Identification of novel Nrf2 activators from Cinnamomum chartophyllum H.W. Li and their potential application of preventing oxidative insults in human lung epithelial cells

• Main Authors: Ming-Xing Zhou, Guo-Hui Li, Bin Sun, You-Wei Xu, Ai-Ling Li, Yan-Ru Li, Dong-Mei Ren, Xiao-Ning Wang, Xue-Sen Wen, Hong-Xiang Lou, Tao Shen
• Format: Article
• Language: English
• Published: Elsevier 2018-04-01
• Series: Redox Biology
• Online Access: http://www.sciencedirect.com/science/article/pii/S2213231717305773

Human lung tissue, directly exposed to the environmental oxidants and toxicants, is apt to be harmed to bring about acute or chronic oxidative insults. The nuclear factor erythroid 2-related factor 2 (Nrf2) represents a central cellular defense mechanism, and is a target for developing agents against oxidative insult-induced human lung diseases. Our previous study found that the EtOH extract of Cinnamomum chartophyllum protected human bronchial epithelial cells against oxidative insults via Nrf2 activation. In this study, a systemic phytochemical investigation of the aerial parts of C. chartophyllum led to the isolation of thirty chemical constituents, which were further evaluated for their Nrf2 inducing potential using NAD(P)H: quinone reductase (QR) assay. Among these purified constituents, a sesquiterpenoid bearing α, β-unsaturated ketone group, 3S-(+)-9-oxonerolidol (NLD), and a diphenyl sharing phenolic groups, 3, 3â², 4, 4â²-tetrahydroxydiphenyl (THD) significantly activated Nrf2 and its downstream genes, NAD(P)H quinone oxidoreductase 1 (NQO-1), and γ-glutamyl cysteine synthetase (γ-GCS), and enhanced the nuclear translocation and stabilization of Nrf2 in human lung epithelial cells. Importantly, NLD and THD had no toxicities under the Nrf2 inducing doses. THD also demonstrated a potential of interrupting Nrf2-Keap1 proteinâprotein interaction (PPI). Furthermore, NLD and THD protected human lung epithelial cells against sodium arsenite [As(III)]-induced cytotoxicity. Taken together, we conclude that NLD and THD are two novel Nrf2 activators with potential application of preventing acute and chronic oxidative insults in human lung tissue. Keywords: Cinnamomum chartophyllum, Nrf2 activator, Arsenic, Oxidative insult