Antibacterial Activities of Metabolites from Vitis rotundifolia (Muscadine) Roots against Fish Pathogenic Bacteria

Enteric septicemia of catfish, columnaris disease and streptococcosis, caused by , and , respectively, are the most common bacterial diseases of economic significance to the pond-raised channel catfish industry. Certain management practices are used by catfish farmers to prevent large financial losses from these diseases such as the use of commercial antibiotics. In order to discover environmentally benign alternatives, using a rapid bioassay, we evaluated a crude extract from the roots of muscadine against these fish pathogenic bacteria and determined that the extract was most active against . Subsequently, several isolated compounds from the root extract were isolated. Among these isolated compounds, (+)-hopeaphenol ( ) and (+)-vitisin A ( ) were found to be the most active (bacteriostatic activity only) against , with 24-h 50% inhibition concentrations of 4.0 ± 0.7 and 7.7 ± 0.6 mg/L, respectively, and minimum inhibitory concentrations of 9.1 ± 0 mg/L for each compound which were approximately 25X less active than the drug control florfenicol. Efficacy testing of and is necessary to further evaluate the potential for these compounds to be used as antibacterial agents for managing columnaris disease.