NOS2 and major depressive disorder: In the present study, the HPLC analysis showed that erinacine A-enriched H. erinaceus mycelia contained 5 mg/g erinacine A. Interestingly, erinacine A was recently reported to exert its antioxidant activity via inducible NO synthase (iNOS)/p38 MAPK/ CCAAT/enhancer-binding protein (C/EBP) homologous protein (CHOP) pathway in an animal model of ischemic stroke [28], Jun N-terminal kinase (JNK)/p38 MAPK/nuclear factor-κB (NF-κB)/CHOP/Fas/Bax pathway in an animal model of Parkinson’s Disease [29], and PI3K/Akt/glycogen synthase kinase-3β (GSK-3β) in an animal model of depression [30].