title: Acid-base catalysis of N-[(morpholine)methylene]daunorubicin.
abstract: The stability of N-[(morpholine)methylene]-daunorubicin hydrochloride (MMD) was investigated in the pH range 0.44-13.54, at 313, 308, 303 and 298 K. The degradation of MMD as a result of hydrolysis is a pseudo-first-order reaction described by the following equation: ln c = ln c(0) - k(obs)• t. In the solutions of hydrochloric acid, sodium hydroxide, borate, acetate and phosphate buffers, k(obs) = k(pH) because general acid-base catalysis was not observed. Specific acid-base catalysis of MMD comprises the following reactions: hydrolysis of the protonated molecules of MMD catalyzed by hydrogen ions (k(1)) and spontaneous hydrolysis of MMD molecules other than the protonated ones (k(2)) under the influence of water. The total rate of the reaction is equal to the sum of partial reactions: k(pH) = k(1) • a(H)+ • f(1) + k(2) • f(2) where: k(1) is the second-order rate constant (mol(-1) l s(-1)) of the specific hydrogen ion-catalyzed degradation of the protonated molecules of MMD; k(2) is the pseudo-first-order rate constant (s(-1)) of the water-catalyzed degradation of MMD molecules other than the protonated ones, f(1) - f(2) are fractions of the compound. MMD is the most stable at approx. pH 2.5.
authors: PozLab Sp z o.o., Parcowa, Poznań, Poland.
authors: Anna
authors: A
authors: Krause
authors: Anna
authors: A
authors: Jelińska
authors: Judyta
authors: J
authors: Cielecka-Piontek
authors: Maria
authors: M
authors: Klawitter
authors: Przemysław
authors: P
authors: Zalewski
authors: Irena
authors: I
authors: Oszczapowicz
authors: Małgorzata
authors: M
authors: Wąsowska
mesh_terms: D000136:Acid-Base Equilibrium; D002021:Buffers; D002384:Catalysis; D003630:Daunorubicin / Q000031:analogs & derivatives* / Q000737:chemistry; D004355:Drug Stability; D006863:Hydrogen-Ion Concentration; D006868:Hydrolysis; D007700:Kinetics; D009025:Morpholines / Q000737:chemistry*; D011522:Protons; D012996:Solutions / Q000737:chemistry; D013696:Temperature; D014867:Water / Q000737:chemistry
chemical_list: C561665:((N-morpholine)metylene)daunorubicin; D002021:Buffers; D009025:Morpholines; D011522:Protons; D012996:Solutions; D014867:Water; D003630:Daunorubicin