Barbeya oleoides Leaves Extracts: In Vitro Carbohydrate Digestive Enzymes Inhibition and Phytochemical Characterization

This study investigated the in vitro inhibitory potential of different solvent extracts of leaves of Barbeya oleoides on key enzymes related to type 2 diabetes mellitus (α-glucosidase and α-amylase) in combination with an aggregation assay (using 0.01% Triton X-100 detergent) to assess the specificity of action. The methanol extract was the most active in inhibiting α-glucosidase and α-amylase, with IC₅₀ values of 6.67 ± 0.30 and 25.62 ± 4.12 µg/mL, respectively. However, these activities were significantly attenuated in the presence of 0.01% Triton X-100. The chemical analysis of the methanol extract was conducted utilizing a dereplication approach combing LC-ESI-MS/MS and database searching. The chemical analysis detected 27 major peaks in the negative ion mode, and 24 phenolic compounds, predominantly tannins and flavonol glycosides derivatives, were tentatively identified. Our data indicate that the enzyme inhibitory activity was probably due to aggregation-based inhibition, perhaps linked to polyphenols.     

Ein Thiolato‐Zink‐Komplex mit einem Zn4O4‐Bicyclooctan‐Gerüst

A Thiolate‐Zinc Complex with a Zn₄O₄ Bicyclooctane Framework The reaction of diethyl zinc with 2,4,6‐triisopropyl thiophenol (HSR*) and N‐methyl‐2‐hydroxymethyl imidazole (ImCH₂OH) in methanol yields the complex Zn₄(SR*)₄ (ImCH₂O)₃(OMe) with terminal SR* and bridging ImCH₂O and MeO ligands. The structure of its Zn₄O₄ framework is that of a bicyclo[2.2.2]octane with Zn and O at the two apices.     

Synthesis and Structures of some Lithium and Sodium (Aminoalcoholato)hydrido Aluminates

LiAlH₄ and NaAlH₄ were allowed to react in a 1 : 1, 1 : 2 and 1 : 3 ratio with 2-dimethylaminoethanol, 1-dimethylamino-2-propanol, and (–)-N-methylephedrine. Reactions in the 1 : 1 ratio leads to mixtures of M(AlH_4–n(OR′NMe₂)_n) in thf solution showing a temperature dependent composition. From the solutions obtained in a 1 : 2 or 1 : 3 ratio the following compounds were isolated as single crystals: (thf)NaAlH₂ · (OCH₂–CH₂NMe₂)₂ ( 2 ), LiAlH₂(OCHMe–CH₂NMe₂)₂ ( 3 ), LiAlH₂(OCHPh–CHMe–NMe₂)₂ ( 4 ), LiAlH(OCH₂CH₂NMe₂)₃ ( 5 ), NaAlH(OCH₂CH₂NMe₂)₃ ( 6 ). All compounds are dimers in the solid state and their Al atoms are pentacoordinated. M–H–Al bridges were found only in the dihydridoaluminate  2 .     

Partitioning infinite trees

A graph G is bisectable if its edges can be colored by two colors so that the resulting monochromatic subgraphs are isomorphic. We show that any infinite tree of maximum degree Δ with infinitely many vertices of degree at least Δ −1 is bisectable as is any infinite tree of maximum degree Δ ≤ 4. Further, it is proved that every infinite tree T of finite maximum degree contains a finite subset E of its edges so that the graph T − E is bisectable. To measure how “far” a graph G is from being bisectable, we define c(G) to be the smallest number k > 1 so that there is a coloring of the edges of G by k colors with the property that any two monochromatic subgraphs are isomorphic. An upper bound on c(G), which is in a sense best possible, is presented. © 2000 John Wiley & Sons, Inc. J Graph Theory 34: 113–127, 2000     

Oxygen and Water Additions to a Tetrasilabuta‐1,3‐diene

The reaction of hexakis(2,4,6‐triisopropylphenyl)tetrasilabuta‐1,3‐diene R₂Si=SiR–SiR=SiR₂ ( 1 ) with atmospheric oxygen furnishes the oxidation product R₂Si(O)₂SiROSiR(O)₂SiR₂ ( 5 ) by oxygen insertion into all Si–Si bonds. However, treatment of 1 with meta‐chloroperoxobenzoic acid provides R₂Si(O)₂SiR–SiR(O)₂SiR₂ ( 7 ) with retention of the Si–Si single bond. Reaction of 1 with traces of water gives the oxatetrasilacyclopentane derivative 10 analogous to THF. With excess water a tetrasilane‐1,4‐diol is formed. The structures of 5 , 7 , and 10 were determined by X‐ray crystallography.     

Synthesis,Characterization, and Crystal Structures of Various Energetic Urotropinium Salts with Azide,Nitrate, Dinitramide and Azotetrazolate Counter Ions

Urotropinium nitrate, N‐methylurotropinium azide, dinitramide and azotetrazolate salts have been prepared and fully characterized by analytical and spectoscopic (¹H, ¹³C, ¹⁴N NMR, IR, Raman) methods. The structures of all four compounds have been determined using X‐ray diffraction techniques and represent new examples of the class of high energy density materials (HEDMs).     

1, 4‐Additions of HCl and HBr to a Tetrasilabutadiene: Formation of Unsymmetrically Substituted Disilenes [1]

The reactions of hexakis(2,4,6‐triisopropylphenyl)tetrasilabuta‐1,3‐diene R₂Si=SiR—SiR=SiR₂ ( 1 ) with HCl and HBr, slowly generated from HSiCl₃ or LiBr and CF₃COOH, respectively, furnish the unsymmetrically substituted disilenes R₂XSi—SiR=SiR—SiHR₂, X = Cl ( 2 ), Br ( 3 ), by formal 1,4‐addition of the hydrogen halides to 1 . However, passing gaseous hydrogen halides over the solution of 1 yields the 1,4‐dihalotetrasilanes by two‐fold 1,2‐additions to the double bonds of 1 . The structures of 2 and 3 which crystallize isotypically with one another have been determined by X‐ray crystallography.