Pharmacological Potential Effects of Algerian Propolis Against Oxidative Stress, Multidrug-Resistant Pathogens Biofilm and Quorum-Sensing.

Objectives: This study sought to examine the chemical profile, antioxidant, antimicrobial, antibiofilm, and anti-quorum sensing potential of two propolis ethanolic extracts (PEEs) collected from northeast Algeria. Materials and Methods: To achieve the main objectives of this study, multiple in vitro tests were employed. The phenolic and flavonoid contents were analyzed, and the chemical composition of both PEE was determined by high-performance liquid chromatography. The antioxidant properties of the propolis extracts were investigated using six complementary tests. The inhibitory effects of propolis extracts were evaluated against multidrug-resistant (MDR) clinical isolates using agar well diffusion and microdilution methods, whereas their antibiofilm and quorum-sensing disruption effects were determined by spectrophotometric microplate methods. Results: The results demonstrated that phenolic and flavonoid contents were higher in propolis from the Guelma (PEEG) region (PEEG; 188.50 ± 0.33 µg GAE/mg E, 144.23 ± 1.03 µg QE/mg E), respectively. Interestingly, different components were identified, and cynarin was the major compound detected. The PEEG sample exhibited potential antioxidant effects in scavenging ABTS•+ radicals with minimal inhibitory concentration values equal to 10.46 ± 1.40 µg/mL. Furthermore, the highest antibacterial activity was recorded by PEEG against Gram-positive Staphylococcus aureus MDR1. Similarly, PEEG effectively inhibited the biofilm formation of S. aureus MDR1 and the degradation of biofilm was up to 60%. In addition, quorum sensing disruption revealed that both extracts have a moderate capacity for violacein inhibition by the Chromobacterium violaceum ATCC 12472 strain in a concentration-dependent manner. Conclusion: These findings indicate that propolis can be regarded as a natural therapeutic agent for health problems associated with MDR bacteria and oxidative stress.

Comparative assessment of phenolic composition profile and biological activities of green extract and conventional extracts of Salvia sclarea.

In recent years, there have been an attempt to develop safe and environmental friendly solvents to replace conventional solvents, and use for extraction bioactive compounds from natural sources. A current investigation involved the preparation of green, methanolic, and ultrasonic extracts of S. sclarea, and compared their phenolic profiling using HPLC-DAD, antibacterial, antioxidant, and enzyme inhibition activities. The HPLC-DAD analysis revealed that Rosmarinic acid was the main content in all extracts, with Ellagic acid only present in the green extract. The green extract exhibited superior anti-biofilm activity against S. Aureus and E. Faecalis compared to the other extracts at MIC concentration. Furthermore, the green extract also displayed the highest inhibition of swarming motility in P. Aeruginosa with inhibition range 68.0 ± 2.1 (MIC) to 19.5 ± 0.6 (MIC/4). and better enzyme inhibitory activity against BChE (with IC50 = 131.6 ± 0.98 µg/mL) and AChE (with inhibition 47.00 ± 1.50%) compared to the other extracts; while, the ultrasonic extract showed strong inhibition of violacein production by C. Violaceum with a inhibition range 05.5 ± 0.1 (MIC/32) to 100 ± 0.00 (MIC), followed by the green extract with a inhibition range 15.0 ± 0.5 (MIC/8) to 100 ± 0.00 (MIC), additionally, the ultrasonic and methanoic extracts showed significant activity against urease enzyme with (IC50 = 171.6 ± 0.95 µg/mL and IC5 0 = 187.5 ± 1.32 µg/mL) respectively. Both the green and methanolic extracts showed considerable antioxidant activities, as ß-carotene-linoleic acid (IC50 = 5.61 ± 0.47 µg/mL and 5.37 ± 0.27 µg/mL), DPPH· (IC50 = 19.20 ± 0.70 µg/mL and 16.31 ± 0.23 µg/mL), ABTS·+(IC50 = 8.64 ± 0.63 µg/mL and 6.50 ± 0.45 µg/mL) and CUPRAC (A0.5 = 17.22 ± 0.36 µg/mL and 12.28 ± 0.12 µg/mL) respectively, likewise the green extract performing better in metal chelating compared to the other extracts. The green extraction is reported as a cost effective and solvent free method for extracting natural products that produces compounds free of toxic chemicals. This could be the method to be used in the industries as a renewable method.

Inhibition of biofilm, quorum-sensing, and swarming motility in pathogenic bacteria by magnetite, manganese ferrite, and nickel ferrite nanoparticles.

Resistance to antibiotics by pathogenic bacteria constitutes a health burden and nanoparticles (NPs) are being developed as alternative and multipurpose antimicrobial substances. Magnetite (Fe3O4 np), manganese ferrite (MnFe2O4 np) and nickel ferrite (NiFe3O4 np) NPs were synthesized and characterized using thermogravimetric analysis, transmission electron microscopy, Fourier transformed infra-red, and X-ray diffraction. The minimal inhibitory concentrations (MIC) ranged from 0.625 to 10 mg/mL against gram-positive (Staphylococcus aureus ATCC 25923 and Enterococcus faecalis ATCC 29212), gram-negative (Escherichia coli ATCC 25922 and Pseudomonas aeruginosa ATCC 27853) and candida (Candida albicans ATCC 10239 and Candida tropicalis ATCC 13803) species. The NPs exhibited violacein inhibition against Chromobacterium violaceum CV12472 of 100% at MIC and reduced to 27.2% ± 0.8% for magnetite NPs, 12.7% ± 0.3% for manganese ferrite NPs and 43.1% ± 0.2% for nickel ferrite NPs at MIC/4. Quorum-sensing (QS) inhibition zones against C. violaceum CV026 were 12.5 ±0.6 mm for Fe3O4 np, 09.1 ± 0.5 mm for MnFe3O4 NP and 17.0 ± 1.2 mm for NiFe3O4 np. The NPs inhibited swarming motility against P. aeruginosa PA01 and biofilm against six pathogens and the gram-positive biofilms were more susceptible than the gram-negative ones. The NiFe2O4 np had highest antibiofilm activity against gram-positive and gram-negative bacteria as well as highest QS inhibition while Fe3O4 NP had highest biofilm inhibition against candida species. The synthesized magnetic NPs can be used in developing anti-virulence drugs which reduce pathogenicity of bacteria as well as resistance.

Assessment of Chemical Composition and In Vitro Antioxidant, Antidiabetic, Anticholinesterase and Microbial Virulence-Quenching Effects of Salad Burnet (Sanguisorba minor L.) Harvested from Algeria.

Sanguisorba minor is a medicinal vegetable used in seasoning desserts, juices, and beverages. An evaluation of the total flavonoid, phenolic, tannin and anthocyanin contents indicated that these classes of compounds are distributed variably in the different fractions. In summary, the HPLC-DAD analyses enabled the identification and quantification of thirteen phenolic compounds in an ethyl acetate extract (EAE), nine in a dichloromethane extract (DCME), seven in an aqueous extract (AQE) and four in a butanol extract (BE). Rutin was the most abundant phenolic compound in the BE (278.4 ± 1.20 µg/g) and AQE (32.87 ± 0.23 µg/g) fractions, while apigenin was the most abundant in the DCME (84.75 ± 0.60 µg/g) and EAE (156.8 ± 0.95 µg/g) fractions. The presence of phenolic compounds in the fractions conferred good antioxidant capacity, especially the EAE and DCME fractions, which both exhibited higher antioxidant effects than BHA and α-tocopherol in DPPH• and CUPRAC assays. Additionally, in the ABTS•+ assay, EAE (IC50 = 9.27 ± 0.33 µg/mL) was more active than α-tocopherol (IC50 = 35.50 ± 0.55 µg/mL), and BHA (IC50 = 12.70 ± 0.10 µg/mL). At 200 µg/mL, the fractions inhibited acetylcholinesterase and butyrylcholinesterase as well as α-amylase and α-glucosidase, indicating that they can slow neurodegeneration and hyperglycemia. Minimal inhibitory concentration (MIC) values ranged from 0.312 mg/mL to 1.25 mg/mL, and fractions showed good biofilm inhibition against Staphylococcus aureus and Escherichia coli. The extracts exhibited good violacein inhibition in Chromobacterium violaceum CV12472 and Chromobacterium violaceum CV026, despite the supply of external acyl-homoserine lactone to CV026. The antioxidant, quorum-sensing, antibiofilm and enzyme inhibition attributes indicate the potential for the application of S. minor as a food preservative.

Evaluation of anti-quorum sensing and antibiofilm effects of secondary metabolites from Gambeya lacourtiana (De Wild) Aubr. & Pellegr against selected pathogens.

BACKGROUND: Microbial infections cause serious health problems especially with the rising antibiotic resistance which accounts for about 700,000 human deaths annually. Antibiotics which target bacterial death encounter microbial resistance with time, hence, there is an urgent need for the search of antimicrobial substances which target disruption of virulence factors such as biofilm and quorum sensing (QS) with selective pressure on the pathogens so as to avoid resistance. METHODS: Natural products are suitable leads for antimicrobial drugs that can inhibit bacterial biofilms and QS. Twenty compounds isolated from the medicinal plant Gambeya lacourtiana were evaluated for their antibiofilm and anti-quorum sensing effects against selected pathogenic bacteria. RESULTS: Most of the compounds inhibited violacein production in Chromobacterium violaceum CV12472 and the most active compound, Epicatechin had 100% inhibition at MIC (Minimal Inhibitory Concentration) and was the only compound to inhibit violacein production at MIC/8 with percentage inhibition of 17.2 ± 0.9%. Since the bacteria C. violaceum produces violacein while growing, the inhibition of the production of this pigment reflects the inhibition of signal production. Equally, some compounds inhibited violacein production by C. violaceum CV026 in the midst of an externally supplied acylhomoserine lactone, indicating that they disrupted signal molecule reception. Most of the compounds exhibited biofilm inhibition on Staphyloccocus aureus, Escherichia coli and Candida albicans and it was observed that the Gram-positive bacteria biofilm was most susceptible. The triterpenoids bearing carboxylic acid group, the ceramide and epicatechin were the most active compounds compared to others. CONCLUSION: Since some of the compounds disrupted QS mediated processes in bacteria, it indicates that this plant is a source of antibiotics drugs that can reduce microbial resistance.

HPLC-DAD Analysis and Versatile Bioactivities of Turkish Sunflower Honeys Using Chemometric Approaches.

Sunflower honey (SH) is bright yellow, fragrant, pollen-flavoured, slightly herbaceous and has a unique taste. The present research aims to examine the enzyme inhibitory, antioxidant, anti-inflammatory, antimicrobial and anti-quorum sensing activities and phenolic compositions of 30 sunflower honeys (SHs) produced from several regions of Turkey with chemometric study. SAH from Samsun exhibited the best antioxidant activity in ß-carotene linoleic acid (IC50 : 7.33±0.17 mg/mL) and CUPRAC (A0.50 : 4.94±0.13 mg/mL) assays, anti-urease activity (60.63±0.87 %) and anti-inflammatory activity against COX-1 (73.94±1.08 %) and COX-2 (44.96±0.85 %). SHs exhibited mild antimicrobial activity against the test microorganisms while they showed high quorum sensing inhibition zones measured in the range of 42-52 mm against the CV026 strain. The phenolic composition was determined by high performance liquid chromatography with diode array detection (HPLC-DAD) system and levulinic, gallic, p-hydroxybenzoic, vanillic and p-coumaric acids were identified in all studied SHs. The classification of SHs was performed the using PCA and HCA. This study revealed that phenolic compounds and biological properties are effective in classification of SHs according to their geographical origin. The results suggest that studied SHs could be valued as potential agents with versatile bioactivities in oxidative stress-related disease, microbial infections, inflammation, melanoma, and peptic ulcer.

Chemometric classification of chestnut honeys from different regions in Turkey based on their phenolic compositions and biological activities.

The objective of this study was to investigate the phenolic composition and biological properties of chestnut honeys of 41 stations in Turkey's the Black Sea and Marmara regions. A total of sixteen phenolic compounds and organic acids were detected using HPLC-DAD and levulinic, gallic, protocatechuic, vanilic, trans-cinnamic acids and (4-hydroxyphenyl) ethanol were identified in all studied chestnut honeys. Antioxidant activities were measured by ABTS•+, ß-carotene-linoleic acid, CUPRAC, DPPH•, and metal chelating assays. Antimicrobial activities were carried out against gram positive, gram negative bacteria and Candida species using well diffusion test. Anti-inflammatory activities were evaluated against COX-1 and COX-2 whereas enzyme inhibitory activities were assessed on AChE, BChE, urease, and tyrosinase. The chemometric classification of chestnut honeys were carried out using PCA and HCA and it was seen that some phenolic compounds contributed significantly to the classification of chestnut honeys from various geographical origin.

Disruption of Biofilm Formation and Quorum Sensing in Pathogenic Bacteria by Compounds from Zanthoxylum Gilletti (De Wild) P.G. Waterman.

Microbial resistance is facilitated by biofilm formation and quorum-sensing mediated processes. In this work, the stem bark (ZM) and fruit extracts (ZMFT) of Zanthoxylum gilletii were subjected to column chromatography and afforded lupeol (1), 2,3-epoxy-6,7-methylenedioxyconiferyl alcohol (3), nitidine chloride (4), nitidine (7), sucrose (6) and sitosterol-ß-D-glucopyranoside (2). The compounds were characterized using MS and NMR spectral data. The samples were evaluated for antimicrobial, antibiofilm and anti-quorum sensing activities. Highest antimicrobial activity was exhibited by compounds 3, 4 and 7 against Staphylococcus aureus (MIC 200 µg/mL), compounds 3 and 4 against Escherichia coli (MIC = 100 µg/mL) and compounds 4 and 7 against Candida albicans (MIC = 50 µg/mL). At MIC and sub-MIC concentrations, all samples inhibited biofilm formation by pathogens and violacein production in C. violaceum CV12472 except compound 6. Good disruption of QS-sensing in C. violaceum revealed by inhibition zone diameters were exhibited by compounds 3 (11.5 ± 0.5 mm), 4 (12.5 ± 1.5 mm), 5 (15.0 ± 0.8 mm), 7 (12.0 ± 1.5 mm) as well as the crude extracts from stem barks (16.5 ± 1.2 mm) and seeds (13.0 ± 1.4 mm). The profound inhibition of quorum sensing mediated processes in test pathogens by compounds 3, 4, 5 and 7 suggests the methylenedioxy- group that these compounds possess as the possible pharmacophore.

Antibiofilm and Anti-Quorum Sensing Potential of Cycloartane-Type Triterpene Acids from Cameroonian Grassland Propolis: Phenolic Profile and Antioxidant Activity of Crude Extract.

Propolis is very popular for its beneficial health properties, such as antimicrobial activity and antioxidant effects. It is one of the most long-serving traditional medicines to mankind due to its interesting chemical diversity and therapeutic properties. The detailed chemical information of propolis samples is very necessary to guarantee its safety and for it to be accepted into health care systems. The phenolic profile of the hydroethanolic extract was determined using HPLC-DAD, and the antioxidant was evaluated using five complementary methods. Triterpenoids were isolated using column chromatography and characterized using 1H NMR and 13C NMR. The effects of the extract and the isolated compounds on quorum sensing mediated processes and biofilm formation in bacteria were evaluated. Protocatechic acid (40.76 ± 0.82 µg/g), 4-hydroxybenzoic acid (24.04 ± 0.21 µg/g), vanillic acid (29.90 ± 1.05 µg/g), quercetin (43.53 ± 1.10 µg/g), and luteolin (4.44 ± 0.48 µg/g) were identified and quantified. The extract showed good antioxidant activity in the DPPH•, ABTS•+, CUPRAC, and metal chelating assays, and this antioxidant effect was confirmed by cyclic voltammetry. 27-Hydroxymangiferonic acid (1), Ambolic acid (2), and Mangiferonic acid (3) were isolated from anti-quorum sensing activity at MIC, and it was indicated that the most active sample was the extract with inhibition diameter zone of 18.0 ± 1.0 mm, while compounds 1, 2, and 3 had inhibition zones of 12.0 ± 0.5 mm, 9.0 ± 1.0 mm, and 12.3 ± 1.0 mm, respectively. The samples inhibited the P. aeruginosa PA01 swarming motility at the three tested concentrations (50, 75, and 100 µg/mL) in a dose-dependent manner. The propolis extract was able to inhibit biofilm formation by S. aureus, E. coli, P. aeruginosa, C. albicans, and C. tropicalis at MIC concentration. Compound 1 proved biofilm inhibition on S. aureus, L. monocytogenes, E. faecalis, E. coli, and C. tropicalis at MIC and MIC/2; compound 2 inhibited the formation of biofilm at MIC on S. aureus, E. faecalis, E. coli, S. typhi, C. albicans, and C. tropicalis; and compound 3 inhibited biofilm formation on E. faecalis, E. coli, C. albicans, and C. tropicalis and further biofilm inhibition on E. coli at MIC/4 and MIC/8. The studied propolis sample showed important amounts of cycloartane-type triterpene acids, and this indicates that there can be significant intra-regional variation probably due to specific flora within the vicinity. The results indicate that propolis and its compounds can reduce virulence factors of pathogenic bacteria.

Phytochemical Profiling of Allium subhirsutum L. Aqueous Extract with Antioxidant, Antimicrobial, Antibiofilm, and Anti-Quorum Sensing Properties: In Vitro and In Silico Studies.

The present study was the first to evaluate the phytochemical composition, antioxidant, antimicrobial, antibiofilm, and anti-quorum sensing potential of Allium subhirsutum L. (hairy garlic) aqueous extract through in vitro and in silico studies. The phytochemical profile revealed the presence of saponins, terpenes, flavonols/flavonones, flavonoids, and fatty acids, particularly with flavonoids (231 ± 0.022 mg QE/g extract), tannins (159 ± 0.006 mg TAE/g extract), and phenols (4 ± 0.004 mg GAE/g extract). Gas chromatography-mass spectrometry (GC-MS) analysis identified 15 bioactive compounds, such as 5-hydroxymethylfurfural (37.04%), methyl methanethiolsulfonate (21.33%), furfural (7.64%), beta-D-glucopyranose, 1,6-anhydro- (6.17%), 1,6-anhydro-beta-D-glucofuranose (3.6%), trisulfide, di-2-propenyl (2.70%), and diallyl disulfide (1.93%). The extract was found to be non-toxic with 50% cytotoxic concentration higher than 30,000 µg/mL. The investigation of the antioxidant activity via DPPH (2, 2-diphenyl-1-picrylhydrazyl) and FRAP (IC50 = 1 µg/mL), ABTS (2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid); IC50 = 0.698 ± 0.107 µg/mL), and ß-carotene (IC50 = 0.811 ± 0.036 mg/mL) was assessed. Nevertheless, good antimicrobial potential against a diverse panel of microorganisms with bacteriostatic and fungistatic effect was observed. Quorum sensing inhibition effects were also assessed, and the data showed the ability of the extract to inhibit the production of violacein by the mutant C. violaceum strain in concentration-dependent manner. Similarly, the biofilm formation by all tested strains was inhibited at low concentrations. In silico pharmacokinetic and toxicological prediction indicated that, out of the sixteen identified compounds, fourteen showed promising drug ability and could be used as lead compounds for further development and drug design. Hence, these findings support the popular use of hairy garlic as a source of bioactive compounds with potential application for human health.

Thymus musilii Velen. Methanolic Extract: In Vitro and In Silico Screening of Its Antimicrobial, Antioxidant, Anti-Quorum Sensing, Antibiofilm, and Anticancer Activities.

Thymus musilii Velen. is a rare plant species cultivated in the Ha'il region (Saudi Arabia) under greenhouse conditions. In this work, we described, for the first time, the phytochemical composition, antimicrobial, antioxidant, anti-quorum sensing, and anticancer activities of T. musilii methanolic extract using both experimental and computational approaches. The obtained results showed the identification of eight small-like peptides and eighteen phyto-compounds by using high-resolution liquid chromatography-mass spectrometry (HR-LCMS) dominated mainly by compounds belonging to isoprenoid, fatty acyl, flavonoid, and alkaloid classes. The tested extracts exhibited high antifungal and antibacterial activity with the mean diameter of growth inhibition zones ranging from 12.33 ± 0.57 mm (Pseudomonas aeruginosa ATCC 27853) to 29.33 ± 1.15 mm (Candida albicans ATCC 10231). Low minimal inhibitory concentrations were recorded for the tested micro-organisms ranging from 0.781 mg/mL to 12.5 mg/mL. While higher doses were necessary to completely kill all tested bacterial and fungal strains. Thyme extract was able to scavenge DPPH•, ABTS•+, ß-carotene, and FRAP free radicals, and the IC50 values were 0.077 ± 0.0015 mg/mL, 0.040 ± 0.011 mg/mL, 0.287 ± 0.012 mg/mL, and 0.106 ± 0.007 mg/mL, respectively. The highest percentage of swarming and swimming inhibition was recorded at 100 µg/mL with 39.73 ± 1.5% and 25.18 ± 1%, respectively. The highest percentage of biofilm inhibition was recorded at 10 mg/mL for S. typhimurium ATCC 14028 (53.96 ± 4.21%) and L. monocytogenes ATCC 7644 (49.54 ± 4.5 mg/mL). The in silico docking study revealed that the observed antimicrobial, antioxidant, and anticancer activities of the constituent compounds of T. musilii are thermodynamically feasible, notably, such as those of the tripeptides (Asn-Met-His, His-Cys-Asn, and Phe-His-Gln), isoprenoids (10-Hydroxyloganin), and diterpene glycosides (4-Ketoretinoic acid glucuronide).

Chemical Composition, Anti-Quorum Sensing, Enzyme Inhibitory, and Antioxidant Properties of Phenolic Extracts of Clinopodium nepeta L. Kuntze.

Phenolic extracts of Clinopodium nepeta were prepared and their preliminary phenolic profiles determined using HPLC-DAD with 26 phenolic standards. Apigenin (21.75 ± 0.41 µg/g), myricetin (72.58 ± 0.57 µg/g), and rosmarinic acid (88.51 ± 0.55 µg/g) were the most abundant compounds in DCM (dichloromethane), AcOEt (ethyl acetate), and BuOH (butanol) extracts, respectively. The DCM and AcOEt extracts inhibited quorum-sensing mediated violacein production by C. violaceum CV12472. Anti-quorum-sensing zones on C. violaceum CV026 at MIC (minimal inhibitory concentration) were 10.3 ± 0.8 mm for DCM extract and 12.0 ± 0.5 mm for AcOEt extract. Extracts showed concentration-dependent inhibition of swarming motility on flagellated P. aeruginosa PA01 and at the highest test concentration of 100 µg/mL, AcOEt (35.42 ± 1.00%) extract displayed the best activity. FRAP assay indicated that the BuOH extract (A0.50 = 17.42 ± 0.25 µg/mL) was more active than standard α-tocopherol (A0.50 = 34.93 ± 2.38 µg/mL). BuOH extract was more active than other extracts except in the ABTS●+, where the DCM extract was most active. This antioxidant activity could be attributed to the phenolic compounds detected. C. nepeta extracts showed moderate inhibition on acetylcholinesterase (AChE), butyrylcholinesterase (BChE), tyrosinase, and α-amylase. The results indicate that C. nepeta is a potent source of natural antioxidants that could be used in managing microbial resistance and Alzheimer's disease.

[Antibody Screening and Risk Assessment of Healthcare Professionals in the COVID-19 Pandemic]. / COVID-19 Pandemisinde Saglik Çalisanlarinin Antikor Taramasi ve Risk Degerlendirmesi.

Globally 364102 healthcare professionals have been infected with severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) and 1253 of them died until 15 January 2021. Healthcare professionals serving at the forefront of combating the pandemic are in the high risk group. In our country, the data about coronavirus-2019 (COVID-19) among healthcare professionals are limited. The aim of this study was to investigate the anti-SARS-CoV-2 IgG seroprevalence in healthcare professionals, to evaluate the risks they encountered during work, and to examine their relationships with antibody positivity. A total of 572 healthcare professionals serving in various units of our hospital participated in our study and the presence of anti-nucleocapsid IgG was investigated by chemiluminescent microparticle immunoassay (SARS-CoV-2 IgG test, Abbott Laboratories Diagnostics, USA) method in serum samples collected between May 18, 2020 and June 30, 2020. The demographic characteristics, medical history, work conditions, medical procedures performed and possible risk factors were questioned with a questionnaire form. The average age of the participants was 33.5 ± 9.2 (19-61) years, and 62.9% (360/572) of them were women. In our study, the anti-SARS-CoV-2 IgG seroprevalence was 3.7% (21/572). The association of the antibody positivity with age, gender and occupational status was not statistically significant (p> 0.05). Comorbid diseases which were significantly higher in seropositive healthcare professionals were hypertension (19%) and diabetes mellitus (14.3%) (p<0.05). It was observed that antibody positivity was significantly higher in healthcare professionals working in high (52.4%) and medium risk (33.3%) areas, those who treat and/or examine patients with suspicious or positive COVID-19 (66.7%) and those who spend more than 30 minutes in COVID-19 patient rooms (76%) (p<0.05). The symptoms associated with seropositivity in healthcare workers with a history of symptoms (46%) were loss of smell (23.5%), loss of taste (20.0%) and respiratory distress (16.7%) (p<0.05). It was observed that the probability of being infected with SARS-CoV-2 increased 12 times if there was a colleague with COVID-19 in the hospital, four times if there was a patient in the house/lodging and six times if there was an infected person in the social environment (p<0.05). The rate of those who had the flu vaccine among the participants was 10.8% (62/572) and 9.7% of them were found to be anti-SARS-CoV-2 IgG positive (p<0.05, 95% CI= 1.31-9.48). The seropositivity was significantly higher in non-smokers (4.8 %) compared to smokers (0.0%) (p<0.05). In our study, it was determined that the rate of seropositivity was 12 times higher in healthcare professionals who stated that they received hydroxychloroquine prophylaxis due to risky contact compared to those who did not receive prophylaxis (p<0.05, 95% CI= 4.11-40.64). The ratio of the personnel who answered "always" to the frequency of wearing gloves, masks, goggles/face shields and overalls was 85.7%, 96.9%, 62.1% and 65.4%, respectively. In conclusion, regular and large-scale seroepidemiological screening of healthcare professionals in the COVID-19 pandemic can contribute to the control of the pandemic by providing a better understanding of transmission dynamics and risk factors.

A Preliminary Study of Chemical Profiles of Honey, Cerumen, and Propolis of the African Stingless Bee Meliponula ferruginea.

Recently, the honey and propolis of stingless bees have been attracting growing attention because of their health-promoting properties. However, studies on these products of African Meliponini are still very scarce. In this preliminary study, we analyzed the chemical composition of honey, two cerumen, and two resin deposits (propolis) samples of Meliponula ferruginea from Tanzania. The honey of M. ferruginea was profiled by NMR and indicated different long-term stability from Apis mellifera European (Bulgarian) honey. It differed significantly in sugar and organic acids content and had a very high amount of the disaccharide trehalulose, known for its bioactivities. We suggested trehalulose to be a potential marker for African stingless bee honey analogously to the recent proposal for Meliponini honey from Asia, South America, and Australia and demonstrated its easy discrimination by 13C NMR. Propolis and cerumen were studied by GC-MS (gas chromatography-mass spectometry). The samples contained mainly terpenoids (di-and triterpenes) but demonstrated qualitative and quantitative differences. This fact was an indication that possibly M. ferruginea has no strict preferences for resins used to construct and protect their nests. The antimicrobial and anti-quorum sensing properties of the two materials were also tested. These first results demonstrated that the honey, cerumen, and propolis of African stingless bees were rich in biologically active substances and deserved further research.

Facile UV-induced covalent modification and crosslinking of styrene-isoprene-styrene copolymer via Paterno-Büchi [2 + 2] photocycloaddition.

The chemical functionalization or modification of polymers to alter or improve the physical and mechanical properties constitutes an important field in macromolecular research. Fabrication of polymeric materials via structural tailoring of commercial or commodity polymers that are produced in vast quantities especially possess unique advantages in material applications. In the present study, we report on benign chemical modification of unsaturated styrene-isoprene-styrene (SIS) copolymer using available backbone alkene groups. Covalent attachment of aldehyde functional substrates onto reactive isoprene double bond residues was conveniently carried out using UV-induced Paterno-Büchi [2 + 2] cycloaddition. Model organic compounds with different structures were utilized in high efficiency chemical modification of parent polymer chains via oxetane ring formation. Functionalization studies were confirmed via 1H NMR, FT-IR and SEC analyses. The methodology was extended to covalent crosslinking of polymer chains to obtain organogels with tailorable crosslinking degrees and physical characteristics. Considering the outstanding elastic properties of unsaturated rubbers and their high commercial availability, abundant reactive double bonds in backbone chains of these polymers offer easy to implement structural modification via proposed Paterno-Büchi photocycloaddition.

Design and in vitro antibiofilm activity of propolis diffusion-controlled biopolymers.

In this study, a novel pH-sensitive hydrogel beads that is based on gelatin/sodium alginate/chitosan (GEL/SA/CS) loaded with propolis ethanolic extracts (PE) were synthesized. The swelling behavior of GEL/SA/CS hydrogel beads was studied in different pH solutions and compared with unloaded CS (GEL/SA) hydrogel beads. The in vitro release studies have been revealed using four different pH (1.3, 5.0, 6.0, and 6.8), a saliva environment (pH 6.8), a simulated gastric fluid (SGF) (pH 1.3), and a simulated intestinal fluid (SIF) (pH 6.8) to simulate the physiological conditions in gastrointestinal (GI) tract. Propolis-loaded hydrogel beads were found to be stable at pH 1.3, 5.0, 6.0, simulated saliva, SGF, and SIF mediums, whereas the beads lose their stability at pH 6.8 buffer solution. Tested microorganisms displayed greater sensitivity to PE-loaded hydrogel beads compared with pure propolis. Contrary to antimicrobial activity results, antibiofilm activity results of PE-loaded GEL/SA and GEL/SA/CS hydrogel beads were found at low levels. According to the obtained results, the propolis-loaded GEL/SA/CS hydrogel beads synthesized within this study can be used in the treatment of GI tract diseases such as oral mucositis, gastric ulcer, ulcerative colitis, and GI cancer, as controlled releasing carriers of propolis.

Antibiofilm and Enzyme Inhibitory Potentials of Two Annonaceous Food Spices, African Pepper (Xylopia aethiopica) and African Nutmeg (Monodora myristica).

Food pathogens represent an important health threat, and it is relevant to study the effect of foodstuffs such as spices which can inhibit bacterial growth. This study reports the antimicrobial, antibiofilm, and enzyme (Acetylcholinesterase, Butyrylcholinesterase, urease, tyrosinase) inhibitory activities of two medicinal food spices belonging to the Annonaceae family, Monodora myristica and Xylopia aethiopica. GC-MS (gas chromatography mass spectrometry) analysis of silylated samples of Methanol-Dicloromethane (50:50) extracts of both plants led to the identification of nine compounds in M. myristica and seven compounds in X. aethiopica. M. myristica and X. aethiopica had the same minimum inhibitory concentration (MIC) values of 0.625 mg/mL and 2.5 mg/mL on C. albicans and E. coli, respectively. However, M. myristica had better activity than X. aethiopica on Staphylococcus aureus, while Pseudomonas aeruginosa was more susceptible to X. aethiopica than M. myristica. The lowest MIC value was 0.1325 mg/mL, exhibited by M. myristica on S. aureus. Both extracts showed good antibiofilm activity. On S. aureus, at the same concentration, M. myristica had better antibiofilm activity than X. aethiopica. On E. coli and Candida albicans, X. aethiopica had better antibiofilm activity than M. myristica at the same concentration. X. aethiopica showed better violacein inhibition in Chromobacterium violaceum CV12472, as its percentage inhibition of violacein varied from 80.5% ± 3.0% at MIC to 5.6 ± 0.2 at MIC/8, as compared to M. myristica with 75.1% ± 2.5% at MIC and 15.5% ± 1.1% at MIC/8. The anti-motility activity by swimming and swarming inhibition on P. aeruginosa PA01 was low at test concentrations and in both models, M. myristica showed higher motility inhibition than X. aethiopica. Although in enzyme inhibitory assays all extracts had low inhibitions compared to standards tested at the same concentrations, the results show that these plants can be used to manage food-borne infections.

Antibiofilm and anti-quorum sensing activities of polyethylene imine coated magnetite and nickel ferrite nanoparticles.

This study was aimed at synthesizing polyethyleneimine-coated magnetic nanoparticles and evaluating their effect on pathogenic bacteria. Polyethyleneimine-coated magnetite (PEIMnF) and nickel ferrite (PEINF) nanoparticles were succesfully synthesized and their surface groups, morphology and chemical structures were characterized using ATR-FTIR (Attenuated Total Reflectance Fourrier Transformed Infra-Red) and SEM (Scanning Electron Microscopy). TGA (Thermogravimetric analysis) was used to analyse the thermal behaviour and stability of synthesized nanomaterials. The minimal inhibitory concentration (MIC) values of the polyethylene imine coated magnetite and nickel ferrite nanomaterials against Staphylococcus aureus, Escherichia coli and Candida albicans was found to be 10 mg/mL. Both nanomaterials (PEIMnF and PEINF) showed very excellent and concentration-dependent biofilm inhibition especially at the highest test concentration of 10 mg/mL at which PEIMnF inhibited biofilm formation on E. coli (89.04 ± 0.50%), S. aureus (82.85 ± 2.42%) and C. albicans (91.37 ± 0.66%). At this concentration, PEINF equally inhibited biofilm formations of E. coli (90.48 ± 2.05%), S. aureus (87.04 ± 1.59%) and C. albicans (90.94 ± 1.03%). Only PEINF showed a concentration-dependent violacein inhibition with highest inhibition of 51.2 ± 3.5% at MIC and quorum sensing with inhibition zones of 16.3 ± 1.0 mm at MIC and 11.5 ± 0.5 mm at MIC/2 which could be attributed to the presence of nickel. The nanomaterials inhibited swimming and swarming motilities in Pseudomonas aeruginosa PA01 and it was found that at the same concentration, swimming inhibition was greater than swarming inhibitions and PEINF showed better inhibition than PEIMnF in both models. Polyethyleneimine-coated magnetite and nickel ferrite nanomaterials could be used in overcoming health problems associated with microbial infections and resistance.

Phytochemical Screening, Antibacterial, Antifungal, Antiviral, Cytotoxic, and Anti-Quorum-Sensing Properties of Teucrium polium L. Aerial Parts Methanolic Extract.

The chemical profile of Teucrium polium L. (T. polium) methanolic extract was tested using liquid chromatography coupled with high resolution mass spectrometry (HR-LCMS). Disc diffusion and microdilution assays were used for the antimicrobial activities. Coxsackievirus B-3 (CVB3) and Herpes simplex virus type 2 (HSV-2) were used for the antiviral activities. Chromobacterium violaceum (ATCC 12472 and CV026) and Pseudomonas aeruginosa PAO1 were used as starter strains for the anti-quorum sensing tests. Isoprenoids are the main class of compounds identified, and 13R-hydroxy-9E,11Z-octadecadienoic acid, valtratum, rhoifolin, sericetin diacetate, and dihydrosamidin were the dominant phytoconstituents. The highest mean diameter of growth inhibition zone was recorded for Acinetobacter baumannii (19.33 ± 1.15 mm). The minimal inhibitory concentrations were ranging from 6.25 to 25 mg/mL for bacterial strains, and from 6.25 to 25 mg/mL for Candida species. The 50% cytotoxic concentration on VERO (African Green Monkey Kidney) cell lines was estimated at 209 µg/mL. No antiviral activity was recorded. Additionally, T. polium extract was able to inhibit P. aeruginosa PAO1 motility in a concentration-dependent manner. However, the tested extract was able to inhibit 23.66% of the swarming and 35.25% of swimming capacities of PAO1 at 100 µg/mL. These results highlighted the role of germander as a potent antimicrobial agent that can interfere with the virulence factors controlled by the quorum-sensing systems.

Antibiofilm, antiquorum sensing and antioxidant activity of secondary metabolites from seeds of Annona senegalensis, Persoon.

The increasing resistance of bacteria to antibiotics has motivated the interest in potent natural compounds capable of disrupting bacterial cell-to-cell communication. Column chromatography of seed extract of Annona senegalensis afforded N-cerotoyltryptamine (1), asimicin (2) and ent-19-carbomethoxykauran-17-oic acid (3). The compounds were tested for their antimicrobial, antibiofilm, and anti-quorum sensing activities. The minimum inhibitory concentrations (MIC) values ranged from 50 µg/mL to 100 µg/mL for C. albicans ATCC 10239 and S. aureus ATCC 25923 E. coli ATCC 25922, C. violaceum CV026 and C. violaceum CV12472. All the compounds inhibited biofilm formations of all microorganisms tested in various percentages at MIC and MIC/2. Compound 2 also exhibited the highest antibiofilm activity against C. albicans (yeast) and E. coli with percentage inhibitions ranging from 6.3 ± 4.1 (MIC/4) to 37.9 ± 4.5 (MIC) for C. albicans and from 18.8 ± 1.1 (MIC/4) to 43.2 ± 0.5 (MIC) for E. coli. Compound 1, however, showed highest biofilm inhibition on S. aureus as the percentage inhibition varied from 26.7 ± 3.6 (MIC/4) to 43.8 ± 2.1 (MIC). Compound 2 showed highest percentage violacein inhibition on C. violaceum CV12472 ranging from 10.2 ± 0.5 (MIC/8), 65.76 ± 1.3 (MIC/2) and 100 (MIC). Compound 1 and 3 had percentage violacein formation inhibitions on C. violaceum CV12472 ranging from 9.66 ± 1.1 (MIC/4) to 100 (MIC), and from 17.4 ± 2.4 (MIC/4) to 100 (MIC), respectively. Swimming and swarming motility of P. aeruginosa PA01 strain was evaluated at three concentrations of 50, 75 and 100 µg/mL. The compounds inhibited the P. aeruginosa swimming and swarming motility at the three tested concentrations (50, 75 and 100 µg/ml) in a dose-dependent manner. The extents of inhibition of motility migration was relatively higher in the swimming model than in the swarming model for all compounds. Compound 1 exhibited the highest percentage inhibition of motility of 41.50 ± 3.5 and 39.73 ± 1.5 in swimming model and swarming model respectively at 100 µg/ml. Compound 3 showed the lowest percentage inhibition of 30.36 ± 2.0 and 23.50 ± 2.5 in swimming and swarming respectively at 100 µg/ml. At the lowest tested concentration of 50 µg/ml, it was compound 2 showing the highest inhibition of motility of 17.49 ± 0.5 and 14.29 ± 1.0 in swimming and swarming respectively. Compound 1 showed highest quorum sensing (QS) activity with QS inhibition zone of 20.0 ± 1.5 mm at MIC and 11.0 ± 1.0 mm at MIC/8 while compound 2 had the highest antimicrobial (AM) zone diameter amongst the compounds at MIC. Compound 3 was the QS inhibitory sample and did not show any QS inhibition at MIC/8 while showing its highest QS inhibition zone of 13.0 ± 1.6 mm at MIC. For antioxidant assays, no sample showed better activity than the standards. Compound 2 had highest activity with IC50 values of 87.79 ± 2.70 and 42.77 ± 1.53 µg/mL in DPPH and ß-carotene-linoleic acid assay respectively and was more active (IC50 of 97.69 ± 1.40 µg/mL) than standard quercetin (IC50 250.09 ± 0.87 µg/mL) in metal chelation assay.