Brown Rice Extract Ameliorates Oxidative Status in Human Placental Cell Line (JEG-3) Induced by Cadmium Chloride

Abstract

Cadmium (Cd) can induce oxidative stress by producing reactive oxygen species (ROS) and affect the antioxidant defense systems, leading to cellular damage. Supplementation with antioxidants may protect against Cd-induced oxidative stress. This study aimed to investigate the effect of germinated brown rice (GBR), brown rice (BR), and white rice (WR) extracts against Cd-induced toxicity in human placenta (JEG-3) cells. The cytotoxicity of Cd and rice extracts was measured by MTT assay, and pre-treatments with GBR, BR, and WR before Cd exposure were examined. Intracellular ROS levels and the expression of SOD2 and GPx4 were determined by DCFH-DA assay and western blot, respectively. An antioxidant N-acetylcysteine (NAC) was used as a positive control. The antioxidant capacity and total phenolic content of rice extracts were investigated by DPPH and Folin-Ciocalteu methods, respectively. The GBR extract exhibited the highest antioxidant activity and total phenolic content, followed by BR and WR, respectively. Cd decreased cell viability in a dose-dependent manner, whereas incubation with 0.1 - 0.5 mg/mL showed no toxicity in all rice extracts. Moreover, Cd treatments significantly (p < 0.05) increased ROS levels. Conversely, treatments with GBR and BR extracts decreased ROS. Similar results were observed for combinatorial treatments of GBR and BR with Cd, except for WR treatment. Additionally, significant increased SOD2 and decreased GPx4 expression levels were evident in the GBR group and in both GBR and BR pre-treated groups, respectively, compared to Cd exposure alone. These results suggest that brown rice pre-treatments may ameliorate oxidative status induced by Cd in cultured human placental cells.