Adsorption of sulfonamides to marine diatoms and arthropods

Sulfonamides are frequently detected in the environment, where these compounds adsorb to soil particles and are retained in the environment. However, adsorption of sulfonamides to planktonic particles in the sea is not known. Here we demonstrate that sulfonamides adsorb to a diatom (Chaetoceros) and an arthropod (Artemia), albeit at low levels, under laboratory conditions. In both plankton, sulfamethazine (SMT) was more readily adsorbed than was sulfamethoxazole (SMX). The adsorption occurred quickly and the concentration on the plankton was stable for at least 24 h (Chaetoceros) or 5 h (Artemia). These data suggest that marine plankton may retain sulfonamides, although the adsorbed concentration per cell or individual is not high.     

Carbonic anhydrase activity of isolated brush border and basal-lateral membranes of renal tubular cells

Summary Carbonic anhydrase activity was found and characterized in isolated homogeneous preparations of microvilli and basal infoldings of the rat renal tubular cells. This membrane-bound activity was about 3% of the total carbonic anhydrase activity of the renal cortex. Compared to the renal cytoplasmic soluble form, the membrane-bound enzymes had the sameK _m for CO₂ and were equally resistant to inhibition by chloride. However, they were less inhibited by different sulfonamides. The implication of the existence of membrane-bound enzymes in the renal tubular cells is discussed.     

Environmental levels of ultraviolet light potentiate the toxicity of sulfonamide antibiotics in Daphnia magna

We assessed the phototoxicity of several major sulfonamide antibiotics, i.e., sulfathiazole, sulfamethazine, and sulfamethoxazole, using acute 48 and 96 h Daphnia magna immobilization toxicity test under several indoor and outdoor lighting conditions. The lighting conditions were as follows: (1) fluorescent light only, (2) continuous irradiation with 15 μW/cm² UVB, (3) pulsed irradiation with 90 μW/cm² UVB for 4 h/d, and (4) natural sunlight (outdoors). Laboratory tests showed that phototoxicity resulting from exposure to continuous UVB light generally increased the acute toxicity of the sulfonamides in D. magna by up to 2.3-fold. However, pulsed UVB exposure resulted in a greater increase in phototoxicity. Compared to fluorescent light only (no UVB), pulsed UVB irradiation (96 h) resulted in 12.0-, 5.8-, and 4.4-fold increases in toxicity for sulfamethazine, sulfathiazole, and sulfamethoxazole, respectively. This suggests that the mode of UV irradiation is more important than the dose (UV-intensity × exposure time) for the photo-enhancement of sulfonamide toxicity. Natural sunlight enhanced the toxicity of the sulfonamides to an even greater degree, likely because of the contribution of UVA light. This study suggests that without taking into account the effects of UV irradiation, it is possible to underestimate the actual consequences of phototoxic sulfonamide antibiotics in the aquatic environment.     

磺胺醌亚胺类化合物抑菌活性的测定

目的：通过抗菌活性测定来探讨磺胺醌亚胺化合物的抗菌效力及其结构与活性间的关系,为新的抗菌药物研制提供依据。方法：利用二倍稀释法测定了五种磺胺醌亚胺化合物对Staphylococcus aureus、Bacillus subtilis的最低抑菌浓度。结果：磺胺醌亚胺类化合物具有很强的抑菌活性,大多较母体磺胺化合物强,其中磺胺醌亚胺对S.aureus和B.subtilis的抑菌活性分别为氨基苯磺胺的2．5和1．2倍,磺胺嘧啶醌亚胺的抑菌活性分别为其母体化合物的13．1和6．1倍,磺胺噻唑醌亚胺的抑菌活性为其母体化合物的1．05和65．8倍,而磺胺吡啶醌亚胺对B.subtilis的抑菌活性有较大程度降低,仅为母体化合物的6．7％。结论：磺胺醌亚胺化合物有比磺胺类药物更强的抗菌活性,或者有与其母体化合物不同的抗菌谱。