Μg mL-1 Research Articles

Chemical profile and biological potential of essential oil of Psidium bahianum Landrum & Funch (Myrtaceae).

The genus Psidium, belonging to the family Myrtaceae, encompasses several plant species rich in essential oils. Several studies involving different research areas have shown promising results for essential oils, which has attracted interest from diverse sectors, including pharmaceutical, food, and cosmetic industries. Thus, the objective of this study was to evaluate the biological activity of the essential oil extracted from Psidium bahianum leaves (EOPb) collected in an Atlantic Forest remnant in the northern coast of the state of Bahia, Brazil. EOPb was extracted by steam distillation and analyzed through proton nuclear magnetic resonance (1H-NMR). The free radical scavenging activity was assessed using the DPPH methodology (analyzing the scavenging of the stable free radical 1,1-diphenyl-2-picrylhydrazyl). Antimicrobial disk diffusion assays were conducted; toxicity was determined through assays on sheep erythrocytes and Artemia salina. 1H-NMR evaluation showed the presence mainly of monoterpenes and sesquisterpenes. The percentage of antioxidant activity was 18.03±2.53 53 for 125 125 µg mL-1. Antimicrobial assays showed that the essential oil at a concentration of 10 mg mL-1 inhibited the growth of the microorganisms Staphylococcus aureus, Bacillus subtilis, B. cereus, Micrococcus luteus, Escherichia coli, Aspergillus niger, Candida albicans, and C. glabrata. The toxicity results indicated that concentrations of EOPb at 10, 100, 250, and 500 µg mL-1 were not toxic to sheep erythrocytes. The toxicity assay on A. salina showed that the lethal concentration for 50% of individuals (LC50) within 24 and 48 hours were 371.48 and 302 µg mL-1 of EOPb, respectively, which were considered moderately toxic, whereas the LC50 within 72 horas was 33.11 µg mL-1, considered highly toxic. These findings are promising, as the essential oil from P. bahianum leaves showed antimicrobial activity against both Gram-positive and Gram-negative bacteria and fungi. The data obtained for the essential oil toxicity in A. salina could be tested on different tumor cell lines.

CHEMICAL CONSTITUENTS AND ANTIBACTERIAL ACTIVITY OF THREE TYPES OF AMAZONIAN Melipona spp. GEOPROPOLIS

This work describes the first chemical study on the metabolic profile of three geopropolis samples from Melipona fulva, M. compressipes, and M. paraensis collected in the Amazonian region. The samples were submitted to solvent extractions. The silylated hexane extracts were submitted to GC-MS analysis and tentatively identified mainly the presence of triterpenes, steroids, fatty acids, and alcohols. The chemical profile of M. fulva of and M. compressipes geopropolis are similar. However, cholesterol, triacontanol, and palmitic acid are the main compounds in M. fulva; in M. compressipes, palmitic acid, linoleic acid, and oleic acid are predominant. The chemical profile of the M. paraensis sample is entirely different once more than 60% of the extract comprises lupenone and triacontanol. The CHCl3 soluble fraction of the MeOH extract of the M. paraensis geopropolis was submitted to chromatographic techniques, and it afforded cycloartenol, 24-methylene-cycloartenol, lupeol, α- and β-amirins, and 7-O-methylaromadendrin. The MeOH extract of this sample presents antimicrobial activities against strains of Streptococcus mutans, S. sobrinus, and S. aureus (MIC of 15.6-62.5 µg mL-1 and MBC of 62.5-1000 µg mL-1). The M. fulva and M. compressipes geopropolis were not active in this test.

In vitro and in vivo anthelmintic response of the seeds of Amomum subulatum roxb and Vitex negundo.

The current study was designed to check the anthelmintic activities of some local plants. Seeds of Amomum (A.) subulatum and Vitex (V.) negundo in different solvents were subjected to in vitro (adult motility assay; AMA and egg hatch assay; EHA) and in vivo (faecal egg count reduction test; FECRT) anthelmintic activity testing protocols using Haemonchus (H.) contortus as an experimental model. The results of AMA, EHA, and FECRT were statistically analysed through linear regression and Duncan multiple range test. In AMA test, at 50 mg mL-1 concentration, the percent mortality of H. contortus was higher in A. subulatum than V. negundo, whereas, in EHA test, A. subulatum was proven better ovicidal (LC50=14.2 µg mL-1) than V. negundo (LC50= 65.7405 µg mL-1). The FECRT also indicated the better efficacy of A. subulatum than V. negundo against natural infection of gastrointestinal (GI) parasites. The crude powder of plants used in this study showed 29.6% to 57.7% anthelmintic. The reduction rate was found higher for A. subulatum (3 g kg-1) as compared to V. negundo (7 g kg-1). Reagrding efficacy analysis of solvents used for plants extract, ethyl acetate and chloroform were found better in increasing ovicidal activity in adult worms (in vitro testing), whereas, the crude aqueous methanol was found better than the crude powders in in vivo testing. It will be beneficial to document the indigenous knowledge to standard scientific procedures for their validation. This study will help to motivate the farmers to make a better choice of cultivation of the indigenous plants because of their varying efficacies as an alternative preventive approach against the GI parasitic infections.

Direct immunoassay on a polyester microwell plate for colorimetric detection of the spike protein in swab and saliva samples.

This study presents the development of a polyester microplate for detecting the S-protein of the SARS-CoV-2 virus in saliva and nasopharyngeal swab samples using direct enzyme-linked immunosorbent assay (ELISA) technology. The polyester microplate was designed to contain 96 zones with a 3 mm diameter each, and a volume of 2-3 μL. The experimental conditions including reagent concentration and reaction time were optimized. The microplate image was digitized and analyzed using graphical software. The linear range obtained between protein S concentrations and pixel intensity was 0-10 μg mL-1, with a correlation coefficient of 0.99 and a limit of detection of 0.44 μg mL-1. The developed methodology showed satisfactory intraplate and interplate repeatability with RSD values lower than 7.8%. The results achieved through immunoassay performed on polyester microplates were consistent with those of the RT-PCR method and showed a sensitivity of 100% and 90% and specificity of 85.71% and 100% for saliva and nasopharyngeal samples, respectively. The proposed direct immunoassay on polyester microplates emerges as an alternative to conventional immunoassays performed on commercial polystyrene plates, given the low cost of the device, low consumption of samples and reagents, lower waste generation, and shorter analysis time. Moreover, the immunoassay has shown great potential for diagnosing COVID-19 with precision and accuracy.

Construction of a layer-by-layer self-assembled rosemarinic acid delivery system on the surface of CFRPEEK implants for enhanced anti-inflammatory and osseointegration activities.

Carbon fiber-reinforced polyether ether ketone (CFRPEEK) implants have attracted widespread attention in the field of clinical bone defect repair. However, the surface bioinertness confines the application of CFRPEEK implants. Inspired by the study of rosmarinic acid (RA)-promoted osteogenic differentiation, a self-assembly surface modification method based on electrostatic interactions, involving deposition of sodium carboxymethyl cellulose/chitosan and rosmarinic acid layer by layer on the surface of poly-L-lysine modified hydroxy CFRPEEK (SCPP/CC5@RA), is proposed to introduce RA on the surface of CFRPEEK for bioactivation. After layer-by-layer self-assembly (LBL), the surface of SCPP/CC5@RA exhibits weak electrophoresis (11.43 eV), suitable hydrophilicity, and bioactivity. The results of in vitro studies indicate that the RA release behavior of SCPP/CC5@RA effectively regulates the immune-inflammatory response and promotes the differentiation of osteoblasts. The rapid release of RA (0.17 μg mL-1) in the initial stage can downregulate the secretion of inflammation-related cytokines and significantly reduce oxidative stress levels; the sustained release of RA (0.06 μg mL-1) in the late stage can upregulate the expression of osteogenesis-related genes and induce mineralization of osteoblasts. Moreover, the rabbit tibia defect model demonstrates that the LBL technique can enhance the osseointegration of CFRPEEK implants. Compared with the control group, the bone trabecular thickness of the SCPP/CC5@RA group increases by 1.36 times, and the maximum pushing force increases by 2.67 times. In summary, this study provides a promising LBL based RA delivery system for the development of a dual-functional CFRPEEK implant in the field of bone implant biomaterials.

Rapid colorimetric sensing of chlorpromazine HCl antipsychotic through in situ growth of gold nanoparticles.

Antipsychotic drugs like chlorpromazine hydrochloride (CPZ) are widely used to treat mental illnesses but can accumulate in the environment if not properly disposed of. Long-term exposure to trace levels of such pharmaceuticals may pose health risks. This study reports a colorimetric assay for detection of the antipsychotic drug chlorpromazine hydrochloride (CPZ) based on its ability to reduce gold ions and form gold nanoparticles (AuNPs). Optimization of reaction conditions such as pH, temperature and reagent concentrations enabled quantitative analysis of CPZ concentrations from 0.1-30 μg mL-1, with a detection limit of 0.06 μg mL-1, 0.23 μg mL-1 quantification limit and less than 3.5% RSD. The AuNPs exhibited a characteristic surface plasmon resonance band at 527 nm detectable by UV-vis spectrophotometry. Method validation with spiked serum, urine and environmental water samples demonstrated acceptable accuracy and precision. Interfering substances showed minimal impact, indicating resilience and specificity. This rapid, inexpensive colorimetric assay could facilitate environmental monitoring and biomedical analysis of antipsychotic drugs.

Naphthoquinone derivatives as potential immunomodulators: prospective for COVID-19 treatment.

Inflammation plays a crucial role in COVID-19, and when it becomes dysregulated, it can lead to severe outcomes, including death. Naphthoquinones, a class of cyclic organic compounds widely distributed in nature, have attracted significant interest due to their potential biological benefits. One such naphthoquinone is 3,5,8-trihydroxy-6-methoxy-2-(5-oxohexa-1,3-dienyl)-naphthanthene-1,4-dione (3,5,8-TMON), a compound produced by fungi. Despite its structural similarity to shikonin, limited research has been conducted to investigate its biological properties. Therefore, the objective of this study was to evaluate the effects of 3,5,8-TMON and its synthetic derivatives in the context of inflammation induced by lipopolysaccharide (LPS) and SARS-CoV-2 infection in vitro using cell cultures. 3,5,8-TMON was obtained by acid treatment of crude extracts of fermentation medium from Cordyceps sp., and two derivatives were accessed by reaction with phenylhydrazine under different conditions. The results revealed that the crude extract of the fungi (C. Ex) inhibited the activity of transcription factor NF-kB, as well as the production of nitric oxide (NO) and interleukin-6 (IL-6) when LPS induced it in RAW 264.7 cells. This inhibitory effect was observed at effective concentrations of 12.5 and 3.12 μg mL-1. In parallel, 3,5,8-TMON and the new derivatives 3 and 4 demonstrated the ability to decrease IL-6 production while increasing TNF, with a specific effect depending on the concentration. These concentration-dependent agonist and antagonist effects were observed in THP-1 cells. Furthermore, 3,5,8-TMON inhibited IL-6 production at concentrations of 12.5 and 3.12 μg mL-1 in Calu-3 cells during SARS-CoV-2 viral infection. These findings present promising opportunities for further research into the therapeutic potential of this class of naphthoquinone in the management of inflammation and viral infections.

Aminoguanidine-based bioactive proligand as AIEE probe for anticancer and anticovid studies.

The emission features of a novel bioactive compound, 1,3-bis(2-hydroxy-3,5-diiodophenyl-methylideneamino)guanidine is found impressive with aggregation induced emission enhancement. The nitrogen and iodine rich multidentate proligand was characterized physicochemically. SCXRD and Hirshfeld surface investigation have revealed the presence of significant triangular iodine bonding apart from hydrogen bonding, weak C-H⋯π and π⋯π intermolecular interactions. These interactions collectively contribute to the solid-state packing arrangement of the molecules within the crystal lattice. The band gap of the compound was estimated experimentally and is supported with theoretical calculations. The solid-state fluorescence quantum yield of Φ = 0.36 emphasizes the utility of the proligand and the AIEE characteristics is attributed to restricted intramolecular motions as indicated by fluorescence lifetime decay studies. Strong interaction of the compound with calf thymus DNA was explored experimentally and found to align with in silico docking results. Notably, in vitro anticancer assessment on MCF-7 breast cancer cells show an IC50 value of 181.05 μg mL-1 and signifying its potent cytotoxic properties. Also, the compound is found to have lesser cytotoxicity against L929 normal cell line with an IC50 value of 356.54 μg mL-1. Computational studies further underscore the exceptional binding affinity with active sites in the SARS-CoV-2 main protease 3CLpro, surpassing established repurposed drugs. Furthermore, the proligand demonstrates excellent putative affinity towards the SARS-CoV-2 spike glycoprotein, accompanied by its distinctive AIEE attributes, drug likeness and DNA binding capability rendering it a valuable tool for prospective research investigations.

Activity against Mycobacterium tuberculosis of a new class of spirooxindolopyrrolidine embedded chromanone hybrid heterocycles.

A new class of structurally intriguing heterocycles embedded with spiropyrrolidine, oxindole and chromanones was prepared by regio- and stereoselectively in quantitative yields using an intermolecular tandem cycloaddition protocol. The compounds synthesized were assayed for their anti-mycobacterial activity against Mycobacterium tuberculosis (Mtb) H37Rv and isoniazid-resistant (katG and inhA promoter mutations) clinical Mtb isolates. Four compounds exhibited significant antimycobacterial activity against Mtb strains tested. In particular, a compound possessing a fluorine substituted derivative displayed potent activity at 0.39 μg mL-1 against H37Rv, while it showed 0.09 μg mL-1 and 0.19 μg mL-1 activity against inhA promoter and katG mutation isolates, respectively. A molecular docking study was conducted with the potent compound, which showed results that were consistent with the in vitro experiments.

Design and synthesis of novel 2-(2-(4-bromophenyl)quinolin-4-yl)-1,3,4-oxadiazole derivatives as anticancer and antimicrobial candidates: in vitro and in silico studies.

Cancer is the second leading cause of death globally, surpassed only by heart disease. Moreover, bacterial infections remain a significant global health burden, contributing substantially to morbidity and mortality, especially among hospitalized patients. EGFR has emerged as a prime therapeutic target due to its pivotal role in driving uncontrolled cell growth and survival across numerous cancer types. In addition, DNA gyrase represents a promising target for the development of novel antimicrobial agents. Therefore, we aimed to design and synthesize new multi-target quinoline hybrids (7-17e) capable of acting as anti-proliferative and antimicrobial agents by inhibiting EGFR and microbial DNA gyrase, respectively. The inhibitory potential of the synthesized compounds was determined using in vitro and in silico approaches. The antiproliferative activity of the synthesized quinoline-oxadiazole derivatives 7-17e was assessed against two cancer cell lines, namely, hepatocellular carcinoma (HepG2) and breast adenocarcinoma (MCF-7). The assessed compounds 7-17e showed considerable cytotoxic activity activities against HepG2 and MCF-7 with IC50 values of 0.137-0.332 and 0.164-0.583 μg mL-1, respectively, in comparison to erlotinib as the positive control, which showed an IC50 value of 0.308 and 0.512 μg mL-1, respectively. Moreover, an EGFR tyrosine kinase inhibition assay was conducted on the most prominent candidates. The results showed good IC50 values of 0.14 and 0.18 μM for compounds 8c and 12d, respectively, compared to lapatinib (IC50 value of 0.12 μM). Furthermore, the minimum antimicrobial inhibitory concentration was evaluated for the most prominent candidates with S. aureus, E. coli, and C. albicans. Compounds 17b, 17d and 17e displayed the most potent inhibitory activity, exhibiting 4-, 16- and 8-fold more activity, respectively, than the reference neomycin. Hence, we can conclude that the afforded compounds can be used as lead dual anticancer and antimicrobial candidates for future optimization.

Antibacterial activity of hydrophobicity modulated cationic polymers with enzyme and pH-responsiveness.

The membrane lipid compositions of prokaryotic and eukaryotic cells are inherently different in many aspects, although some similarities exist in their structure and composition. Therefore, selective targeting of membrane lipids with a compound of therapeutic value, such as an antibacterial copolymer, is often challenging. Hence, developing an ideal copolymer with antibacterial properties demands hydrophobicity/hydrophilicity balance with a high biosafety profile. To integrate hydrophobic/hydrophilic balance and cationic charge in an alternating antibacterial copolymer with enzyme and pH-responsiveness, a lysine appended styrenic monomer was copolymerized with a fatty acid (octanoic acid (OA) or myristic acid (MA)) tethered maleimide monomer via reversible addition-fragmentation chain transfer (RAFT) polymerization. A range of microscopic analyses, including dynamic light scattering (DLS), confirmed the formation of nanoaggregates (size ∼30-40 nm) by these polymers in aqueous solution with positive zeta potential (cationic surface charge). Hydrophobic Nile red (NR) dye was successfully encapsulated in the nanoaggregates, and the in vitro release kinetics of the NR dye were monitored at different pHs and in the presence or absence of esterase/lipase. The in vitro release kinetics of NR revealed ∼85% dye release in the presence of pH 5.5 and lipase, suggesting their suitability for pH/enzyme-triggered therapeutic payload delivery. The standard broth microdilution assay showed significant bactericidal activity against both Gram-positive (Bacillus subtilis) and Gram-negative (Escherichia coli) bacteria with an MIC50 value <30 μg mL-1. The effect of polymeric nanoaggregates on bacterial morphology and in vitro survival was further confirmed by field emission scanning electron microscopy (FESEM), agar gel disk diffusion assay, and bacterial live/dead cell count. The significantly low hemolytic activity against red blood cells (RBCs) (HC50 >103 μg mL-1) and nontoxic effect on human intestinal epithelial cells (INT 407) (EC50 >500 μg mL-1) ensure that the polymer nanoaggregates are safe for in vivo use and can serve as a potent antibacterial polymer.

Folate-assisted targeted photocytotoxicity of red-light-activable iron(III) complex co-functionalized gold nanoconjugates (Fe@FA-AuNPs) against HeLa and triple-negative MDA-MB-231 cancer cells.

Photo-redox chemistry resulting from ligand to metal charge transfer in red-light-activable iron(III) complexes could be a potent strategic tool for next-generation photochemotherapeutic applications. Herein, we developed an iron(III) complex and folate co-functionalized gold nanoconjugate (Fe@FA-AuNPs) and thoroughly characterized it with NMR, ESI MS, UV-visible, EPR, EDX, XPS, powder X-ray diffraction, TEM and DLS studies. There was a remarkable shift in the SPR band of AuNPs to 680 nm, and singlet oxygen (1O2) and hydroxyl radicals were potently generated upon red-light activation, which were probed by UV-visible and EPR spectroscopic assays. Cellular uptake studies of the nanoconjugate (Fe@FA-AuNPs) revealed significantly higher uptake in folate(+) cancer cells (HeLa and MDA-MB-231) than folate(-) (A549) cancer cells or normal cells (HPL1D), indicating the targeting potential of the nanoconjugate. Confocal imaging indicated primarily mitochondrial localization. The IC50 values of the nanoconjugate determined from a cell viability assay in HeLa, MDA-MB-231, and A549 cells were 27.83, 39.91, and 69.54 μg mL-1, respectively in red light, while in the dark the values were >200 μg mL-1; the photocytotoxicity was correlated with the cellular uptake of the nanoconjugate. The nanocomposite exhibited similar photocytotoxicity (IC50 in red light, 37.35 ± 8.29 μg mL-1 and IC50 in the dark, >200 μg mL-1). Mechanistic studies revealed that intracellular generation of ROS upon red-light activation led to apoptosis in HeLa cells. Scratch-wound-healing assays indicated the inhibition of the migration of MDA-MB-231 cells treated with the nanoconjugate and upon photo-activation. Overall, the nanoconjugate has emerged as a potent tool for next-generation photo-chemotherapeutics in the clinical arena of targeted cancer therapy.

Synthesis of carbon dot based Schiff bases and selective anticancer activity in glioma cells.

Schiff bases have remarkable anticancer activity and are used for glioma therapy. However, the poor water solubility/dispersibility limits their therapeutic potential in biological systems. To address this issue, carbon dots (CDs) have been utilized to enhance the dispersibility in water and biological efficacy of Schiff bases. The amino groups on the surface of CDs were conjugated effectively with the aldehyde group of terephthalaldehyde to form novel CD-based Schiff bases (CDSBs). The results of the MTT assays demonstrate that CDSBs have significant anticancer activity in glioma GL261 cells and U251 cells, with IC50 values of 17.9 μg mL-1 and 14.9 μg mL-1, respectively. CDSBs have also been found to have good biocompatibility with normal glial cells. The production of reactive oxygen species (ROS) in GL261 glioma cells showed that CDSBs, at a concentration of 44 μg mL-1, resulted in approximately 13 times higher intracellular ROS production than in the control group. These experiments offer evidence that CDSBs induce mitochondrial damage, leading to a reduction in mitochondrial membrane potential in GL261 cells. In particular, in this work, CDs serve not as carriers, but as an integral part of the anticancer drugs, which can expand the role of CDs in cancer treatment.

Comparative transcriptomics reveals the mechanism of antibacterial activity of fruit-derived dihydrochalcone flavonoids against Porphyromonas gingivalis.

Porphyromonas gingivalis causes various health issues through oral infections. This study investigates the antibacterial activities of food-derived dihydrochalcone flavonoids against Porphyromonas gingivalis and their mechanisms of antibacterial action through comparative transcriptome profiling. Susceptibility tests showed that two typical dihydrochalcone flavonoids (phloretin and phlorizin) had much lower minimum inhibitory concentrations (12.5 μg mL-1 and 50 μg mL-1, respectively) than the common flavanone naringenin (100 μg mL-1). SEM observations and the LDH activity assay indicated obvious anomalies in cell morphology and increased cell membrane permeability, indicating the destructive effect of those compounds on the cell structure. These compounds might also induce apoptosis in P. gingivalis, as shown by the CLSM fluorescence images. Transcriptomic analysis revealed that the flavonoid treatment impacted DNA function and oxidative damage. These flavonoids may activate antioxidant-related pathways that are lethal to anaerobic bacteria like P. gingivalis. Additionally, the compounds resulted in the silencing of transposition-related genes, potentially inhibiting resistance-gene acquisition and expression. Phloretin regulated fatty acid metabolism pathways, which are related to the construction and maintenance of the cell membrane. This suggests a relationship between the structure and antibacterial activities of the tested compounds that share a flavonoid skeleton but differ in the C-ring and glucose moiety. This is the first report of the antibacterial activities and mechanisms of action of food-derived dihydrochalcone flavonoids at the transcriptome level, offering a promising approach for the development of new antibacterial agents from natural products and enhancing their applicability in treating diseases associated with oral pathogens as a substitute for antibiotics.

Submicron- and nanoplastic detection at low micro- to nanogram concentrations using gold nanostar-based surface-enhanced Raman scattering (SERS) substrates.

The presence of submicron- (1 μm-100 nm) and nanoplastic (<100 nm) particles within various sample matrices, ranging from marine environments to foods and beverages, has become a topic of increasing interest in recent years. Despite this interest, very few analytical techniques are known that allow for the detection of these small plastic particles in the low concentration ranges that they are anticipated to be present at. Research focused on optimizing surface-enhanced Raman scattering (SERS) to enhance signal obtained in Raman spectroscopy has been shown to have great potential for the detection of plastic particles below conventional resolution limits. In this study, we produce SERS substrates composed of gold nanostars and assess their potential for submicron- and nanoplastic detection. The results show 33 nm polystyrene could be detected down to 1.25 μg mL-1 while 36 nm poly(ethylene terephthalate) was detected down to 5 μg mL-1. These results confirm the promising potential of the gold nanostar-based SERS substrates for nanoplastic detection. Furthermore, combined with findings for 121 nm polypropylene and 126 nm polyethylene particles, they highlight potential differences in analytical performance that depend on the properties of the plastics being studied.

Versatile Applications of Cyanoacetic Acid in Organic Chemistry: Active Methylene Compound for the Knoevenagel Condensation and Organocatalyst for the Biginelli Reaction

The application of cyanoacetic acid as a catalyst for the Biginelli reaction and as an active methylene compound for the Knoevenagel condensation reaction was evaluated. Using cyanoacetic acid as a Bronsted acid catalyst, after a synthetic optimization process, it was possible to synthesize eight dihydropyrimidinones with good yields (80-99%) using ethanol as solvent. It is the first time, to our knowledge, that the use of cyanoacetic acid is reported in the synthesis of this class of compounds, which have a wide bioactive potential. Also, cyanoacetic acid was used as a reagent in the Knoevenagel condensation, through which polyfunctionalized olefins were obtained and can be used as building blocks for structurally complex molecules. By using KOH as catalyst, eleven Knoevenagel adducts were synthesized with good yields (65-97%), under microwave irradiation as heating source, in water. Moreover, Knoevenagel adducts containing halogenated substituents (F, Cl) showed potential larvicidal activity with lethal concentrations (LC50) of 19.63, 33.84 µg mL-1 and LC90 of 27.46 and 48.16 µg mL-1. This study showed the versatility of cyanoacetic acid as a catalyst for the synthesis of dihydropirimidinones, aldol compounds and presented the first study showing their larvicidal activity against Aedes aegypti.

Inhibition of SARS-CoV-2 3CLpro by chemically modified tyrosinase from Agaricus bisporus.

Antiviral compounds are crucial to controlling the SARS-CoV-2 pandemic. Approved drugs have been tested for their efficacy against COVID-19, and new pharmaceuticals are being developed as a complementary tool to vaccines. In this work, a cheap and fast purification method for natural tyrosinase from Agaricus bisporus (AbTyr) fresh mushrooms was developed to evaluate the potential of this enzyme as a therapeutic protein via the inhibition of SARS-CoV-2 3CLpro protease activity in vitro. AbTyr showed a mild inhibition of 3CLpro. Thus, different variants of this protein were synthesized through chemical modifications, covalently binding different tailor-made glycans and peptides to the amino terminal groups of the protein. These new tyrosinase conjugates were purified and characterized through circular dichroism and fluorescence spectroscopy analyses, and their stability was evaluated under different conditions. Subsequently, all these tyrosinase conjugates were tested for 3CLpro protease inhibition. From them, the conjugate between tyrosinase and a dextran-aspartic acid (6 kDa) polymer showed the highest inhibition, with an IC50 of 2.5 μg ml-1 and IC90 of 5 μg ml-1, with no cytotoxicity activity by polymer insertion. Finally, SARS-CoV-2 virus infection was studied. It was found that this new AbTyr-Dext6000 protein showed an 80% decrease in viral load. These results show the capacity of these tyrosinase bioconjugates as potential therapeutic proteins, opening the possibility of extension and applicability against other different viruses.

Green synthesis of carbon dots from fish scales for selective turn off-on detection of glutathione.

Carbon dots as fluorescent probes were fabricated using readily available grass carp fish scales as the carbon source via one-step synthesis based on a pyrolytic reaction. The as-prepared grass carp fish scale carbon dots (GF-CDs) exhibited good biocompatibility and excellent optical properties with a high fluorescence quantum yield of 23.8%. Glutathione (GSH) is an essential small tri-peptide molecule present in every body cell and plays a crucial role in vivo and performs a wide range of biological functions. Ag+ can effectively quench the fluorescence of GF-CDs because of the electron transfer between GF-CDs and Ag+; however, the addition of GSH can significantly increase GF-CD-Ag+ fluorescence. Because of their combination with Ag+ and GSH, GF-CDs show selective fluorescence recovery. GF-CDs can serve as fluorescent probes for GSH detection. This detection method covered a wide linear range (1.6-36.0 μg mL-1) with the lowest detection limit of 0.77 μg mL-1 and manifested great advantages such as a short analysis time, good stability, repeatability, and ease of operation.

Assessment of laser-synthesized Si nanoparticle effects on myoblast motility, proliferation and differentiation: towards potential tissue engineering applications.

Due to their biocompatibility and biodegradability and their unique structural and physicochemical properties, laser-synthesized silicon nanoparticles (Si-NPs) are one of the nanomaterials which have been most studied as potential theragnostic tools for non-invasive therapeutic modalities. However, their ability to modulate cell behavior and to promote proliferation and differentiation is still very little investigated or unknown. In this work, ultrapure ligand free Si-NPs of 50 ± 11.5 nm were prepared by femtosecond (fs) laser ablation in liquid. After showing the ability of Si-NPs to be internalized by murine C2C12 myoblasts, the cytotoxicity of the Si-NPs on these cells was evaluated at concentrations ranging from 14 to 224 μg mL-1. Based on these findings, three concentrations of 14, 28 and 56 μg mL-1 were thus considered to study the effect on myoblast differentiation, proliferation and motility at the molecular and phenotypical levels. It was demonstrated that up to 28 μg mL-1, the Si-NPs are able to promote the proliferation of myoblasts and their subsequent differentiation. Scratch tests were also performed revealing the positive Si-NP effect on cellular motility at 14 and 28 μg mL-1. Finally, gene expression analysis confirmed the ability of Si-NPs to promote proliferation, differentiation and motility of myoblasts even at very low concentration. This work opens up novel exciting prospects for Si-NPs made by the laser process as innovative tools for skeletal muscle tissue engineering in view of developing novel therapeutic protocols for regenerative medicine.

Dual SARS-CoV-2 and MERS-CoV inhibitors from Artemisia monosperma: isolation, structure elucidation, molecular modelling studies, and in vitro activities.

The COVID-19 pandemic has spread throughout the whole globe, so it is imperative that all available resources be used to treat this scourge. In reality, the development of new pharmaceuticals has mostly benefited from natural products. The widespread medicinal usage of species in the Asteraceae family is extensively researched. In this study, compounds isolated from methanolic extract of Artemisia monosperma Delile, a wild plant whose grows in Egypt's Sinai Peninsula. Three compounds, stigmasterol 3-O-β-D-glucopyranoside 1, rhamnetin 3, and padmatin 6, were first isolated from this species. In addition, five previously reported compounds, arcapillin 2, jaceosidin 4, hispidulin 5, 7-O-methyleriodictyol 7, and eupatilin 8, were isolated. Applying molecular modelling simulations revealed two compounds, arcapillin 2 and rhamnetin 3 with the best docking interactions and energies within SARS-CoV-2 Mpro-binding site (-6.16, and -6.70 kcal mol-1, respectively). The top-docked compounds (2-3) were further evaluated for inhibitory concentrations (IC50), and half-maximal cytotoxicity (CC50) of both SARS-CoV-2 and MERS-CoV. Interestingly, arcapillin showed high antiviral activity towards SARS-CoV-2 and MERS-CoV, with IC50 values of 190.8 μg mL-1 and 16.58 μg mL-1, respectively. These findings may hold promise for further preclinical and clinical research, particularly on arcapillin itself or in collaboration with other drugs for COVID-19 treatment.