ABSTRACT
<p><b>OBJECTIVE</b>To determine the visible light-induced photodegradation kinetics of two xanthene photosensitizers, phloxine B and uranine, in solution and on the surface of silica TLC plates, and to examine the phototoxicity of residues of degradation, which could provide valuable safety data on the two photosensitizers and other xanthene chemicals when applied in the environment.</p><p><b>METHODS</b>UV-Vis absorption during photodegradation was monitored with a Unico 2102 spectrophotometer. Organic content of samples was measured with a Shimadzu TOC 4100. Phototoxicity tests were carried out using Saccharomyces cerevisiae with the methods modified from Daniels.</p><p><b>RESULTS</b>When phloxine B and uranine degraded in solution, their apparent rate constant k was 0.0019 and 0.0027 min(-1), respectively. The total organic carbon (TOC) content decreased by approximately 50% during the 8 h irradiation period, which led to a gradual decrease in phototoxicity of the residues. The photodegradation of photosensitizers on the surface of silica TLC plates was much faster than that in the solution. The apparent rate constant k and the half life of phloxine B were 0.0073 min(-1) and 95 min, respectively.</p><p><b>CONCLUSION</b>Visible light can rapidly induce photodegradation of phloxine B and uranine. The phototoxicity of residues is also decreased. The environmental risk of applications of phloxine B and uranine is minimal.</p>
Subject(s)
Eosine I Bluish , Chemistry , Toxicity , Fluorescein , Chemistry , Toxicity , Kinetics , Molecular Structure , Photolysis , Photosensitizing Agents , Toxicity , Saccharomyces cerevisiae , Radiation EffectsABSTRACT
<p><b>OBJECTIVE</b>To evaluate the molluscicidal activities of three Chinese plants N. indicum Mill, R stenoptera DC, and R. japonicum Houtt, and to clarify the molluscicidal mechanism.</p><p><b>METHODS</b>N-butanol extracts and water extracts of the three plants were obtained. The reactions of EST isozyme, glycogen and total protein of snails to the plant extracts were studied.</p><p><b>RESULTS</b>EST electrophoresis showed that EST was an important antidotal enzyme system and reacted strongly to environment. EST changed greatly during the whole exposure period so that it could be viewed as a pathological index of toxicity. Extracts decreased the glycogen content of the snails' soft tissues greatly, and also the protein content.</p><p><b>CONCLUSION</b>All extracts show strong molluscicidal activity. The LD50 value of the water extract of N. indicum Mill is as low as 13.2 mg/L. EST can be viewed as a pathological index of toxicity. The energy metabolism abnormity is the key reason for the molluscicidal activities. The biochemical mechanism needs further research.</p>