Isolation, characterization and modulatory potentials of ß-stigmasterol, ergosterol and xylopic acid from Anchomanes difformis on mitochondrial permeability transition pore in vitro.

Objective: Secondary metabolites and polyphenolic compounds from medicinal plants have been demonstrated to have multiple biological functions with promising research and development prospects. This study examined the effect of ß-stigmasterol (with ergosterol) and xylopic acid isolated from Anchomanes difformis on liver mitochondrial permeability transition pore (mPTP). Methods: The compounds were isolated by vacuum liquid chromatography. Mitochondrial swelling was assessed as changes in absorbance under succinate-energized conditions. Results: 1H and 13C NMR spectroscopic elucidation of the isolates affirmed the presence of ß-stigmasterol with ergosterol (1:0.3) and xylopic acid. The isolates reversed the increase in lipid peroxidation and inhibited the opening of mitochondrial permeability transition pores caused by calcium and glucose. Pharmacological inhibition of mPTP offers a promising therapeutic target for the treatment of mitochondrial-associated disorders. Conclusion: Reduction in the activity of calcium ATPase and the expression of Caspase-3 and -9 were observed, suggesting that they could play a role in protecting physicochemical properties of membrane bilayers from free radical-induced severe cellular damage and be useful in the management of diseases where much apoptosis occurs.

Silica Nanopowder Supported Frustrated Lewis Pairs for CO2 Capture and Conversion to Formic Acid.

Treatment of hydroxylated silica nanopowders S1 and allyl-functionalized silica nanopowders S2 with 3-(diphenylborano)- or 3-bis(pentafluorophenylborano)propyltrimethoxysilane or 2-(diphenylphosphino)- or 2-(dicyclohexylphosphino)ethyltriethoxysilane generates silica nanopowder supported Lewis acids S3 and silica nanopowder supported Lewis bases S4. These surfaces were characterized by 13C, 11B, and 31P cross-polarization magic angle spinning nuclear magnetic resonance (CP MAS NMR), X-ray photoelectron spectroscopy (XPS), and attenuated total reflection Fourier transform infrared (ATR FTIR). When S3 is combined with solution-phase Lewis bases PR3 (R = C6F5, C6H5, mesityl), six associated silica nanopowder supported frustrated Lewis pairs (FLPs) are formed. In another set of six reactions, the interactions between the supported Lewis bases S4 and solution-phase Lewis acids BR3 with R = C6F5, C6H5, mesityl produced six more associated supported FLPs. The capture of CO2 by these FLPs producing FLP-CO2 Lewis pair adducts S5 and S6 were highlighted by ATR FTIR, and it was found that FLP S5e with R = C6H5 on both the supported Lewis acid and solution-phase Lewis base trapped the largest quantities of CO2 on the silica nanopowder supports. Conversion of CO2 to HCOOH was achieved by first activating H2 to generate activated FLP-H2 surfaces S7 and S9. Addition of CO2 then generated HCOOH via the silica nanopowder supported FLP-HCOOH adducts S8 and S10. Qualitative identification of HCOOH generation was achieved by ATR FTIR measurements, and surface 10b with R = C6H5 proved to be the most successful silica nanopowder surface bound FLP in HCOOH generation. In some cases, diborano formates (-BO(CH)OB-) S11 and S12 were also identified as side products during HCOOH formation. Spectroscopic characterization of purposefully synthesized S11 and S12 included 11B and 31P CP MAS NMR.

Structures of rhenium(I) complexes with 3-hydroxyflavone and benzhydroxamic acid as O,O'-bidentate ligands and confirmation of π-stacking by solid-state NMR spectroscopy.

The synthesis and crystal structures of two new rhenium(I) complexes obtained utilizing benzhydroxamic acid (BHAH) and 3-hydroxyflavone (2-phenylchromen-4-one, FlavH) as bidentate ligands, namely tetraethylammonium fac-(benzhydroxamato-κ2O,O')bromidotricarbonylrhenate(I), (C8H20N)[ReBr(C7H6NO2)(CO)3], 1, and fac-aquatricarbonyl(4-oxo-2-phenylchromen-3-olato-κ2O,O')rhenium(I)-3-hydroxyflavone (1/1), [Re(C15H9O3)(CO)3(H2O)]·C15H10O3, 3, are reported. Furthermore, the crystal structure of free 3-hydroxyflavone, C15H10O3, 4, was redetermined at 100 K in order to compare the packing trends and solid-state NMR spectroscopy with that of the solvate flavone molecule in 3. The compounds were characterized in solution by 1H and 13C NMR spectroscopy, and in the solid state by 13C NMR spectroscopy using the cross-polarization magic angle spinning (CP/MAS) technique. Compounds 1 and 3 both crystallize in the triclinic space group P-1 with one molecule in the asymmetric unit, while 4 crystallizes in the orthorhombic space group P212121. Molecules of 1 and 3 generate one-dimensional chains formed through intermolecular interactions. A comparison of the coordinated 3-hydroxyflavone ligand with the uncoordinated solvate molecule and free molecule 4 shows that the last two are virtually completely planar due to hydrogen-bonding interactions, as opposed to the former, which is able to rotate more freely. The differences between the solid- and solution-state 13C NMR spectra of 3 and 4 are ascribed to inter- and intramolecular interactions. The study also investigated the potential labelling of both bidentate ligands with the corresponding fac-99mTc-tricarbonyl synthon. All attempts were unsuccessful and reasons for this are provided.