Screening for in vitro inhibiting Nrf2 of some Vietnamese medicinal plants

Abstract

Nuclear factor erythroid 2–related factor 2 (Nrf2) is vital in regulating cellular defenses against oxidative or environmental aggressors. Some studies reveal that increasing Nrf2 activity affects chemotherapy drug resistance in cancer; thus, Nrf2 has become an attractive target in cancer therapeutics research. Our study screened the effects of 52 methanol extracts from different parts of 24 medicinal plants used in traditional and folk medicine to evaluate the ability to inhibit Nrf2 and the cell viability by an in vitro model of Huh7 liver cancer cells at the crude extract concentration of 100 µg/mL. The study has successfully suggested a screening model for Nrf2 expression based on luciferase fluorescence assay of Huh7 cells transfected with the Nrf2 gene. The results of our study show that the Piper sarmentosum roots can inhibit nearly 90% of Nrf2 activity in cancer cells. We also found that the extracts of Vernonia amygdalina leaves, Phyllanthus amarus leaves, Zingiber zerumbet leaves, Hyptis suaveolens leaves and roots, Curcuma zedoaria leaves and roots, Luvunga scandens leaves, Helicteres hirsuta leaves, Oroxylum indicum stem and leaves, Lasia spinosa fruits and Crotalaria pallida leaves inhibited more than 60% of Nrf2 expression levels. Furthermore, the extracts from the leaves of Luvunga scandens and Curcuma zedoaria can cause toxicity on cancer cell of more than 70% at 100 µg/mL. From the study, we have the basis for further studies on natural active substances that have the effect of drug resistance by inhibiting the expression of Nrf2 on cancer cells.