Synthesis And Function Of Natural Tyrosinase Inhibitor,T1,and Analogs

Bis(4-hydroxybenzyl)sulfide(T1),a tyrosinase inhibitor first isolated from the Chinese herbal plant Gastrodia elata,was found to prevent the generation of melanin effectively.So far,two syntheses of T1 have been reported.However,these somewhat complex and inefficient methods are neither economical nor environmentally friendly.In this thesis,for the first time,we reported a one-step synthesis of T1,using 4-hydroxybenzyl alcohol and sodium thiosulfate in acetate buffer.This is a simple,efficient,and economic method with little by-product.The optimal recipe have been found as follows,a)a mole ratio of 4-hydroxybenzyl alcohol and sodium thiosulfate as 1:0.71,b)a mass ratio between solvent and 4-hydroxybenzyl alcohol as 20,c)a mass ratio between 4-hydroxybenzyl alcohol,acetic acid,and sodium acetate as 1:1.2:0.82.With this prescription,crude T1 is produced after 13 hours of reflux.Further recrystallization from 50%ethanol(7.5 x volume/mass ratio)affords pure T1.The final yield is 67.6%.The generality of our method has been demonstrated by synthesizing 3 more T1 analogs,including T2,T3 and T4,which processing additional aryl methoxyl/ethoxyl functional groups.The DPPH radical scavenging activity and reducing ability have been tested.T2,T3 and T4 show improved oxidation resistance than T1,reaching the level of BHT and VE.Our experimental results indicate that T2 is an effective food additive,preventing fresh apple slices or juice,and fresh shrimp from browning.Moreover,T1 and T2 have a good antioxidation effect for vegetable oil.