Search Results (9)

The current research investigation aimed to screen the bioactive compounds in the latex of Calotropis gigantea L. and evaluate its antibacterial and antioxidant properties towards clinical applications. The chemical moiety and volatile compounds of the latex of C. gigantea were detected by UV–Vis spectroscopy, FT-IR, and GC–MS analysis. The antibacterial activity was assessed using wound-inducing pathogens by well diffusion method. In addition, the antioxidant properties were determined through DPPH, ABTS, and FRAP methods. The functional groups of O–H stretch, diketonic bonds, C–O, C–N, O–C bonds, and consecutive C–H bonds were observed in the latex of C. gigantea. The major bioactive compounds were 5H-3,5a-Epoxynaphth[2,1-c]oxepin, Cholesta-5-en-3-ol, 24-propylidene-, dodecane, Lup-20(29)-Ene-3,28-Diol, (3.Beta)-, Veridiflorol, and Lanosta-8,24-dien-3-ol, acetatate, (3.beta.). Oxazole derivatives were found in the latex of C. gigantea, proved by GC–MS analysis. The aqueous-mixed latex exhibited maximum antioxidant activity as compared to methanol-mixed latex. Aqueous-mixed latex and methanol-mixed latex inhibited the growth of K. pneumoniae, P. mirabilis, S. pyogenes, Micrococcus spp., S. aureus, P. aeruginosa, and E. coli. The present study clearly reveals that latex of C. gigantea has rich bioactive compounds with significant biological activities, and can be employed to produce a novel herbal formulation against wound-inducing pathogens. Full article

Natural clay minerals are among the most versatile materials used in the biomedical field. Palygorskite has found various applications in this field, from the treatment of diarrheal diseases in the past to materials with antibacterial properties and platforms carrying bioactive compounds used in the treatment of diseases, cosmetic and healthcare products in the present. In this study, a possible delivery method of some bioactive asymmetric β-diketonic compounds is presented. Palygorskite modified with amphionic groups (P) and copper ions (PCu) was used as a platform to load bioactive curcumin derivatives (1 and 2). By varying the copper ions, the amounts of charged active compounds were monitored. Studies have shown that the hybrid materials resulting from the loading of 1 and 2 compounds on palygorskite with 30% copper ions (PCu₃₀) can be used as delivery methods for these asymmetric curcumin derivatives, while palygorskite with 50% copper ions(PCu₅₀) loaded with the same type of bioactive compounds has antibacterial properties. Full article

As potential precursors for the synthesis of fluoroperovskites, a family of heavy alkali metal (M^I = K, Cs) fluorinated β-diketonates were prepared and characterized by elemental analysis, IR, and powder-XRD. The crystal structures of the new six complexes, M^I(β-dik^F)(H₂O)_X, X = 0 or 1, were also determined. The structural diversity of this poorly explored class of complexes was discussed, including the preferred types of cation polyhedra and the ligand coordination modes, and the thermal properties of the metal β-diketonates were studied by TG–DTA in an inert (He) atmosphere. The data obtained allowed us to reveal the effect of the metal cation and the terminal substituent on the structural and thermal features of this family of complexes. Full article

The reaction of [Ln(btfa)₃(H₂O)₂] (btfa⁻ = 4,4,4-trifluoro-1-phenyl-1,3-butanedionate) with additional 4,4,4-trifluoro-1-phenyl-1,3-butanedione (Hbtfa) and acridine (Acr) in ethanol allows the isolation of the mononuclear compounds HAcr[Nd(btfa)₄]·EtOH, (1) and HAcr[Ln(btfa)₄], Ln = Dy (2) and Yb (3); HAcr⁺ = acridinium cation. Magnetic measurements indicate that complexes 1–3 show field-induced single-ion magnet behavior with anisotropy energy barriers and preexponential factors of U_eff = 20.7 cm⁻¹, τ₀ = 24.5 × 10⁻⁸ s; U_eff = 40.5 cm⁻¹, τ₀ = 8.6 × 10⁻¹⁰ s and U_eff = 22.7 cm⁻¹, τ₀ = 8.4 × 10⁻⁸ s, for 1–3 respectively. The solid-state luminescence emission in the NIR region shows efficient energy transfer from the 4,4,4-trifluoro-1-phenyl-1,3-butanedionate ligands to the central Ln³⁺ ion in the case of compounds 1 and 3. Full article

The possibility of obtaining volatile polynuclear heterometallic complexes containing lanthanides and transition metals bound by methoxy-β-diketonates was studied. New compounds were prepared by cocrystallization of monometallic complexes from organic solvents. Ln(tmhd)₃ were used as initial monometallic complexes (Ln = La, Pr, Sm, Gd, Tb, Dy, Lu; tmhd = 2,2,6,6-tetramethylheptane-3,5-dionate) in combination with TML₂ in various ratios (TM = Cu, Co, Ni, Mn; L: L¹ = 1,1,1-trifluoro-5,5-dimethoxypentane-2,4-dionate, L² = 1,1,1-trifluoro-5,5-dimethoxy-hexane-2,4-dionate, L³ = 1,1,1-trifluoro-5-methoxy-5-methylhexane-2,4-dionate). Heterometallic complexes of the composition [(LnL₂tmhd)₂TM(tmhd)₂] were isolated for light lanthanides Ln= La, Pr, Sm, Gd, and L= L¹ or L². By single crystal XRD, it has been established that heterometallic compounds containing La, Pr, Cu, Co, and Ni are isostructural linear coordination polymers of alternating mononuclear transition metal complexes and binuclear heteroleptic lanthanide complexes, connected by donor–acceptor interactions between oxygen atoms of the methoxy groups and transition metal atoms. A comparison of powder XRD patterns has shown that all heterometallic complexes obtained are isostructural. Havier lanthanides Ln = Tb, Dy, Lu did not form heterometallics. Instead, homometallic complexes Ln(L³)₃ were identified for Ln = Dy, Lu as well as for Ln = La. The thermal properties of the complexes were investigated by TG-DTA and vacuum sublimation tests. The heterometallic complexes were found to be not volatile and decomposed under heating to produce inorganic composites of TM oxides and Ln fluorides. In contrast, Ln(L³)₃ is volatile and may be sublimed in a vacuum. Results of magnetic measurements are discussed for several heterometallic and homometallic complexes. Full article

The biotransformation of hop aroma, particularly by the cysteine S-conjugate beta-lyase enzyme (CSL), has been a recent topic of tremendous interest among brewing scientists and within the brewing community. During a process often referred to as biotransformation, yeast-encoded enzymes convert flavorless precursor molecules found in barley and hops into volatile thiols that impart a variety of desirable flavors and aromas in beer. Two volatile thiols of particular interest are 3-mercaptohexan-1-ol (3MH) and its acetate ester, 3-mercaptohexyl acetate (3MHA), which impart guava and passionfruit flavors, respectively. In this study, a parental Saccharomyces cerevisiae brewing strain that displayed low thiol biotransformation activity was genetically manipulated (GM) to substantially increase its thiol biotransformation potential. Construction of this GM strain involved integration of a gene encoding a highly active CSL enzyme that converts thiol precursors into the volatile thiol, 3MH. Three additional strains were subsequently developed, each of which paired CSL expression with expression of an alcohol acyltransferase (AAT) gene. It was hypothesized that expression of an AAT in conjunction with CSL would increase production of 3MHA. Fermentation performance, sensory characteristics, and 3MH/3MHA production were evaluated for these four GM strains and their non-GM parent in 1.5hL fermentations using 100% barley malt wort hopped at low levels with Cascade hops. No significant deviations in fermentation performance (time to attenuation, final gravity, alcohol content, wort fermentability) or finished beer chemistry were observed between the GM strains and the parent strain with the exception of the speed of vicinal diketones reduction post-fermentation, which was quicker for the GM strains. The GM strains produced beer that had up to 73-fold and 8-fold higher 3MH and 3MHA concentrations than the parent strain, achieving concentrations that were up to 79-fold greater than their sensory detection thresholds. The beers were described as intensely tropical and fruity, and were associated with guava, passionfruit, mango, pineapple and sweaty aromas. These experiments demonstrate the potential of genetic modification to dramatically enhance yeast biotransformation ability without creating off flavors or affecting fermentation performance. Full article

Four new Pr(III) mononuclear complexes of formula [Pr(ntfa)₃(MeOH)₂] (1), [Pr(ntfa)₃(bipy)₂] (2), [Pr(ntfa)₃(4,4′-Mt₂bipy)] (3) and [Pr(ntfa)₃(5,5′-Me₂bipy)] (4), where ntfa = 4,4,4-trifuoro-1-(naphthalen-2-yl)butane-1,3-dionato(1-), 5,5′-Me2bipy = 5,5′-dimethyl-2,2′-dipyridine, 4,4′-Mt2bipy = 4,4′-dimethoxy-2,2′-dipyridine, have been synthesized and structurally characterized. The complexes display the coordination numbers 8 for 1, 3 and 4, and 10 for 2. Magnetic measurements of complexes 1–4 were consistent with a magnetically uncoupled Pr³⁺ ion in the ³H₄ ground state. The solid state luminescence studies showed that the ancillary chelating bipyridyl ligands in the 2–4 complexes greatly enhance the luminescence emission in the visible and NIR regions through efficient energy transfer from the ligands to the central Pr³⁺ ion; behaving as “antenna” ligands. Full article

Highly luminescent europium complexes modified mesoporous silica particles (MSP) were synthesized as an imaging probes for both in-vitro diagnostic and in-vivo cellular tracking agents. Europium β-diketone chelates (4,4,4-trifluoro-l-(2-thienyl)-l,3-butanedione) trioctylphosphine europium (III) (Eu(TTA)₃(P(Oct)₃)₃) were incorporated inside the nanocavities that existed in hierarchical MSP (Eu@MSP). The MSP and Eu@MSP on mouse bone marrow-derived macrophages (BMDMs) did not show any toxic effect. The MSP and Eu@MSP in the BMDMs were found at cytoplasm without any degradation and immunogenicity. However, both pro- and anti-inflammatory cytokines of macrophages were significantly increased when lipopolysaccharide and a high concentration (100 μg/mL) of MSP and Eu@MSP were treated simultaneously. Full article

A series of new ferrocene- and ruthenocene-containing iridium(III) heteroleptic complexes of the type [(ppy)₂Ir(RCOCHCOR′)], with ppy = 2-pyridylphenyl, R = Fc = Fe^II(η⁵-C₅H₄)(η⁵-C₅H₅) and R′ = CH₃ (1) or Fc (2), as well as R = Rc = Ru^II(η⁵-C₅H₄)(η⁵-C₅H₅) and R′ = CH₃ (3), Rc (4) or Fc (5) was synthesized via the reaction of appropriate metallocene-containing β-diketonato ligands with [(ppy)₂(μ-Cl)Ir]₂. The single crystal structure of 3 (monoclinic, P2₁/n, Z = 4) is described. Complexes 1–5 absorb light strongly in the region 280−480 nm the metallocenyl β-diketonato substituents quench phosphorescence in 1–5. Cyclic and square wave voltammetric studies in CH₂Cl₂/[N(ⁿBu)₄][B(C₆F₅)₄] allowed observation of a reversible Ir^III/IV redox couple as well as well-resolved ferrocenyl (Fc) and ruthenocenyl (Rc) one-electron transfer steps in 1−5. The sequence of redox events is in the order Fc oxidation, then Ir^III oxidation and finally ruthenocene oxidation, all in one-electron transfer steps. Generation of Ir^IV quenched phosphorescence in 6, [(ppy)₂Ir(H₃CCOCHCOCH₃)]. This study made it possible to predict the Ir^III/IV formal reduction potential from Gordy scale group electronegativities, χ_R and/or Σχ_R′ of β-diketonato pendent side groups as well as from DFT-calculated energies of the highest occupied molecular orbital of the species involved in the Ir^III/IV oxidation at a 98% accuracy level. Full article