The by-product from adlay endosperm processing, oil-rich adlay bran, is frequently extracted and consumed as dietary lipid supplements. In previous reports, the lipophilic fractions from supercritical fluid extracted adlay seeds has exceptional antioxidant activity and, at the same time, could suppress intracellular tyrosinase activity and decrease the amount of melanin in B16F10 cells. Since adlay seeds and adlay oil both are rich in lipophilic components, it is expected that consumption of adlay oil may have skin brightening effect through inhibiting the melanin production. For this reason, we would like to further investigate the inhibitory effect of adlay oil on melanin production using in vitro cell line model, B16F10 cells, and in vivo model using zebrafish embryos. Since adlay oil is insoluble in the aqueous environment, the extracted adlay oil is first encapsulating in an optimized nanoemulsion system for the convenience of later studies. In MTT assay, no significant cytotoxicity appeared in B16F10 melanoma cells was observed after 48-hour treatments of adlay oil nanoemulsion at concentration up to 20,000 ppm. In the melanin contents and tyrosinase activity in B16F10 cells, at 50 ppm level the adlay oil nanoemulsion could reduce the cellular melanin production by 27.28% and also effectively inhibit the tyrosinase activity. In in vivo zebrafish embryos model, the adlay oil nanoemulsion significantly suppressed the melanin contents and tyrosinase activity while not causing toxicity effects on zebrafish, in which the hear-beating rate and mortality rate falls within the normal range. The results from this study indicated that adlay oil is a potential tyrosinase inhibitor and potent skin whitening agent as proven by our in vitro and in vivo screening systems. Moreover, emulsion system is an effective means that allow mechanistically study and to deliver the skin brightening functionality of adlay oil into the living system. Thus, this application is a good example of how bioactive oily extract obtained through by-product revising can be re-cycled and used as dietary supplements whereas proper delivery system could optimized its application.

Inhibitory effect of adlay oil nanoemulsion on melanin production in B16F10 melanoma cells and zebrafish

254th National Meeting (2017)

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