Personalized medicine: Vinpocetine to reverse effects of GABRB3 mutation.

OBJECTIVE: To screen a library of potential therapeutic compounds for a woman with Lennox-Gastaut syndrome due to a Y302C GABRB3 (c.905A>G) mutation. METHODS: We compared the electrophysiological properties of cells with wild-type or the pathogenic GABRB3 mutation. RESULTS: Among 1320 compounds, multiple candidates enhanced GABRB3 channel conductance in cell models. Vinpocetine, an alkaloid derived from the periwinkle plant with anti-inflammatory properties and the ability to modulate sodium and channel channels, was the lead candidate based on efficacy and safety profile. Vinpocetine was administered as a dietary supplement over 6 months, reaching a dosage of 20 mg three times per day, and resulted in a sustained, dose-dependent reduction in spike-wave discharge frequency on electroencephalograms. Improved language and behavior were reported by family, and improvements in global impression of change surveys were observed by therapists blinded to intervention. SIGNIFICANCE: Vinpocetine has potential efficacy in treating patients with this mutation and possibly other GABRB3 mutations or other forms of epilepsy. Additional studies on pharmacokinetics, potential drug interactions, and safety are needed.

A comprehensive approach to identifying repurposed drugs to treat SCN8A epilepsy.

OBJECTIVE: Many previous studies of drug repurposing have relied on literature review followed by evaluation of a limited number of candidate compounds. Here, we demonstrate the feasibility of a more comprehensive approach using high-throughput screening to identify inhibitors of a gain-of-function mutation in the SCN8A gene associated with severe pediatric epilepsy. METHODS: We developed cellular models expressing wild-type or an R1872Q mutation in the Nav 1.6 sodium channel encoded by SCN8A. Voltage clamp experiments in HEK-293 cells expressing the SCN8A R1872Q mutation demonstrated a leftward shift in sodium channel activation as well as delayed inactivation; both changes are consistent with a gain-of-function mutation. We next developed a fluorescence-based, sodium flux assay and used it to assess an extensive library of approved drugs, including a panel of antiepileptic drugs, for inhibitory activity in the mutated cell line. Lead candidates were evaluated in follow-on studies to generate concentration-response curves for inhibiting sodium influx. Select compounds of clinical interest were evaluated by electrophysiology to further characterize drug effects on wild-type and mutant sodium channel functions. RESULTS: The screen identified 90 drugs that significantly inhibited sodium influx in the R1872Q cell line. Four drugs of potential clinical interest-amitriptyline, carvedilol, nilvadipine, and carbamazepine-were further investigated and demonstrated concentration-dependent inhibition of sodium channel currents. SIGNIFICANCE: A comprehensive drug repurposing screen identified potential new candidates for the treatment of epilepsy caused by the R1872Q mutation in the SCN8A gene.

Synthesis and evaluation of the anti-proliferative and NF-κB activities of a library of simplified tylophorine analogs.

Tylophorine and many related phenanthropiperidine alkaloids are extraordinarily potent anti-proliferative agents. Despite their impressive anti-cancer activity, clinical development of these alkaloids has been hampered by their poor solubility and neurological side effects. Although it has been suggested that developing polar phenanthropiperidines will mitigate these undesired properties, the lack of practical methods for the synthesis of such analogues has limited this effort. Here, we present a concise synthetic approach to N-substituted phenanthropiperidines, which enabled a systematic investigation of structure-activity relationships at an underexplored region of the tylophorine scaffold. This work suggests that ring E of tylophorine is essential for the anti-proliferative activity of the 6,7,10,11-tetramethoxy-1,2,3,4-tetrahydrodibenzo[f,h]isoquinoline core scaffold.

Evaluation of Density Functionals, SCC-DFTB, Neglect of Diatomic Differential Overlap (NDDO) Models and Molecular Mechanics Methods for Prolyl-Leucyl-Glycinamide (PLG) and Structural Derivatives.

Prolyl-leucyl-glycinamide (PLG) is a unique endogenous peptide that modulates dopamine receptor subtypes of the D(2) receptor family within the CNS. We seek to elucidate the structural basis and molecular mechanism by which PLG and its analogues modulate dopamine receptors, toward the development of new therapeutics to treat Parkinson's disease, tardive dyskinesia and schizophrenia. As a first step toward establishing a validated protocol for accurate computational modeling of PLG and associated peptidomimetic analogues, we evaluated the accuracy of density functional theory (DFT), wavefunction theory (WFT), and molecular mechanics (MM) calculations for PLG and for a library of structurally related small molecules. We first tested twelve local and nonlocal density functionals, Hartree-Fock (HF) theory, four "semiempirical" methods of the neglect of diatomic differential overlap (NDDO) type, and one self-consistent-charge nonorthogonal tight-binding (SCC-DFTB) method as implemented in two software suites, against coupled-cluster benchmark geometries for 4-methylthiazolidine, a small molecule that comprises key structural features present in our PLG analogue library. DFT and HF calculations were done with the MG3S augmented polarized triple-zeta basis set. We find that for 4-methylthiazolidine bond distances, DFT significantly outperforms NDDO, and both SCC-DFTB versions we evaluated perform worse than HF theory and are less accurate than 83% of the density functionals tested. The top five functionals for 4-methylthiazolidine were M05-2X, mPW1PW, B97-2, M06-2X, and PBEh, with mean unsigned errors (MUEs) in bond length of 0.0017, 0.0020, 0.0023, 0.0025 and 0.0027 Å, respectively. The widely used B3LYP functional ranked 11(th) out of twelve functionals evaluated, slightly below SCC-DFTB, and is significantly less accurate for 4-methylthiazolidine bond distances (MUE = 0.0095 Å) than the best local functional (M06-L, MUE = 0.0030 Å), which is far less computationally costly. Based on that initial analysis, we obtained new M05-2X benchmark geometric parameters for PLG and a library of eleven peptidomimetic derivatives, which we in turn used to examine the accuracy of thirty-four popular molecular mechanics (MM) force fields, four NDDO approaches, and SCC-DFTB for the full compound structures. Here, we found that ∼70% of the MM force fields tested superior to the best semiempirical and SCC-DFTB codings. Moreover, AMBER-type force fields proved most accurate among MM methods for this class of small-molecule peptidomimetics; the AMBER-type methods comprised eight out of the top ten molecular mechanics options we tested.