Nanoemulsified adlay bran oil reduces tyrosinase activity and melanin synthesis in B16F10 cells and zebrafish

Abstract

The efficacy of oily components is often difficult to evaluate due to their incompatibility with most models. Here, we emulsified adlay bran oil (ABO), processed it to a nanoscale, and investigated its anti-hyperpigmentation efficacy, assessed for its inhibitory effects against tyrosinase activity and melanin production, in an in vitro system (mouse melanoma B16F10 cells) and an in vivo system (zebrafish embryos). ABO induced dose-dependent reductions in tyrosinase activity and melanin production in both the melanoma cells and zebrafish, without affecting viability. The efficacy of ABO was strongly influenced by emulsion particle size in the zebrafish but not in the cells. These results indicate that ABO has potential as a tyrosinase inhibitor and anti-hyperpigmentation agent and that the emulsion system is an effective method for delivering the bioactive components of ABO to living systems that could be utilized for other oily components.

Keywords: adlay bran oil; anti‐hyperpigmentation; melanin; nanoemulsion; tyrosinase; zebrafish.

Figure 1

Viability of B16F10 cells after incubation with different surfactants at various concentrations for 48 hr

Figure 2

(A) Viability and (B) intracellular melanin concentration of B16F10 cells after incubation with adlay bran oil emulsions (at 50 µg/ml) of various particle sizes (100–800 nm) for 48 hr. Different lower case letter indicate significant difference p < 0.05

Figure 3

(A) Viability, (B) intracellular melanin concentration, and (C) tyrosinase activity of B16F10 cells after 48 hr of incubation with different concentrations of adlay bran oil emulsion. Different lower case letter indicate significant difference p < 0.05

Figure 4

The 48‐hr survival rate of zebrafish cultured with different concentrations of Tween 80. Different lower case letter indicate significant difference p < 0.05

Figure 5

(A) Melanin production in zebrafish after culture with adlay bran oil (ABO) emulsions (at 500 µg/ml) of various particle sizes for 48 hr. (B) Photographs of zebrafish cultured in medium containing (a) nothing added (negative control), (b) 0.2 mM 1‐phenyl‐2‐thiourea (positive control), (c) 200 µg/ml Tween 80, and (d–f) 500 µg/ml ABO emulsion with particle sizes of (d) 97.03 nm, (e) 243.8 nm, and (f) 665.5 nm. Different lower case letter indicate significant difference p < 0.05

Figure 6

(A) Melanin production and (B) tyrosinase activity in zebrafish after culturing with adlay bran oil (ABO) emulsions of various concentrations for 48 hr. (C) Photographs of zebrafish cultured in medium with (a) nothing added (control), (b) 0.2 mM 1‐phenyl‐2‐thiourea (positive control), (c) 200 µg/ml Tween 80, and (d–f) ABO emulsions at (d) 500 µg/ml, (e) 1,000 µg/ml, and (f) 2,000 µg/ml. Different lower case letter indicate significant difference p < 0.05