A large series of coumarin derivatives (71 compounds) were tested for their monoamine oxidase A and B (MAO-A and MAO-B) inhibitory activity. Most of the compounds acted preferentially on MAO-B with IC(50) values in the micromolar to low-nanomolar range; high inhibitory activities toward MAO-A were also measured for sulfonic acid esters. The most active compound was 7-[(3, 4-difluorobenzyl)oxy]-3,4-dimethylcoumarin, with an IC(50) value toward MAO-B of 1.14 nM. A QSAR study of 7-X-benzyloxy meta-substituted 3,4-dimethylcoumarin derivatives acting on MAO-B yielded good statistical results (q(2)() = 0.72, r(2)() = 0.86), revealing the importance of lipophilic interactions in modulating the inhibition and excluding any dependence on electronic properties. CoMFA was performed on two data sets of MAO-A and MAO-B inhibitors. The GOLPE procedure, with variable selection criteria, was applied to improve the predictivity of the models and to facilitate the graphical interpretation of results.

Inhibition of monoamine oxidases by functionalized coumarin derivatives: biological activities, QSARs, and 3D-QSARs.

Solvent polarity and temperature effect on the photophysical properties of two 1,2-benzopyrone dyes, namely, coumarin-152 (C152) and coumarin-481 (C481), have been investigated using steady-state and time-resolved fluorescence measurements. In nonpolar (NP) solvents (e.g., hexane, cyclohexane, methylcyclohexane, 2-methylpentane, and 3-methylpentane), the Stokes' shifts (Δν) and fluorescence lifetimes (τf) for both the dyes are unexpectedly lower. Excluding NP solvents, for all other solvents the Δν correlates linearly with the solvent polarity function, Δf = {(e − 1)/(2e + 1) − (n2 − 1)/(2n2 + 1)}, and the slopes of these plots indicate that the fluorescent states for both the dyes in these solvents are of intramolecular charge transfer (ICT) character. The unusually lower Δν and τf values in NP solvents have been rationalized considering nonpolar structures for the fluorescent states of the dyes in these solvents. The fluorescence quantum yields (Φf) and τf values of the two dyes also show an unusual ...

http://nathan.instras.com/documentDB/paper-439.pdf

Photophysical Properties of Coumarin-152 and Coumarin-481 Dyes: Unusual Behavior in Nonpolar and in Higher Polarity Solvents

The photophysical properties of 7-amino-4-trifluoromethyl-1,2-benzopyrone (coumarin-151; C151) in nonpolar (NP) solvents are drastically different than those in other solvents of moderate to higher polarities. Thus, the absorption and fluorescence maxima are largely blue-shifted and the Stokes' shifts unusually low in NP solvents compared to those in the other solvents. The fluorescence quantum yields (Φf) in NP solvents are also exceptionally lower. While in all other solvents the fluorescence decays of C151 are single-exponential, in NP solvents the decays show non-single-exponential behavior. The average fluorescence lifetimes (τf) in NP solvents are also substantially shorter. Low Φf and τf values in NP solvents indicate very fast nonradiative deactivation for the S1 state of C151. Investigating the triplet characteristics of C151 by using picosecond laser flash photolysis and pulse radiolysis techniques, it has been established that the fast nonradiative deactivation in NP solvents is not due to an e...

Unusual Photophysical Properties of Coumarin-151

We have developed a series of new ultrafluorogenic probes in the blue-green region of the visible-light spectrum that display fluorescence enhancement exceeding 11 000-fold. These fluorogenic dyes integrate a coumarin fluorochrome with the bioorthogonal trans-cyclooctene(TCO)–tetrazine chemistry platform. By exploiting highly efficient through-bond energy transfer (TBET), these probes exhibit the highest brightness enhancements reported for any bioorthogonal fluorogenic dyes. No-wash, fluorogenic imaging of diverse targets including cell-surface receptors in cancer cells, mitochondria, and the actin cytoskeleton is possible within seconds, with minimal background signal and no appreciable nonspecific binding, opening the possibility for in vivo sensing.

/pdf/ultrafluorogenic-coumarin-tetrazine-probes-for-real-time-2oe1b8j5bq.pdf

Ultrafluorogenic Coumarin-Tetrazine Probes for Real-Time Biological Imaging

Non-steroidal compounds which are high affinity, high selectivity modulators for steroid receptors are disclosed. Also disclosed are pharmaceutical compositions incorporating such compounds, methods for employing the disclosed compounds and compositions for treating patients requiring steroid receptor agonist or antagonist therapy, intermediates useful in the preparation of the compounds and processes for the preparation of the steroid receptor modulator compounds.

Dan E. Bliss

Papers

Substituted coumarins and azacoumarins. Synthesis and fluorescent properties