TY - JOUR
T1 - Action mechanism of 6, 6′-dihydroxythiobinupharidine from Nuphar japonicum, which showed anti-MRSA and anti-VRE activities
AU - Okamura, Shinya
AU - Nishiyama, Eri
AU - Yamazaki, Tomohiro
AU - Otsuka, Nao
AU - Taniguchi, Shoko
AU - Ogawa, Wakano
AU - Hatano, Tsutomu
AU - Tsuchiya, Tomofusa
AU - Kuroda, Teruo
N1 - Funding Information:
We would like to thank Drs. K. Hiramatsu and T. Takenouchi for kindly providing other S. aureus strains. We appreciate Ms. S. Nishioka at the Division of Instrumental Analysis for MS spectrum measurements, and the SC-NMR Laboratory of Okayama University for the acquisition of NMR spectra. This work was supported by the Drug Discovery for Intractable Infectious Diseases Project, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University to T.K.
Publisher Copyright:
© 2015 Elsevier B.V.
PY - 2015/6
Y1 - 2015/6
N2 - Background Multidrug-resistant bacteria, such as methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin resistant enterococci (VRE), cause serious infections at clinical sites, for which the development of new drugs is necessary. We screened candidates for new antibiotics and investigated its action mechanism. Methods An antimicrobial compound was isolated from an extract of Nuphar japonicum. Its chemical structure was determined by NMR, MS, and optical rotation. We measured its minimum inhibitory concentration (MIC) using the microdilution method. The effects of the compound on DNA gyrase and DNA topoisomerase IV were investigated with DNA supercoiling, decatenation, and cleavage assay. Results We isolated and identified 6,6′-dihydroxythiobinupharidine as the antimicrobial compound. The MIC of this compound was 1-4 μg/mL against various MRSA and VRE strains. We also demonstrated that this compound inhibited DNA topoisomerase IV (IC50 was 10-15 μM), but not DNA gyrase in S. aureus, both of which are known to be the targets of quinolone antibiotics and necessary for DNA replication. However, this compound only exhibited slight cross-resistance to norfloxacin-resistant S. aureus, which indicated that DTBN might inhibit other targets besides topoisomerase IV. These results suggest that 6,6′-dihydroxythiobinupharidine may be a potent candidate or seed for novel antibacterial agents. Conclusions DTBN from N. japonicum showed anti-MRSA and anti-VRE activities. DTBN might be involved in the inhibition of DNA topoisomerase IV. General significance DTBN might be useful as a seed compound. The information on the inhibition mechanism of DTBN will be useful for the modification of DTBN towards developing novel anti-MRSA and anti-VRE drug.
AB - Background Multidrug-resistant bacteria, such as methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin resistant enterococci (VRE), cause serious infections at clinical sites, for which the development of new drugs is necessary. We screened candidates for new antibiotics and investigated its action mechanism. Methods An antimicrobial compound was isolated from an extract of Nuphar japonicum. Its chemical structure was determined by NMR, MS, and optical rotation. We measured its minimum inhibitory concentration (MIC) using the microdilution method. The effects of the compound on DNA gyrase and DNA topoisomerase IV were investigated with DNA supercoiling, decatenation, and cleavage assay. Results We isolated and identified 6,6′-dihydroxythiobinupharidine as the antimicrobial compound. The MIC of this compound was 1-4 μg/mL against various MRSA and VRE strains. We also demonstrated that this compound inhibited DNA topoisomerase IV (IC50 was 10-15 μM), but not DNA gyrase in S. aureus, both of which are known to be the targets of quinolone antibiotics and necessary for DNA replication. However, this compound only exhibited slight cross-resistance to norfloxacin-resistant S. aureus, which indicated that DTBN might inhibit other targets besides topoisomerase IV. These results suggest that 6,6′-dihydroxythiobinupharidine may be a potent candidate or seed for novel antibacterial agents. Conclusions DTBN from N. japonicum showed anti-MRSA and anti-VRE activities. DTBN might be involved in the inhibition of DNA topoisomerase IV. General significance DTBN might be useful as a seed compound. The information on the inhibition mechanism of DTBN will be useful for the modification of DTBN towards developing novel anti-MRSA and anti-VRE drug.
KW - DNA topoisomerase IV
KW - MRSA
KW - Nuphar japonicum
KW - VRE
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U2 - 10.1016/j.bbagen.2015.02.012
DO - 10.1016/j.bbagen.2015.02.012
M3 - Article
C2 - 25731981
AN - SCOPUS:84924066603
VL - 1850
SP - 1245
EP - 1252
JO - Biochimica et Biophysica Acta - General Subjects
JF - Biochimica et Biophysica Acta - General Subjects
SN - 0304-4165
IS - 6
ER -