New Halogenated Compounds from Halimeda macroloba Seaweed with Potential Inhibitory Activity against Malaria

Malaria is one of the most important infectious diseases worldwide. The causative of the most severe forms of malaria, Plasmodium falciparum, has developed resistances against all the available antimalarial drugs. In the present study, the phytochemical investigation of the green seaweed Halimeda macroloba has afforded two new compounds 1–2, along with 4 known ones 3–6. The structures of the compounds had been confirmed using 1& 2D-NMR and HRESIMS analyses. Extensive machine-learning-supported virtual-screening suggested cytochrome-C enzyme as a potential target for compound 2. Docking, absolute-binding-free-energy (ΔG_binding) and molecular-dynamics-simulation (MDS) of compound 2 revealed the strong binding interaction of this compound with cytochrome-C. In vitro testing for crude extract and isolated compounds revealed the potential in vitro inhibitory activity of both extract and compound 2 against P. falciparum. The crude extract was able to inhibit the parasite growth with an IC₅₀ value of 1.8 ± 0.35 µg/mL. Compound 2 also showed good inhibitory activity with an IC₅₀ value of 3.2 ± 0.23 µg/mL. Meanwhile, compound 6 showed moderate inhibitory activity with an IC₅₀ value of 19.3 ± 0.51 µg/mL. Accordingly, the scaffold of compound 2 can be considered as a good lead compound for the future development of new antimalarial agents.     

Kinetics of substitution at bis-cyclopentadienylvanadium dichloride

Rate constants are reported for substitution at vanadium(IV) in bis-cyclopentadienylvanadium dichloride by a range of anionic and uncharged nucleophiles in acetonitrile solution. Rate constants have been determined for replacement of the first and of the second chloride. The reactivity of V(cp)₂Cl₂ is compared with that of Ti(cp)₂Cl₂. © 1997 John Wiley & Sons, Inc. Int J Chem Kinet 29: 835–838, 1997     

Hepatoprotective Effects of Bioflavonoid Luteolin Using Self-Nanoemulsifying Drug Delivery System

Luteolin (LUT) is a natural pharmaceutical compound that is weakly water soluble and has low bioavailability when taken orally. As a result, the goal of this research was to create self-nanoemulsifying drug delivery systems (SNEDDS) for LUT in an attempt to improve its in vitro dissolution and hepatoprotective effects, resulting in increased oral bioavailability. Using the aqueous phase titration approach and the creation of pseudo-ternary phase diagrams with Capryol-PGMC (oil phase), Tween-80 (surfactant), and Transcutol-HP (co-emulsifier), various SNEDDS of LUT were generated. SNEDDS were assessed for droplet size, polydispersity index (PDI), zeta potential (ZP), refractive index (RI), and percent of transmittance (percent T) after undergoing several thermodynamic stability and self-nanoemulsification experiments. When compared to LUT suspension, the developed SNEDDS revealed considerable LUT release from all SNEDDS. Droplet size was 40 nm, PDI was <0.3, ZP was −30.58 mV, RI was 1.40, percent T was >98 percent, and drug release profile was >96 percent in optimized SNEDDS of LUT. For in vivo hepatoprotective testing in rats, optimized SNEDDS was chosen. When compared to LUT suspension, hepatoprotective tests showed that optimized LUT SNEDDS had a substantial hepatoprotective impact. The findings of this investigation suggested that SNEDDS could improve bioflavonoid LUT dissolution rate and therapeutic efficacy.     

Structure of a precursor in the synthesis of low-spin iron(II) complexes of Schiff base ligands

Crystals obtained in the course of preparing the tris-Schiff base iron(II) complex from 2-acetylpyridine and benzylamine have been shown by an X-ray diffraction structure determination to contain an iron(II) complex cation containing two molecules of the target Schiff base and one molecule of 2-acetylpyridine coordinated to the metal. The mechanistic implications of this fact are discussed.     

Thermal degradation and evolved gas analysis of thiourea-formaldehyde resin (TFR) during pyrolysis and combustion

Thiourea formaldehyde resin (TFR) has been synthesized by condensation of thiourea and formaldehyde in acidic medium and its thermal degradation has been investigated using TG-FTIR-MS technique during pyrolysis and combustion. The results revealed that the thermal decomposition of TFR occurs in three steps assigned to drying of the sample, fast thermal decomposition of polymers, and further cracking. The similar TG and DTG characteristics were found for the first two stages during pyrolysis and combustion. The combustion process was almost finished at 680?°C, while during pyrolysis a total mass loss of 93 wt% is found at 950?°C. The release of volatile products during pyrolysis are NH₃, CS₂, CO, HCN, HNCS, and NH₂CN. The main products in the second stage are NH₃ CO₂, CS₂, SO₂, and H₂O during combustion. In the next stage, the combustion products mentioned above keep on increasing, but some new volatiles such as HCN, COS etc., are identified. Among the above volatiles, CO₂ is the dominant gaseous product in the whole combustion process. It is found that the thermal degradation during pyrolysis of TFR produced more hazardous gases like HCN, NH₃, and CO when compared with combustion in similar conditions.     

Interaction of double-stranded DNA inside single-walled carbon nanotubes

Deoxyribonucleic acid (DNA) is the genetic material for all living organisms, and as a nanostructure offers the means to create novel nanoscale devices. In this paper, we investigate the interaction of deoxyribonucleic acid inside single-walled carbon nanotubes. Using classical applied mathematical modeling, we derive explicit analytical expressions for the encapsulation of DNA inside single-walled carbon nanotubes. We adopt the 6–12 Lennard–Jones potential function together with the continuous approach to determine the preferred minimum energy position of the dsDNA molecule inside a single-walled carbon nanotube, so as to predict its location with reference to the cross-section of the carbon nanotube. An analytical expression is obtained in terms of hypergeometric functions which provides a computationally rapid procedure to determine critical numerical values. We observe that the double-strand DNA can be encapsulated inside a single-walled carbon nanotube with a radius larger than 12.30 ?, and we show that the optimal single-walled carbon nanotube to enclose a double-stranded DNA has radius 12.8 ?.     

Reactivity and solvatochromism of pentacyanoferrate(II) complexes in diol–water mixtures

Rate constants are reported for substitution at the pentacyanoferrate(II) ions [Fe(CN)5L]3−, where L=3,5-dimethylpyridine or 3-cyanopyridine, in binary aqueous mixed solvents containing up to 60vol% 1,2-ethanediol, 1,2-butanediol, methanol or ethanol. Trends for diol-containing mixtures are compared with those for monohydroxylic alcohols, and the reactivity pattern for these complexes is compared with those established earlier for base hydrolysis of tris(1,10-phenanthroline)iron(II) and for the aquation of cis-dichloro-bis- (1,2-ethanediamine)cobalt(III). The solvatochromic behaviour of several pentacyanoferrate(II) ions has been established in binary aqueous mixtures containing 1,2-ethanediol, 1,2-butanediol, 1,4-butanediol and 1,2-pentanediol. A correlation between reactivity and solvatochromism is presented. This revised version was published online in June 2006 with corrections to the Cover Date.     

Optical Solitons in Fiber Bragg Gratings with Polynomial Law Nonlinearity and Cubic–Quartic Dispersive Reflectivity

Optics and Spectroscopy - Optical solitons with fiber Bragg gratings and polynomial law of nonlinear refractive index are addressed in the paper. The auxiliary equation approach together with an...     

DyF3: An Efficient Electrocatalyst for N2 Fixation to NH3 under Ambient Conditions

NH₃ synthesis by the Haber–Bosch method is regarded as the dominant method in industry. Such a process is energy‐intensive, accompanied by a large amount of CO₂ emission. Electrocatalytic N₂ reduction is a sustainable avenue for NH₃ production at ambient conditions. However, it needs a catalyst to boost the N₂ reduction reaction. Here, we demonstrate that DyF₃ is an efficient electrocatalyst. In 0.1 m Na₂SO₄, DyF₃ attains a large NH₃ yield of 10.9 μg h^?1 mg^?1_cat. at ?0.45 V vs. the reversible hydrogen electrode, with the corresponding Faradaic efficiency of 8.8 %. Furthermore, this catalyst exhibits high electrochemical stability.     

Advances in Fungal Phenaloenones—Natural Metabolites with Great Promise: Biosynthesis,Bioactivities, and an In Silico Evaluation of Their Potential as Human Glucose Transporter 1 Inhibitors

Phenaloenones are structurally unique aromatic polyketides that have been reported in both microbial and plant sources. They possess a hydroxy perinaphthenone three-fused-ring system and exhibit diverse bioactivities, such as cytotoxic, antimicrobial, antioxidant, and anti-HIV properties, and tyrosinase, α-glucosidase, lipase, AchE (acetylcholinesterase), indoleamine 2,3-dioxygenase 1, angiotensin-I-converting enzyme, and tyrosine phosphatase inhibition. Moreover, they have a rich nucleophilic nucleus that has inspired many chemists and biologists to synthesize more of these related derivatives. The current review provides an overview of the reported phenalenones with a fungal origin, including their structures, sources, biosynthesis, and bioactivities. Moreover, more than 135 metabolites have been listed, and 71 references have been cited. SuperPred, an artificial intelligence (AI) webserver, was used to predict the potential targets for selected phenalenones. Among these targets, we chose human glucose transporter 1 (hGLUT1) for an extensive in silico study, as it shows high probability and model accuracy. Among them, aspergillussanones C (60) and G (60) possessed the highest negative docking scores of −15.082 and −14.829 kcal/mol, respectively, compared to the native inhibitor of 5RE (score: −11.206 kcal/mol). The MD (molecular dynamics) simulation revealed their stability in complexes with GLUT1 at 100 ns. The virtual screening study results open up a new therapeutic approach by using some phenalenones as hGLUT1 inhibitors, which might be a potential target for cancer therapy.