Potent Nrf2-inducing, antioxidant, and anti-inflammatory effects and identification of constituents validate the anti-cancer use of Uvaria chamae and Olax subscorpioidea

Abstract

Background: Uvaria chamae (UC) and Olax subscorpioidea (OS) roots are included in traditional anti-cancer remedies and some studies have identified their chemopreventive/chemotherapeutic potential. This study aimed to identify some cellular/molecular mechanisms underlying such potential and the associated chemical constituents. Methods: Effect on the viability of cancer cells was assessed using the Alamar Blue assay; ability to modulate oxidative stress was assessed using the 2′,7′-dichlorofluorescein diacetate (DCFDA) assay; potential to modulate Nuclear factor erythroid 2-related factor like-2 (Nrf2) activity was assessed in the AREc32 luciferase reporter cell line; and anti-inflammatory effect was assessed using lipopolysaccharide-induced nitric oxide release model in the RAW264.7 cells (Griess Assay). Chemical constituents were identified through liquid chromatography-mass spectrometry (LC-MS). Results: Extracts up to 100 μg/ml were non-toxic or mildly toxic to HeLa, AREc32, PC3 and A549 cells (IC50 > 200 μg/ml). Each extract reduced basal and peroxide-induced levels of reactive oxygen species (ROS) in HeLa cells. OS and UC activated Nrf2, with UC producing nearly four-fold induction. Both extracts demonstrated anti-inflammatory effects. Chamanetin, isochamanetin, isouvaretin, uvaricin I and other compounds were found in U. chamae root extract. Conclusion: As Nrf-2 induction, antioxidant and anti-inflammatory activities are closely linked with chemoprevention and chemotherapy of cancers, the roles of these plants in traditional anti-cancer remedies are further highlighted, as is their potential as sources of drug leads.