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Chemical Science May 2024Singlet fission is an exciton multiplication process that allows for the conversion of one singlet exciton into two triplet excitons. Organic semiconductors, such as...
Singlet fission is an exciton multiplication process that allows for the conversion of one singlet exciton into two triplet excitons. Organic semiconductors, such as acenes and their soluble bis(triisopropylsilylethynyl) (TIPS) substituted counterparts, have played a major role in elucidating the understanding of the underlying mechanisms of singlet fission. Despite this, one prominent member of the acene family that has received little experimental attention to date is TIPS-anthracene, even with computational studies suggesting potential high singlet fission yields in the solid state. Here, time-resolved spectroscopic and magneto-photoluminescence measurements were performed on spin-cast films of TIPS-anthracene, showing evidence for singlet fission. A singlet fission yield of 19% (out of 200%) is estimated from transient absorption spectroscopy. Kinetic modeling of the magnetic field effect on photoluminescence suggests that fast rates of triplet dissociation lead to a low magnetic photoluminescence effect and that non-radiative decay of both the S and (TT) states is the cause for the low triplet yield.
PubMed: 38699250
DOI: 10.1039/d3sc06774b -
NAR Molecular Medicine Apr 2024Antibiotic resistance poses a significant global health threat, necessitating innovative strategies to combat multidrug-resistant bacterial infections. , a pathogen...
Antibiotic resistance poses a significant global health threat, necessitating innovative strategies to combat multidrug-resistant bacterial infections. , a pathogen responsible for various infections, harbors highly conserved DNA quadruplexes in genes linked to its pathogenesis. In this study, we introduce a novel approach to counter antibiotic resistance by stabilizing G-quadruplex structures within the open reading frames of key resistance-associated genes (, and ). We synthesized , a bis-anthracene derivative, using Cu(I)-catalyzed azide-alkyne cycloaddition, which exhibited remarkable binding and stabilization of the G-quadruplex in the gene responsible for drug efflux. effectively permeated multidrug-resistant strains, leading to a substantial 12.5-fold reduction in ciprofloxacin resistance. Furthermore, downregulated gene expression, enhancing drug retention within bacterial cells. Remarkably, the G-quadruplex cloned into the pET28a(+) plasmid transformed into BL21 cells can template Cu-free bio-orthogonal synthesis of from its corresponding alkyne and azide fragments. This study presents a pioneering strategy to combat antibiotic resistance by genetically reducing drug efflux pump expression through G-quadruplex stabilization, offering promising avenues for addressing antibiotic resistance.
PubMed: 38694210
DOI: 10.1093/narmme/ugae005 -
Veterinary World Mar 2024Mill. () is an aromatic plant used in traditional medicine as an anti-inflammatory, anti-tussive, anti-rheumatic, and anti-diarrheal agent. This study aimed to evaluate...
BACKGROUND AND AIMS
Mill. () is an aromatic plant used in traditional medicine as an anti-inflammatory, anti-tussive, anti-rheumatic, and anti-diarrheal agent. This study aimed to evaluate the effect of Mill. on a var. -induced breast cancer model.
MATERIALS AND METHODS
We collected from the province of Julcán, La Libertad Region, Per, and prepared an ethanolic extract using pulverized leaves macerated in 96° ethanol for 72 h with magnetic stirring. In the evaluation of anticancer activity, four experimental groups with 10 female rats each were formed: Group I (Control-7,12-dimethylbenz[a]anthracene [DMBA]), which received DMBA (single dose) and physiological saline solution for 4 months, and Groups II, III, and IV, which received DMBA (single dose) and 200, 400, and 600 mg/kg/day of the ethanolic extract of , respectively, for 4 months.
RESULTS
The DMBA control group presented histological characteristics of ductal carcinoma with necrotic and inflammatory areas, whereas the extract group showed a decrease in tumor volume and recovery of the ductal duct.
CONCLUSION
Ethanol extract of leaves decreases tumor development in rats with induced breast cancer, and this effect is dose-dependent.
PubMed: 38680140
DOI: 10.14202/vetworld.2024.700-704 -
Dalton Transactions (Cambridge, England... May 2024Low-valent nickelates have recently been shown to be key intermediates in challenging cross-coupling reactions using aryl ethers as electrophiles. Key for the success of...
Low-valent nickelates have recently been shown to be key intermediates in challenging cross-coupling reactions using aryl ethers as electrophiles. Key for the success of these transformations is the activation of the substrate through π-coordination to the nickelate intermediate, however there is still limited knowledge about the fundamental structure and coordination chemistry of these heterobimetallic complexes. Herein, we report the synthesis, structures, and spectroscopic analysis of a diverse family of alkali-metal nickelates derived from phenyl-alkali-metal reagents and Ni(-CDT), where -CDT = ,,-1,5,9-cyclododecatriene. The co-complexation of PhLi with Ni(-CDT) was found to yield 1 : 1, 2 : 1 or 4 : 2 lithium nickelates depending on the stoichiometry and reaction conditions employed. The high lability of the -CDT ligand enables facile ligand exchange with an assorted series of organic π-acceptors, ranging from polyaromatic hydrocarbons to ketones, imines and nitriles. For anthracene and phenanthrene, a homologous series of Li, Na and K nickelates could be obtained, which lead to different structural motifs or degrees of aggregation in the solid-state spanning solvated monomers to complex polymeric arrangements. For π-extended systems such as perylene or coronene, competing single-electron-transfer to give the corresponding radical anions was observed, illustrating the highly reducing nature of the alkali-metal nickelates. X-ray crystallographic analysis and NMR spectroscopy of the phenyl-alkali-metal nickelates reveal extreme back-bonding from Ni(0) to the organic π-acceptors due to strong σ-donation from the carbanionic ligands.
PubMed: 38680126
DOI: 10.1039/d4dt00889h -
Spectrochimica Acta. Part A, Molecular... Aug 2024DNA is a key target for anticancer and antimicrobial drugs. Assessing the bioactivity of compounds involves in silico and instrumental studies to determine their...
DNA is a key target for anticancer and antimicrobial drugs. Assessing the bioactivity of compounds involves in silico and instrumental studies to determine their affinity for biomolecules like DNA. This study explores the potential of the switchSense technique in rapidly evaluating compound bioactivity towards DNA. By combining switchSense with computational methods and UV-Vis spectrophotometry, various bioactive compounds' interactions with DNA were analyzed. The objects of the study were: netropsin (as a model compound that binds in the helical groove), as well as derivatives of pyrazine (PTCA), sulfonamide (NbutylS), and anthraquinone (AQ-NetOH). Though no direct correlation was found between switchSense kinetics and binding modes, this research suggests the technique's broader utility in assessing new compounds' interactions with DNA. used as analytes whose interactions with DNA have not been yet fully described in the literature.
Topics: DNA; Spectrophotometry, Ultraviolet; Anthraquinones; Netropsin; Sulfonamides; Kinetics; Molecular Docking Simulation
PubMed: 38676984
DOI: 10.1016/j.saa.2024.124313 -
Life Sciences in Space Research May 2024The cortical anthraquinone yellow-orange pigment parietin is a secondary lichen substance providing UV-shielding properties that is produced by several lichen species....
The cortical anthraquinone yellow-orange pigment parietin is a secondary lichen substance providing UV-shielding properties that is produced by several lichen species. In our work, the secondary metabolite has been extracted from air-dried thalli of Xanthoria parietina. The aims of this study were to characterize parietin absorbance through UV-VIS spectrophotometry and with IR spectroscopy and to evaluate its photodegradability under UV radiation through in situ reflectance IR spectroscopy to understand to what extent the substance may have a photoprotective role. This allows us to relate parietin photo-degradability to the lichen UV tolerance in its natural terrestrial habitat and in extreme environments relevant for astrobiology such as Mars. Extracted crystals were UV irradiated for 5.59 h under N flux. After the UV irradiation, we assessed relevant degradations in the 1614, 1227, 1202, 1160 and 755 cm bands. However, in light of Xanthoria parietina survivability in extreme conditions such as space- and Mars-simulated ones, we highlight parietin UV photo-resistance and its relevance for astrobiology as photo-protective substance and possible bio-hint.
Topics: Ultraviolet Rays; Exobiology; Lichens; Emodin; Photolysis; Spectrophotometry, Infrared
PubMed: 38670647
DOI: 10.1016/j.lssr.2024.03.004 -
ACS Chemical Biology May 2024Angucyclines are an important group of microbial natural products that display tremendous chemical diversity. Classical angucyclines are composed of a tetracyclic...
Angucyclines are an important group of microbial natural products that display tremendous chemical diversity. Classical angucyclines are composed of a tetracyclic benz[]anthracene scaffold with one ring attached at an angular orientation. However, in atypical angucyclines, the polyaromatic aglycone is cleaved at A-, B-, or C-rings, leading to structural rearrangements and enabling further chemical variety. Here, we have elucidated the branching points in angucycline biosynthesis leading toward cleavage of the C-ring in lugdunomycin and thioangucycline biosynthesis. We showed that 12-hydroxylation and 6-ketoreduction of UWM6 are shared steps in classical and C-ring-cleaved angucycline pathways, although the bifunctional 6-ketoreductase LugOIIred harbors additional unique 1-ketoreductase activity. We identified formation of the key intermediate 8--methyltetrangomycin by the LugN methyltransferase as the branching point toward C-ring-cleaved angucyclines. The final common step in lugdunomycin and thioangucycline biosynthesis is quinone reduction, catalyzed by the 7-ketoreductases LugG and TacO, respectively. In turn, the committing step toward thioangucyclines is 12-ketoreduction catalyzed by TacA, for which no orthologous protein exists on the lugdunomycin pathway. Our results confirm that quinone reductions are early tailoring steps and, therefore, may be mechanistically important for subsequent C-ring cleavage. Finally, many of the tailoring enzymes harbored broad substrate promiscuity, which we utilized in combinatorial enzymatic syntheses to generate the angucyclines SM 196 A and hydranthomycin. We propose that enzyme promiscuity and the competition of many of the enzymes for the same substrates lead to a branching biosynthetic network and formation of numerous shunt products typical for angucyclines rather than a canonical linear metabolic pathway.
Topics: Streptomyces; Anthraquinones; Biological Products; Hydroxylation; Angucyclines and Angucyclinones
PubMed: 38668630
DOI: 10.1021/acschembio.4c00082 -
Organometallics Apr 2024The bimetallic species, [{SiN}MgNa] [{SiN} = {CHSiMeN(Dipp)}; (Dipp = 2,6--PrCH)], is shown to be a potent reducing agent, able to effect one- or two-electron reduction...
The bimetallic species, [{SiN}MgNa] [{SiN} = {CHSiMeN(Dipp)}; (Dipp = 2,6--PrCH)], is shown to be a potent reducing agent, able to effect one- or two-electron reduction of either dioxygen, TEMPO, anthracene, benzophenone, or diphenylacetylene. In most cases, the bimetallic reaction products imply that the dissimilar alkaline metal centers react with a level of cooperativity. EPR analysis of the benzophenone-derived reaction and the concurrent isolation of [{SiN}Mg(OCPh)], however, illustrate that treatment with such reducible, but -basic, species can also result in reactivity in which the metals provide independent reaction products. The notable -stereochemistry of the diphenylacetylene reduction product prompted a computational investigation of the PhC≡CPh addition. This analysis invokes a series of elementary steps that necessitate ring-opening via Mg → Na amido group migration of the SiN ligand, providing insight into the previously observed lability of the bidentate dianion and its consequent proclivity toward macrocyclization.
PubMed: 38665773
DOI: 10.1021/acs.organomet.4c00076 -
Heliyon Apr 2024This study aimed at analysing the effects of coconut ( L.) kernel extract (CKE) on oxidative stress, C-MYC proto-oncogene, and tumour formation in a skin cancer model....
This study aimed at analysing the effects of coconut ( L.) kernel extract (CKE) on oxidative stress, C-MYC proto-oncogene, and tumour formation in a skin cancer model. Tumorigenesis was induced by dimethylbenz[a]anthracene (DMBA)/12--tetradecanoylphorbol-13-acetate (TPA). In vitro antioxidant activity of CKE was assessed using 2, 2-diphenyl-1-picrylhydrazyl (DPPH), hydrogen peroxide (HO), total phenolic and flavonoid content assays. CKE showed a higher antioxidant activity then ascorbic acid (*P < 0.05, ****P < 0.0001). HPLC and NMR study of the CKE revealed the presence of lauric acid (LA). Following the characterization of CKE, mice were randomly assigned to receive DMBA/TPA Induction and CKE treatment at different doses (50, 100, and 200 mg/kg) of body weight. LA 100 mg/kg of body weight used as standard. Significantly, the CKE200 and control groups' mice did not develop tumors; however, the CKE100 and CKE50 treated groups did develop tumors less frequently than the DMBA/TPA-treated mice. Histopathological analysis revealed that the epidermal layer in DMBA-induced mice was thicker and had squamous pearls along with a hyperplasia/dysplasia lesion, indicating skin squamous cell carcinoma (SCC), whereas the epidermal layers in CKE200-treated and control mice were normal. Additionally, the CKE treatment demonstrated a significant stimulatory effect on the activities of reactive oxygen species (ROS), glutathione (GSH), catalase (CAT), and superoxide dismutase (SOD), as well as an inhibitory effect on lipid peroxidase (*P < 0.05, **P < 0.01, ***P < 0.001, ****P < 0.0001) and c-MYC protein expression (*P < 0.05, **P < 0.01, ***P < 0.001, ****P < 0.0001). In conclusion, CKE prevents the growth of tumors on mouse skin by reducing oxidative stress and suppressing c-MYC overexpression brought on by DMBA/TPA induction. This makes it an effective dietary antioxidant with anti-tumor properties.
PubMed: 38665592
DOI: 10.1016/j.heliyon.2024.e29385 -
The Science of the Total Environment Jun 2024Benz[a]anthracene (BaA), a prevalent environmental contaminant within the polycyclic aromatic hydrocarbon class, poses risks to both human health and aquatic ecosystems....
Benz[a]anthracene (BaA), a prevalent environmental contaminant within the polycyclic aromatic hydrocarbon class, poses risks to both human health and aquatic ecosystems. The impact of BaA on neural development and subsequent social behavior patterns remains inadequately explored. In this investigation, we employed the zebrafish as a model to examine the persisting effects of BaA exposure on social behaviors across various developmental stages, from larvae, juveniles to adults, following embryonic exposure. Our findings indicate that BaA exposure during embryogenesis yields lasting neurobehavioral deficits into adulthood. Proteomic analysis highlights that BaA may impair neuro-immune crosstalk in zebrafish larvae. Remarkably, our proteomic data also hint at the activation of the aryl hydrocarbon receptor (AHR) and cytochrome P450 1A (CYP1A) pathway by BaA, leading to the hypothesis that this pathway may be implicated in the disruption of neuro-immune interactions, contributing to observable behavioral disruptions. In summary, our findings suggest that early exposure to BaA disrupts social behaviors, such as social ability and shoaling behaviors, from the larval stage through to maturity in zebrafish, potentially through the detrimental effects on neuro-immune processes mediated by the AHR-CYP1A pathway.
Topics: Animals; Zebrafish; Water Pollutants, Chemical; Benz(a)Anthracenes; Social Behavior; Behavior, Animal; Receptors, Aryl Hydrocarbon; Embryo, Nonmammalian
PubMed: 38657801
DOI: 10.1016/j.scitotenv.2024.172615