Recovery and Purity of High Molar Mass Bio-hyaluronic Acid Via Precipitation Strategies Modulated by pH and Sodium Chloride

Applied Biochemistry and Biotechnology - The effects of ethanol/broth proportions and the number of steps at varying pH in the presence or absence of sodium chloride (NaCl) were studied as...     

Magnetic properties of a polyfluorene derivative containing complexed neodymium ions

Poly[9,9′‐dihexylfluorene‐2,7‐diyl)‐6,6″‐(2,2′:6′,2″‐terpyridine)] (LaPPS75) and its complexes with neodymium were synthesized and characterized. Magnetic measurements showed that the noncomplexed polymer presented a ferromagnetic contribution due to the formation of π stacking, and that in absence of those, the ferromagnetic behavior is suppressed. The pristine polymer, the complexed one and a low‐molecular‐weight model compound with the same structure of the complexed site in the parent polymer were studied. The observed behavior found is presented and discussed, the most important finding was that when a conjugated chain is used as a host for the metallic ion, an amplification of four times for the magnetization is achieved, using the same metallic content for complexed polymer and model compound for comparison. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2019 , 57, 304–311     

Determination of cocaine adulterants in human urine by dispersive liquid-liquid microextraction and high-performance liquid chromatography

Analytical and Bioanalytical Chemistry - This study aimed to determine simultaneously five major street cocaine adulterants (caffeine, lidocaine, phenacetin, diltiazem, and hydroxyzine) in human...     

Host-guest Assembly Based on γ-Cyclodextrin-functionalized Multiwalled Carbon Nanotubes for Rutin Electrochemical Sensing

Here, we report multiwalled carbon nanotubes (MWCNTs) functionalized with γ-cyclodextrins (γCD) as a novel electrochemical strategy for Rutin determination, showing superior performance than β-cyclodextrins (βCD) modified MWCNTs, suggesting an adequate environment for host-guest interactions. Under optimized conditions, the sensor showed a linear range of 39–975 nmol L⁻¹ and a limit of detection of 7 nmol L⁻¹. When tested with quercetin, catechin, and caffeine, the platform presented high selectivity with an interference response <10 %. The method was employed to quantify Rutin in spiked pharmaceutical and herbal extracts, providing recovery of 93–98.4 %. Also, HPLC-PDA confirmed the method‘s accuracy.     

Co-Catalyzed Metal-Ligand Cooperative Approach for N-alkylation of Amines and Synthesis of Quinolines via Dehydrogenative Alcohol Functionalization

Herein we report a cobalt-catalyzed sustainable approach for C−N cross-coupling reaction between amines and alcohols. Using a well-defined Co-catalyst 1 a bearing 2-(phenyldiazenyl)-1,10-phenanthroline ligand, various N-alkylated amines were synthesized in good yields. 1 a efficiently alkylates diamines producing N, N′-dialkylated amines in good yields and showed excellent chemoselectivity when oleyl alcohol and β-citronellol, containing internal carbon-carbon double bond were used as alkylating agents. 1 a is equally compatible with synthesizing N-heterocycles via dehydrogenative coupling of amines and alcohols. 1H-Indole was synthesized via an intramolecular dehydrogenative N-alkylation reaction, and various substituted quinolines were synthesized by coupling of 2-aminobenzyl alcohol and secondary alcohols. A few control reactions and spectroscopic experiments were conducted to illuminate the plausible reaction mechanism, indicating that the 1 a -catalyzed N-alkylation proceeds through the borrowing hydrogen pathway. The coordinated arylazo ligand participates actively throughout the reaction; the hydrogen eliminated during dehydrogenation of alcohols was set aside in the ligand backbone and subsequently gets transferred in the reductive amination step to imine intermediates yielding N-alkylated amines. On the other hand, 1 a -catalyzed quinoline synthesis proceeds through dehydrogenation followed by successive C−C and C−N coupling steps forming H₂O₂ as a by-product under air.     

Chemical Composition and Antioxidant Activity of Essential Oils from Eugenia patrisii Vahl,E. punicifolia (Kunth) DC., and Myrcia tomentosa (Aubl.) DC., Leaf of Family Myrtaceae

Essential oils (EOs) were extracted from Eugenia patrisii, E. punicifolia, and Myrcia tomentosa, specimens A and B, using hydrodistillation. Gas chromatography coupled with mass spectrometry (GC/MS) was used to identify the volatile constituents present, and the antioxidant capacity of EOs was determined using diphenylpicryl-hydrazyl (DPPH) and trolox equivalent antioxidant capacity (TEAC) assays. For E. patrisii, germacrene D (20.03%), bicyclogermacrene (11.82%), and (E)-caryophyllene (11.04%) were identified as the major constituents of the EOs extracted from specimen A, whereas specimen B primarily comprised γ-elemene (25.89%), germacrene B (8.11%), and (E)-caryophyllene (10.76%). The EOs of E. punicifolia specimen A contained β-Elemene (25.12%), (E)-caryophyllene (13.11%), and bicyclogermacrene (9.88%), while specimen B was composed of (E)-caryophyllene (11.47%), bicyclogermacrene (5.86%), β-pinene (5.86%), and γ-muurolene (5.55%). The specimen A of M. tomentosa was characterized by γ-elemene (12.52%), germacrene D (11.45%), and (E)-caryophyllene (10.22%), while specimen B contained spathulenol (40.70%), α-zingiberene (9.58%), and γ-elemene (6.89%). Additionally, the chemical composition of the EOs was qualitatively and quantitatively affected by the collection period. Furthermore, the EOs of the studied specimens, especially specimen A of E. punicifolia, showed a greater antioxidant activity in DPPH rather than TEAC, as represented by a significantly high inhibition percentage (408.0%).