Adsorption of aflatoxin B1, zearalenone and ochratoxin A by microorganisms isolated from Kefir grains

A strategy to reduce the deleterious effects of mycotoxins is to use dietary supplements that contain microorganisms that bind mycotoxins and diminish their gastrointestinal absorption. Novel strains were isolated from a Kefir culture and assessed for their mycotoxin adsorption and biotransformation ability. The most active strains were identified using DNA sequencing, and the stability of microorganism/mycotoxin complexes was evaluated using buffer solutions to simulate the pH conditions in the gastrointestinal tract. Our results showed that the microorganism consortium of Kefir grains adsorbed 82 to 100% of aflatoxin B1 (AFB1), zearalenone (ZEA) and ochratoxin A (OTA) when cultivated in milk. The main strains that were capable of mycotoxin adsorption were identified as Lactobacillus kefiri, Kazachstania servazzii and Acetobacter syzygii. The strain L. kefiri KFLM3 was the most active, adsorbing 80 to 100% of the studied mycotoxins when cultivated in milk. Nonetheless, the strain K. servazzii KFGY7 retained more mycotoxin after the desorption experiments (65, 69 and 67% for AFB1, OTA and ZEA, respectively). These findings suggest that Kefir consumption may help to reduce gastrointestinal absorption of these mycotoxins and consequently reduce their toxic effects. The isolated strains may be of interest for the development of fermented dairy products for human consumption that have a new probiotic characteristic, the adsorption of mycotoxins.This study was supported by the Portuguese Foundation for Science and Technology (FCT) under the scope of the strategic funding of the UID/BIO/04469/2013 unit and COMPETE 2020 (POCI-01-0145-FEDER-006684), by the BioTecNorte operation (NORTE-01-0145-FEDER-000004) funded by the European Regional Development Fund under the scope of Norte2020 - Programa Operacional Regional do Norte and by the Project RECI/BBB-EBI/0179/2012 (FCOMP-01-0124-FEDER-027462). Luís Abrunhosa was supported by a grant, UMINHO/BPD/51/2015, from the project UID/BIO/04469/2013 financed by FCT/MEC (OE).info:eu-repo/semantics/publishedVersio

Mycotoxins adsorption by microorganisms isolated from Kefir grains

ICFC 2017 - International Conference on Food Contaminants (Book of Abstracts)A novel alternative for mycotoxins decontamination is the use of microorganisms that bind mycotoxins and reduce their gastrointestinal absorption. Lactic acid bacteria and yeasts were isolated from a Kefir culture and evaluated for their mycotoxin adsorption and biotransformation ability. Strains with high binding ability were identified based on DNA sequenci ng. The binding stability was determined by washing the complexes microorganism/mycotoxin with buffer solutions to simulate the pH conditions in the gastrointestinal tract. The results indicate that the microorganism consortium of Kefir grains adsorbed 82 to 100% of aflatoxin B 1(AFB1), zearalenone (ZEA) and ochratoxin A (OTA) when cultivated in milk. The most effective strains in adsorbing the mycotoxins were identified as Lactobacillus kefiri, Kazachstania servazzii and Acetobacter syzygii. The strains L. kefiri KFLM3 was able to adsorb 80 to 100% of the mycotoxins when cultivated in milk. However, desorption experiments showed that yeast K. servazzii KFGY7 retained more mycotoxin (65, 69 and 67% for AFB 1, OTA and ZEA, respectively) in the cells. Our findings revealed that kefir consumption can possibly reduce gastrointestinal absorption of these mycotoxins and consequently reduce their toxic effects. These Kefir isolates are promising for the development of fermented dairy products for human consumptionGrant UMINHO/BPD/51/2015 from project UID/BIO/04469/2013 financed by FCT/MEC (OE). This study was supported by FCT under the scope of the strategic funding of UID/BIO/04469/2013 unit and COMPETE 2 020 (POCI-01-0145-FEDER-006684); of BioTecNorte operation (NORTE-01-0145-FEDER-000004) funded by European Regional Development Fund under the scope f orte2020 -Programa Operacional Regional do Norte; and under the scope of the projects RECI/BBB-EBI/0179/2012 (FCOMP-01-0124-FEDER- 027462)info:eu-repo/semantics/publishedVersio

Synthesis, antibacterial, antibiofilm evaluation and molecular docking studies of 3-methyl- 2-propyl-2H-[1,2,4]triazolo[4,3b] [1,2,4,6]thiatriazine-1,1-dioxide

ABSTRACT. In the current study, a simple method for the synthesis of 3-methyl-2-propyl-2H-[1,2,4]triazolo[4,3b][1,2,4,6]thiatriazine-1,1-dioxide (2) was carried out. In the presence of pyridine, a reaction between amidine (1) and sulfuryl chloride occurs. FTIR spectroscopy, 1H and 13C NMR, mass spectra, and elemental analysis were utilized in order to verify the structure of a novel synthetic molecule. The antibacterial activities of compound (2) were tested against eight pathogenic bacteria and the minimum inhibitory concentration as well as minimum bactericidal concentration were determined. Moreover, the possible antibiofilm effect of compound (2) was evaluated. Molecular docking was investigated to determine the interaction between compound (2) and eight crystal structures of bacterial and yeast proteins associated with virulence activity and antimicrobial resistance. Our results showed that the new 3-methyl-2-propyl-2H-[1,2,4]triazolo[4,3b][1,2,4,6]thiatriazine-1,1-dioxide (2) compound has a moderate antibacterial activity toward the selected pathogenic bacteria. The obtained MICs varied from 32 to 512 µg/mL being the lowest values attributed to Staphylococcus epidermidis ATCC 14990 and Streptococcus mutans ATCC 25175 (MIC = 32 µg/mL).We noted also that heterocyclic compound (2) may inhibit bacterial biofilm formation at concentration depend manner with a lowest value obtained against S.mutans ATCC 25175 (BIC50 = 490 µg/mL). Molecular docking showed a promising inhibitory activity of compound (2) on TetM-mediated tetracycline resistance (3J25) and Staphylococcus aureus gyrase (3G7B) with lower binding energy compared to the other target proteins.                 KEY WORDS: Synthesis, Thiatriazine-1,1-dioxide, Antibacterial, Antibiofilm, Molecular docking Bull. Chem. Soc. Ethiop. 2022, 36(1), 109-117.                                                             DOI: https://dx.doi.org/10.4314/bcse.v36i1.10                                                      &nbsp

Virucidal Effect of Guggulsterone Isolated from Commiphora gileadensis

Commiphora gileadensis, locally known as becham, is a plant used in traditional Arabian medicine for treating headache, constipation, stomach, joint pain, and inflammatory disorders. Several studies have reported its antibacterial properties; however, no study has demonstrated its antiviral activity. This study aimed to evaluate the antiviral activity of C. gileadensis as well as to isolate its active compound and investigate its mode of action. This activity was evaluated using 4 viruses, herpes simplex virus type 2 (HSV-2), respiratory syncytial virus type B (RSV‑B), coxsackie virus B type 3, and adenovirus type 5 by performing the plaque reduction assay and the 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assays for enveloped and nonenveloped viruses, respectively. The methanol extract of C. gileadensis leaves only showed antiviral activity against enveloped viruses with a selectivity index of 11.19 and 10.25 for HSV-2 and RSV‑B, respectively. The study of the mechanism underlying antiviral activity demonstrated a virucidal effect by direct contact with these target viruses. The active compound, isolated using bio-guided assays involving TLC, was identified as guggulsterone by HPLC-diode array detection coupled with electrospray ionization mass spectrometry. Guggulsterone is an antagonist of the bile acid receptor and a modulator of cholesterol metabolism; however, its antimicrobial properties have been reported for the first time in this study

Antibacterial and resistance-modifying activities of thymoquinone against oral pathogens

<p>Abstract</p> <p>Background</p> <p>The presence of resistant bacteria in the oral cavity can be the major cause of dental antibiotic prophylaxis failure. Multidrug efflux has been described for many organisms, including bacteria and fungi as part of their drugs resistance strategy. The discovery of a new efflux pump inhibitor could extend the useful lifetime of some antibiotics.</p> <p>Methods</p> <p>In this study, the MICs of thymoquinone (TQ), tetracycline and benzalkonium chloride (BC) were determined in absence and in presence of a sub-MIC doses of thymoquinone (1/2 MIC). In addition the 4,6-diamidino-2-phenylindole (DAPI) efflux assay was carried out to determine the effect of TQ on DAPI cells accumulation.</p> <p>Results</p> <p>TQ induced a selective antimicrobial activity. Its synergic effect resulted in at least a 4-fold potentiation of the tested antibiotics and antiseptic. In addition, TQ inhibited the DAPI efflux activity in a concentration-dependent manner. The rate of DAPI accumulation in clinical isolates was enhanced with TQ (0 to 200 μg/ml). There is also a decrease in loss of DAPI from bacteria in the presence of TQ. The concentration causing 50% of DAPI efflux inhibition after 15 minutes was approximately 59 μg/ml for <it>Pseudomonas aeroginosa </it>and 100 μg/ml and <it>Staphylococcus aureus </it>respectively.</p> <p>Conclusions</p> <p>TQ possesses a selective antibacterial activity against oral bacteria. It is therefore suggested that TQ could be used as a source of natural products with resistance-modifying activity. Further investigation is needed to assess their clinical relevance.</p

Mycotoxin Occurrence in Milk and Durum Wheat Samples from Tunisia Using Dispersive Liquid–Liquid Microextraction and Liquid Chromatography with Fluorescence Detection

Food and feed contamination with mycotoxins is a major public health concern. Humans and animals are exposed to these toxins by consuming contaminated products throughout their lives. In this study, a method based on dispersive liquid–liquid microextraction (DLLME), followed by liquid chromatography with fluorescence detection (LC-FLD), was validated for the determination of aflatoxins (AFs) M1, B1, B2, G1, G2, zearalenone (ZEN), and ochratoxin A (OTA). The method was applied to 150 raw cow milk samples and 90 market durum wheat samples from two Tunisian climatic regions: the littoral region (Mahdia) and the continental region (Béja). This work was carried out to obtain more surveillance data to support rapid initiatives to assure safe foods and protect consumer health and to estimate the daily exposure of the Tunisian population consuming those products. AFG2 and OTA were found in wheat with incidences of 54.4 and 11.1%, respectively. On the other side, milk samples were contaminated by AFG2, AFB1, and AFB2 with incidences of 8.7%, 2.0%, and 0.67%, respectively. Some of the samples showed OTA concentrations above the maximum limit allowed by the European Union, which represents a health risk for consumers in Tunisia, where no legislation exists about the maximum content of mycotoxins in food.Project PID2021-127804OB-I00 funded by Spanish MCIN/AEI/ 10.13039/501100011033 and by “ERDF A way of making Europe”Project PROYEXCEL_00195 – Andalusia GovernmentScholarship offered by the University of Jendouba, TunisiaTunisian Ministry of Higher Education and Scientific Research and Egyptian Government for the postdoctoral grant offered by the Cultural Affairs and Mission Sector (Central Administration of Mission) for the year 2020/2022, grant number PD02-201

Antibacterial activity of Thymoquinone, an active principle of Nigella sativa and its potency to prevent bacterial biofilm formation

<p>Abstract</p> <p>Background</p> <p>Thymoquinone is an active principle of <it>Nigella sativa </it>seed known as "Habbah Al-Sauda" in Arabic countries and "Sinouj" in Tunisia. Bacterial biofilms tend to exhibit significant tolerance to antimicrobials drugs during infections.</p> <p>Methods</p> <p>The antibacterial activity of Thymoquinone (TQ) and its biofilm inhibition potencies were investigated on 11 human pathogenic bacteria. The growth and development of the biofilm were assessed using the crystal violet (CV) and the 2, 3-bis [2-methyloxy-4-nitro-5-sulfophenyl]-2H-tetrazolium-5-carboxanilide (XTT) reduction assay.</p> <p>Results</p> <p>TQ exhibited a significant bactericidal activity against the majority of the tested bacteria (MICs values ranged from 8 to 32 μg/ml) especially Gram positive cocci (<it>Staphylococcus aureus </it>ATCC 25923 and <it>Staphylococcus epidermidis </it>CIP 106510). Crystal violet assay demonstrated that the minimum biofilm inhibition concentration (BIC50) was reached with 22 and 60 μg/ml for <it>Staphylococcus aureus </it>ATCC 25923 and <it>Staphylococcus epidermidis </it>CIP 106510 respectively. In addition our data revealed that cells oxidative activity was influenced by TQ supplementation. In the same way, TQ prevented cell adhesion to glass slides surface.</p> <p>Conclusion</p> <p>The ability of TQ to prevent biofilm formation warrants further investigation to explore its use as bioactive substances with antibiofilm potential.</p