- PH-triggered solubility and cytotoxicity changes of malachite green derivatives incorporated in liposomes for killing cancer cells
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Three different malachite green leuco derivatives (MG-Xs) are incorporated in liposomes. In all three cases, a substituent (X) is covalently linked to the central carbon atom, abbreviated as MG-OH, MG-OCH3, and MG-CN. The three MG-X compounds are solubilized separately in liposome membranes and become cationic (MG+) and water soluble under acidic conditions. MG+ is consequently released from the liposome to the aqueous exterior. Their release behavior corresponds to their ionization ability: MG-OH > MG-OCH3 > MG-CN. The cellular uptake of the liposomes, the cytotoxic effect, and the location of MG+ in cancer cells are investigated using murine cells derived from colon cancer (Colon 26 cells) and human embryonic kidney cells (HEK 293 cells). The toxic effect on cancer cells is correlated to the ionization ability of MG-Xs. The liposomes effectively deliver MG+via the endocytic pathway, resulting in the cytotoxicity of liposomes containing MG-OH which is higher than that of free MG-OH and MG+. The difference in the phospholipids constituting the liposome membranes barely had an effect on the ionization ratio and the cytotoxicity of MG-OH. Confocal fluorescence microscopic observations revealed that MG+ is ultimately transported into the nuclei after being released in acidic cellular compartments.
- Hayashi, Keita,Iwasaki, Tomoyuki,Uda, Ryoko M.,Yoshida, Nao
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- The Relative Electrophilic Reactivities of Tropylium Cation and its (OC)3M ?-Complexes: Kinetic Studies of Alkoxide Transfer and Reversible Nucleophilic Addition
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?-Complexation of the tropylium cation (Tr)(1+) with an (OC)3Cr group increases thermodynamic stability (ΔpKR+ ca. 4.3 in methanol) and reduces reactivity towards abstraction of methoxide ion from Malachite Green methyl ether (MG)OMe (krel. ca. 110) in MeNO2 - MeCOEt (40:60 v/v) and nucleophilic exoaddition of methanol (krel. ca. 2100) in methanol.The organometallic cation (1a) is stable in aqueous solutions of pH(1+), (1+), and (1+) in MeNO2-MeCOEt (40:60 v/v) are 1:10:6, respectively.The rates of transfer to (Tr)(1+) of alkoxide ion from (η-7-exo-alkoxycycloheptatriene)Cr(CO)3 complexes (2a-d) in MeCN decrease through the series: alkoxy=methoxy>ethoxy>isopropoxy>t-butoxy, but the overall rate change is only about five-fold.In methanol, the 7-exo-methoxycycloheptatriene complex (2a) is about ten times more reactive towards acid heterolysis than is methyl tropyl ether.This conversion is general acid-catalysed.In aqueous solutions of pH>ca. 6, the rate of spontaneous heterolysis of the ether (2a) is substantially faster than that of consumption of the resulting cation (1a) which increases with increasing pH.The 7-endo-methoxy stereoisomer (3) is inert to acid heterolysis in aqueous solutions to give cation (1a), but undergoes decomplexation to give (Tr)(1+).
- Lal, Kasturi,Leckey, Nigel T.,Watts, William, E.,Bunton, Clifford A.,Mhala, Marutirao M.,Moffatt, John R.
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p. 1091 - 1098
(2007/10/02)
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- EFFECT OF ELECTROPHILE STRUCTURE ON RITCHIE EQUATION PARAMETERS
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A joint examination of the Ritchie and Hammett equations on the basis of a spectrophotometric study of the kinetics for the formation of methyl esters of triarylcarbinols and literature data on the kinetics for the formation of triarylcarbinols showed that, contrary to Ritchie's proposal, the N+ nucleophilicity parameter of any nucleophilic system depends on the selection of the standard electrophile.The merits for introducing the parameter α, which is dependent on the nature of the substrate, into the Ritchie equation were confirmed.The significant deviation of this parameter from unity observed for a series of antipyrine cations was attributed to direct polar conjugation of +C substituents with the reaction site and through-space screening of this site by antipyryl radicals.
- Sinev, V. V.,Ginzburg, O. F.,Kuznetsova, V. P.
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p. 991 - 995
(2007/10/02)
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- CORRELATION ANALYSIS OF THE TRANSFORMATIONS OF TRIARYLMETHYL CATIONS IN A NUCLEOPHILE-MIXED SOLVENT SYSTEM
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The nucleophilicity parameters N+ were determined for systems containing a mixed solvent.It was shown that for a more accurate description of the reactivity of triarylcarbocations it is necessary to use the equation log k = log k0 + αN+; in this α does not depend on the nature of the nucleophilic system and is a characteristic of the electrophilic reagent.
- Sinev, V. V.,Kuznetsova, V. P.,Ginzburg, O. F.
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p. 860 - 864
(2007/10/02)
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