Determination of the Absolute Configuration of Aegelinol by Crystallization of Its Inclusion Complex with β-Cyclodextrin

The absolute configuration and structure of aegelinol, a pyranocoumarin isolated from Ferulago asparagifolia Boiss (Apiaceae), has been determined by crystallography. Crystal structure of the inclusion complex of aegelinol in β-cyclodextrin was determined (a = 15.404(1) Å, b = 15.281(1) Å, c = 17.890(1) Å, α = 99.662(1), β = 113.4230(1), γ = 102.481(1)°, P1; R1 = 6.71%) and allowed unambiguous determination of the absolute configuration of the stereogenic center of aegelinol. The pyranocoumarin guest is included within the cylindrical cavity formed by dimeric β-cyclodextrin molecules with a head-to-head arrangement. Crystal structure of aegelinol alone was also determined (a = 6.8921(3) Å, b = 11.4302(9) Å, c = 44.964(3) Å, P212121; R1 = 4.44%) and allowed precise determination of its geometry. Aegelinol crystallizes with three molecules in the asymmetric unit held together by H-bonds and π-stacking interactions

Asthma exacerbation and proximity of residence to major roads: a population-based matched case-control study among the pediatric Medicaid population in Detroit, Michigan

<p>Abstract</p> <p>Background</p> <p>The relationship between asthma and traffic-related pollutants has received considerable attention. The use of individual-level exposure measures, such as residence location or proximity to emission sources, may avoid ecological biases.</p> <p>Method</p> <p>This study focused on the pediatric Medicaid population in Detroit, MI, a high-risk population for asthma-related events. A population-based matched case-control analysis was used to investigate associations between acute asthma outcomes and proximity of residence to major roads, including freeways. Asthma cases were identified as all children who made at least one asthma claim, including inpatient and emergency department visits, during the three-year study period, 2004-06. Individually matched controls were randomly selected from the rest of the Medicaid population on the basis of non-respiratory related illness. We used conditional logistic regression with distance as both categorical and continuous variables, and examined non-linear relationships with distance using polynomial splines. The conditional logistic regression models were then extended by considering multiple asthma states (based on the frequency of acute asthma outcomes) using polychotomous conditional logistic regression.</p> <p>Results</p> <p>Asthma events were associated with proximity to primary roads with an odds ratio of 0.97 (95% CI: 0.94, 0.99) for a 1 km increase in distance using conditional logistic regression, implying that asthma events are less likely as the distance between the residence and a primary road increases. Similar relationships and effect sizes were found using polychotomous conditional logistic regression. Another plausible exposure metric, a reduced form response surface model that represents atmospheric dispersion of pollutants from roads, was not associated under that exposure model.</p> <p>Conclusions</p> <p>There is moderately strong evidence of elevated risk of asthma close to major roads based on the results obtained in this population-based matched case-control study.</p

Structural characterization of cyclodextrins: from inclusion complexes to Metal-Organic Frameworks (MOFs)

Cyclodextrins (CD) are cyclic oligosaccharides composed of six to more than sixty glucose units. α-CD, β-CD and γ-CD are well known CD consisting of 6, 7 and 8 glycopyranose units, respectively, that are torus-like rings built up from glycopyranose units. The secondary hydroxyl groups are situated on one of the two edges of the ring, whereas all the primary ones are placed on the other edge. The ring is a conical cylinder, which is frequently characterized as a doughnut or wreath shaped truncated cone. The cavity is lined with hydrogen atoms and glycosidic oxygen bridges, respectively. The primary and secondary hydroxyls on the outside of the cyclodextrins make cyclodextrins water-soluble. The cavity of the cyclodextrin consists of a ring of C-H groups, a ring of glycosidic oxygen atoms and again a ring of C-H groups. This renders the interior of the cyclodextrin rings less polar. As a consequence, the hydrophilic sites which are outside of the torus enable CD to be soluble in water, whereas the apolar cavity site which provides a hydrophobic matrix, enables CD to form inclusion complex with a variety of hydrophobic guest molecules. In addition, CD contains repeating units of ‒OCCO‒ binding motif on both their primary and secondary faces. This makes CD able to form extended structures with metal cations of Group IA and IIA (MOFs). The main goal of this thesis was to design, prepare and characterize new crystal systems based on cyclodextrins properties in combination with: 1. Para aminobenzoic acid (pABA) as a drug model to study the effect of complexation phenomena on the solubility of drugs. Their structure and mode of interaction were characterized by combination a theoretical and experimental approaches. 2. Potassium hydroxide to prepare cyclodextrin Metal-Organic Frameworks (CD-MOFs) formed by coordinating the cyclodextrins to potassium cation. Consequently, taking the advantages of this interaction between cyclodextrin and alkali metal cation, formation of inclusion complexes as CD-MOFs drug carrier was favored. 3. Aegelinol, a natural product, for analytical purposes to determine the absolute configuration of this compound by formation of an inclusion complex with a host of known chirality (cyclodextrins consists of several optically active D-glucose units). This should allow direct determination of the absolute configuration of the guest (aegelinol).(DOCSC02) -- FUNDP, 201

CCDC 845857: Experimental Crystal Structure Determination

An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures

CCDC 884099: Experimental Crystal Structure Determination

An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures