Radical scavenging, antioxidant and melanogenesis stimulating activities of diiferent species of rice (Oryza sativa L.) extracts

Abstract

Keywords: Radical scavenging assay, Antioxidant activities, Melanogenesis stimulating activities, Melanocyte
                    proliferation, Hair treatment
 
Objectives: The goal of the present study was to evaluate the radical scavenging, antioxidant and melanogenesis stimulating activities of different species of rice (Oryza sativa L.) extracts i.e., Sri-Nin, Tabtim Lanna, Hom-Nin, Rice Berry, Dang Sungyod and Kum-Doy-Moo-Ser for hair treatment formulation.  
Methods: The radical scavenging and antioxidant activities of different species of rice (Oryza sativa L.) extracts were assessed by using DPPH radical scavenging assay and ferric ions reducing antioxidant power assay (FRAP), while the melanogenesis stimulating activity of ethanolic extracts were determined by using the stimulation of tyrosinase enzyme activity and melanocyte proliferation. The stimulation of tyrosinase enzyme was tested by tyrosinase activity assay, and the melanocyte proliferation of these extracts at different concentrations (10 - 500 μg/ml) was evaluated using mouse melanoma cells (B16F10) by MTT assay.
Results: For the DPPH radical scavenging activity, both ethanolic extracts of Gum-Doy-Moo-Ser and Rice Beery had an effective DPPH radical scavenging activity with EC50 about 140.00 ± 1.73 μg/ml and 169.67 ± 2.51 μg/ml. For the determination of ferric ions (Fe3+) reducing antioxidant power (FRAP) of all extracts, Hom-Nin and Gum-Doy-Moo-Ser showed the strongest value of FRAP and the value were 1996.67 ± 3.67 and 1933.06 ± 3.37 FeFug/ml respectively. From the results of stimulating activity of tyrosinase enzyme, the ethanolic extract of Rice Berry had the highest stimulating activity (91.8 ± 0.10 %), while Sri-Nin extract showed the only lowest stimulating activity (32.59 ± 1.17 %). Among all tests, the extract of Rice Berry (500 μg/ml) showed the strongest stimulating on melanocyte proliferation with the proliferation index (P.I.) at 1.3 ± 0.02, but the extract of Gum-Doy-Moo-Ser had no effect on the stimulating activity of melanocyte proliferation with the proliferation index (P.I.) about 1.0 ± 0.02.
Conclusion: The effect of various species of rice (Oryza sativa L.) extracts had the high antioxidant,  and it was able to stimulate the melanogenesis activity, providing the increase in potential value added of Thai rice with different species. It could beneficially apply for hair treatment formulation in cosmetic products.