| Alpha-arbutin, as a new kind of whitening agent of cosmetic, has a verybroad market prospects and value of use. The kinetic effects of mushroomtyrosinase were studied in this paper, which proved the dynamic mechanism ofα-arbutin whitening. Meanwhile,the effects of matrix materials in cosmetic ofwhitening effect of α-arbutin were investigated by building a tyrosinasecatalyzed reaction system for evaluating the safety of α-arbutin in cosmeticapplications and compatibility. Otherwise, the stability of α-arbutin wasstudied by the method of HPLC.1. The effects of alpha-arbutin on the activities of tyrosinase were studiedby the enzymological kinetic method, and the reaction mechanism wasobtained from the Lineweaver Burk plots by using the Cary50UV-Visiblespectrophotometer. The results showed that alpha-arbutin could inhibit themonophenolase activities but activate the diphenolase activities of mushroomtyrosinase. Moreover, the concentration leading to50%relative inhibition ratewas2.7mmol L-1 for monophenolase, and the lag time of monophenolase wasextended significantly by alpha-arbutin, from46.4s to347.4s by9.18mmol L-1alpha-arbutin, which was improved about6.5times. There was no lag time forthe activation of diphenolase. Kinetic analysis showed that the activationeffect of alpha-arbutin was a competitive-uncompetitive combined type withMichaelis constant （Km） decreasing and maximum velocity （Vmax）increasing as the alpha-arbutin concentration increases. In conclusion,alpha-arbutin not only can be used as the cosmetic whitening agent, but alsocan be added together with L-Dopa into shampoo blackening agent.2. The effects of matrix materials in cosmetic of whitening effect ofα-arbutin were investigated by building a tyrosinase catalyzed reaction system.The results showed that there were inhibition effects on the mushroomtyrosinase by the surfactants （TEA, Tween80, AES, AEO9）, moisturize （glycerin）, and preservative （methyl4-hydroxybenzoate）, and the inhibitioneffects between them and α-arbutin showed an additive effect. However, therewere activation effects by metal ions (Cu2+, Mg`（2+）), and the activation rate ofCu2+ was more than Mg2+, about75times.3. The effects of matrix materials in cosmetic of stability of α-arbutin werestudied by HPLC to detect the content of hydroquinone. And the resultsshowed that α-arbutin performed good stabilities in the solution of thesurfactants （TEA, Tween80, AES, AEO9）, moisturize （Glycerin）, preservative（Methyl4-hydroxybenzoate） and the metal ions (Cu2+, Mg2+) because of nohydroquinone generated, but not good stability in methyl4-hydroxybenzoate,and the content of hydroquinone was4.45%in the solution of methyl4-hydroxybenzoate.4. The stability of α-arbutin in basic environment was studied by the methodof High performance liquid chromatography （HPLC）. And the results showedthat,（1）, the temperature had little effect on the stability of alpha-arbutin.When the temperature reached about100℃, there was still no detection ofhydroquinone in the solvent of α-arbutin;（2）, in the conditions of pH5.2andpH8.0, there was no detection of hydroquinone in the solvent of α-arbutin, butunder conditions of pH1.0and pH13.0solution of α-arbutin, hydroquinonedetected;（3）, when α-arbutin was stored in dark conditions for72h, there wasstill no detection of hydroquinone, however, when α-arbutin was stored inlight conditions for72h, there was detection of hydroquinone, and under thecondition UV irradiation, there was detection of hydroquinone;（4）, there wasno detection in the solvent of α-arbutin, which was added to the analogprepared cream. |
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