Evaluation of Antityrosinase and Antioxidant activities of Raphanus Sativus root extract for cosmetic applications

Abstract

There is considerable demand for skin whitening and anti-wrinkle/anti-aging from natural plants. Thai women have long used fresh white radish root as a treatment of melasma although no systematic study has been made. In this study, two extracts (freeze-dried water extract and methanol extract) from the root of Thai radish (Raphanus sativus L.) were compared and evaluated to determine their role in protection of skin against melasma and aging. The two extracts were assayed for total phenolics, total flavonoids and vitamin C content. The total phenolics, total flavonoids and vitamin C content of the two extracts expressed as per 1 mg on the extract weight basis were 10.09 ± 0.07, 0.51 ± 0.007 and 24.11 ± 0.01 µg for freeze-dried water extract and 6.59 ± 0.05, 0.33 ± 0.004 and 8.28 ± 0.20 µg for methanol extract, respectively. Data showed that freeze-dried water extract had higher total phenolics, total flavonoids and vitamin C content than methanol extract. Anti-tyrosinase activity of the two extracts was also measured and compared with that of licorice extract and L-ascorbic acid. Freeze-dried water extract apparently showed higher extent of tyrosinase inhibition than methanol extract (IC50 = 3.09 and 9.62 mg/ml, respectively) but generally lower anti-tyrosinase activity than other reference anti-tyrosinase agent. The antioxidant properties of the two extracts were also tested for their scavenging effect on DPPH radical, superoxide anion and singlet oxygen and compared with those of Trolox® and L-ascorbic acid. Freeze-dried water extract exhibited higher potency than methanol extract (IC50 = 0.643 and 1.248 mg/ml for antioxidant activity against DPPH, 4.20 and 6.28 mg/ml for superoxide anion scavenging activity and 1.42 and 2.40 mg/ml for singlet oxygen scavenging activity) but generally lower than other reference antioxidants. The in-vitro cytotoxicity of the two extracts were determined by LDH assay. Both the freeze-dried water extract and methanol extract showed mild cytotoxicity even at high concentrations. Considering its various properties, the inexpensive and easily available freeze-dried water extract has potential for use in both the pharmaceutical and cosmetic applications.