of sterilized CNF dispersions were compared with those of control and autoclaved CNF dispersions.

RESULTS

Phosphorylated CNF dispersions at a concentration of 2.0 mg/mL or lower and the addition of 10 µg/mL benzalkonium chloride alone or 250 µg/mL methyl parahydroxybenzoate and 250 µg/mL propyl parahydroxybenzoate in combination can sterilize CNF dispersions without changing the physical and chemical properties of CNFs.

CONCLUSIONS

We developed sterilization method for CNF dispersions that uses multiple preservatives with different hydrophilicities without affecting the physical and chemical properties of CNFs. This sterilization method for CNFs dispersions can be applied to the safety assessment of CNF with different physicochemical properties in the future.

Enhancement of paraben-fungicidal activity by sulforaphane, a cruciferous vegetable-derived isothiocyanate, via membrane structural damage in Saccharomyces cerevisiae

Parabens have been widely used as antimicrobial preservatives in cosmetics, pharmaceuticals, foods and beverages. Commonly, methyl-, ethyl-, propyl- and butylparaben are used independently or in combination to maintain the quality of industrial products, and they are considered to have low toxicity. However, recent evidence has suggested that parabens are toxic in mammalian cells, and parabens have been associated with allergic-contact dermatitis, breast cancer and changes in testosterone levels. Sulforaphane, a cruciferous vegetable-derived isothiocyanate, was effective in decreasing the growth inhibitory concentrations of ethyl-, propyl-, butyl- and methylparaben in the yeast Saccharomyces cerevisiae. The sulforaphane-enhanced fungicidal effects of methylparaben were deemed to be caused by drastic cell membrane damage and the leakage of internal substances, such as nucleotides, from S. cerevisiae cells. Moreover sulforaphane markedly decreased the minimum concentration of methyl- and ethylparaben required to inhibit the growth of various microbes, such as the pathogenic yeast that causes severe mycosis, Candida albicans; the filamentous fungi Aspergillus niger; and the Gram-negative bacterium Escherichia coli. Enhanced antimicrobial activity from the beneficial components of edible plants may increase paraben efficacy at low concentrations and minimize preservative-induced side effects in consumers. SIGNIFICANCE AND IMPACT OF THE STUDY: Sulforaphane, a natural and beneficial cruciferous vegetable-derived isothiocyanate, increased the ability of parabens to disrupt fungal cell membranes. Paraben-containing products have been reported to cause allergic contact dermatitis and drug hypersensitivity; therefore, methods to preserve organic products that may reduce the concentrations of parabens are both timely and necessary. In this study, we found that the combined antimicrobial effects of sulforaphane and parabens had the potential to reduce the paraben concentration needed to preserve organic products, thereby indicating that paraben toxicity may be reduced without affecting its activity as a preservative.

Comparison of Photocatalytic and Photosensitized Oxidation of Paraben Aqueous Solutions Under Sunlight

It is well-established that aquatic wildlife is exposed to natural and synthetic endocrine disrupting compounds which are able to interfere with the hormonal system. Although advanced oxidation processes (AOPs) have shown to be effective, their application is limited by a relatively high operational cost. In order to reduce the cost of energy consumed in the AOPs, widely available solar energy instead of UV light may be applied either as photocatalytic oxidation or as photosensitized oxidation. The main goal of the present study was to investigate the sunlight photodegradation of paraben mixture. Two processes, namely the photocatalytic oxidation with modified TiO2 nanoparticles and photosensitized oxidation with photosensitive chitosan beads, were applied. The oxidants were identified as singlet oxygen and hydroxyl radicals for photosensitized and photocatalytic oxidation, respectively. The toxicity, as well as ability to water disinfection of both processes under natural sunlight, has been investigated. Application of sunlight for the processes led to degradation of parabens. The efficiency of both processes was comparable. Despite the fact that singlet oxygen is weaker oxidant than hydroxyl radicals, the photosensitized oxidation seems to be more promising for wastewater purification, due to the possibility of chitosan bead reuse and more effective water disinfection. Graphical Abstractᅟ.

Interaction between Different Pharmaceutical Excipients in Liquid Dosage Forms-Assessment of Cytotoxicity and Antimicrobial Activity

Nowadays, the safety of parabens as pharmaceutical preservatives is debated. Recent studies investigated their interference with the oestrogen receptors, nevertheless their carcinogenic activity was also proved. That was the reason why the re-evaluation of the biocompatibility and antimicrobial activity of parabens is required using modern investigation methods. We aimed to test the cytotoxic, antifungal and antibacterial effect of parabens on Caco-2 cells, C. albicans, C. parapsilosis, C. glabrata, E. coli, P. aeruginosa and S. aureus. Two complex systems (glycerol-Polysorbate 20; ethanol-Capryol PGMC™) were formulated to study-with the MTT-assay and microdilution method, respectively-how other excipients may modify the biocompatibility and antimicrobial effect of parabens. In the case of cytotoxicity, the toxicity of these two systems was highly influenced by co-solvents and surfactants. The fungi and bacteria had significantly different resistance in the formulations and in some cases the excipients could highly modify the effectiveness of parabens both in an agonistic and in a counteractive way. These results indicate that with appropriate selection, non-preservative excipients can contribute to the antimicrobial safety of the products, thus they may decrease the required preservative concentration.

In vitro genotoxic and cytotoxic effects of some paraben esters on human peripheral lymphocytes

Parabens (PBs) are p-hydroxybenzoic acid ester compounds commonly employed as antimicrobial preservatives, mainly in food, cosmetic, and pharmaceutical products. The aim of the present study was to investigate the genotoxic and cytotoxic effects of some paraben esters (butyl paraben, propyl paraben, isobutyl paraben, and isopropyl paraben) on human peripheral lymphocytes, using in vitro sister chromatid exchange (SCE), chromosome aberration (CA), and cytokinesis-block micronucleus (CBMN) tests. Lymphocyte cultures were treated with four concentrations of PBs (100, 50, 25 and 10 µg/mL) for 24 and 48 h. Paraben esters significantly induced MN formations as compared to solvent control. Furthermore, butyl paraben and propyl paraben increased MN formations a concentration-dependent manner at 24 and 48 h. PBs increased the CA at 24 and 48 h. However, this increase was not meaningful for butyl paraben and isopropyl paraben at 48 h when compared with solvent control. Butyl, isobutyl, and isopropyl paraben significantly increased the SCE at 24 and 48 h. However, propyl paraben did not induce SCE meaningfully in both treatment periods. A significant decrease in the cytokinesis-block proliferation index and mitotic index was observed in cells exposed to all concentrations of PBs at 24 and 48 h. However, proliferation index was not affected at all concentrations of PBs after 24 h treatment, although it was decreased at the highest concentration of PBs at 48 h. It is concluded that all of the paraben esters used in this study have highly genotoxic and cytotoxic effects on human lymphocytes cells in vitro.

A QSAR Study Based on SVM for the Compound of Hydroxyl Benzoic Esters

Hydroxyl benzoic esters are preservative, being widely used in food, medicine, and cosmetics. To explore the relationship between the molecular structure and antibacterial activity of these compounds and predict the compounds with similar structures, Quantitative Structure-Activity Relationship (QSAR) models of 25 kinds of hydroxyl benzoic esters with the quantum chemical parameters and molecular connectivity indexes are built based on support vector machine (SVM) by using R language. The External Standard Deviation Error of Prediction (SDEP_ext), fitting correlation coefficient (R²), and leave-one-out cross-validation (Q²_LOO) are used to value the reliability, stability, and predictive ability of models. The results show that R² and Q²_LOO of 4 kinds of nonlinear models are more than 0.6 and SDEP_ext is 0.213, 0.222, 0.189, and 0.218, respectively. Compared with the multiple linear regression (MLR) model (R² = 0.421, RSD = 0.260), the correlation coefficient and the standard deviation are both better than MLR. The reliability, stability, robustness, and external predictive ability of models are good, particularly of the model of linear kernel function and eps-regression type. This model can predict the antimicrobial activity of the compounds with similar structure in the applicability domain.

Crystal structure of the co-crystal butyl-paraben-isonicotinamide (1/1)

The title 1:1 co-crystal, C11H14O3·C6H6N2O [systematic name: butyl 4-hy-droxy-benzoate-isonicotinamide (1/1)], crystallizes with one mol-ecule of butyl-paraben (BPN) and one mol-ecule of isonicotinamide (ISN) in the asymmetric unit. In the crystal, BPN and ISN mol-ecules form hydrogen-bonded (O-H⋯N and N-H⋯O) dimers of paired BPN and ISN mol-ecules. These dimers are further connected to each other via N-H⋯O=C hydrogen bonds, creating ribbons in [011] which further stack along the a axis to form a layered structure with short C⋯C contacts of 3.285 (3) Å. Packing inter-actions within the crystal structure were assessed using PIXEL calculations.

Influence of inorganic ions and selected emerging contaminants on the degradation of Methylparaben: A sonochemical approach

The study on the possible pathway of hydroxyl radicals mediated sonolytic degradation of paraben in water is reported. Methylparaben (MPB) which is the most utilized of paraben family is selected as a model emerging pollutant. The influence of common anions and some selected emerging contaminants that may coexist in typical water matrix on the degradation pattern is analyzed alongside. Among the anions, carbonate presents a negative influence which is attributed to the competition for OH radical. Some emerging contaminants also showed negative impact on degradation as was clear from HPLC data. The intermediates, analyzed by LC-Q-TOF-MS include hydroxylated and hydrolytic products. Three major steps (aromatic hydroxylation, hydroxylation at the ester chain and hydrolysis) are proposed to involve in the reaction of OH radical with MPB which ultimately leads to mineralization. The intensity of formation and decay of mono and dihydroxy products of MPB in the presence of additives have also been evaluated. COD analysis indicates a percentage reduction of 98% at 90 min of sonolysis and further increase in the degradation time resulted complete mineralization, which became evident from the mass spectrometric data. MTT assay revealed considerable decrease in the potential cytotoxicity.

Antimicrobial lubricant formulations containing poly(hydroxybenzene)-trimethoprim conjugates synthesized by tyrosinase

Poly(hydroxybenzene)-trimethoprim conjugates were prepared using methylparaben as substrate of the oxidative enzyme tyrosinase. MALDI-TOF MS analysis showed that the enzymatic oxidation of methylparaben alone leads to the poly(hydroxybenzene) formation. In the presence of trimethoprim, the methylparaben tyrosinase oxidation leads poly(hydroxybenzene)-trimethoprim conjugates. All of these compounds were incorporated into lubricant hydroxyethyl cellulose/glycerol mixtures. Poly(hydroxybenzene)-trimethoprim conjugates were the most effective phenolic structures against the bacterial growth reducing by 96 and 97% of Escherichia coli and Staphylococcus epidermidis suspensions, respectively (after 24 h). A novel enzymatic strategy to produce antimicrobial poly(hydroxybenzene)-antibiotic conjugates is proposed here for a wide range of applications on the biomedical field.

Sandwich crystals of butyl paraben

Sandwich crystals: one polymorph. Opaque middle layer: 0.1 μm scale size pores. Parallel outer layer: translucent crystalline layers.