Synthesis, platelet adhesion and cytotoxicity studies of new glycerophosphoryl-containing polyurethanes.

In this work we synthesized new MDI -based poly(ether)urethanes (PEUs) with phospholipid-like residue as chain extender. Polymers were prepared by a conventional two-step solution polymerization procedure using 4,4' diphenylmethanediisocyanate (MDI) and poly(1,4- butanediol) with 1000 as molecular weight to form prepolymers which were successively polymerized with 1 glycerophosphorylcholine (1-GPC), 2-glycerophosphorylcholine (2-GPC) or glycerophosphorylserine (GPS) as chain extenders. Two reference polymers bearing 1,4-butandiol (BD) have been also synthesized. The polymers obtained were characterized by Fourier transform infrared spectroscopy (FT-IR), nuclear magnetic resonance (NMR), differential scanning calorimetry (DSC) and modulated scanning calorimetry (MDSC). The biocompatibility of synthesized segmented polyurethanes was then investigated by platelet-rich plasma contact studies and related scanning electron microscopy (SEM) photographs for blood compatibility and cytotoxicity assay (MTT test) on material elution to assess the effect of any toxic leachables on cellular viability. Three polymers among all have given very satisfactory results suggesting to investigate more deeply their possible use in biomedical devices.

Noncovalent association phenomena of 2,5-dihydroxybenzoic acid with cyclic and linear oligosaccharides. A matrix-assisted laser desorption/ionization time-of-flight mass spectrometric and X-ray crystallographic study.

D-Glucose and 19 glucose derivatives were investigated by positive and negative ion matrix assisted laser desorption/ionization time-of-flight mass spectrometry using 2,5-dihydroxybenzoic acid (DHB) as the matrix. The set of substrates includes oligomers of amylose and cellulose, native alpha-, beta-, and gamma-cyclodextrin, and chemically modified beta- and gamma-cyclodextrins. These analytes were chosen to modulate molecular weight, polarity, and capability of establishing noncovalent interactions with guest molecules. In the negative-ion mode, the DHB matrix gave rise to charged multicomponent adducts of type [M + DHB - H]- (M = oligosaccharide) selectively for those analytes matching the following conditions: (i) underivatized chemical structure and (ii) number of glucose units > or = 4. In the positive-ion polarity, only some amylose and cellulose derivatives and methylated beta-cyclodextrins provided small amount of cationized adducts with the matrix of type [M + DHB + X]+ (X = Na or K), along with ubiquitous [M + X]+ ions. The results are discussed by taking into account analyte-matrix association phenomena, such as hydrogen bond and inclusion phenomena, as a function of the molecular structure of the analyte. The conclusions derived by mass spectrometric data are compared with the X-ray diffraction data obtained on a single crystal of the 1:1 alpha-cyclodextrin - DHB noncovalent adduct.

Structure of elsinochrome A: a perylenequinone metabolite.

trans-1,2-Diacetyl-1,2-dihydro-5,10-dihydroxy-3,7,8,12- tetramethoxybenzo[ghi]perylene-4,11-dione, C30H24O10, Mr = 544.51, orthorhombic, P2(1)2(1)2(1), Z = 4, a = 12.428 (3), b = 13.048 (3), c = 14.933 (3) A, V = 2421.5 (9) A3, Dx = 1.494, Dm (by flotation) = 1.48 g cm-3, lambda(Mo K alpha) = 0.71069 A, mu = 1.057 cm-1, F(000) = 1136, T = 293 K, R = 0.046 (2065 observed reflections). Elsinochrome A is shown to exist in the solid state as a nonplanar quinone tautomer; the pigment adopts a helical conformation, in analogy with the related cercosporin, but the perylenequinone moiety in elsinochrome A appears to be significantly less skewed.