The Sour Taste-Modifying Protein (Miraculin), Tyrosinase Inhibitors and Antioxidants from Synsepalum dulcificum

There are four basic tastes, including sweet, sour, bitter and salty. Any other taste is merely combination of these four. Red berries of Synsepalum dulcificum, which is an evergreen shrub native of tropical West Africa, have a property in modifying taste by switching sour into a sweet taste remarkably, so the berry has been called miracle fruit. Among all taste proteins, there is one in particular - miraculin - which lacks taste completely when absorbed on its own but has the power of modifying a disagreeable taste into a pleasant one. The active miraculin causes citric acid, ascorbic acid, acetic acid and hydrochloric acid which are normally sour to be perceived as sweet after being held in the mouth. In this review, we demonstrated the miracle fruit development and miraculin identification, including glycosylation and protein structure. We also extracted the fruit of S. dulcificum with methanol (MeOH), and the pulp with chloroform (CHCl3), respectively. All obtained extracts were evaluated for their tyrosinase inhibition and free radical scavenging. The anti-tyrosinase effects were to calculate the hydroxylation of L-tyrosine to L-dopa according to in vitro mushroom tyrosinase assay. The antioxidant potential was evaluated using the following in vitro method: scavenging of 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical. This was the first time to reveal these bioactivities from this species plant to date.