Recent developments and comparison of transformation strategies for organic halides to aldehydes and ketones

Molecular Diversity - Aldehydes and ketones are parts of millions of compounds and are important classes of chemicals which serve as important precursors for the synthesis of library of compounds....     

Uncommon Terpenoids from Salvia Species: Chemistry,Biosynthesis and Biological Activities

The search for new bioactive compounds from plant sources has been and continues to be one of the most important fields of research in drug discovery. However, Natural Products research has continuously evolved, and more and more has gained a multidisciplinary character. Despite new developments of methodologies and concepts, one intriguing aspect still persists, i.e., different species belonging to the same genus can produce different secondary metabolites, whereas taxonomically different genera can produce the same compounds. The genus Salvia L. (Family Lamiaceae) comprises myriad distinct medicinal herbs used in traditional medicine worldwide that show different pharmacological activities due to the presence of a variety of interesting specialized metabolites, including mono-, sesqui-, di-, sester-, tri-, tetra-, and higher terpenoids as well as phenylpropanoids, phenolic acid derivatives, lignans, flavonoids, and alkaloids. We herein summarize the research progress on some uncommon terpenoids, isolated from members of the genus Salvia, which are well recognized for their potential pharmacological activities. This review also provides a current knowledge on the biosynthesis and occurrence of some interesting phytochemicals from Salvia species, viz. C₂₃-terpenoids, sesterterpenoids (C₂₅), dammarane triterpenoids (C₃₀), and uncommon triterpenoids (C₂₀+C₁₀). The study was carried out by searching various scientific databases, including Elsevier, ACS publications, Taylor and Francis, Wiley Online Library, MDPI, Springer, Thieme, and ProQuest. Therefore, 106 uncommon terpenoids were identified and summarized. Some of these compounds possessed a variety of pharmacological properties, such as antibacterial, antiviral, antiparasitic, cytotoxic and tubulin tyrosine ligase inhibitory activities. Due to the lack of pharmacological information for the presented compounds gathered from previous studies, biological investigation of these compounds should be reinvestigated.     

Isolation,Characterization and In Silico Studies of Secondary Metabolites from the Whole Plant of Polygala inexpectata Peşmen & Erik

Polygala species are frequently used worldwide in the treatment of various diseases, such as inflammatory and autoimmune disorders as well as metabolic and neurodegenerative diseases, due to the large number of secondary metabolites they contain. The present study was performed on Polygala inexpectata, which is a narrow endemic species for the flora of Turkey, and resulted in the isolation of nine known compounds, 6,3′-disinapoyl-sucrose (1), 6-O-sinapoyl,3′-O-trimethoxy-cinnamoyl-sucrose (tenuifoliside C) (2), 3′-O-(O-methyl-feruloyl)-sucrose (3), 3′-O-(sinapoyl)-sucrose (4), 3′-O-trimethoxy-cinnamoyl-sucrose (glomeratose) (5), 3′-O-feruloyl-sucrose (sibiricose A5) (6), sinapyl alcohol 4-O-glucoside (syringin or eleutheroside B) (7), liriodendrin (8), and 7,4′-di-O-methylquercetin-3-O-β-rutinoside (ombuin 3-O-rutinoside or ombuoside) (9). The structures of the compounds were determined by the spectroscopic methods including 1D-NMR (¹H NMR, ¹³C NMR, DEPT-135), 2D-NMR (COSY, NOESY, HSQC, HMBC), and HRMS. The isolated compounds were shown in an in silico setting to be accommodated well within the inhibitor-binding pockets of myeloperoxidase and inducible nitric oxide synthase and anchored mainly through hydrogen-bonding interactions and π-effects. It is therefore plausible to suggest that the previously established anti-inflammatory properties of some Polygala-derived phytochemicals may be due, in part, to the modulation of pro-inflammatory enzyme activities.     

Characterisation of Flavour Attributes in Egg White Protein Using HS-GC-IMS Combined with E-Nose and E-Tongue: Effect of High-Voltage Cold Plasma Treatment Time

Egg white protein (EWP) is susceptible to denaturation and coagulation when exposed to high temperatures, adversely affecting its flavour, thereby influencing consumers’ decisions. Here, we employ high-voltage cold plasma (HVCP) as a novel nonthermal technique to investigate its influence on the EWP’s flavour attributes using E-nose, E-tongue, and headspace gas-chromatography-ion-mobilisation spectrometry (HS-GC-IMS) due to their rapidness and high sensitivity in identifying flavour fingerprints in foods. The EWP was investigated at 0, 60, 120, 180, 240, and 300 s of HVCP treatment time. The results revealed that HVCP significantly influences the odour and taste attributes of the EWP across all treatments, with a more significant influence at 60 and 120 s of HVCP treatment. Principal component analyses of the E-nose and E-tongue clearly distinguish the odour and taste sensors’ responses. The HS-GC-IMS analysis identified 65 volatile compounds across the treatments. The volatile compounds’ concentrations increased as the HVCP treatment time was increased from 0 to 300 s. The significant compounds contributing to EWP characterisation include heptanal, ethylbenzene, ethanol, acetic acid, nonanal, heptacosane, 5-octadecanal, decanal, p-xylene, and octanal. Thus, this study shows that HVCP could be utilised to modify and improve the EWP flavour attributes.     

Dielectric Properties of Colossal-Dielectric-Constant Na1/2La1/2Cu3Ti4O12 Ceramics Prepared by Spark Plasma Sintering

In the current study, we report on the dielectric behavior of colossal-dielectric-constant Na_1/2La_1/2Cu₃Ti₄O₁₂ (NLCTO) ceramics prepared by mechanochemical synthesis and spark plasma sintering (SPS) at 850 °C, 900 °C, and 925 °C for 10 min. X-ray powder diffraction analysis showed that all the ceramics have a cubic phase. Scanning electron microscope observations revealed an increase in the average grain size from 175 to 300 nm with an increase in the sintering temperature. SPS NLCTO ceramics showed a room-temperature colossal dielectric constant (>10³) and a comparatively high dielectric loss (>0.1) over most of the studied frequency range (1 Hz–40 MHz). Two relaxation peaks were observed in the spectra of the electrical modulus and attributed to the response of grain and grain boundary. According to the Nyquist plots of complex impedance, the SPS NLCTO ceramics have semiconductor grains surrounded by electrically resistive grain boundaries. The colossal dielectric constant of SPS NLCTO ceramics was attributed to the internal barrier layer capacitance (IBLC) effect. The high dielectric loss is thought to be due to the low resistivity of the grain boundary of SPS NLCTO.     

Fumigant Activity of Bacterial Volatile Organic Compounds against the Nematodes Caenorhabditis elegans and Meloidogyne incognita

Plant-parasitic nematodes infect a diversity of crops, resulting in severe economic losses in agriculture. Microbial volatile organic compounds (VOCs) are potential agents to control plant-parasitic nematodes and other pests. In this study, VOCs emitted by a dozen bacterial strains were analyzed using solid-phase microextraction followed by gas chromatography–mass spectrometry. Fumigant toxicity of selected VOCs, including dimethyl disulfide (DMDS), 2-butanone, 2-pentanone, 2-nonanone, 2-undecanone, anisole, 2,5-dimethylfuran, glyoxylic acid, and S-methyl thioacetate (MTA) was then tested against Caenorhabditis elegans. DMDS and MTA exhibited much stronger fumigant toxicity than the others. Probit analysis suggested that the values of LC₅₀ were 8.57 and 1.43 μg/cm³ air for DMDS and MTA, respectively. MTA also showed stronger fumigant toxicity than DMDS against the root-knot nematode Meloidogyne incognita, suggesting the application potential of MTA.     

Effect of Erosive Agents on Surface Characteristics of Nano-Fluorapatite Ceramic: An In-Vitro Study

Erosive beverages cause dissolution of natural teeth and intra-oral restorations, resulting in surface characteristic changes, particularly roughness and degradation. The purpose of this study was to evaluate the surface roughness and topography of a dental ceramic following immersion in locally available erosive solutions. A total of 160 disc specimens of a nano-fluorapatite type ceramic (12 mm diameter and 2 mm thickness) were fabricated and equally distributed into two groups (n = 80) and then evenly distributed among the following five testing groups (n = 16): lemon juice, citrate buffer solution, 4% acetic acid, soft cola drink, and distilled water which served as a control. The surface roughness (Ra) and topography were evaluated using a profilometer and scanning electron microscope at baseline, 24 h, 96 h, and 168 h respectively. Data were analyzed using ANOVA and Tukey’s multiple comparisons (p ≤ 0.05). Surface changes were observed upon exposure to all acidic beverages except distilled water. Amongst all immersion media, 4% acetic acid produced the most severe surface roughness across all time periods (i.e., baseline, 24 h, 96 h, and 168 h). A statistically significant difference in the surface roughness values between all immersion media and across all four time intervals was observed. Erosive agents had a negative effect on the surface roughness and topography of the tested ceramic. The surface roughness increased with increased storage time intervals.     

Swelling behavior, mechanical properties and network parameters of pH- and temperature-sensitive hydrogels of poly((2-dimethyl amino) ethyl methacrylate-co-butyl methacrylate)

In this study, swelling behavior and mechanical properties of polyelectrolyte cationic hydrogels of poly((2-dimethylamino) ethyl methacrylate) (PDMAEMA), and poly((2-dimethylamino) ethyl methacrylate-co-butyl methacrylate) (P(DMAEMA-co-BMA)), were investigated. Hydrogels were prepared by free-radical solution copolymerization of DMAEMA and BMA using ethylene glycol dimethacrylate (EGDMA) as the crosslinking agent. Compression-strain measurements were used to analyze the mechanical properties of the hydrogels. It was found that increasing the amount of BMA comonomer in the gel structure increases the compression modulus of the material. The results of mechanical measurements were used to characterize the network structure of the hydrogels, namely the effective crosslinking density (. It was found that exceeds the theoretical crosslinking density (ν_t) calculated from the initial amount of EGDMA used for hydrogel synthesis. These hydrogels demonstrated dual sensitivity to both pH and temperature. It was shown that the pH-sensitive or temperature-sensitive phase transition behavior of the gels can be changed by changing the temperature or pH of the swelling medium at constant hydrogel composition. Increasing the temperature decreased the transition pH of the pH-sensitive phase transition. On the other hand, increasing the pH of the surrounding medium decreased the transition temperature of the temperature-sensitive phase transition. Incorporation of BMA in the gel structure has a significant effect on the transition point of the gel. Increasing the BMA content reduced the transition pH and temperature of the pH- and temperature-sensitive phase transition, respectively. The similar effect of increasing temperature or BMA content can be explained by the role of hydrophobicity in the phase transition behavior of hydrogels. Finally, the results of equilibrium swelling and compression-strain measurements were used to calculate the polymer-solvent interaction parameters of these hydrogels using the Flory-Rehner equation of equilibrium swelling.