(Biphenyl-4-yl)methylammonium chlorides: potent anticonvulsants that modulate Na+ currents

Semisynthetic guanidino lipoglycopeptides with potent in vitro and in vivo antibacterial activity

Gram-positive bacterial infections present a major clinical challenge, with methicillin- and vancomycin-resistant strains continuing to be a cause for concern. In recent years, semisynthetic vancomycin derivatives have been developed to overcome this problem as exemplified by the clinically used telavancin, which exhibits increased antibacterial potency but has also raised toxicity concerns. Thus, glycopeptide antibiotics with enhanced antibacterial activities and improved safety profiles are still necessary. We describe the development of a class of highly potent semisynthetic glycopeptide antibiotics, the guanidino lipoglycopeptides, which contain a positively charged guanidino moiety bearing a variable lipid group. These glycopeptides exhibited enhanced in vitro activity against a panel of Gram-positive bacteria including clinically relevant methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant strains, showed minimal toxicity toward eukaryotic cells, and had a low propensity for resistance selection. Mechanistically, guanidino lipoglycopeptides engaged with bacterial cell wall precursor lipid II with a higher binding affinity than vancomycin. Binding to both wild-type d-Ala-d-Ala lipid II and the vancomycin-resistant d-Ala-d-Lac variant was confirmed, providing insight into the enhanced activity of guanidino lipoglycopeptides against vancomycin-resistant isolates. The in vivo efficacy of guanidino lipoglycopeptide EVG7 was evaluated in a S. aureus murine thigh infection model and a 7-day sepsis survival study, both of which demonstrated superiority to vancomycin. Moreover, the minimal to mild kidney effects at supratherapeutic doses of EVG7 indicate an improved therapeutic safety profile compared with vancomycin. These findings position guanidino lipoglycopeptides as candidates for further development as antibacterial agents for the treatment of clinically relevant multidrug-resistant Gram-positive infections.

Chimeric derivatives of functionalized amino acids and α-aminoamides: compounds with anticonvulsant activity in seizure models and inhibitory actions on central, peripheral, and cardiac isoforms of voltage-gated sodium channels

Six novel 3″-substituted (R)-N-(phenoxybenzyl) 2-N-acetamido-3-methoxypropionamides were prepared and then assessed using whole-cell, patch-clamp electrophysiology for their anticonvulsant activities in animal seizure models and for their sodium channel activities. We found compounds with various substituents at the terminal aromatic ring that had excellent anticonvulsant activity. Of these compounds, (R)-N-4'-((3″-chloro)phenoxy)benzyl 2-N-acetamido-3-methoxypropionamide ((R)-5) and (R)-N-4'-((3″-trifluoromethoxy)phenoxy)benzyl 2-N-acetamido-3-methoxypropionamide ((R)-9) exhibited high protective indices (PI=TD50/ED50) comparable with many antiseizure drugs when tested in the maximal electroshock seizure test to mice (intraperitoneally) and rats (intraperitoneally, orally). Most compounds potently transitioned sodium channels to the slow-inactivated state when evaluated in rat embryonic cortical neurons. Treating HEK293 recombinant cells that expressed hNaV1.1, rNaV1.3, hNaV1.5, or hNaV1.7 with (R)-9 recapitulated the high levels of sodium channel slow inactivation.

Chimeric agents derived from the functionalized amino acid, lacosamide, and the α-aminoamide, safinamide: evaluation of their inhibitory actions on voltage-gated sodium channels, and antiseizure and antinociception activities and comparison with lacosamide and safinamide

The functionalized amino acid, lacosamide ((R)-2), and the α-aminoamide, safinamide ((S)-3), are neurological agents that have been extensively investigated and have displayed potent anticonvulsant activities in seizure models. Both compounds have been reported to modulate voltage-gated sodium channel activity. We have prepared a series of chimeric compounds, (R)-7–(R)-10, by merging key structural units in these two clinical agents, and then compared their activities with (R)-2 and (S)-3. Compounds were assessed for their ability to alter sodium channel kinetics for inactivation, frequency (use)-dependence, and steady-state activation and fast inactivation. We report that chimeric compounds (R)-7–(R)-10 in catecholamine A-differentiated (CAD) cells and embryonic rat cortical neurons robustly enhanced sodium channel inactivation at concentrations far lower than those required for (R)-2 and (S)-3, and that (R)-9 and (R)-10, unlike (R)-2 and (S)-3, produce sodium channel frequency (use)-dependence at low micromolar concentrations. We further show that (R)-7–(R)-10 displayed excellent anticonvulsant activities and pain-attenuating properties in the animal formalin model. Of these compounds, only (R)-7 reversed mechanical hypersensitivity in the tibial-nerve injury model for neuropathic pain in rats.

Substituted N-(biphenyl-4'-yl)methyl (R)-2-acetamido-3-methoxypropionamides: potent anticonvulsants that affect frequency (use) dependence and slow inactivation of sodium channels

We prepared 13 derivatives of N-(biphenyl-4′-yl)methyl (R)-2-acetamido-3-methoxypropionamide that differed in type and placement of a R-substituent in the terminal aryl unit. We demonstrated that the R-substituent impacted the compound’s whole animal and cellular pharmacological activities. In rodents, select compounds exhibited excellent anticonvulsant activities and protective indices (PI = TD₅₀/ED₅₀) that compared favorably with clinical antiseizure drugs. Compounds with a polar, aprotic R-substituent potently promoted Na⁺ channel slow inactivation and displayed frequency (use) inhibition of Na⁺ currents at low micromolar concentrations. The possible advantage of affecting these two pathways to decrease neurological hyperexcitability is discussed.