A facile synthesis of substituted coumarins via Pechmann condensation catalyzed by SnCl4 grafted on silica gel is described, which was conducted under solvent-free condition in high yields. The catalyst is noncorrosive and can be easily prepared and separated from the reaction mixture. This methodology offers some advantages with regard to yield of products, simplicity in operation and green aspects.

The glycoprotein IIb/IIIa receptor is the final common pathway of platelet aggregation, regardless of the agonist, and thus represents an ideal therapeutic target for blocking thrombus formation. RUC-2 is a novel glycoprotein IIb/IIIa inhibitor of adenosine-5′-diphosphate (ADP)-induced platelet aggregation, importantly which exhibits a unique mode of binding with respect to classical Arg-Gly-Asp (RGD)-based glycoprotein IIb/IIIa antagonists. To identify new chemotypes that inhibit glycoprotein IIb/IIIa-mediated platelet aggregation like RUC-2, we performed a combination of structure-based pharmacophore screening and structure-based virtual screening approach to screen over 7.3 million small molecules based on the RUC-2–glycoprotein IIb/IIIa crystal structure. Three of the eleven hit compounds identified by virtual screening showed promising activity with IC50 values between 16.9 and 90.6 μmol L−1 in a human platelet aggregation assay induced by ADP and thrombin. The binding conformations of these three were analyzed to provide a rationalization of their activity profile. These compounds may serve as potential novel scaffolds for further development of glycoprotein IIb/IIIa antagonists.

The dissociation constants (pKa) of dalbergin and nordalbergin were measured at 298.2 K using ultraviolet (UV) spectroscopy method. The solubilities of dalbergin and nordalbergin in water, methanol, propanone, ethyl ethanoate, trichloromethane, and hexane have been determined by the UV spectrophotometric method from 283.2 to 308.2 K at atmospheric pressure. The experimental solubility values were correlated with a modified Apelblat equation, λh model, and ideal model. The pKa value of dalbergin is 8.91 ± 0.12, and the pKa1 and pKa2 values of nordalbergin are 7.31 ± 0.29 and 9.79 ± 0.39, respectively. The solubilities of dalbergin and nordalbergin in six solvents increase with an increase in temperature. The solubility order of dalbergin in six pure solvents was trichloromethane > propanone > ethyl ethanoate > methanol > hexane > water, whereas that of nordalbergin was propanone > methanol > ethyl ethanoate > trichloromethane > water > hexane. A comparison of the solubility of dalbergin with that of nordalbergin shows that the 7-methoxyl moiety of dalbergin leads to a significantly higher solubility in trichloromethane and hexane, a little higher solubility in ethyl ethanoate, an approximately equal solubility in propanone, and a little lower solubility in methanol and water (exception 283.2 K). For dalbergin, the modified Apelblat equation shows the best correlation for all solvents, and for nordalbergin, correlation results by three models are similar.

The dissociation constants (pKa) of daidzein and genistein were determined at 298.2 K by ultraviolet (UV) spectroscopy method. The pKa1 and pKa2 values of daidzein are 7.51 ± 0.07 and 9.47 ± 0.14 and ones of genistein are 7.25 ± 0.84 and 9.53 ± 0.15, respectively. The solubilities of daidzein and genistein in water, methanol, ethyl ethanoate, propanone, trichloromethane, and hexane have been measured using UV spectrophotometric method from (288.2 to 328.2) K at atmospheric pressure. The solubilities of daidzein and genistein in all solvents increase with an increase in temperature. The solubility of daidzein in the six solvents was in the order propanone > methanol > ethyl ethanoate > hexane > trichloromethane > water, whereas the solubility order of genistein was propanone > ethyl ethanoate > methanol > hexane > trichloromethane > water. In comparing the solubility of genistein with that of daidzein, the 5-hydroxyl group of genistein causes a significantly higher solubility in methanol and ethyl ethanoate, a little higher solubility in trichloromethane (exception 328.2 K), an approximately equivalent solubility in water, and a slightly lower solubility in propanone. The measured solubility data were correlated with a modified Apelblat equation, λh model, and ideal model. From solubility of daidzein and genistein in these six solvents, the dissolution enthalpy, entropy, and change of the free Gibbs energy were evaluated using the van’t Hoff equation.

Several members of a new family of non-sugar-type α-glycosidase inhibitors, bearing a 5-(p-toluenesulfonylamino)phthalimide moiety and various substituent at the N2 position, were synthesized and their activities were investigated. The newly synthesized compounds displayed different inhibition profile towards yeast α-glycosidase and rat intestinal α-glycosidase. Almost all the compounds had strong inhibitory activities against yeast α-glycosidase. Regarding rat intestinal α-glycosidase, only analogs with N2-aromatic substituents displayed varying degrees of inhibitory activities on rat intestinal maltase and lactase and nearly all compounds showed no inhibition against rat intestinal α-amylase. Structure–activity relationship studies indicated that 5-(p-toluenesulfonylamino)phthalimide moiety is a favorable scaffold to exert the α-glucosidase inhibitory activity and substituents at the N2 position have considerable influence on the efficacy of the inhibition activities.(a) Mapping of pharmacophore model for α-glucosidase inhibitory compounds.15 (b) The general structure of target compounds.