MORUS ALBA CALLUS JUICE AS NEW TYROSINASE INHIBITOR

Tyrosinase is a key regulatory multifunctional enzyme containing copper that is responsible for the biosynthesis of melanin in human. For avoid the overproduction and accumulation of melanin in the skin which leads to hyperpigmentation, tyrosinase inhibitors were and still are widely used both in pharmaceutical and cosmetic field1. Tyrosinase is also involved in enzymatic browning in most fresh fruits and vegetable, which affects not only the sensory qualities of foods, but even the nutritional characteristics resulting in tremendous economic loss for the agricultural and food industry2,3. A large number of tyrosinase inhibitors have been reported in the literature, however, some of them show poor activity and/or safety profile on human health in food fields. Therefore, it is important to search for green, safe and efficient tyrosinase inhibitors or their combinations. Among tyrosinase inhibitors from plants, Morus alba L. (Moraceae) extracts exhibit notable antityrosinase activity4. In this study Morus alba callus (line VDC-17) crude and fractionated juice samples as new tyrosinase inhibitors were evaluated. The inhibition of different sample concentrations were studied by using ascorbic acid as positive control5. The results showed that all the fractionated samples possess less inhibitory activity than the crude juice. In particular, 15 µL of crude juice inhibited 76,4% of tyrosinase activity comparable to 0,6 mg/mL of ascorbic acid. Whereas fractionated juice samples activity was in the range of 10-45%. Therefore, we speculated that a synergistic effect might exist among the crude juice components which is worthy of further research. TLC and HPLC UV-Vis analyses to characterize the phytoconstituents of the crude and fractionated juice samples are currently going on.