Search Results (123)

The Red Sea is rich in symbiotic microorganisms that have been identified as sources of bioactive compounds with antimicrobial, antifungal, and antioxidant properties. In this study, we aimed to explore the potential of marine sponge-associated bacteria as sources of antibacterial compounds, emphasizing their significance in combating antibiotic resistance (AMR). The crude extracts of Micrococcus, Bacillus, and Staphylococcus saprophyticus exhibited significant antibacterial activity, with inhibition zones measuring 12 mm and 14 mm against Escherichia coli, Staphylococcus aureus, Candida albicans, and other infectious strains. The DPPH assay showed that the bacterial isolates AN3 and AN6 exhibited notable antioxidant activity at a concentration of 100 mg/mL. To characterize the chemical constituents responsible for the observed bioactivity, a GC–MS analysis was performed on ethyl acetate extracts of the potent strains. The analysis identified a range of antimicrobial compounds, including straight-chain alkanes (e.g., Tetradecane), cyclic structures (e.g., Cyclopropane derivatives), and phenolic compounds, all of which are known to disrupt microbial membranes or interfere with metabolic pathways. The bioprospecting and large-scale production of these compounds are challenging. In conclusion, this study underscores the potential for marine bacteria associated with sponges from the Red Sea to be a source of bioactive compounds with therapeutic relevance. Full article

Untapped bioactive compounds from microbial endophytes offer a promising solution to counter antimicrobial and chemotherapeutic drug resistance when complexed as silver nanoparticles (AgNPs). AgNPs were biosynthesized using cell-free supernatants from endophytic Streptomyces sp. KE4D and Bacillus safensis KE4K isolated from the Kenyan medicinal plant Teclea nobilis, following fermentation in three different media. Bacterial extracts were analyzed using gas chromatography–mass spectrometry. AgNPs were characterized using Fourier-transform infrared spectroscopy and high-resolution transmission electron microscopy. Antimicrobial activity was assessed using agar well diffusion assays, and quorum sensing inhibition (QSI) was investigated using Chromobacterium violaceum. Anti-cancer potential was evaluated against breast (MCF-7) and prostate cancer (DU-145) cell lines using MTT assays. AgNPs were 5–55 nm in size, with KE4D AgNPs being spherical and KE4K AgNPs exhibiting various shapes. Cyclopropane acetic acids and fatty acids were identified as possible capping agents. Medium-dependent antimicrobial activity was observed, with medium Mannitol and medium 5294 AgNPs displaying stronger activity, particularly against Gram-negative indicators. KE4D medium 5294 AgNPs demonstrated 85.12% violacein inhibition at 140 µg/mL and better QSI activity, whilst KE4K AgNPs were better antimicrobials. The AgNPs IC₅₀ values were <3.5 µg/mL for MCF-7 and <2.5 µg/mL for DU-145 cells. The bioactivity of biosynthesized AgNPs is influenced by the bacterial isolate and fermentation medium, suggesting that AgNP synthesis can be tailored for specific bioactivity. Full article

The [3+2] cycloaddition chemistry of (2S)-5-methylene-2-t-butyl-1,3-dioxolan-4-one, derived from lactic acid, has been examined, and spiro adducts have been obtained with benzonitrile oxide, acetonitrile oxide, diazomethane and diphenyldiazomethane. The structure and absolute stereochemistry of the benzonitrile oxide adduct has been confirmed by X-ray diffraction, and all the adducts have been fully characterised by ¹H and ¹³C NMR. Attempted cycloaddition with a nitrile sulfide, a nitrile imine and azides failed. Pyrolysis results in a range of novel gas-phase reactions, with the nitrile oxide adducts giving pivalaldehyde, CO₂, the nitrile and ketene, the diazomethane adduct losing only N₂ to give a cyclopropane-fused dioxolanone, and the diphenylcyclopropane derived from diphenyldiazomethane giving mainly benzophenone in a sequence involving the loss of pivalaldehyde and methyleneketene. Full article

In hay milk production, fermented feed, like silage, is forbidden. This study aims to reveal the presence of silages made from maize or grass in the diet of dairy cows through the detection of cyclopropane fatty acids (CPFAs) in their milk. It also investigates how CPFAs in their milk declines when the diets of the cows are transitioned from one containing silage to one that does not include silage. CPFAs were quantified in silages collected on the farm, and the relationship between the dietary intake of CPFAs from silages and the marker concentration in milk was investigated. Except for one sample (below LOQ), CPFAs were never detected in hay milk, while they were found in 98% and 85% of milk samples obtained from cows whose diet included maize or grass silage as the only fermented component, respectively. CPFAs were found to still be detectable in milk 56 days after the removal of maize silage from the diet, while they were no longer detectable about three weeks after removing grass silage from the ration. A quantitative positive relationship was detected between CPFAs content in the milk and the dietary intake of CPFAs from silages. CPFAs can be regarded as reliable markers to detect the occurrence of silages in the ration, but it is more effective for maize than for grass silage. Full article

This review probes the recent developments in stereoselective reactions within the area of sulfoxonium ylide chemistry since the early 2000s. An abundance of research has been applied to sulfoxonium ylide chemistry since its emergence in the early 1960s. There has been a continued effort since then with work in traditional areas, such as epoxidation, aziridination and cyclopropanation. Efforts have also been applied in novel areas, such as olefination and insertion reactions, to develop stereoselective methodologies using organocatalysis and transition metal catalysis. The growing research area of interrupted Johnson–Corey–Chaykovsky reactions is also described, whereby unexpected stereoselective cyclopropanation and epoxidation methodologies have been developed. In general, the most observed mechanistic pathway of sulfoxonium ylides is the formal cycloaddition: (2 + 1) (e.g., epoxides, cyclopropanes, aziridines), (3 + 1) (e.g., oxetanes, azetidines), (4 + 1) (e.g., indanones, indolines). This pathway involves the formation of a zwitterionic intermediate through nucleophilic addition of the carbanion to an electrophilic site. An intramolecular cyclization occurs, constructing the cyclic product. Insertion reactions of sulfoxonium ylides to X–H bonds (e.g., X = S, N or P) are also observed, whereby protonation of the carbanion is followed by a nucleophilic addition of X, to form the inserted product. Full article

The formation of the four 3-ring systems c-(CH₂)_3−k(SiH₂)_k ($k=0$: cyclopropane, $k=1$: silirane, $k=2$: disilirane, $k=3$: cyclotrisilane) by addition of methylene and silylene to the double bond in ethene, disilene, and silaethene, as well as the elimination of the carbene analogs from the 3-rings, was studied with CAS(4,4) wave functions in both $C_{2v}$ and $C_s$ symmetry. To reveal the charge and spin redistribution during these reactions the CAS(4,4) wave functions were analyzed using the orthogonal valence bond method (OVB). The potential energy curves, different internal coordinates, and the results of the OVB analysis show that, frequently, the addition and elimination reactions follow different minimum energy paths, because they are indeed diabatic reactions. In these cases, there are no energy barriers corresponding to saddle points on the potential energy surfaces but the energy increases during one diabatic reaction until, at a certain point, the system jumps to the other diabatic state and, in the following, the energy decreases. This happens for reactions in $C_{2v}$ symmetry; as soon as the system can change to the lower symmetry, the diabatic states combine to an adiabatic one and the reaction follows a single minimum energy path. Full article

Ethyl diazoacetate can react with 2,5-dimethyl-2,4-hexadiene to yield ethyl chrysanthemumate, an important raw material for synthesizing various pesticides. In conventional conditions, this cyclopropanation process suffers from low efficiency and yield due to ethyl diazoacetate. This demands more understanding of the catalytic process from the mechanism and modeling to find a solution. In this work, we set up a micro-flow platform to carefully study the kinetic characteristics of the cyclopropanation reaction of ethyl diazoacetate catalyzed by a complex of copper stearate and phenylhydrazine. Through a reasonable simplification of the reaction network, we established a reaction kinetic model with good prediction capacity within a wide range of operating conditions. It provides a basis for guiding the development of efficient conversion processes and condition optimization. Full article

Atopic dermatitis (AD) or eczema is an important inflammatory chronic skin disease that brings many complications in its management and treatment. Although several chemical agents are used for treatment, the search for better anti-inflammatory and antibacterial agents of plant origin has been ongoing, since natural compounds, it is commonly believed, are less dangerous than synthetic ones. Therefore, the present study explored a medicinal plant—Eclipta prostrata (L.) L.—for its anti-inflammatory activity alone and in combination with a non-steroidal anti-inflammatory drug (NSAID), diclofenac. The plant extract was used to make a cream formulation for treating atopic dermatitis and as an antibacterial agent against Staphylococcus aures, the major infectious agent associated with AD. The phytochemical analysis of the E. prostrata extract showed the presence of various phytochemicals, including flavonoids, Tannin, saponin, terpenoids, glycosides, phenol, alkaloids, quinone, and protein. The GC-MS profiling of methanolic E. prostrata extract was performed predicted the presence of twenty important phytochemicals, including 2-[5-(2-Hydroxypropyl) oxolan-2-yl]propanoic acid, dl-Menthol, dodecane, undecane, 4,7-dimethyl-, dodecane, 2,6,10-trimethyl-, decane, 2,3,5,8-tetramethyl-, cholest-5-en-3-ol, (3.alpha.)-, TMS derivative, cyclopropane carboxylic acid, 1-hydroxy-, (2,6-di-t-butyl-4-methylphenyl) ester, alpha.-farnesene, propanoic acid, 2-methyl-, 2-ethyl-1-propyl-1,3-propanediyl ester, diethyl phthalate, corticosterone, 2-methylpropionate, hentriacontan-13-ol, O-TMS, phthalic acid, 2,4-dimethylpent-3-yl dodecyl ester, hexasiloxane, 1,1,3,3,5,5,7,7,9,9,11,11-dodecamethyl-, acetic acid, 4-t-butyl-4-hydroxy-1,5-dimethyl-hex-2-ynyl ester, octadecane, 2-methyl- octacosane, 1-iodo-, nonacosane, and eicosyl isopropyl ether. Using an egg albumin denaturation inhibition assay, the anti-inflammatory activities of E. prostrata alone and in combination with diclofenac were investigated, and they showed 93% and 99% denaturation inhibition at 5 mg concentration of E. prostrata in alone and combination with diclofenac, respectively. Heat-induced haemolysis showed 2.5% and 2.4% of haemolysis at 5 mg of E. prostrata alone and in combination with diclofenac, respectively. An MTT assay performed using L₉₂₉ cells proved that the extract has no cytotoxic effect. The plant extract displayed potential antibacterial activity against Staphylococcus aureus; the growth was inhibited at 1 mg/mL of E. prostrata extract. Thus, based on this evidence, the authors suggest that E. prostrata extract should be studied further for its anti-inflammatory and antibacterial activities and topical application in the treatment of atopic dermatitis. Full article

A one-carbon difluorocyclopropanation/ring-expansion has been developed for the chiral synthon Cyrene, which is obtained via cellulose pyrolysis. The ring-enlargement was achieved by converting Cyrene (dihydrolevoglucosenone) into an enamine, reacting it with an in situ-generated difluorocarbene, and then heating it to ring-open the cyclopropane. Access to the product provides access to fluorinated analogues of this valuable chiral biomass derivative. Full article

1,5-Acrylodan (1-(5-(dimethylamino)naphthalen-1-yl)prop-2-en-1-one) is prepared in six steps from 1-nitronaphthalene and 19% overall yield. The last three steps involve an aryllithium-directed nucleophilic addition, catalytic Kulinkovich cyclopropanation, and copper-catalyzed oxidative ring-opening to generate the acryloyl moiety. The fluorescent properties of 1,5-Acrylodan (AC) are reported. These include its solvatochromism and H-bond quenching by protic solvents. Its use as a bioconjugate sensor is demonstrated with Human Serum Albumin (HSA) through its covalent attachment to Human Serum Albumin (HSA) at the free cysteine-34 moiety. Unfolding studies with guanidinium chloride (GdmCl) and sodium dodecyl sulfate (SDS) are conducted to illustrate how the fluorophore responds to changes in both micropolarity and exposure to water. Full article

Carbon–carbon bond formation represents a key reaction in organic synthesis, resulting in paramount importance for constructing the carbon backbone of organic molecules. However, traditional metal-based catalysis, despite its advantages, often struggles with issues related to efficiency, selectivity, and sustainability. On the other hand, while biocatalysis offers superior selectivity due to an extraordinary recognition process of the substrate, the scope of its applicable reactions remains somewhat limited. In this context, Artificial Metalloenzymes (ArMs) and Metallo Peptides (MPs) offer a promising and not fully explored solution, merging the two fields of transition metal catalysis and biotransformations, by inserting a catalytically active metal cofactor into a customizable protein scaffold or coordinating the metal ion directly to a short and tunable amino acid (Aa) sequence, respectively. As a result, these hybrid catalysts have gained attention as valuable tools for challenging catalytic transformations, providing systems with new-to-nature properties in organic synthesis. This review offers an overview of recent advances in the development of ArMs and MPs, focusing on their application in the asymmetric carbon–carbon bond-forming reactions, such as carbene insertion, Michael additions, Friedel–Crafts and cross-coupling reactions, and cyclopropanation, underscoring the versatility of these systems in synthesizing biologically relevant compounds. Full article

Cystic fibrosis (CF) is a hereditary disease characterized by the progression of respiratory disorders, especially in adult patients. The purpose of the study was to identify volatile organic compounds (VOCs) as predictors of respiratory dysfunction, chronic respiratory infections of Staphylococcus aureus, Pseudomonas aeruginosa, Burkholderia cepacia, and VOCs associated with severe genotype and highly effective modulator treatment (HEMT). Exhaled breath samples from 102 adults with CF were analyzed using PTR-TOF-MS, obtained during a forced expiratory maneuver and normal quiet breathing. Using cross-validation and building gradient boosting classifiers (XGBoost), the importance of VOCs for functional and clinical outcomes was determined. The presence of the previously identified VOCs indole, phenol, and dimethyl sulfide were metabolic outcomes associated with impaired respiratory function. New VOCs associated with respiratory disorders were methyl acetate, carbamic acid, 1,3-Pentadiene, and 2,3-dimethyl-2-butene; VOCs associated with the above mentioned respiratory pathogens were non-differentiable nitrogen-containing organic compounds m/z = 47.041 (CH5NO)+ and m/z = 44.044 (C2H5NH+), hydrocarbons (cyclopropane, propene) and methanethiol; and VOCs associated with severe CFTR genotype were non-differentiable VOC m/z = 281.053. No significant features associated with the use of HEMT were identified. Early non-invasive determination of VOCs as biomarkers of the severity of CF and specific pathogenic respiratory flora could make it possible to prescribe adequate therapy and assess the prognosis of the disease. However, further larger standardized studies are needed for clinical use. Full article

Endophytic bacteria from pea (Pisum sativum L.) plants play important roles in regulating plant growth, health, and nutrition. To enhance the understanding of endophytic bacteria in peas, twenty pea cultivars, two chickpeas, and two broad bean cultivars were planted into artificial soils for 4 weeks. Leaves and roots were collected from plants and sterilized. Endophytic bacterial DNAs were isolated from sterilized materials (leaves, roots, and seeds) and used as templates to detect the bacterial diversity by amplifying the 16S V3–V4 region. The Remel Tryptose Soya Agar (TSA) medium, the aluminum sec-butoxide (ASb) medium, and the yeast extract mannitol agar (YMA) medium were used to isolate bacteria from sterilized leaves and roots, respectively. The plant growth-promoting (PGP) properties of these isolated bacteria, such as the solubilization of phosphorus and potassium and the production of Indole-3-acetic acid (IAA), 1-aminocyclopropane-1-carboxylic acid (ACC) deaminase, nitrogenase, pectinase, and cellulose, were studied in vitro. Bacterial isolates were processed for 16S rDNA gene sequencing and performed molecular identification by reconstruction of the phylogenetic tree using the neighborhood association approach in the software MEGA X. Results indicated that the majority of the bacterial communities were shared among leaves, roots, and seeds of pea plants. In both the leaves and roots of pea plants, the prominent phyla identified were Pseudomonadota, Bacteroidota, and Bacillota, with dominant genera such as Rhizobium, Bacteroides, Blautia, and Prevotella prevailing at the genus level. The samples from leaves and roots had unique dominant bacterial genera. In total, 48 endophytic bacteria strains were isolated from leaves and roots, of which 16 strains were from roots and 32 strains were from leaves. The majority of the isolates from leaves (78.13%) and roots (75%) had the ability to produce indole-3-acetic acid (IAA). Moreover, isolates from roots also had greater ability to produce 1-amino-cyclopropane-1-carboxylic acid (ACC) deaminase (81.25%) than those from leaves (62.5%). This study demonstrated the unique distribution of endophytes in leaves and roots of pea, which can have great potential in pea production. Full article

As an important small organic molecule, cyclopropane is widely used in drug design. In this paper, fifty-three amide derivatives containing cyclopropane were designed and synthesized by introducing amide groups and aryl groups into cyclopropane through the active splicing method, and their antibacterial and antifungal activities were evaluated in vitro. Among them, thirty-five compounds were new compounds, and eighteen compounds were known compounds (F14, F15, F18, F20–F26, F36, and F38–F44). Bioassay results disclosed that four, three, and nine of the compounds showed moderate activity against Staphylococcus aureus, Escherichia coli, and Candida albicans, respectively. Three compounds were sensitive to Candida albicans, with excellent antifungal activity (MIC₈₀ = 16 μg/mL). The molecular docking results show that compounds F8, F24, and F42 have good affinity with the potential antifungal drug target CYP51 protein. Full article

It is found that the reaction of dimethyl 2-phenylcyclopropane-1,1-dicarboxylate with 2 equivalents each of aromatic aldehydes and TaCl₅ in 1,2-dichloroethane at 23 °C for 24 h after hydrolysis gives substituted 4-phenyl-3,4-dihydronaphtalene-2,2(1H)-dicarboxylates in good yield. This represents a new type of reactions between 2-arylcyclopropane-1,1-dicarboxylates and aromatic aldehydes, yielding chlorinated tetrahydronaphthalenes with a cis arrangement of the aryl and chlorine substituents in the cyclohexene moiety. A plausible reaction mechanism is proposed. Full article