Analysis of hyperforin (St. John's wort) action at TRPC6 channel leads to the development of a new class of antidepressant drugs.

St. John's wort is an herb, long used in folk medicine for the treatment of mild depression. Its antidepressant constituent, hyperforin, has properties such as chemical instability and induction of drug-drug interactions that preclude its use for individual pharmacotherapies. Here we identify the transient receptor potential canonical 6 channel (TRPC6) as a druggable target to control anxious and depressive behavior and as a requirement for hyperforin antidepressant action. We demonstrate that TRPC6 deficiency in mice not only results in anxious and depressive behavior, but also reduces excitability of hippocampal CA1 pyramidal neurons and dentate gyrus granule cells. Using electrophysiology and targeted mutagenesis, we show that hyperforin activates the channel via a specific binding motif at TRPC6. We performed an analysis of hyperforin action to develop a new antidepressant drug that uses the same TRPC6 target mechanism for its antidepressant action. We synthesized the hyperforin analog Hyp13, which shows similar binding to TRPC6 and recapitulates TRPC6-dependent anxiolytic and antidepressant effects in mice. Hyp13 does not activate pregnan-X-receptor (PXR) and thereby loses the potential to induce drug-drug interactions. This may provide a new approach to develop better treatments for depression, since depression remains one of the most treatment-resistant mental disorders, warranting the development of effective drugs based on naturally occurring compounds.

Fluoro-substituted phenylazocarboxamides: Dopaminergic behavior and N-arylating properties for irreversible binding.

Phenylazocarboxamides can serve as bioisosteres for cinnamides, which are widely occurring substructures in medicinal chemistry. Starting from our lead compound 2, the introduction of additional fluoro substituents and the exchange of the methoxyphenylpiperazine head group by an aminoindane moiety was investigated resulting in dopamine D3 receptor antagonists and agonists with Ki values in the sub- and low-nanomolar range. As a potentially irreversible ligand, the 3,4,5-trifluoro-substituted phenylazocarboxamide 7 was investigated for its N-arylating properties by incubation with the protected lysine analog 18 and with the L89K mutant of the dopamine D3 receptor. Whereas covalent bond formation with the lysine unit in TM2 of D3 could not be detected, substantial N-arylation of the side chain of the model compound 18 has been observed.

Identification of novel allosteric modulators for the G-protein coupled US28 receptor of human cytomegalovirus.

The highly constitutively active G-protein coupled receptor US28 of human cytomegalovirus (HCMV) is an interesting pharmacological target because of its implication on viral dissemination, cardiovascular diseases and tumorigenesis. We found that dihydroisoquinolinone and tetrahydroisoquinoline scaffolds may be promising lead structures for novel US28 allosteric inverse agonists. These scaffolds were rapidly synthesized by radical carboamination reactions followed by non-radical transformations. Our novel US28 allosteric modulators provide valuable scaffolds for further ligand optimization and may be helpful chemical tools to investigate molecular mechanisms of US28 constitutive signaling and its role in pathogenesis.