Inspecting Histamine Isolated from Fish through a Highly Selective Molecularly Imprinted Electrochemical Sensor Approach.

Numerous analytical approaches have been developed to determine histamine levels in food samples due to its health consequences. Consuming histamine over the Food and Drug Administration (FDA)-regulated 50 mg kg-1 limit would result in chronic toxicity. Consequently, the present study discusses a novel electrochemical approach to evaluate histamine levels in fish products via a molecularly imprinted polymer (MIP) on an electrode surface. The film was produced with electropolymerized polyurethane (PU), which maintained the histamine compound. Fourier-transform infrared (FTIR) spectroscopy was applied to verify the MIP manufactured in this study. The capability of the polymer was measured by assessing its electron shifts with cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). Differential pulse voltammetry (DPV) was also employed to validate the sensing method. The MIP/screen-printed electrode (SPE) and non-imprinted polymer (NIP)/SPE recorded a linear response ranging from 1 to 1000 nmol L-1 at the 1.765 and 709 nmol L-1 detection limits. The sensing technique was subsequently utilized to determine the histamine levels in selected samples at room temperature (25 °C). Generally, the sensor allowed the accurate and precise detection of histamine in the fish samples. Furthermore, the approach could be categorized as a simple technique that is low-cost and suitable for on-site detections.

Polyurethane Application to Transform Screen-Printed Electrode for Rapid Identification of Histamine Isolated from Fish.

The toxicity of histamine has attracted numerous researchers to develop a method for histamine determination purposes. The Food and Drug Administration (FDA) unequivocally prohibits the consumption of histamine above 50 mg·kg-1. Thus, an innovation in histamine detection in fish has been developed in this research. The investigation of the histamine level in fish has been conducted by using an electrochemical sensor approach and producing a polymer via molecularly imprinted polymer (MIP) on a screen-printed electrode. The technique was validated by assessing the shifts in electron shifting using the cyclic voltammetry (CV) approach and electrochemical impedance spectroscopy (EIS), whereas differential pulse voltammetry (DPV) was applied to validate the sensor method. The instruments showed a linear response ranging from 1-1000 nmol·L-1, with a detection limit of MIP/SPE at 1.765 nmol·L-1 and 709 nmol·L-1 for the NIP/SPE, respectively. The sensing technique was employed to determine the histamine level in selected samples at room temperature (25°C). The outcomes of this study indicated that the validated chemical sensor allowed accurate and precise detection of fish samples and can be categorized as a simple approach. The instrument is inexpensive and suitable for on-site detection.

Surface-engineered liposomes for dual-drug delivery targeting strategy against methicillin-resistant Staphylococcus aureus (MRSA).

This study focused on the encapsulation of vancomycin (VAN) into liposomes coated with a red blood cell membrane with a targeting ligand, daptomycin-polyethylene glycol-1,2-distearoyl-sn-glycero-3-phosphoethanolamine, formed by conjugation of DAPT and N-hydroxysuccinimidyl-polyethylene glycol-1,2-distearoyl-sn-glycero-3-phosphoethanolamine. This formulation is capable of providing controlled and targeted drug delivery to the bacterial cytoplasm. We performed MALDI-TOF, NMR and FTIR analyses to confirm the conjugation of the targeting ligand via the formation of amide bonds. Approximately 45% of VAN could be loaded into the aqueous cores, whereas 90% DAPT was detected using UV-vis spectrophotometry. In comparison to free drugs, the formulations controlled the release of drugs for > 72 h. Additionally, as demonstrated using CLSM and flow cytometry, the resulting formulation was capable of evading detection by macrophage cells. In comparison to free drugs, red blood cell membrane-DAPT-VAN liposomes, DAPT liposomes, and VAN liposomes reduced the MIC and significantly increased bacterial permeability, resulting in > 80% bacterial death within 4 h. Cytotoxicity tests were performed in vitro and in vivo on mammalian cells, in addition to hemolytic activity tests in human erythrocytes, wherein drugs loaded into the liposomes and RBCDVL exhibited low toxicity. Thus, the findings of this study provide insight about a dual antibiotic targeting strategy that utilizes liposomes and red blood cell membranes to deliver targeted drugs against MRSA.

Anti-Allergic Rhinitis Effects of Medicinal Plants and Their Bioactive Metabolites via Suppression of the Immune System: A Mechanistic Review.

Allergic rhinitis (AR) is a common inflammatory condition of the nasal mucosa and it is an immunoglobulin E-mediated disease. The incidence and prevalence of AR globally have been escalating over recent years. Antihistamines, intranasal corticosteroids, decongestants, intranasal anticholinergics, intranasal cromolyn, leukotriene receptor antagonists and immunotherapy have been used in the treatment of AR. However, there is a need to search for more effective and safer remedies as many of the current treatments have reported side effects. Medicinal plants have been used traditionally to relief symptoms of AR but their efficacy and safety have not been scientifically proven. In this review, up-to-date reports of studies on the anti-allergic rhinitis of several medicinal plants and their bioactive metabolites through suppression of the immune system are compiled and critically analyzed. The plant samples were reported to suppress the productions of immunoglobulin E, cytokines and eosinophils and inhibit histamine release. The suppression of cytokines production was found to be the main mechanistic effect of the plants to give symptomatic relief. The prospect of these medicinal plants as sources of lead molecules for development of therapeutic agents to treat AR is highlighted. Several bioactive metabolites of the plants including shikonin, okicamelliaside, warifteine, methylwarifteine, luteolin-7-O-rutinoside, tussilagone, petasin, and mangiferin have been identified as potential candidates for development into anti-allergic rhinitis agents. The data collection was mainly from English language articles published in journals, or studies from EBSCOHOST, Medline and Ovid, Scopus, Springer, and Google Scholar databases from the year 1985-2020. The terms or keywords used to find relevant studies were allergic rhinitis OR pollinosis OR hay fever, AND medicinal plant OR single plant OR single herb OR phytotherapy. This comprehensive review serves as a useful resource for medicinal plants with anti-allergic rhinitis potential, understanding the underlying mechanisms of action and for future exploration to find natural product candidates in the development of novel anti-allergic rhinitis agents.

Rapid detection of sildenafil analogue in Eurycoma longifolia products using a new two-tier procedure of the near infrared (NIR) spectra database.

A simple and cost-effective two-tier drug screening procedure comprises a 'dedicated' NIR spectral database of common medicines and a 'unified' database was developed to detect the sildenafil analogue in Eurycoma longifolia products. Diffuse reflectance spectra of ten commercial herbal products containing E. longifolia were obtained over the wavelength range of 1100-2500 nm. The spectral search of two products purchased via the internet against a dedicated database of reputable E. longifolia products have resulted in the similarity index of more than 0.1 which indicated significantly different spectra. Further searches against the unified database showed a close match to the spectra of drug containing sildenafil citrate suggesting the presence of a sildenafil analogue. This finding was supported by clustering of these spectra in the PCA score plot within 5% significance level. This approach has alleviated the use of reference product or standard active for direct comparison and has a potential to be used for adulterated food and drugs detection.