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Analysis of Photodegradation Products of Organic Photochromes by LC/MS

  • Lim, Young-Hee;Youn, Yeu Young;Kim, Kyung Hoon;Cho, Hye-Sung
    • Mass Spectrometry Letters
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    • v.3 no.4
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    • pp.101-103
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    • 2012
  • The ultraviolet (UV) degradation products of photochromic naphthoxazine and naphthopyran derivatives in acetonitrile were separated and identified using liquid chromatography-mass spectrometry (LC-MS). Photodegradation resulted in oxidation of products.

Post-Antibiotic Effect of LB20304, A New Quinolone Antibiotic (새로운 퀴놀론 항생제 LB20304의 Post-Antibiotic Effect)

  • Ahn, Mi-Jeong;Paek, Kyoung-Sook;Kim, Mu-Yong;Kim, In-Chull;Kwak, Jin-Hwan
    • YAKHAK HOEJI
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    • v.40 no.3
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    • pp.347-350
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    • 1996
  • The post-antibiotic effect (PAE), which is defined as the period of time lag that the target organisms resume normal growth rate after complete removal of the antibiotics, of LB 20304 and ciprofloxacin was evaluated against Staphylococcus aureus 6538p and Escherichia coli 3190Y, respectively. The PAE was estimated by adding each antibiotic to a log phase of growth and incubating at $37^{\circ}$C for 1 h.Antibiotic was removed by centrifugation, and total viable cell counts were determined hourly for a further 10 h. The PAEs of LB20304 against S. aureus at concentrations of $1{\times}MIC\;and\;2{\mu}g/ml$ were 10 min and 93min, respectively. LB20304 showed a comparable PAE to ciprofloxacin. Against E. coli, the PAE of LB20304 was also similar to that of ciprofloxacin at concentration of $4{\times}MIC$ but it was much longer than that of ciprofloxacin at concentration of 2${\mu}g/ml$. LB20304 showed higher lethality than ciprofloxacin against both S. aureus and E. coli strains.

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