Palladium‐Catalyzed Chemoselective Allylic Substitution,Suzuki–Miyaura Cross‐Coupling,and Allene Formation of Bifunctional 2‐B(pin)‐Substituted Allylic Acetate Derivatives

A formidable challenge at the forefront of organic synthesis is the control of chemoselectivity to enable the selective formation of diverse structural motifs from a readily available substrate class. Presented herein is a detailed study of chemoselectivity with palladium‐based phosphane catalysts and readily available 2‐B(pin)‐substituted allylic acetates, benzoates, and carbonates. Depending on the choice of reagents, catalysts, and reaction conditions, 2‐B(pin)‐substituted allylic acetates and derivatives can be steered into one of three reaction manifolds: allylic substitution, Suzuki–Miyaura cross‐coupling, or elimination to form allenes, all with excellent chemoselectivity. Studies on the chemoselectivity of Pd catalysts in their reactivity with boron‐bearing allylic acetate derivatives led to the development of diverse and practical reactions with potential utility in synthetic organic chemistry.     

Mechanism of styrene emulsion polymerization during interval II

A systematic study of the kinetics of styrene emulsion polymerization in the postnucleation stage by the way of seed particle growth of monodisperse latices was undertaken, in which the colloidally important parameters were varied: R_p was independent (within limits) of (a) ionic strength, (b) pH, (c) initiator concentration (potassium persulfate), and (d) surfactant (sodium dodecyl sulfate) concentration; R_pp was independent (within limits) of (a) seed particle number concentration N, (b) oil:water phase ratio, and (c) monomer:polymer ratio; R_p was directly proportional to seed-particle surface area. The viscosity average molecular weight of the polymer formed during interval II, M_v(i–j), was approximately constant and increased linearly with N. Log M_v(i–j) was inversely proportional to reaction temperature; M_v(i–j) was inversely proportional to initiator concentration. The overall activation energy of polymerization E′_p was equal to the activation energy of propagation E_p during interval II. The value of k_p at 60°C was 615 dm³ mol^?1 s^?1. Trace of oxygen seems to affect the average number of radicals per particle ī during interval II polymerization.     

Asymmetric diels - alder reactions with α-chloronitroso compounds - I. Application of α-chloronitroso epiandrosterone in synthesis

The Diels - Alder reaction of 1,3-cyclohexadiene (9) with the enantiomerically pure α-chloronitroso compound 8, synthesized from epiandrosterone (7a), gives the adduct 10a with 1-(R),4-(S) configuration in 69 % chemical yield and ?95 % enantiomeric excess.     

Determination of viable <Emphasis Type="Italic">Escherichia coli</Emphasis> using antibody-coated paramagnetic beads with fluorescence detection

A rapid and convenient assay system was developed to detect viable Escherichia coli in water. The target bacteria were recovered from solution by immunomagnetic separation and incubated in tryptic soy broth with isopropyl-β-d-thiogalactopyranoside, which induces formation of β-galactosidase in viable bacteria. Lysozyme was used to lyse E. coli cells and release the β-galactosidase. β-Galactosidase converted 4-methylumbelliferyl-β-d-galactoside to 4-methylumbelliferone (4-MU), which was measured by fluorescence spectrophotometry using excitation and emission wavelengths of 355 and 460 nm, respectively. Calibration graphs of 4-MU fluorescence intensity versus E. coli concentration showed a detection range between 8 × 10⁴ and 1.6 × 10⁷ cfu mL⁻¹, with a total analysis time of less than 3 h. The advantage of this method is that it detects viable cells because it is based on the activity of the enzyme intrinsic to live E. coli.     

Volatile components,antioxidant and antimicrobial activity of Citrus acida var. sour lime peel oil

Essential oil of Citrus acida Roxb. var. sour lime was analyzed by GC–MS. Out of 59 components 18 were identified from their fragmentation pattern. Among the identified constituents, o-cymene (16.62%) was found as a major component followed by α-cedrene (10.57%), decadienal (8.043%), bisabolene (5.066%) and β-humelene (4.135%). Citronellyl acetate (2.371%), linalool acetate (2.371%), carvone (1.806%), decanone (1.474%), isopulegol acetate (1.296%), farnesol (1.254%), 4′-methoxyacetophenone (1.207%), and Δ-carene (1.070%) were found in minor quantities whereas α-terpineole (0.607%), dihydroxylinalool acetate (0.650%), cis-nerone (0.574%), caryophyllene oxide (0.433%), and 2,2-dimethyl-3,4-octadienal (0.375%) were found in minute amounts.The antimicrobial activity of the essential oil of C. acida was determined by disc diffusion method, against different bacteria (Bacillus subtilis, Bacillus cereus, Staphylococcus aureus, Escherichia coli, Enterobacter aerogenes, Salmonella typhymurium) and fungi (Aspergillus ficuum, Aspergillus niger, Aspergillus fumigatus, Aspergillus flavis, Fusarium saloni, Fusarium oxysporum, Pencillium digitatum, Candida utilis). Maximum zone of inhibition was resulted against B. subtilis (22 mm) followed by C. utilis (20 mm) and B. cereus (19.8 mm), whereas the minimum zone of inhibition was shown by P. digitatum (10 mm). The inhibition zones, measured after 48 h and 96 h, showed that it is active against all tested bacteria and fungi. The results of antioxidant activity of essential oil of C. acida var. sour lime showed that it was able to reduce the stable radical DPPH to yellow-colored DPPH-H reaching 91.7% of DPPH scavenging effect comparative to ascorbic acid being a strong antioxidant reagent.     

Lipid classes of in vitro cultivar of Pakistani citrus

The in vitro cultivar of citrus contained 18.0% lipids after 12 weeks of germination of seed. The lipid was analyzed by GC procedure for its fatty acid composition. The oil contained seven major fatty acid constituents which were later identified by GC. The oil was further analyzed for its classes by means of thin layer chromatography and gas chromatography. The major portion of the lipid classes comprised of neutral lipids (93.9%) and polar lipids (6.1%). The identified neutral lipids comprised of hydrocarbon (1.4%), wax esters (1.5%), sterol esters (5.2%), triglycerides (52.3%), free fatty acids (1.3%), 1,3-diglycerides (6.0%), 1,2-diglycerides (5.0%), glycol (15.2%), sterols (6.0%), 2-monoglycerides (6.4%), 1-monoglycerides (5.3%) and the identified polar lipids comprised of phosphatidyl ethanolamine (1.8%) phosphatidyl choline (0.9%) lysophosphatidyl ethanolamine (1.8%) and phosphatidyl inositol (1.1%).     

Integrated Machine Learning and Chemoinformatics-Based Screening of Mycotic Compounds against Kinesin Spindle ProteinEg5 for Lung Cancer Therapy

Among the various types of cancer, lung cancer is the second most-diagnosed cancer worldwide. The kinesin spindle protein, Eg5, is a vital protein behind bipolar mitotic spindle establishment and maintenance during mitosis. Eg5 has been reported to contribute to cancer cell migration and angiogenesis impairment and has no role in resting, non-dividing cells. Thus, it could be considered as a vital target against several cancers, such as renal cancer, lung cancer, urothelial carcinoma, prostate cancer, squamous cell carcinoma, etc. In recent years, fungal secondary metabolites from the Indian Himalayan Region (IHR) have been identified as an important lead source in the drug development pipeline. Therefore, the present study aims to identify potential mycotic secondary metabolites against the Eg5 protein by applying integrated machine learning, chemoinformatics based in silico-screening methods and molecular dynamic simulation targeting lung cancer. Initially, a library of 1830 mycotic secondary metabolites was screened by a predictive machine-learning model developed based on the random forest algorithm with high sensitivity (1) and an ROC area of 0.99. Further, 319 out of 1830 compounds screened with active potential by the model were evaluated for their drug-likeness properties by applying four filters simultaneously, viz., Lipinski’s rule, CMC-50 like rule, Veber rule, and Ghose filter. A total of 13 compounds passed from all the above filters were considered for molecular docking, functional group analysis, and cell line cytotoxicity prediction. Finally, four hit mycotic secondary metabolites found in fungi from the IHR were screened viz., (−)-Cochlactone-A, Phelligridin C, Sterenin E, and Cyathusal A. All compounds have efficient binding potential with Eg5, containing functional groups like aromatic rings, rings, carboxylic acid esters, and carbonyl and with cell line cytotoxicity against lung cancer cell lines, namely, MCF-7, NCI-H226, NCI-H522, A549, and NCI H187. Further, the molecular dynamics simulation study confirms the docked complex rigidity and stability by exploring root mean square deviations, root mean square fluctuations, and radius of gyration analysis from 100 ns simulation trajectories. The screened compounds could be used further to develop effective drugs against lung and other types of cancer.     

Fluid rheological effects on streaming dielectrophoresis in a post-array microchannel

Recent studies have demonstrated the strong influences of fluid rheological properties on insulator-based dielectrophoresis (iDEP) in single-constriction microchannels. However, it is yet to be understood how iDEP in non-Newtonian fluids depends on the geometry of insulating structures. We report in this work an experimental study of fluid rheological effects on streaming DEP in a post-array microchannel that presents multiple contractions and expansions. The iDEP focusing and trapping of particles in a viscoelastic polyethylene oxide solution are comparable to those in a Newtonian buffer, which is consistent with the observations in a single-constriction microchannel. Similarly, the insignificant iDEP effects in a shear-thinning xanthan gum solution also agree with those in the single-constriction channel except that gel-like structures are observed to only form in the post-array microchannel under large DC electric fields. In contrast, the iDEP effects in both viscoelastic and shear-thinning polyacrylamide solution are significantly weaker than in the single-constriction channel. Moreover, instabilities occur in the electroosmotic flow and appear to be only dependent on the DC electric field. These phenomena may be associated with the dynamics of polymers as they are electrokinetically advected around and through the posts.