Evaluation of the Enhanced Antioxidant Activity of Curcumin within Exosomes by Fluorescence Monitoring

In this study, we compared the antioxidant activities of curcumin (Cur) and a Cur formulation using a fluorescence analysis assay. The Cur formulation was prepared by a simple incorporation of Cur into exosomes (EXO) to produce Cur/EXOs. Free Cur had a low fluorescence intensity in aqueous solution because of its poor stability as a result of its autoxidation, whereas a significantly higher fluorescence intensity was observed for Cur/EXOs. Compared to free Cur, the increased level of intact Cur in EXOs allowed for enhanced antioxidant activity in H 2 O 2 scavenging activity and DPPH assays. Compared to Cur at high concentration (200 μM), Cur/ EXOs were significantly less cytotoxic. The antioxidant activity of Cur or Cur/EXOs in cells could be easily demonstrated by monitoring decreases in their fluorescence intensity. Following subcutaneous injection, the fluorescence intensities of Cur/EXOs were much higher than that of Cur, suggesting that Cur/EXOs improve Cur stability in vivo . Taken together, we have demonstrated the superiority of Cur/EXOs over free Cur in terms of aqueous stability and antioxidant activity using fluorescence monitoring both in vitro and in vivo .