著者

相山 律男 永井 久子 沢田 誠吾 横倉 輝男 糸川 秀治 中西 守

出版者

The Pharmaceutical Society of Japan

雑誌

Chemical and Pharmaceutical Bulletin (ISSN:00092363)

巻号頁・発行日

vol.40, no.10, pp.2810-2813, 1992-10-25 (Released:2008-03-31)

参考文献数

16

被引用文献数

12 16

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Self-association of irinotecan hydrochloride (CTP-11) in an aqueous solution was studied using UV, circular dichroism (CD), 1H-NMR and the quasi-elastic light scattering (QLS) method. The UV spectra showed a hypochromic effect in the aqueous solution. In the CD spectra, typically positive Davydov splitting was observed and the Δε value was reduced sigmoidally when the concentraion of CTP-11 was decreased. In the 1H-NMR, the aromatic signals of higher concentration shifted to a diamagnetic direction compared with those of lower concentration. These observations suggested that CPT-11 molecules are present as monomer in the lower concentration, and the self-association with positive helicity occurs by vertical stacking more than 10 μM of concentration. Its molecules form complete aggregates at more than 2 mM of the concentration. Results of QLS which coincided in the prediction of partition coefficient experiments suggested that CPT-11 molecules formed dimer under the condition. By the regression analysis of CD spectral data, the equilibrium constant for the self-association was calculated to be 2.41×10-4 M-1.