• Bulletin of the Korean Chemical Society
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• v.12 no.4
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• pp.411-413
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• 1991

The effects of electrolyte on the critical micelle concentration (cmc) and bromide counterion binding in the micelles of cetylpyridinium bromide (CPB) have been investigated by UV spectroscopy and conductance measurements. Salts used in this study decreased cmc in the order $Cl^-\;<\;Br^-\;<\;NO3^-$ (which parallels the lyotropic series for the inorganic anions) and the effects on cmc followed the equation proposed by Shinoda: log cmc = A - B log (cmc + [NaX]). In the equation, constant B represents the counterion binding to the micelles at cmc and for the micelle of CPB at $25^{\circ}C$, B=80.76%. The association constant for the binding of counterions to long chain cations within micelles was also derived from the cmc values and counterion binding constant to the micelles.

• Bulletin of the Korean Chemical Society
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• v.26 no.11
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• pp.1843-1845
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• 2005

• Bulletin of the Korean Chemical Society
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• v.31 no.2
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• pp.464-466
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• 2010

• Bulletin of the Korean Chemical Society
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• v.31 no.1
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• pp.202-204
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• 2010

• Bulletin of the Korean Chemical Society
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• v.28 no.9
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• pp.1598-1600
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• 2007

• Bulletin of the Korean Chemical Society
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• v.33 no.4
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• pp.1341-1344
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• 2012

• Bulletin of the Korean Chemical Society
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• v.30 no.11
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• pp.2782-2784
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• 2009

• Bulletin of the Korean Chemical Society
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• v.34 no.1
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• pp.283-286
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• 2013

• Bulletin of the Korean Chemical Society
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• v.25 no.4
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• pp.539-544
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• 2004

The ability of protoberberine alkaloids, berberine and berberrubine, to act as topoisomerase II poisons is linked to the anti-cancer activity. Minor alterations in structure have a significant effect on their relative activity. Berberine, which has methoxy group at the 19-position, is significantly less potent than berberrubine. Several observations support non-specific binding to HP14 by the berberine: (i) nonspecific upfield changes in $^1H$ chemical shift for protons of the berberine; (ii) the broadening of imino protons of HP14 upon binding of the berberine; (iii) very small increases in duplex melting temperature in the presence of the berberine. Our results reveal that substitution of a hydroxyl group to a methoxy group on the 19-position, thereby converting the berberrubine to the berberine is associated with a non-specific DNA binding affinity and a reduced topoisomerase II poisoning. The presence of a bulky 19-methoxy substituent decreases intercalating properties of berberine and makes it inactive as topoisomerase II poison.

• Archives of Pharmacal Research
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• v.19 no.6
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• pp.462-468
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• 1996

The present study was undertaken to investigate the effects of age on angiotensin II (AII) response and antagonistic activity of losartan using aortic rings and liver homogenates from rats ranging in age from 0.7 to 20 months. Whether the endothelium was present or not, the maximum contractile response to AII decreased with age. Removal of the endothelium enhanced AII-induced maximum contraction and these endothelial effects seemed to be due to endothelium-derived relaxing factor (EDRF) in all ages. Equilibrium binding studies demonstrated an age-related decrease in maximum binding $(B_{max})$ with little change in binding affinity $(K_d)$. In rat aorta, the extent of losartan-induced parallel shifts $(K_B)$ in AII concentration-response curves was not significantly different between ages. In addition, $IC_{50}$ value of losartan in competition binding was not changed with age in rat liver homogenates. These results suggest that the potency of losartan is not altered with age in rat aorta and liver, although AII-induced contractile response and the maximum AII binding decreased significantly with age.