In this study, we conducted a screen of 30 traditional medicinal herbs to identify novel autophagy regulators and found that PG and its bioactive compound, PD elevated both LC3B‐II and p62 levels in GBM cells, and these changes were also observed in various different types of cancers including lung, colon, liver, and breast cancer, suggesting that PD might act as an general inhibitor of autophagy. The gene discussed is SQSTM1; the disease is cancer.