Search

Musty "off-flavor" in pond-cultured channel catfish (Ictalurus punctatus) costs the catfish production industry in the United States at least $30 million annually. The cyanobacterium Oscillatoria perornata (Skuja) is credited with being the major cause of musty off-flavor in farm-raised catfish in Mississippi. The herbicides diuron and copper sulfate, currently used by catfish producers as algicides to help mitigate musty off-flavor problems, have several drawbacks, including broad-spectrum toxicity towards the entire phytoplankton community that can lead to water quality deterioration and subsequent fish death. By use of microtiter plate bioassays, a novel group of compounds derived from the natural compound 9,10-anthraquinone have been found to be much more selectively toxic towards O. perornata than diuron and copper sulfate. In efficacy studies using limnocorrals placed in catfish production ponds, application rates of 0.3 µM (125 µg/liter) of the most promising anthraquinone derivative, 2-[methylamino-N-(1'-methylethyl)]-9,10-anthraquinone monophosphate (anthraquinone-59), dramatically reduced the abundance of O. perornata and levels of 2-methylisoborneol, the musty compound produced by O. perornata. The abundance of green algae and diatoms increased dramatically 2 days after application of a 0.3 µM concentration of anthraquinone-59 to pond water within the limnocorrals. The half-life of anthraquinone-59 in pond water was determined to be 19 h, making it much less persistent than diuron. Anthraquinone-59 appears to be promising for use as a selective algicide in catfish aquaculture. [ABSTRACT FROM AUTHOR]

Abstract: Anti-inflammatory and analgesic activities as well as the median lethal dose (LD50) of water–ethanolic extract (PHE) of the aerial parts of Pothomorphe umbellata were evaluated in animal models. The ED50 (oral) for the inhibition of carrageenan-induced rat paw edema assay was determined to be 550mg/kg, while the LD50 was higher than 2.0g/kg. At a dose of 550mg/kg, PHE inhibited the inflammatory process by 48.7% (P <0.05) on the third hour of the assay (edema peak) when compared to the untreated control. Indomethacin, the positive control used in this test, inhibited the edema by 58.6% at a dose of 10mg/kg, when compared to the untreated control (P <0.05). All three fractions – hexane, methylene chloride and ethyl acetate – obtained by partition of PHE with respective solvents also showed inhibition of the edema induced by carrageenan over a period of 4h but the methylene chloride fraction showed the best activity. The activity shown by the methylene chloride fraction at 200mg/kg was comparable to that exhibited by indomethacin at a dose of 10mg/kg. The number of writhings induced by a 0.6% acetic acid solution intraperitoneal injection was decreased by 22% (P <0.05) in the group treated orally with Pothomorphe umbellata crude extract. PHE also inhibited the granulomatous tissue formation in rats by 6.2% (P <0.05). In the same assay, topically applied dexamethasone decreased the granuloma formation by 14.2%. The above results suggest that Pothomorphe umbellata crude extract has analgesic and anti-inflammatory properties supporting its folkloric use for the treatment of these conditions. [Copyright &y& Elsevier]