Identification of Dihydromyricetin and Metabolites in Serum and Brain Associated with Acute Anti-Ethanol Intoxicating Effects in Mice.

Dihydromyricetin is a natural bioactive flavonoid with unique GABAA receptor activity with a putative mechanism of action to reduce the intoxication effects of ethanol. Although dihydromyricetin's poor oral bioavailability limits clinical utility, the promise of this mechanism for the treatment of alcohol use disorder warrants further investigation into its specificity and druggable potential. These experiments investigated the bioavailability of dihydromyricetin in the brain and serum associated with acute anti-intoxicating effects in C57BL/6J mice. Dihydromyricetin (50 mg/kg IP) administered 0 or 15-min prior to ethanol (PO 5 g/kg) significantly reduced ethanol-induced loss of righting reflex. Total serum exposures (AUC0→24) of dihydromyricetin (PO 50 mg/kg) via oral (PO) administration were determined to be 2.5 µM × h (male) and 0.7 µM × h (female), while intraperitoneal (IP) administration led to 23.8-fold and 7.2- increases in AUC0→24 in male and female mice, respectively. Electrophysiology studies in α5ß3γ2 GABAA receptors expressed in Xenopus oocytes suggest dihydromyricetin (10 µM) potentiates GABAergic activity (+43.2%), and the metabolite 4-O-methyl-dihydromyricetin (10 µM) negatively modulates GABAergic activity (-12.6%). Our results indicate that administration route and sex significantly impact DHM bioavailability in mice, which is limited by poor absorption and rapid clearance. This correlates with the observed short duration of DHM's anti-intoxicating properties and highlights the need for further investigation into mechanism of DHM's potential anti-intoxicating properties.

Acylpyrazoline-Based Third-Generation Selective Antichlamydial Compounds with Enhanced Potency.

Chlamydiae are obligate intracellular Gram-negative bacteria and widespread pathogens in humans and animals. Broad-spectrum antibiotics are currently used to treat chlamydial infections. However, broad-spectrum drugs also kill beneficial bacteria. Recently, two generations of benzal acylhydrazones have been shown to selectively inhibit chlamydiae without toxicity to human cells and lactobacilli, which are dominating, beneficial bacteria in the vagina of reproductive-age women. Here, we report the identification of two acylpyrazoline-based third-generation selective antichlamydials (SACs). With minimal inhibitory concentrations (MIC) and minimal bactericidal concentrations (MBC) of 10-25 µM against Chlamydia trachomatis and Chlamydia muridarum, these new antichlamydials are 2- to 5-fold more potent over the benzal acylhydrazone-based second-generation selective antichlamydial lead SF3. Both acylpyrazoline-based SACs are well tolerated by Lactobacillus, Escherichia coli, Klebsiella, and Salmonella as well as host cells. These third-generation selective antichlamydials merit further evaluation for therapeutic application.