Primer sequences are supplied in supplementary information. PRKD3 Statistical analyses Values are reported as the means??SEM. that Sul reversed the cytotoxic effect stimulated by the autophagy inhibitors 3-methyladenine (3-MA) and chloroquine (CQ), and its cytoprotective effect was almost eliminated when the autophagy-related 5 (Atg5) gene was knocked down. These studies suggest that, in addition to its antioxidative effects, Sul stimulates mitophagy and restores impaired autophagic flux, thus protecting hepatic cells from apoptosis, and that Sul has potential future medical applications for hepatoprotection. and is known to have various biological activities, including anti-inflammatory  antimutagenic , anticancer , antioxidative stress , antiplatelet , and Icilin anti-rheumatoid arthritis effects . In Icilin previous studies, most of the reports focused on the anti-inflammatory activity of Sul. Here, we sought to validate the hepatoprotective effect of Sul on human hepatic L02 cells, and we found evidence that Sul promotes mitophagy, decreases p62 levels, and eliminates ROS to protect L02 cells from apoptosis. In addition, we made an effort to prove that Sul could be a potential mitophagy stimulator and restore autophagic flux to protect against cell apoptosis. Materials and methods Chemistry of Sul and its derivatives Compounds S1, S2, S3, S4, and S5 were synthesized according to previously reported procedures [47, 48]. Sul was purchased from BioBioPha (China; #120C05C8). Starting materials, reagents and solvents were purchased from commercial suppliers and used without further purification. All nonaqueous Icilin reactions were performed under an inert atmosphere (argon) with rigid exclusion of moisture from reagents, and all reaction flasks were oven-dried. TLC was carried out on precoated TLC plates with silica gel HSGF 254. Spots were visualized under UV at 254?nm. 1H and 13C?NMR spectra were measured on a Brucker AVANCE III 500 spectrometer using deuterated chloroform (CDCl3), deuterated methanol (CD3OD-SDS, 10% glycerol, 1% -mercaptoethanol, 0.01% bromophenyl blue pH 6.8). Cell lysates were separated by SDS-PAGE and transferred to nitrocellulose (NC) filter membranes. The membranes were first incubated with blocking buffer (TBS with 0.1% Tween 20 and 5% non-fat milk) for 1?h at room temperature and then incubated overnight at 4?C in buffer containing primary antibodies. The membranes were washed three times and then incubated with secondary antibodies for 1?h. After three washes, immunostaining was visualized using an electrochemiluminescence and ChemiDoc imaging system (Bio-Rad). Anti-PARP (#9542), anti-cleaved caspase 3 (#9664), anti-cleaved caspase 9 (#9509) and anti-p-TBK1 (#5483) antibodies were purchased from Cell Signaling Technologies (Danvers, MA, USA). Anti-LC3B antibody (#L7543) was purchased from Sigma-Aldrich (St. Louis, MO, USA). Anti-p62 antibody (#sc-25575) was purchased from Santa Cruz Biotechnology. Anti–actin (#AM1021B) antibody was purchased from ABGENT (San Diego, CA, USA). FCM analyses For cell flow cytometric (FCM) analysis, cells were trypsinized, and the single-cell suspensions were then stained with annexin V and propidium iodide (KeyGEN BioTECH; #KGA108) in binding buffer for 15?min at room temperature. Cells were then analyzed with a Guava Flow Cytometer (Millipore, St. Charles, MO, USA), and the data were collected with FlowJo software. Fluorescence staining For mitochondrial morphology analysis, cells were incubated with MitoTracker Deep Red FM (Invitrogen, Carlsbad, CA, USA; #”type”:”entrez-nucleotide”,”attrs”:”text”:”M22426″,”term_id”:”197107″,”term_text”:”M22426″M22426) for 20?min at room temperature. After washing with PBS, cells were fixed with 4% PFA (Sigma-Aldrich, St. Louis, MO, USA; #158127) for 10?min at room temperature. For autophagosome puncta formation analysis, nuclei were stained with Hoechst (Sigma-Aldrich, St. Louis, MO, USA; final concentration, 10 g/mL; #14530) for 10?min. Cells were analyzed by laser confocal microscopy (Olympus, Tokyo, Japan). Isolation of primary hepatocytes Primary hepatocyte isolation was performed as described previously . In detail, the male C57BL/6J mice at 6C8 weeks of age were anesthetized with 10% chloral hydrate, and 50?mL perfusion buffer was perfused through the portal vein at 37?C. The perfusion buffer consisted of Krebs Ringer buffer, EGTA (0.19?mg/mL, Sangon Biotech, Shanghai; #A100732C0005) and Glucose (0.9?mg/mL). Then, 50?mL of collagenase-I (0.48?mg/mL, Worthington, Lakewood; #”type”:”entrez-nucleotide”,”attrs”:”text”:”LS004196″,”term_id”:”1321650528″,”term_text”:”LS004196″LS004196) dissolved in collagenase buffer was infused into the liver through the portal vein. The collagenase buffer consisted of Krebs Ringer buffer, HEPES (0.19?mg/mL, Sangon Biotech, Shanghai; #A600264C0250) and CaCl2 (2.5?mol/L) at 37?C. The liver was aseptically removed to a sterile 6-cm cell culture dish made up of 5?mL of cold perfusion buffer without collagenase. The excised liver was cut, and hepatocytes were dispersed by aspirating with a large-bore pipette, filtered through a 70-m cell strainer (Thermo Fisher Scientific) into a 50-mL centrifuge tube and spun at 700 r/min for 5?min at 4?C. The cells.