To the N-terminus of a nonamer peptide nucleic acid sequence, H-GCACGACTT-NH2, was attached a number of lipophilic conjugate molecules including three synthetic tocopherol (vitamin E) analogues. Studies were then undertaken with complementary PNA and DNA sequences to explore the effects of the conjugates using the techniques of UV monitored melting curves and isothermal calorimetry. Duplex form...

Propolis from central Chile was investigated for its plant origin by microscopical analysis of pollen grains and leaf fragments found in the sample. The pollen grains that appear with significant higher frequency in the sample corresponded to four native and two introduced species, whereas leaf fragments corresponded to four native species. Seventeen phenolic compounds that belong to the phenyl...

The title compound, C(18)H(16)O(7)·H(2)O, is a flavonoid isolated from Dodonaea viscosa-. The benzopyran ring system of the flavonoid is essentially planar [maximum deviation = 0.025 (2) Å] and inclined at 5.83 (2)° to the attached benzene ring. The water of hydration is involved in extensive hydrogen bonding, assembling the mol-ecules into a supra-molecular network via classical inter-molecula...

In this work, the behavior of the polycyclic musks 6-acetyl-1,1,2,4,4,7-hexamethyltetraline (AHTN) and 1,3,4,6,7,8-hexahydro-4,6,6,7,8,8-hexamethylcyclopenta-γ-2-benzopyran (HHCB) was investigated upon disinfection by using sodium hypochlorite as disinfectant in a model disinfection basin in order to find new disinfection by-products (DBP). In the case of AHTN, the carboxylic acid 3,5,5,6,8,8-h...

The title compound, C(16)H(12)N(2)O(4)S, was obtained by the condensation of 3-acetyl-4-hy-droxy-coumarin with thien-2-ylcarbonyl hydrazide. The pyran ring adopts a 2,4-dione tautomeric form. The benzopyran ring system is almost coplanar with the thio-phene ring [dihedral angle 0.9 (2)°]. The exocyclic C=C double bond has an E geometry. The mol-ecular conformation is stabilized by an intra-mole...

Coumarin (2H-1-benzopyran-2-one) is a plant-derived natural product known for its pharmacological properties such as anti-inflammatory, anticoagulant, antibacterial, antifungal, antiviral, anticancer, antihypertensive, antitubercular, anticonvulsant, antiadipogenic, antihyperglycemic, antioxidant, and neuroprotective properties. Dietary exposure to benzopyrones is significant as these compounds...

In the title compound, C(14)H(12)O(5), the benzopyran-2-one ring system is approximately planar [maximum deviation = 0.018 (1) Å]; the mean plane is oriented at dihedral angles of 52.26 (11) and 72.92 (7)°, respectively, to the acetyl and acet-oxy groups. In the crystal, π-π stacking is observed between parallel benzene rings of adjacent mol-ecules, the centroid-centroid distance being 3.6774 (...

The relative and absolute configurations of xiamenmycin A, a benzopyran compound isolated from Streptomyces xiamenensis 318 with a highly potent anti-fibrotic activity, have been characterized through the total synthesis. The key steps include the construction of the 3-chromanol moiety via Sharpless epoxidation followed by regio- and diastereo-selective cyclization and introduction of the threo...

The first syntheses are described of the four enantiopure naphthopyranquinones (1R,3R,4S)- and (1R,3R,4R)-3,4-dihydro-4,7,9-trihydroxy-1,3-dimethylnaphtho[2,3-c]pyranquinone (quinone A 1 and quinone A' 2) and their two C-3 epimers, the (1R,3S,4S)- and (1R,3S,4R)-diastereoisomers 5 and 6, using enantiopure lactate as the source of asymmetry. Key factors in these syntheses are the maintenance of ...