modified Eagle’s
medium (DMEM), trypsin with/without ethylenediaminetetraacetic acid
(EDTA), penicillin–streptomycin, and sterile phosphate-buffered
saline (PBS) were obtained from Solarbio Co., Ltd. (Beijing, China).
Reduced GSH, quercetin, rutin, andrographolide, resveratrol, polydatin,
curcumin, and ursolic acid were obtained from Solarbio Co., Ltd. (Beijing,
China), and all of the plant components are standards with purity
greater than 99%. Fetal bovine serum (FBS) was purchased from Gibico
(Gaithersburg, MD). quercetin stock (25 mM) was dissolved in dimethyl
sulfoxide (DMSO) and preserved under −20 °C. Dextran sulfate
sodium salt (DSS, 36 000–50 000 Da) was purchased
from MP Biomedicals.