In the title compound, C25H29FO4, each cyclo­hexenone ring has an envelope conformation with the dimethyl-substituted atom as the flap. The hy­droxy and carbonyl groups form two intra­molecular O—H⋯O hydrogen bonds, as is typical for xanthene derivatives. In the crystal, very weak C—H⋯O hydrogen bonds link mol­ecules into dimers.

In the title compound, C21H16N2O2, the 3-nitro­phenyl and two phenyl rings are twisted from the mean plane of the enimino fragment by 44.4 (1), 37.2 (1) and 74.1 (1)°, respectively. The crystal packing exhibits no classical inter­molecular contacts.

In the title compound, C21H16N2O2, the dihedral angles between the mean planes of the 4-nitro­phenyl ring and the two phenyl rings are 57.3 (5) and 16.8 (6)°. The imine group displays a C—C—N—C torsion angle of −24.9 (3)°.

In the title compound, C25H29NO6, each of the cyclo­hexenone rings adopts a half-chair conformation. The hy­droxy and carbonyl O atoms face each other and are oriented to allow for the formation of two intra­molecular O—H⋯O hydrogen bonds. In the crystal, weak C—H⋯O hydrogen bonds are formed between molecules, generating a two-dimensional supramolecular structure.

In the title compound, C25H27NO5, each of the cyclo­hexenone rings adopts a half-chair conformation, whereas the six-membered pyran ring adopts a flattened boat conformation, with the O and methine C atoms deviating from the plane of the other four atoms. In the crystal, weak C—H⋯O hydrogen bonds link mol­ecules into chains parallel to the c axis.

In the title compound, C21H19ClO3, the two cyclo­hexenone rings adopt half-chair conformations, whereas the pyran ring adopts a boat conformation. The 4-chloro­phenyl ring is almost perpendicular to the plane through the four C atoms of the pyran ring [dihedral angle = 87.97 (6)°]. In the crystal, weak C—H⋯O hydrogen bonds link the mol­ecules into a chain parallel to the a-axis.

In the title compound, C22H22O4, the two cyclo­hexenone rings adopt half-chair conformations, whereas the six-membered pyran ring adopts a flattened boat conformation, with the O and methine C atoms deviating from the plane of the other four atoms by 0.142 (2) and 0.287 (2)Å, respectively. In the crystal, weak C—H⋯O hydrogen bonds link mol­ecules into chains running parallel to the a axis.

In the title compound, C21H21NO6, each of the cyclo­hexenone rings adopts a half-chair conformation. Each of the pairs of hy­droxy and carbonyl O atoms are oriented to allow for the formation of intra­molecular O—H⋯O hydrogen bonds, which are typical of xanthene derivatives.

In the title compound, C22H21ClO2, the oxolane ring adopts a twisted conformation. The dihedral angles between the mean plane of the oxolane ring and the mean planes of the 4-chloro­phenyl, phenyl and cyclo­pentenyl rings are 71.81 (18), 76.9 (18) and 82.08 (18)°, respectively.

In the title compound, C27H26O4, each of the cyclo­hexenone rings adopts a half-chair conformation. The dihedral angle between the two phenyl rings is 89.53 (5)°. The hy­droxy and carbonyl O atoms face each other and are orientated to allow the formation of two intra­molecular O—H⋯O hydrogen bonds, which are typical of xanthene derivatives.

In the title compound, C25H29NO6, each of the cyclo­hexenone rings adopts a half-chair conformation. Each of the pairs of hy­droxy and carbonyl O atoms are oriented to allow for the formation of intra­molecular O—H⋯O hydrogen bonds, which are typical of xanthene derivatives. The nitro group is rotationally disordered over two orientations in a 0.544 (6):0.456 (6) ratio. In the crystal, weak inter­molecualr C—H⋯O hydrogen bonds link mol­ecules into layers parallel to the ab plane.

In the title compound, C22H24O5, each of the cyclo­hexenone rings adopts a half-chair conformation. The hy­droxy and carbonyl O atoms face each other and are orientated to allow for the formation of the two intra­molecular O—H⋯O hydrogen bonds which are typical of xanthene derivatives. In the crystal, weak inter­molecular C—H⋯O hydrogen bonds link mol­ecules into layers parallel to the ab plane.

Background

Ca2+-activated Cl- channels (CaCCs) participate in many important physiological processes. However, the lack of effective and selective blockers has hindered the study of these channels, mostly due to the lack of good assay system. Here, we have developed a reliable drug screening method for better blockers of CaCCs, using the endogeneous CaCCs in Xenopus laevis oocytes and two-electrode voltage-clamp (TEVC) technique.

Results

Oocytes were prepared with a treatment of Ca2+ ionophore, which was followed by a treatment of thapsigargin which depletes Ca2+ stores to eliminate any contribution of Ca2+ release. TEVC was performed with micropipette containing chelerythrine to prevent PKC dependent run-up or run-down. Under these conditions, Ca2+-activated Cl- currents induced by bath application of Ca2+ to oocytes showed stable peak amplitude when repetitively activated, allowing us to test several concentrations of a test compound from one oocyte. Inhibitory activities of commercially available blockers and synthesized anthranilic acid derivatives were tested using this method. As a result, newly synthesized N-(4-trifluoromethylphenyl)anthranilic acid with trifluoromethyl group (-CF3) at para position on the benzene ring showed the lowest IC50.

Conclusion

Our results provide an optimal drug screening strategy suitable for high throughput screening, and propose N-(4-trifluoromethylphenyl)anthranilic acid as an improved CaCC blocker.