title: Isolation and identification of Flavobacterium columnare and Streptococcus iniae antibacterial compounds from the terrestrial plant Atraphaxis laetevirens.
abstract: Columnaris disease, enteric septicemia of catfish, and streptococcosis are common bacterial diseases of certain freshwater fish and are caused by  Flavobacterium columnare ,  Edwardsiella ictaluri , and  Streptococcus iniae , respectively. During the process of evaluating several species of plants to isolate and identify compounds with toxicity against these bacteria, a promising extract from the aerial parts of the terrestrial plant  Atraphaxis laetevirens  (Ledeb.) Jaub. et Spach (Polygonaceae Juss.) was selected for bioassay-guided fractionation using a rapid microplate bioassay. The active dichloromethane extract was subjected to liquid-liquid partitioning, and active fractions were further separated by normal-phase column chromatography and normal-phase high-performance liquid chromatography (HPLC). Nepodin (3) and emodin (4) were isolated from two fractions with strong toxicities against  S. iniae . A chloroform fraction was further separated by normal-phase column chromatography to yield two active fractions against  F. columnare , and these fractions contained chrysophanol (1), physcion (2), and nepodin (3). Compound 1 had strong activity, and compound 3 had moderate activity against  F. columnare , while compounds 2 and 4 were not toxic at the concentrations tested.
authors.affiliation: NARO Kyushu Okinawa Agricultural Research Center, 496 Izumi, Chikugo, Fukuoka 833-0041, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Nakano
authors.forename: Kevin K
authors.initials: KK
authors.lastname: Schrader
authors.forename: Leonid K
authors.initials: LK
authors.lastname: Mamonov
authors.forename: Tatyana S
authors.initials: TS
authors.lastname: Kustova
authors.forename: Valentina K
authors.initials: VK
authors.lastname: Mursaliyeva
authors.forename: Charles L
authors.initials: CL
authors.lastname: Cantrell
mesh_terms: D000900:Anti-Bacterial Agents / Q000302:isolation & purification* / Q000494:pharmacology; D002851:Chromatography, High Pressure Liquid; D005417:Flavobacterium / Q000187:drug effects*; D009682:Magnetic Resonance Spectroscopy; D008826:Microbial Sensitivity Tests; D013291:Streptococcus / Q000187:drug effects*
chemical_list: D000900:Anti-Bacterial Agents