Fast and selective production of quercetin and saccharides from rutin using microwave-assisted hydrothermal treatment in the presence of graphene oxide

Rutin is a flavonoid glycoside, well-known for its antioxidant, anticarcinogenic, and cardioprotective properties. However, it exhibits lower bio absorptivity and bioactivity than its aglycon form, quercetin. Although liquid acid catalysts are conventionally utilized to obtain quercetin via rutin hydrolysis, the neutralization procedure is a major disadvantage owing to the added cost. In this study, graphene oxide (GO) was used as an alternative catalyst under microwave (MW) irradiation, owing to its easy separation from the reaction solution and high MW absorptivity, resulting in improved thermal efficiency. Two types of GOs were prepared (GO-HU using Hummer's method and GO-TO using Tour's method), and their catalytic performance for rutin hydrolysis was evaluated and compared. The highest rutin conversion (98.8 %) and quercetin yield (81.9 %) were obtained at 180 °C when the reaction was conducted for 15 min using 3 mg of GO-TO and 2400 ppm of initial rutin concentration in 50 mL of water.