Golden oyster mushroom, scientifically known as Pleurotus citrinopileatus, is an edible and medicinal mushroom widely found in Korea, China, and Japan. It is known to have anti-oxidant activity, which is attributed to phenolic compounds such as flavonoids and phenolic acids. Also, ergothioneine, a naturally occurring amino acid derived from mushrooms, is identified as a major component in golden oyster mushroom and has been reported to exhibit anti-diabetic, anti-neoplastic, and anti-inflammatory effects.