Influence of ethylene-oxy spacer group on the activity of linezolid: synthesis of potent antibacterials possessing a thiocarbonyl group

The influence of an ethylene-oxy spacer element between the heterocycle and the aromatic ring in linezolid is reported. The introduction of such spacer group generated compounds with inferior antibacterial activity. However, the conversion of the acetamide group present in the linezolid analogues to either thiocarbamate or thioacetamide functionality restored the activity. The synthesis of linezolid analogues possessing the ethylene-oxy spacer group along with SAR studies with different heterocycles and preparation of some thiocarbonyl compounds possessing potent antibacterial property are presented.     

Impact of intensive cage fish farming on the phytoplankton and periphyton of a Scottish freshwater loch

Nutrients, phytoplankton and periphyton were monitored in a 71 ha shallow, unstratified lake used for intensive cage culture of rainbow trout. Inorganic nitrogen, ortho-phosphate and suspended solids were significantly higher near the cages and the bottom and, although declining during summer, nutrients did not reach levels which limit phytoplankton growth. Microcystis aeruginosa dominated the phytoplankton, with surface chlorophyll a reaching 189 µg l^–1 in August, but with no subsequent bloom collapse or deoxygenation. A sub-dominant community of vernal diatoms and Pediastrum spp. persisted. Periphyton was dominated by Melosira italica-subarctica. Algal species and water quality showed the lake to be highly eutrophic. Chlorophyll values predicted from a phosphorus-dependent eutrophication model agreed with observations but light limitation by self-shading and suspended farm wastes, aided by wind-induced turbulence, is believed to control algal growth rates and biomass. Implications for environmental management of intensive freshwater cage farms are discussed.