Isoflavonoids and Coumarins from <i>Glycyrrhiza uralensis</i>: Antibacterial Activity against Oral Pathogens and Conversion of Isoflavans into Isoflavan-Quinones during Purification

Phytochemical investigation of a supercritical fluid extract of <i>Glycyrrhiza uralensis</i> has led to the isolation of 20 known isoflavonoids and coumarins, and glycycarpan (<b>7</b>), a new pterocarpan. The presence of two isoflavan-quinones, licoriquinone A (<b>8</b>) and licoriquinone B (<b>9</b>), in a fraction subjected to gel filtration on Sephadex LH-20 is due to suspected metal-catalyzed oxidative degradation of licoricidin (<b>1</b>) and licorisoflavan A (<b>2</b>). The major compounds in the extract, as well as <b>8</b>, were evaluated for their ability to inhibit the growth of several major oral pathogens. Compounds <b>1</b> and <b>2</b> showed the most potent antibacterial activities, causing a marked growth inhibition of the cariogenic species <i>Streptococcus mutans</i> and <i>Streptococcus sobrinus</i> at 10 μg/mL and the periodontopathogenic species <i>Porphyromonas gingivalis</i> (at 5 μg/mL) and <i>Prevotella intermedia</i> (at 5 μg/mL for <b>1</b> and 2.5 μg/mL for <b>2</b>). Only <b>1</b> moderately inhibited growth of <i>Fusobacterium nucleatum</i> at the highest concentration tested (10 μg/mL)

Fungal bis-Naphthopyrones as Inhibitors of Botulinum Neurotoxin Serotype A

An in silico screen of the NIH Molecular Library Small Molecule Repository (MLSMR) of ∼350000 compounds and confirmatory bioassays led to identification of chaetochromin A (<b>1</b>) as an inhibitor of botulinum neurotoxin serotype A (BoNT A). Subsequent acquisition and testing of analogues of <b>1</b> uncovered two compounds, talaroderxines A (<b>2</b>) and B (<b>3</b>), with improved activity. These are the first fungal metabolites reported to exhibit BoNT/A inhibitory activity