1. School of Pharmaceutical Science and Technology (SPST), Tianjin University, Tianjin 300072, P.R. China
2. Key Laboratory for Tibet Plateau Phytochemistry of Qinghai Province, College of Pharmacy, Qinghai Minzu University, Xining 810007, P. R. China
3. Singapore Eye Research Institute (SERI), The Academia, 20 College Road, Singapore 169856, Singapore