Phycobilins as Potent Food Bioactive Broad-Spectrum Inhibitors Against Proteases of SARS-CoV-2 and Other Coronaviruses: A Preliminary Study

In the 21st century, we have witnessed three coronavirus outbreaks: SARS in 2003, MERS in 2012, and the ongoing pandemic coronavirus disease 2019 (COVID-19). The search for efficient vaccines and development and repurposing of therapeutic drugs are the major approaches in the COVID-19 pandemic research area. There are concerns about the evolution of mutant strains (e.g., VUI – 202012/01, a mutant coronavirus in the United Kingdom), which can potentially reduce the impact of the current vaccine and therapeutic drug development trials. One promising approach to counter the mutant strains is the “development of effective broad-spectrum antiviral drugs” against coronaviruses. This study scientifically investigates potent food bioactive broad-spectrum antiviral compounds by targeting main protease (Mpro) and papain-like protease (PLpro) proteases of coronaviruses (CoVs) using in silico and in vitro approaches. The results reveal that phycocyanobilin (PCB) shows potential inhibitor activity against both proteases. PCB had the best binding affinity to Mpro and PLpro with IC50 values of 71 and 62 μm, respectively. Also, in silico studies with Mpro and PLpro enzymes of other human and animal CoVs indicate broad-spectrum inhibitor activity of the PCB. As with PCB, other phycobilins, such as phycourobilin (PUB), phycoerythrobilin (PEB), and phycoviolobilin (PVB) show similar binding affinity to SARS-CoV-2 Mpro and PLpro

Genomic Modeling as an Approach to Identify Surrogates for Use in Experimental Validation of SARS-CoV-2 and HuNoV Inactivation by UV-C Treatment

Severe Acute Respiratory Syndrome coronavirus-2 (SARS-CoV-2) is responsible for the COVID-19 pandemic that continues to pose significant public health concerns. While research to deliver vaccines and antivirals are being pursued, various effective technologies to control its environmental spread are also being targeted. Ultraviolet light (UV-C) technologies are effective against a broad spectrum of microorganisms when used even on large surface areas. In this study, we developed a pyrimidine dinucleotide frequency based genomic model to predict the sensitivity of select enveloped and non-enveloped viruses to UV-C treatments in order to identify potential SARS-CoV-2 and human norovirus surrogates. The results revealed that this model was best fitted using linear regression with r2 = 0.90. The predicted UV-C sensitivity (D90 – dose for 90% inactivation) for SARS-CoV-2 and MERS-CoV was found to be 21.5 and 28 J/m2, respectively (with an estimated 18 J/m2 obtained from published experimental data for SARS-CoV-1), suggesting that coronaviruses are highly sensitive to UV-C light compared to other ssRNA viruses used in this modeling study. Murine hepatitis virus (MHV) A59 strain with a D90 of 21 J/m2 close to that of SARS-CoV-2 was identified as a suitable surrogate to validate SARS-CoV-2 inactivation by UV-C treatment. Furthermore, the non-enveloped human noroviruses (HuNoVs), had predicted D90 values of 69.1, 89, and 77.6 J/m2 for genogroups GI, GII, and GIV, respectively. Murine norovirus (MNV-1) of GV with a D90 = 100 J/m2 was identified as a potential conservative surrogate for UV-C inactivation of these HuNoVs. This study provides useful insights for the identification of potential non-pathogenic (to humans) surrogates to understand inactivation kinetics and their use in experimental validation of UV-C disinfection systems. This approach can be used to narrow the number of surrogates used in testing UV-C inactivation of other human and animal ssRNA viral pathogens for experimental validation that can save cost, labor and time

Phycobilins as Potent Food Bioactive Broad-Spectrum Inhibitors Against Proteases of SARS-CoV-2 and Other Coronaviruses: A Preliminary Study

In the 21st century, we have witnessed three coronavirus outbreaks: SARS in 2003, MERS in 2012, and the ongoing pandemic coronavirus disease 2019 (COVID-19). The search for efficient vaccines and development and repurposing of therapeutic drugs are the major approaches in the COVID-19 pandemic research area. There are concerns about the evolution of mutant strains (e.g., VUI – 202012/01, a mutant coronavirus in the United Kingdom), which can potentially reduce the impact of the current vaccine and therapeutic drug development trials. One promising approach to counter the mutant strains is the “development of effective broad-spectrum antiviral drugs” against coronaviruses. This study scientifically investigates potent food bioactive broad-spectrum antiviral compounds by targeting main protease (Mpro) and papain-like protease (PLpro) proteases of coronaviruses (CoVs) using in silico and in vitro approaches. The results reveal that phycocyanobilin (PCB) shows potential inhibitor activity against both proteases. PCB had the best binding affinity to Mpro and PLpro with IC50 values of 71 and 62 μm, respectively. Also, in silico studies with Mpro and PLpro enzymes of other human and animal CoVs indicate broad-spectrum inhibitor activity of the PCB. As with PCB, other phycobilins, such as phycourobilin (PUB), phycoerythrobilin (PEB), and phycoviolobilin (PVB) show similar binding affinity to SARS-CoV-2 Mpro and PLpro

UV-C inactivation of microorganisms in droplets on food contact surfaces using UV-C light-emitting diode devices

The main objective of this study was to investigate the effectiveness of ultraviolet light (UV-C) emitting diodes for the decontamination of stainless steel food contact surfaces. Listeria monocytogenes (ATCC 19115), Escherichia coli (ATCC 25922), and Salmonella enterica serovar Typhimurium (ATCC 700720) were chosen as challenge microorganisms. Target microorganisms were subjected to UV-C dosages of 0, 2, 4, 6, and 8 mJ cm−2 at an average fluence of 0.163 mW/cm2 using a near-collimated beam operating at 279 nm wavelength. Escherichia coli showed lower sensitivity to UV-C light compared to Salmonella Typhimurium and followed first-order kinetics. Escherichia coli and Salmonella Typhimurium were reduced by more than 3-log10 cycles at the maximum UV dosage of 12 mJ cm−2 . In contrast, Listeria monocytogenes followed the Weibull model with an apparent shoulder in the initial doses. A maximum reduction of 4.4-log10 was achieved at the highest exposure level. This study showed that UV-C LED devices represent an excellent alternative for the inactivation of foodborne microorganisms in droplets. Results clearly demonstrate that UV-C LED devices can serve as an additional sanitation method to routine cleaning practices, which are commonly utilized in the food industry

Performance of a UV-A LED system for degradation of aflatoxins B1 and M1 in pure water: kinetics and cytotoxicity study

The efficacy of a UV-A light emitting diode system (LED) to reduce the concentrations of aflatoxin B1, aflatoxin M1 (AFB1, AFM1) in pure water was studied. This work investigates and reveals the kinetics and main mechanism(s) responsible for the destruction of aflatoxins in pure water and assesses the cytotoxicity in liver hepatocellular cells. Irradiation experiments were conducted using an LED system operating at 365 nm (monochromatic wave-length). Known concentrations of aflatoxins were spiked in water and irradiated at UV-A doses ranging from 0 to 1,200 mJ/cm2. The concentration of AFB1 and AFM1 was determined by HPLC with fluorescence detection. LC–MS/MS product ion scans were used to identify and semi-quantify degraded products of AFB1 and AFM1. It was observed that UV-A irradiation significantly reduced aflatoxins in pure water. In comparison to control, at dose of 1,200 mJ/cm2 UV-A irradiation reduced AFB1 and AFM1 concentrations by 70 ± 0.27 and 84 ± 1.95%, respectively. We hypothesize that the formation of reactive species initiated by UV-A light may have caused photolysis of AFB1 and AFM1 molecules in water. In cell culture studies, our results demonstrated that the increase of UV-A dosage decreased the aflatoxins-induced cytotoxicity in HepG2 cells, and no significant aflatoxin-induced cytotoxicity was observed at UV-A dose of 1,200 mJ/cm2. Further results from this study will be used to compare aflatoxins detoxification kinetics and mechanisms involved in liquid foods such as milk and vegetable oils

Evaluating the UV-C sensitivity of Coxiella burnetii in skim milk using a bench-scale collimated beam system and comparative thermal sensitivity study by high-temperature short-time pasteurization

Introduction:Coxiella burnetii is a zoonotic Gram-negative obligate intracellular bacterial pathogen and the causative agent of query (Q) fever in humans. Contamination of milk by C. burnetii, as a consequence of livestock infection, is a significant public health concern. Effective methods to inactivate C. burnetii in milk are a critical aspect of food safety. Implementation of non-thermal UV-C processing technologies in the dairy industry can effectively preserve the sensory and nutritional quality of raw milk products while ensuring their safety, making them a viable alternative to traditional high-temperature short-time (HTST) pasteurization methods.Methods: Optical light attenuation factors, such as the absorption, scattering, and reflection by skim milk (SM) were evaluated using a spectrophotometer. SM inoculated with an avirulent strain of C. burnetii was irradiated using a collimated beam device equipped with a low-pressure UV-C 254 nm lamp at doses from 0 to 12 mJ/cm2. Optical properties were considered for the evaluation of the delivered UV-C dose. The pasteurization treatment was conducted using a lab scale HTST pasteurizer (72°C/15 s). The verification studies were conducted using Escherichia coli ATCC 25922 inoculated in a phosphate buffer (transparent fluid) and humic acid (opaque fluid). Salmonella enterica serovar Muenchen ATCC BAA 1674 inoculated in SM was tested for its suitability as a surrogate for C. burnetii, a bacterium that requires specialized equipment and expertise for experimentation.Results and Discussion: Absorption, reduced scattering coefficient, and the reflectance of SM at 254 nm were measured as 19 ± 0.3/cm, 26 ± 0.5/cm, and 10.6%, respectively. The UV-C results showed a log-linear inactivation of C. burnetii in SM with the UV-C sensitivity (D10) value of 4.1 ± 0.04 mJ/cm2. The results of HTST pasteurization revealed that C. burnetii was heat-sensitive with a D value of 1.75 min. Salmonella Muenchen showed similar UV inactivation kinetics and is, thereby, suggested as a suitable surrogate to C. burnetii for the pilot-scale UV-C processing studies of SM

In silico Screening of Cyanobacterial and Food Bioactive Compounds to Predict Potential Inhibitors of COVID-19 Main protease (Mpro), Papain-like protease (PLpro) and RNA-dependent RNA polymerase (RdRp)

As novel corona virus (COVID-19) infections has spread throughout the world, world health organization (WHO) has announced COVID-19 as a pandemic infection. Henceforth investigators are conducting extensive research to find possible therapeutic agents against COVID-19. Main protease (Mpro) and papain-like protease (PLpro) that plays an essential role in processing the polyproteins that are translated from the 2019-nCoV RNA and RNA-dependent RNA polymerase (RdRp) that catalyzes the replication of RNA from RNA template becomes as a potential targets for in silico screening of effective therapeutic compounds to COVID-19. In this study we screened binding affinity of cyanobacterial and food bioactive compounds against 2019-nCoV Mpro, PLpro and RdRp using structure-based molecular docking approach. The results showed that cyanobacterial compounds - 7-Deoxy-Desulfo-Cylindrospermopsin, Calothrixins, Eucapsitrione, Tjipanazoles, Ambiguines, Tolyporphyrins, Phycobilins, Microcyclamides, spumigins, cryptophycins and food bioactive compounds – Geraldone, Asarin, Garbanzole, 1-Acetoxy-8-Hydroxy-1,4,4a,9a-Tetrahydroanthraquinone, Sesamolin, Gallocatechin gallate, Quercitrin, Maximol A, Scutellarien, Isoxanthohumol, Gallocatechin gallate, Quercitrin, Maximol A, Scutellarien, Isoxanthohumol, Seasominol, Citracridione I, Anonaine and Momilactone A as potential binders to the selected SARS-CoV-2 receptors with good dock scores and binding pose. Though, further in vitro and/or in vivo research is required to validate the docking results

Influence of UV-A radiation on the Selected Nutrient Composition and Volatile Profiling of Whole Milk: Safety and Quality Evaluation

Aflatoxin (AF), a mycotoxin produced by several genera of fungi, is an important concern in milk-based products due to its toxicity and health consequences. The present study evaluates whether UV-A irradiation can preserve the composition of whole milk (WM) while degradaing these toxins. In addition, this study also investigates the expression of p53 proteins which can be correlated with carcinogenocity. UV-A irradiation experiments were conducted using a near collimated beam system operating at 365 nm. AFs at known concentrations were spiked in WM and irradiated at quantifiable UV doses based on the average volumetric intensity. The impact of ultraviolet light (UV-A) irradiation on volatile compounds, certain amino acids, and oxidative products were evaluated. No significant reduction in amino acids was observed except tryptophan, p<0.05. At 838 mJ/cm2 no significant lipid peroxidation was observed, p<0.05. The volatile profiling showed that alcohols, the key contributor of oxidized flavor was not significantly affected by the UV-A irradiation. Western blotting was used to assess the effect of UV-A irradiated WM on protein expression in HepG2 cells. Because the targeted gene p53 was not considerably altered, we can affirm that UV-A irradiated WM may be safe and not cytotoxic. Herein, the substantial breakdown of AF in WM by UV-A as well as no accumulation of toxic components from protein, lipid, and FAA degradation was observed. This study conclusively proves the performance of the UV-A LED system in degrading AF in WM below the levels recommended by Food and Drug Administration without compromising the product\u27s quality or safety