Three new photochromic coumarins were synthesized. Fluorescence of the open form of 7-hydroxy-3,4-bisthiazolyl-coumarin increased to 1400% by changing the pH only slightly from 6.05 to 7.58. This was subsequently quenched to 1.5% of the maximum intensity at the UV photostationary state in water-methanol media.

A new coumarin, 7-hydroxy-4,6-dimethoxy-5-methylcoumarin (1), was isolated from the aerial parts of Clematis delavayi var. spinescens together with 17 known compounds. Their structures were identified by extensive spectral analysis, especially 2D NMR techniques. Antiangiogenic effects of all compounds were evaluated using a zebrafish model.

Three new compounds, cadalen-15-oic acid (1), 3,7-dihydroxy-3(4H)-isocadalen-4-one (2), and dicadalenol (3), were isolated from the aerial parts of Heterotheca inuloides (Mexican arnica), together with the known compounds 7-hydroxycadalene (4), 7-hydroxy-4alphaH-3,4-dihydrocadalene (5), 1alpha-hydroxy-1(4H)-isocadalen-4-one (6), 1alpha-hydroxy-4alphaH-1,2,3,4-tetrahydrocadalen-15-oic acid (7), ...

A suitable methodology of synthesis of coumarin derivatives by Pechmann reaction over heterogeneous solid acid catalysts in a free solvent media under microwave irradiation is described. Resorcinol, phenol and ethyl acetoacetate were selected as model reactants in the Pechmann condensation. The catalytic activity of several materials-Amberlyst-15, zeolite β and sulfonic acid functionalized hybr...

A new oxyprenyl coumarin was isolated from the lipophilic exudate of Ozothamnus lycopodioides. Its structure was established as 7-(3,3'-dimethylallyloxy)-5-hydroxy-6-methoxycoumarin from its UV, MS and NMR spectral data, especially two dimensional experiments. In addition to six earlier reported flavonols, we found four highly substituted flavones, including two rare methylenedioxyflavones.

To specify the site of action of the synthetic coumarin derivatives 7-hydroxy-3-(4'-hydroxyphenyl) coumarin (HHC) and 7-hydroxy-3-(4'-hydroxyphenyl) dihydrocoumarin (HHDC), we evaluated their effects on extra- and intracellular reactive oxygen species (ROS) formation in phorbol-myristate-13-acetate (PMA) stimulated human neutrophils. We studied also the effects of HHC and HHDC on possible molec...

A series of substituted 8-arylazo 7-hydroxy 4-methyl coumarin (4a-4g) were synthesized and in-vitro evaluation for their preliminary antibacterial activities against E.coli, Staphylococcus aurous, Bacillus subtilis and Pseudomonas aeroginosa were carried out by agar-well diffusion method. Initially, the diazotized primary aryl amines, 3a-3g were synthesized and followed by coupling with 7-hydro...

Z. Naturforsch. 55c, 5 2 8 -5 3 3 (2000); received April 5/April 20. 2000 Pelargonium Species, Umckaloabo, Coumarins, Oxygenation Pattern The coumarin patterns of Pelargonium sidoides DC. and Pelargonium reniforme CURT., forming the origin of the herbal medicine “umckaloabo”, were analysed and compared for therapeutic equivalence. For both species, members of triand tetraoxygenated coumarins al...

A new antiplasmodial coumarin, 5,7-dimethoxy-8-(3'-hydroxy-3'methyl-1'-butene)-coumarin (1), has been isolated from the roots of Toddalia asiatica. This finding supports the traditional use of this plant for the treatment of malaria.