J Food Biochem. 2020;00:e13366. wileyonlinelibrary.com/journal/jfbc | 1 of 11 https://doi.org/10.1111/jfc.13366 © 2020 Wiley Periodicals LLC 1 | INTRODUCTION Morbidity due to Chronic obstructive pulmonary disease (COPD) is estimated to be the fifth largest public health threat and the third most common cause of death across the globe by 2020 (Pauwels & Rabe, 2004). COPD is often associated with respiratory airway oc- clusion caused by exposure to gas and nontoxic particles (Mizumura, Maruoka, Shimizu, & Gon, 2018). Studies reveal cigarette smoke as the Received: 15 April 2020 | Revised: 27 May 2020 | Accepted: 10 June 2020 DOI: 10.1111/jfbc.13366 FULL ARTICLE Thymoquinone (Tq) protects necroptosis induced by autophagy/mitophagy-dependent oxidative stress in human bronchial epithelial cells exposed to cigarette smoke extract (CSE) Ayed A. Dera 1,2 | Majed Al Fayi 1,2 | Hassan Otifi 3 | Mishari Alshyarba 4 | Mohammad Alfhili 5 | Prasanna Rajagopalan 1,2 1 Department of Clinical Laboratory Sciences, College of Applied Medical Sciences, King Khalid University, Abha, Saudi Arabia 2 Central Research Laboratory, College of Applied Medical Sciences, King Khalid University, Abha, Saudi Arabia 3 Department of Pathology, College of Medicine, King Khalid University, Abha, Saudi Arabia 4 Department of Surgery, College of Medicine, King Khalid University, Abha, Saudi Arabia 5 Department of Clinical Laboratory Sciences, College of Applied Medical Sciences, King Saud University, Riyadh, Saudi Arabia Correspondence Prasanna Rajagopalan, Department of Clinical Laboratory Sciences, Chairman, Central Research Laboratory, College of Applied Medical Sciences, King Khalid University, Abha, Saudi Arabia. Email: rajagopalan@kku.edu.sa, prachu.rg@ gmail.com Funding information Deanship of Scientific Research at King Khalid University, Grant/Award Number: G.R.P-3-40 Abstract Chronic obstructive pulmonary disease (COPD) is characterized by cigarette smoke- induced emphysema. Herein, we demonstrate protective effects of Thymoquinone (Tq), an active constituent from Nigella sativa, against cigarette smoke extract (CSE)- induced abnormalities in bronchial epithelial cells. Dose-dependent reduction in cell viability was observed in BEAS-2B cells when exposed to different CSE concentra- tions, which was significantly reversed by Tq evident by LDH release. Levels of SOD, CAT, G R , GSH, and mitochondrial membrane ATPases were significantly reduced upon CSE exposure, an event, again, antagonized in presence of Tq. Similarly, Tq treatment significantly blocked CSE-induced 4HNE elevations. Further, Tq-improved mitochondrial dysfunction caused by CSE and significantly decreased autophagy/ mitophagy markers like LC3II and p-Drp. Tq also reduced necroptosis markers such as p-MLKL, RIP-1, and RIP-3, by stabilizing PINK-1 levels. In summary, Tq possesses protective properties against human bronchial epithelial cell autophagy/mitophagy- dependent necroptosis caused by CSE, which warrants considerable attention for further preclinical evaluations. Practical applications This study demonstrates Thymoquinone (Tq), a natural plant extract to possess pro- tective properties against human bronchial epithelial cell autophagy/mitophagy-de- pendent necroptosis caused by cigarette smoke extract. The demonstrated efficacy of Tq will throw light for further preclinical evaluation of this molecule in CSE- mediated complications. A detailed in vivo research is recommended. KEYWORDS autophagy, cigarette smoke extract, COPD, mitophagy, necroptosis, RIP-1,3, thymoquinone