مقایسه فعالیت آنتی اکسیدانی عصاره شیرین بیان (Glycyrrhiza glabra L) با آنتی اکسیدان های تجاری در کرم هیدروکینون 2 درصد

Background and purpose: Çonsidering different reports on hazardous of commercial antioxidant, Ïn the recent years, researches have been focused on preparation of more effective and safer antioxidant from natural resources. Hydroquinone is a brightner compound which is used for brightening hyperpigmented region and used in cosmetic preparations. This chemical compound has poor stability, and quickly turned to brown colour in oxidation. Ïn this study, antioxidative metanolic effect of licorice extract in comparison with commercial anti oxidants was evaluated. Materials and methods: Ëxtraction of dried root powder of licorice was performed in methanol. Ântioxidative property of the extract was compared with commercial antioxidants hydroxytoluene BHT. 0.1% hydroquinone cream compounds containing antioxidant, and our extracted material were incubated in dark at 25oc ± 0.5 and 45oc ± 0.5 for three mooths. Physical stability and percentage of hydoguinone remaining after 2 weeks and 1, 2 and 3 months were determined by ÜV spectrophotomerty at 294 nm wave length. Results : Results of this study indicated acceleration in deterioration of hydroquinone, by increase in temperature. Ïncreasing in concentration of antioxidant caused increase in percentage of remaining hydroquinone, but increase in concentration of commercial antioxidant, particulary sodium metabisulfite by 1% and BÜT by 2% caused decline in physical stability of the compound. Ïn the third month, at 25oc and 45oc, the extracted material in all of the above mentioned concentrations, had more antioxidative property as compared with commercial antioxidants (P<0.001). Ïn the third month, the preparation contaning 0.1% 0.5%, 1% and 2% had good physical stability Çompared with 72%, 76%, 78% and 81% hydroquinone kept at 25 oc and 51%, 55%, 60% and 63% hydroquinone kept at 45oc respectively. Çonclusion: referring to the findings of this study, it is proposed that, using of the licorice extract with concentrations of 0.5% and 1% as natural antioxidant be used in compounds sensitive to oxidation,