Biopreservative and Anti-Mycotoxigenic Potentials of Lactobacillus paracasei MG847589 and Its Bacteriocin in Soft White Cheese

Probiotics and their bacteriocins have increasingly attracted interest for their use as safe food preservatives. This study aimed to produce soft white cheese fortified with Lacticaseibacillus MG847589 (Lb. paracasei MG847589) and/or its bacteriocin; cheese with Lacticaseibacillus (CP), cheese with bacteriocin (CB), and cheese with both Lacticaseibacillus and bacteriocin (CPB) were compared to control cheese (CS) to evaluate their biopreservative and anti-mycotoxigenic potentials for prolonged shelf life and safe food applications. The effects of these fortifications on physiochemical, microbial, texture, microstructure, and sensory properties were studied. Fortification with Lacticaseibacillus (CP) increased acidity (0.61%) and microbial counts, which may make the microstructure porous, while CPB showed intact microstructure. The CPB showed the highest hardness value (3988.03 g), while the lowest was observed with CB (2525.73 g). Consequently, the sensory assessment reflected the panelists' preference for CPB, which gained higher scores than the control (CS). Fortification with Lb. paracasei MG847589 and bacteriocin (CPB) showed inhibition effects against S. aureus from 6.52 log10 CFU/g at time zero to 2.10 log10 CFU/g at the end of storage, A. parasiticus (from 5.06 to 3.03 log10 CFU/g), and P. chrysogenum counts (from 5.11 to 2.86 log10 CFU/g). Additionally, CPB showed an anti-mycotoxigenic effect against aflatoxins AFB1 and AFM1, causing them to be decreased (69.63 ± 0.44% and 71.38 ± 0.75%, respectively). These potentials can extend shelf life and pave the way for more suggested food applications of safe food production by fortification with both Lb. paracasei MG847589 and its bacteriocin as biopreservatives and anti-mycotoxigenic.

Lacticaseibacillus paracasei KC39 Immobilized on Prebiotic Wheat Bran to Manufacture Functional Soft White Cheese

In the current study, probiotic Lacticaseibacillus paracasei KC39 was immobilized on wheat bran as a carrier. The immobilized synbiotic biocatalyst was freeze-dried and used as an adjunct during the production of functional soft white cheese. Free freeze-dried Lc. paracasei cells as an adjunct and a control cheese with a commercial starter were used for comparison. In addition to a fiber content of 1.12%, the functional cheese made using the synbiotic biocatalyst showed higher cell viabilities in the gastric and intestinal phases as well as an enhanced microstructure and favorable sensory characteristics. The presented immobilization method could be applied to the production of soft cheese and other functional food products for the stabilized delivery of both probiotics and dietary fibers.

Docking Analysis of Some Bioactive Compounds from Traditional Plants against SARS-CoV-2 Target Proteins

COVID-19 is still a global pandemic that has not been stopped. Many traditional medicines have been demonstrated to be incredibly helpful for treating COVID-19 patients while fighting the disease worldwide. We introduced 10 bioactive compounds derived from traditional medicinal plants and assessed their potential for inhibiting viral spike protein (S-protein), Papain-like protease (PLpro), and RNA dependent RNA polymerase (RdRp) using molecular docking protocols where we simulate the inhibitors bound to target proteins in various poses and at different known binding sites using Autodock version 4.0 and Chimera 1.8.1 software. Results found that the chicoric acid, quinine, and withaferin A ligand strongly inhibited CoV-2 S -protein with a binding energy of -8.63, -7.85, and -7.85 kcal/mol, respectively. Our modeling work also suggested that curcumin, quinine, and demothoxycurcumin exhibited high binding affinity toward RdRp with a binding energy of -7.80, -7.80, and -7.64 kcal/mol, respectively. The other ligands, namely chicoric acid, demothoxycurcumin, and curcumin express high binding energy than the other tested ligands docked to PLpro with -7.62, -6.81, and -6.70 kcal/mol, respectively. Prediction of drug-likeness properties revealed that all tested ligands have no violations to Lipinski's Rule of Five except cepharanthine, chicoric acid, and theaflavin. Regarding the pharmacokinetic behavior, all ligand predicted to have high GI-absorption except chicoric acid and theaflavin. At the same way chicoric acid, withaferin A, and withanolide D predicted to be substrate for multidrug resistance protein (P-gp substrate). Caffeic acid, cepharanthine, chicoric acid, withaferin A, and withanolide D also have no inhibitory effect on any cytochrome P450 enzymes. Promisingly, chicoric acid, quinine, curcumin, and demothoxycurcumin exhibited high binding affinity on SARS-CoV-2 target proteins and expressed good drug-likeness and pharmacokinetic properties. Further research is required to investigate the potential uses of these compounds in the treatment of SARS-CoV-2.

Validation of New ELISA Technique for Detection of Aflatoxin B1 Contamination in Food Products versus HPLC and VICAM

Toxin-contaminated foods and beverages are a major source of illness, may cause death, and have a significant negative economic impact worldwide. Aflatoxin B1 (AFB1) is a potent toxin that may induce cancer after chronic low-level exposure. This study developed a quantitative recombinant AflR gene antiserum ELISA technique for aflatoxin B1 detection in contaminated food products. Aflatoxin B1 residuals from 36 food samples were analyzed with HPLC and VICAM. DNA was extracted from aflatoxin-contaminated samples and the AflR gene amplified using PCR. PCR products were purified and ligated into the pGEM-T vector. Recombinant plasmids were sequenced and transformed into competent E. coli (BL21). Molecular size and B-cell epitope prediction for the recombinant protein were assessed. The purified protein was used to induce the production of IgG antibodies in rabbits. Serum IgG was purified and labeled with alkaline phosphatase. Finally, indirect-ELISA was used to test the effectiveness of polyclonal antibodies for detection of aflatoxin B1 in food samples.

Phytochemical Analysis and Toxicity Assessment of Artichoke By-product Extract

BACKGROUND AND OBJECTIVE

Egypt produced 236,314 t of artichoke in 2016, which produce a huge amount of useless by-product, which can be used as cheaper source for many active compounds can be applied for some medical application. The objective of this study was to assess the toxicity of the artichoke by-product extract through its effect on rats' kidney, brain and liver biomarkers.

MATERIALS AND METHODS

Chemical composition of artichoke by-product (crude protein, crude fiber, crude fat and minerals) was determined. Conventional extraction (CE), microwave-assisted extraction (MAE) and ultrasonic-assisted extraction (UAE) extraction methods were used for artichoke by-product and comparison between them were performed according to antioxidant activity using DPPH and the phenolic profile identity using HPLC technique. Chronic oral gavage of thirty adult male albino rats for 4 weeks in the concentrations of (0.1, 0.5, 1 and 5 g kg-1) artichoke by-product extract was used for evaluation of its toxicity.

RESULTS

MAE with ethanol more suitable for extraction of the polyphenols (193.63±4.9 μg gallic acid equivalents (GAE) mg-1) and showed IC50 = 159.7 mg mL-1. Three major active phenolic compounds were identified benzoic acid, ellagic acid and caffeine. Rats administrated 5 g kg-1 artichoke extract have no changes in brain, liver and kidney parameters (p<0.05). Histology of brain and liver exhibited normal architecture.

CONCLUSION

The results showed that the artichoke by-product extract had no any toxic effect on rats and considered be safe for human use even at a high level of doses (up to 5 g kg-1).

Inhibition of COVID-19 RNA-Dependent RNA Polymerase by Natural Bioactive Compounds: Molecular Docking Analysis.. [DOI: 10.21203/rs.3.rs-25850/v1]

Till now there is no approved treatment for COVID-19. Phenolic compounds are known to have antiviral activity against many viruses such as HCV and HIV, through their phenol rings interaction with viral proteins and/or RNA, or via its regulating MAP kinase signaling in host cell defense. The present study aimed to assess polyphenolic compounds (gallic acid, quercetin, caffeine, resveratrol, naringenin, benzoic acid, oleuropein and ellagic acid) as COVID-19 RNA-dependent RNA polymerase (PDB ID 6M71) inhibitors, using a molecular docking. Molecular docking of these polyphenols were performed using Autodock 4.0 and Chimera 1.8.1 programs. Drug likeness and polyphenols pharmacokinetic properties were calculated using SWISSADME prediction website (http://www.swissadme.ch/). Remdesivir and ribavirin were used as standard antiviral drugs for comparison. Docking analysis results, ranked by binding energy value (ΔG) of several tested ligands toward COVID-19 polymerase were; remdesivir > gallic acid > quercetin > caffeine > ribavirin > resveratrol > naringenin > benzoic acid > oleuropein > ellagic acid. The binding energies were -8.51, - 7.55, - 7.17, -6.10, - 6.01, - 5.79, - 5.69, - 5.54, - 4.94 and -4.59 kcal/mol, respectively. All tested polyphenols performed hydrogen bonds with one or two of the nucleotide triphosphate entry channel (NTP) amino acids in COVID-19 polymerase (ARG 555, ARG 555, LYS 545), except caffeine and oleuropein. Binding of polyphenols to NTP of COVID-19 polymerase may influence in the entry of the substrate and divalent cations into the central active site cavity, inhibiting the enzyme activity. It appears promising that, gallic acid and quercetin exhibited high binding affinity than ribavirin toward COVID-19 polymerase and expressed good drug likeness and pharmacokinetic properties. Therefore, gallic acid and quercetin may represent a potential treatment option for COVID-19. Further researches are urgently required to investigate the potential uses of these polyphenols in COVID-19 treatment. Additionally, resveratrol, naringenin, benzoic and ellagic acid seem to have the best potential to act as COVID-19 polymerase inhibitors.