Optimization of Antioxidant and Skin-Whitening Compounds Extraction Condition from Tenebrio molitor Larvae (Mealworm)

Skin-whitening ingredients are a very important part of the development of functional cosmetics and a wide variety of raw materials are used. Tyrosinase is a key enzyme in the animal melanogenic pathway that is the rate-limiting step for the production of melanin. Several synthetic and naturally occurring tyrosinase inhibitors have been studied for skin-whitening. The development of natural agents is becoming more important due to the disadvantages of synthetics such as high cytotoxicity, insufficient penetration power, and low activity. The purpose of this study was to evaluate the total phenol content (TPC), antioxidant, and tyrosinase inhibition activity of mealworm (Tenebrio molitor larvae) extract, and the subsequent optimization of the extraction condition using statistically-based optimization. The major extraction variables extraction temperature, time, and ethanol concentration were optimized using response surface methodology (RSM). The results showed that optimum extraction temperature of 88.1 °C, extraction time of 43.7 min, and ethanol concentration of 72.0 v/v%, provided the predicted maximum levels of total phenolic compounds (TPC) of 5.41 mg GAE/g dry weight (DW) and tyrosinase inhibition activity (TIA) of 82.4%. From the validation experiment, 5.61 ± 0.2 mg GAE/g dry weight (DW), tyrosinase inhibition of 79.6 ± 3.3%, and radical scavenging activity of 91.8 ± 5.1 μg/mL were found and showed to be very similar to the predicted values. These results suggest that mealworm has great potential as a source of bioactive compounds which could be used as cosmetics, food, and pharmaceutical agents.