Thermodynamic parameters
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Kritická micelová koncentrácia (CMC) lokálneho anestetika heptakaíniumchloridu v prostredí NaBr (0,1 mol/l a 0,2 mol/l) bola určená spektrofotometricky v UV oblasti spektra v teplotnom intervale t = 20–40 °C a pri pH ? 4,5–5,0. Závislosť CMC od teploty T mala tvar „U“ (U-shaped) s minimom pri teplote t = 25 °C. Zo závislosti ln (CMC)od T sme fitovaním polynómom druhého stupňa získali parabolické rovnice pre jednotlivé koncentrácie študovanej látky, z ktorých boli pomocou modelu fázovej separácie vypočítané termodynamické parametre micelizácie, ako sú: štandardná mólová Gibbsova energia (?G°), entalpia (?H°) a entropia (?S°).
The critical micellar concentration (CMC) of the local anaesthetic agent heptacainium chloride in the solution of NaBr was determined by the spectrophotometric method in the UV region of the spectrum at the temperature range of t = 20–40 °C and pH ? 4.5–5.0. The dependence of CMC on the temperature T formed a U-shaped curve with the minimum at the temperature of t = 25 °C. The CMC dependence on the temperature T was fitted by the second degree polynomical function. The obtained parabolic equations were applied to the “phase separation model” and the following thermodynamic parameters could be calculated: standard Gibbs free energy (?G°), enthalpy (?H°) and entropy (?S°).
Konduktometricky bol študovaný vplyv teploty na kritickú micelovú koncentráciu a termodynamické parametre micelizácie šiestich hydrochloridových solí lokálnych anestetík - prokaín (I), trimekaín (II), cinchokaín (III), tetrakaín (IV), pentakaín (V) a heptakaín (VI). V intervale teplot 15 až 45 °C boli namerané závislosti mernej vodivosti od koncentrácie, na ktorých boli pozorované dva výrazné zlomy zodpovedajúce atómom dusíka v skelete molekúl študovaných látok.
The effect of temperature on the critical micellar concentration and thermodynamic parameters of micelles formation of six hydrochloride salts of local anesthetics - procaine (I), trimecaine (II), cinchocaine (III), tetracaine (IV), pentacaine (V) and heptacaine (VI) - was studied by using conductometry. At the temperature interval from 15 to 45°C, the dependencies of the measured conductivity versus concentration of the studied compounds showed two explicit breaks in the direction related to the presence of nitrogen atom in the skeleton of these compounds.
Táto práca opisuje teoretickú stránku procesu enantiomerizácie. Vysvetľuje pojem „enantiomerizácia“ a charakterizuje jej základné črty (vznik platá). Venuje sa aj komplikáciám, ktoré tento jav spôsobuje, či už z analytického alebo farmakologického hľadiska. Definuje spôsoby výpočtu energetickej bariéry enantiomerizácie podľa metódy použitej na separáciu racemických zmesí (metóda zastavenia prietoku alebo dynamická chromatografia). Ďalej opisuje matematické modely používané pri dekonvolúcii chromatografických záznamov. Pri dynamických metódach nie je možné bez počítačom asistovanej dekonvolúcie namerané chromatografické záznamy kvantitatívne vyhodnotiť, a teda aj výpočet termodynamických parametrov nie je možný.
The paper explains the theoretical aspects of the process of enantiomerization and describes its characteristic features (generation of a plateau). In addition, some complications are presented that are produced by enantiomerization either from analytical or pharmacological points of view. It also defines the way of how to calculate energy barriers of enantiomerization according to the methods used for the separation of racemic mixtures (stopped-flow or dynamic chromatography). Mathematic models useful in deconvolution of chromatograms are also described. With the use of dynamic methods it is not possible to quantitatively evaluate the obtained chtromatograms and calculate thermodynamic parameters without computer-assisted deconvolution.
Kritická micelová koncentrácia lokálneho anestetika heptakaíniumchloridu v prostredí KBr (0,1 mol/l a 0,2 mol/l) bola určená spektrofotometricky v UV oblasti spektra v teplotnom intervale t =2 0–40 °C a pri pH ? 4,5–5,0. Závislosť CMC od teploty T mala tvar „U“ (U-shaped) s minimom pri teplote t = 25 °C. Parabolická závislosť CMC od teploty T bola fitovaním hodnôt charakterizovaná pomocou tzv. „power-law“ rovnice. Zo závislosti ln (CMC) od T sme fitovaním polynómom druhého stupňa získali parabolické rovnice pre jednotlivé koncentrácie študovanej látky, z ktorých boli pomocou modelu fázovej separácie vypočítané termodynamické parametre, ako sú: štandardná mólová Gibbsova energia (?G°), entalpia (?H°) a entropia (?S°). Z termodynamických parametrov bola ďalej určená tzv. „enthalpy-entropy“ kompenzácia pre študované prostredia. Kompenzačné teploty Tc sa pohybovali v rozmedzí (301 ± 1–303 ± 3) K. Napokon boli určené energetické príspevky entalpie (?H°) a entropie (–T?S°) k štandardnej mólovej Gibbsovej energii (?G°).
The critical micellar concentration (CMC) of the local anaesthetic agent heptacainium chloride in the solution of KBr was determined by the spectrophotometric method in the UV region of the spectrum at the temperature range of t = 20–40 °C and pH ? 4.5–5.0. The dependence of CMC on the temperature T turned out forming the U-shape with the minimum at the temperature of t = 25 °C. The parabolic dependence of CMC on the temperature T was drawn by the fitting of the values using the polynomial function and the so-called power law equation. The CMC dependence on the temperature T was fitted by the second degree polynomial function. The obtained parabolic equations were applied to the “phase separation model”, so the following thermodynamic parameters could be calculated: standard Gibbs free energy (?G°), enthalpy (?H°), and entropy (?S°). The thermodynamic parameters were further used to determine the so-called entropy-enthalpy compensation of the systems under study. The compensation temperature was in the following range: (301 ± 1–303 ± 3)K. Then the temperature dependence of the enthalpy (?H°) and entropy (–T?S°) contributions to the standard Gibbs free energy (?G°) for all prepared concentrations of the compound were calculated.
Three potential anticancer agents {trans-[PtCl(2)(NH(3))(thiazole)], cis-[PtCl(2)(NH(3))(piperidine)], and PtCl(2)(NH(3))(cyclohexylamine) (JM118)} were explored and compared with cisplatin and the inactive [PtCl(dien)](+) complex. Basic electronic properties, bonding and stabilization energies were determined, and thermodynamic and kinetic parameters for the aquation reaction were estimated at the B3LYP/6-311++G(2df,2pd) level of theory. Since the aquation process represents activation of these agents, the obtained rate constants were compared with the experimental IC(50) values for several tumor cells. Despite the fact that the processes in which these drugs are involved and the way in which they affect cells are very complex, some correlations can be deduced.
- MeSH
- chemické modely MeSH
- cisplatina farmakologie chemie MeSH
- elektrony MeSH
- financování organizované MeSH
- inhibiční koncentrace 50 MeSH
- kinetika MeSH
- lidé MeSH
- ligandy MeSH
- nádorové buněčné linie MeSH
- organoplatinové sloučeniny farmakologie chemie MeSH
- počítačová simulace MeSH
- protinádorové látky farmakologie chemie MeSH
- sloučeniny platiny chemie MeSH
- termodynamika MeSH
- thiazoly farmakologie chemie MeSH
- voda chemie MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- srovnávací studie MeSH
Konduktometricky bol študovaný vplyv chloridu sodného a hydrotropných látok - jednosýtnych alkoholov (metylalkoholu, etylalkoholu, propylalkoholu) a glycerolu na kritickú micelovú koncentráciu (CMC) šiestich hydrochloridových solí lokálnych anestetík - prokaín (I), trimekaín (II), cinchokaín (III), tetrakín (IV), pentakaín (V) a heptakaín (VI). Bolo zistené, že CMC lokálnych anestetík v roztoku 0,9% chloridu sodného klesá asi na polovicu, kým prídavok alkoholov zvyšuje CMC študovaných lokálnych anestetík vzhľadom k CMC týchto látok určených vo vode.
The effect of sodium chloride andhydrotropic compounds, 1-alcohols (methanol, ethanol, 1-propanol) and glycerol, on the critical micelle concentration (CMC) of six hydrochloride salts of local anesthetics - procaine (I), trimecaine (II), cinchocaine (III), tetracaine (IV), pentacaine (V) and heptacaine (VI) - has been studied by conductivity measurement. The results showed that CMC of the local anestetics decreased to about 50% in 0.9% sodium chloride solution, while an addition of alcocohols used increased CMC of these local anesthetics in comparison to their CMC in water.
Interaction of hydrated forms of several potential anticancer agents (PtCl2(diaminocyclohexane), trans-[PtCl2(NH3)(thiazole)], cis-[PtCl2(NH3)(piperidine)], and cis-PtCl2(NH3)(cyclohexylamine) complexes) with guanine are explored and compared with an analogous interaction of cisplatin. Basic electronic properties, binding and stabilization energies are determined and energy profiles for the aquation reaction are estimated at the B3LYP/6-311++G(2df,2pd) level of theory. It is found that the substitution reaction is an exothermic and exergonic process with ΔG slightly less negative than -20kcal/mol. The largest energy release occurs for PtCl(H2O)(diaminocyclohexane) complex. The rate constants for the Pt(II) complexes in the chloro- and hydroxo-form are compared and an impact of the ligand in the trans position to water is discussed.
