Kinetics of Aerobic Oxidation of Ascorbic Acid

Blaug, Seymour M.; Hajratwala, B.R.

doi:10.1002/jps.2600610412

Cited by 73 publications

(41 citation statements)

References 21 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…4. Plots of k obs versus pH for the photolysis of ascorbic acid in creams (1)(2)(3)(4)(5)(6)(7)(8)(9) The viscosity of the medium affects the rate at which molecules can diffuse through the solution. This, in turn, may affect the rate at which a compound can suffer oxidation at the liquid surface.…”

Section: Resultsmentioning

confidence: 99%

“…The values of these rate constants indicate that the degradation of AH 2 in the dark is about 70 times slower than those of the creams exposed to UV irradiation (Table III). The degradation of AH 2 in creams in the dark is due to chemical oxidation (3,4) and occurs in the order of emulsifier: myristic acid>stearic acid>palmitic acid.…”

Section: Resultsmentioning

confidence: 99%

“…It is sensitive to air and light (2,3) and is degraded by chemical (4) and photochemical oxidation (5)(6)(7)(8)(9)(10). Ascorbic acid is an ingredient of antiaging cosmetic products (11)(12)(13)(14)(15) and exerts several functions on the skin as collagen synthesis, depigmentation, and antioxidant activity (16).…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Photostability and Interaction of Ascorbic Acid in Cream Formulations

et al. 2011

View full text Add to dashboard Cite

Abstract. The kinetics of photolysis of ascorbic acid in cream formulations on UV irradiation has been studied using a specific spectrophotometric method with a reproducibility of ±5%. The apparent first-order rate constants (k obs ) for the photolysis of ascorbic acid in creams have been determined. The photoproducts formed in the cream formulations include dehydroascorbic acid and 2,3-diketogulonic acid. The photolysis of ascorbic acid appears to be affected by the concentration of active ingredient, pH, and viscosity of the medium and formulation characteristics. The study indicates that the ionized state and redox potentials of ascorbic acid are important factors in the photostability of the vitamin in cream formulations. The viscosity of the humectant present in the creams appears to influence the photostability of ascorbic acid. The results show that the physical stability of the creams is an important factor in the stabilization of the vitamin. In the cream formulations stored in the dark, ascorbic acid undergoes aerobic oxidation and the degradation is affected by similar factors as indicated in the photolysis reactions. The rate of oxidative degradation in the dark is about seventy times slower than that observed in the presence of light.

show abstract

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

See 1 more Smart Citation

Photostability and Interaction of Ascorbic Acid in Cream Formulations

et al. 2011

View full text Add to dashboard Cite

show abstract

“…It has been previously reported that VC was decomposed by oxidation at higher pH than pK a1 (4.12). 13,14) Therefore, these data suggest that the oxidation of VC may interact with the VB12 degradation in mixed solution.…”

Section: Resultsmentioning

confidence: 80%

Effect of Various Halide Salts on the Incompatibility of Cyanocobalamin and Ascorbic Acid in Aqueous Solution

et al. 2005

View full text Add to dashboard Cite

Cyanocobalamin (VB12) and ascorbic acid (VC), both water-soluble vitamins, are essential nutrients involved in many physiological functions. These vitamins are extensively used in many pharmaceutical preparations and dietary supplements. An incompatibility of VB12 and VC in aqueous solutions has been reported. [1][2][3][4][5][6][7] However, it has not been fully elucidated how to stabilize these vitamins in a mixed solution yet. Many researchers have investigated the effect of VC on the stability of VB12 or cobalamin analogues in solution. [8][9][10][11][12] Most of them have focused only on the VB12 degradation, but not on VC. While Bartilucci et al. 6,7) have reported the interaction of VB12 and VC mixed condition in aqueous solutions evaluated by less sensitive methods, microbiological method for VB12 and titration for VC.In the present study, we determined the stabilities of VB12 and VC in acetate buffer using high performance liquid chromatography (HPLC), which shows better accuracy and precision than microbiological method and titration. The effects of halide salts on the stabilities of these vitamins in the buffer were also studied for the improvement of their stability. ExperimentalMaterials and Reagents VC and VB12 regulated by Japanese Pharmacopoeia were obtained from BASF Takeda Vitamins (Tokyo, Japan) and Aventis Pharma S.A. (Alsace, France), respectively. All other chemicals were purchased commercially. Water purified through a Milli-Q Labo (Millipore, Bedford, MA, U.S.A.) water system was used for all dilutions and sample preparations.Determination of VB12 Using HPLC An LC-10AVP system (Shimadzu, Kyoto, Japan) equipped with SIL-10ADVP auto-injector, SPD-10AVVP detector, LC-10ADVP pump, DGU-14A degasser, CTO-10ACVP column oven and C-R6A data processor was used to determine VB12 in the solutions. The HPLC conditions were as follows: column, 150ϫ4.6 mm TSK gel ODS-80TsQA (Tosoh, Tokyo, Japan); column temperature, 25°C; detection wavelength, 361 nm; mobile phase, acetonitrile-50 mM acetate buffer, pH 4.5 (13 : 87, v/v); flow rate, 1.0 ml/min; injection volume, 50 ml. Sample mixtures were directly injected into HPLC.Determination of VC Using HPLC An LC-10AVP system, the same composition system as described above, was used. The HPLC conditions were as follows: column, 150ϫ6 mm YMC pack ODS-AQ312 (YMC, Kyoto, Japan); column temperature, 25°C; detection wavelength, 290 nm; mobile phase, water-methanol-200 mM phosphate solution, pH 3.5 (8 : 1 : 1, v/v/v); flow rate, 1.0 ml/min; injection volume, 5 ml. Samples for HPLC analysis were prepared as follows: 0.3 ml of sample mixtures were transferred to vials for HPLC followed by adding 0.3 ml of 3% metaphosphoric acid containing 2% hydrochloric acid. The mixtures were analyzed immediately by HPLC.Influence of VC on VB12 Stability Various concentrations of VC (0, 1, or 5 mM) with 0.25 mM VB12 in 100 mM ammonium acetate-acetic acid buffer (pH 4.8) were prepared in a 12-ml brown glass vial with cap, and the mixtures were kept at room temperature for 8 h. The conce...

show abstract

“…The activation energy obtained from the Arrhenius plot was 3.0 kJ/mol and very small. Activation energy of the oxidative reaction for ascorbic acid and morphine were reported to be 32.6 17) and 95.3 kJ/mol, 18) respectively. Compared with these values, tretinoin tocoferil is likely to be easily oxidized even at ordinary or lower temperature.…”

Section: Resultsmentioning

confidence: 99%

Photochemical and Oxidative Degradation of the Solid-State Tretinoin Tocoferil.

2001

View full text Add to dashboard Cite

Tretinoin tocoferil ((Ϯ)-3,4-dihydro-2,5,7,8-tetramethyl-2-(4,8,12-trimethyl-tridecyl)-2H-1-benzopyran-6-yl (2E,4E,6E, 8E )-3,7-dimethyl-9-(2,6,6-trimethyl-1-cyclohexen-1-yl)-2,4,6,8-nonatetraenoate) is an a-tocopherol ester of all-trans retinoic acid (RA) and has been safely used in the treatment of decubitus and skin ulcer to stimulate the proliferation of human skin fibroblasts.1) Toxicity tests in animal models have shown that tretinoin tocoferil is at least 150 times less toxic than all-trans RA and does not induce teratogenesis. 13-cis RA and all-trans RA are known to undergo Z-E isomerization (due to the existence of four unsaturated double bonds) and oxidation when exposed to light and air.2) RA underwent autooxidation in 90% ethanol at 25-85.5°C to give epoxides, dioxetanes, an endoperoxide and double-bond cleavage products.3) Therefore tretinoin tocoferil is also likely to be susceptible to photodegradation and oxidation.The information obtained from the stability test of the drug is useful for development and stabilization of the dosage forms, but there are no reports concerning the photostability and the oxidation of tretinoin tocoferil.The purpose of the present investigation was to evaluate photostability and oxidation profiles of tretinoin tocoferil under various environmental conditions to establish a reasonable stabilization design against light and oxygen. Elucidation of the degradation mechanism was therefore beyond the aim of this study. ExperimentalMaterials Bulk tretinoin tocoferil was obtained from Nisshin Flour Milling Co., Japan. The commercial solvents for HPLC analysis and Sudan II as an internal standard were used without further purification.Methods Tretinoin tocoferil (50 mg) was dissolved in 50 ml of dichloromethane. An aliquot of the solution (50 ml) was placed in a glass tube and evaporated to dryness at room temperature. The sample was further dried under vacuum at room temperature.Irradiation Tests Two irradiation apparatuses were employed: To study the effect of specific wavelength of light on the photostability of tretinoin tocoferil, the same grating monochromator (model CRM-FA, Japan Spectroscopic Co., Tokyo, Japan) as described in our previous paper, 4) equipped with a 5-kW xenon lamp, was used. Samples were exposed until the intensity level of the irradiation reached a definite energy(1.8ϫ10 5 J/m 2 ). To study the effect of photon sources on the photostability, a cool white fluorescent lamp (type FL20SW/M), a D65 fluorescent lamp (FLR20S · D-EDL-D65/M), or a UV-A fluorescent lamp (FLR20S · BL/M, all three lamps from Nagano Science Equipment MFG. Co., Japan) were equipped in a light-irradiation tester (LIGHTTRON LT-120(D3CJ), Nagano Science Equipment MFG. Co., Japan). The spectral irradiation intensity curves of these lamps were measured with a portable spectroradiometer (model LI-1800, LI-COR Inc., Neb., U.S.A.). Figure 1 shows the relative spectral power distribution of the lamps as measured on the surface of a sample under an irradiation condition.Unless otherwise spec...

show abstract

Kinetics of Aerobic Oxidation of Ascorbic Acid

Cited by 73 publications

References 21 publications

Photostability and Interaction of Ascorbic Acid in Cream Formulations

Photostability and Interaction of Ascorbic Acid in Cream Formulations

Effect of Various Halide Salts on the Incompatibility of Cyanocobalamin and Ascorbic Acid in Aqueous Solution

Photochemical and Oxidative Degradation of the Solid-State Tretinoin Tocoferil.

Contact Info

Product

Resources

About