Esterification of citric acid (CA) with locust bean gum (LBG) was prepared by hydrochloric acid (HCl) as a catalyst and UV irradiation (254 nm) as esterification energy. This study aims to determine the best conditions of esterification. Other than that, it is to know the effect of amount HCl and UV irradiation time for the esterification process of CA with LBG. The amounts of HCl are 0.18 and 0.30 M, while the variations of UV irradiation time are 75 and 100 minutes. Polyester (CA-LBG) were characterized by Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance (NMR), scanning electron microscopy (SEM), differential scanning calorimetry (DSC), X-ray diffractometer (XRD), esterification degree, and viscosity. Parameters for determining the best conditions for esterification are esterification degree and viscosity. The best conditions of esterification were obtained by using 0.30 M mL HCl and 100 minutes of UV irradiation time resulted in CA-LBG having a value of esterification degree 9.69 % and viscosity 7.46 cPs. HCl accelerates protonation on the O atoms and the formation of positive C atoms of carbonyl groups of citric acid. The time of UV irradiation gives the longer energy for the bond formation between the positive C atoms of the carbonyl group and the O atoms of the hydroxyl group at C-6 atoms of mannose and galactose.
Physicochemical properties of neutral N-acyloxyalkyl derivatives of phenytoin in aqueous, organic solvents and simulated intestinal fluid were evaluated. Based on the hypothesis that these low melting prodrugs may have improved physical properties such as solubility and dissolution rate in gastrointestinal fluid, an enhanced bioavailability of these prodrugs may be observed relative to phenytoin. Melting points, aqueous solubilities, and octanol-water (Poct) and cylcohexane-water (Pcyc) partition coefficients of phenytoin and its prodrugs were determined. A simulated intestinal bile salts-lecithin mixture (SIBLM) was also prepared to possibly mimic the intestinal fluid content. Solubility and dissolution rates of phenytoin and its prodrugs were conducted in aqueous buffer and SIBLM. Apparent micelle-water partition coefficients (Kapp) were calculated by using the aqueous and SIBLM equilibrium solubility data. These properties were qualitatively or quantitatively correlated to the alkyl chain length of the prodrugs. The melting points and aqueous solubilities of all the prodrugs were lower than that of the parent compound, phenytoin. The apparent micelle-water partition coefficient increased with an increase in chain length but unlike the octanol-water and cyclohexane-water partition coefficients the relationship was complex. There was a disproportionate increase in the interaction between the micelle and the prodrug with the prodrugs with alkyl groups larger than four carbons. In SIBLM, the solubilities and dissolution rates were increased to a greater extent for the prodrugs than that for phenytoin. The implications are that the bioavailability of phenytoin from these prodrugs may be comparable to or higher than that of phenytoin despite having lower aqueous solubilities, especially after a meal inducing bile flow.
Some physicochemical properties of N-acyloxyalkyl prodrugs of phenytoin were reported previously.(1,2) It was shown that despite their lower aqueous solubilities relative to phenytoin, these lower-melting prodrugs with apparently disrupted crystalline structures gave either comparable or enhanced in vitro solubility and dissolution rate in simulated intestinal media made up of bile salts and lecithin (SIBLM).(2) The current objective was to compare the in vivo behavior of two of these prodrugs to phenytoin in dogs and attempt to correlate the in vitro behavior to their in vivo behavior. The oral bioavailability of phenytoin after administration of phenytoin (1) and the selected prodrugs, 3-pentanoyloxymethyl 5, 5-diphenylhydantoin (2) and 3-octanoyloxymethyl 5, 5-diphenylhydantoin (3), in fed and fasted beagle dogs were compared to intravenously administered phenytoin. Phenytoin and its prodrugs showed improvement in fed-state phenytoin bioavailability relative to the fasted state indicating that food enhanced the delivery of phenytoin from phenytoin and its prodrugs. The increased bioavailability in the fed state may be due to stimulation of bile release by food and, for the prodrugs, possible catalysis of their dissolution by lipases.(3) In both, fasted and fed states, prodrugs 2 and 3 gave higher AUC values of phenytoin than the parent compound. The enhanced bioavailability of phenytoin after oral administration were more obvious in fed dogs. Although enhanced, AUC values of phenytoin from the prodrugs relative to phenytoin were not statistically different (at 95% confidence level) in fasted state, but were different in fed state. Although the aqueous solubilities and dissolution of both prodrugs were lower than phenytoin, dissolution of 2 and 3 was equivalent and greater, respectively, relative to phenytoin in SIBLM. As expected, the in vivo behavior correlated better with the in vitro SIBLM dissolution behavior. These results indicate that aqueous solubility per se does not adequately predict in vivo behavior.
Background: The ageing process (photoaging) can be caused by sun exposure, especially ultraviolet light. Organic and inorganic sunscreen products are commercially available. Two calixarene organic compounds, namely C-phenylcalix[4]resorcinaryl octacinnamate and C-methylcalix[4]resorcinaryl octabenzoate, have been successfully synthesized. Besides, the antioxidant quercetin can be potentially combined with these two compounds since ultraviolet rays also cause reactive oxygen species. This study aimed to evaluate the acute toxicity profile in vitro by cell line Vero and to develop the optimal activity of the product in New Zealand rabbit skin.Methods: Optimal formulation of three formulas nanoemulgel of sunscreen was using  D Optimal Mixture Design. Acute cytotoxicity test in vitro by culture cell line Vero was using randomized post-test only control group design. The activity of the product was measured by the value of Sun Protection Factor (SPF) in vivo using randomized post-test only control group design. Data of acute toxicity in vitro test (IC50 value) was analyzed using probit analysis and activity sun protection factor was analyzed using one-way ANOVA on SPSS version 20 for Windows. Results: The in-vitro toxicity test of formula 1, 2, 3 nanoemulgel were 2,940.569 µg/mL, 13,489.728 µg/mL, and 6,289.248 µg/mL respectively. The formula 1 nanoemulgel sunscreen products were produced with the three highest SPF values. SPF in vivo test showed that the nanoemulgel protection capability of the formula 1 with three different doses were 34; 36; dan 43 respectively. Conclusion: It can be concluded that the nanoemulgel sunscreen products were successfully formulated with high in vivo SPF value and can be potentially developed as organic sunscreens in the future because it is not toxic in culture cell.
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