Cell experiment:

Human hepatoma cell line HepG2 is cultured in low glucose DMEM supplemented with 10% fetal bovine serum (FBS), 100 U/mL Penicillin and 100 μg/mL Streptomycin and 2 mM l-glutamine. The cells are maintained in 75 cm2 flasks at 37℃ in a humidified atmosphere containing 5% CO2 and split at 80% confluence every 5 days. Cells are seeded in 24-well plate (2×105 cells) and incubated at 37℃ overnight followed by cells pretreatment with complete DMEM containing high glucose concentration in order to downregulate autophagy. After 6 h, cells are treated with different concentrations of postbiotics obtained from Lactobacillus fermentum BGHV110 strain (HV110) in order to select appropriate dose for further experiments. Postbiotic is dissolved in complete DMEM medium and added to the cells in specific final concentration. In all other experiments seeded cells are treated with 50 mM Acetaminophen alone or co-treated with 50 mM Acetaminophen and selected dose of lyophilized HV110. To analyze autophagic flux, simultaneously with treatments, cells are exposed to lysosomotropic agent Chloroquine at a concentration of 25 μM, to inhibit autophagosome-lysosome fusion[2].

Animal experiment:

Mice[3]Male Swiss mice (30-40 g) are used. The experimental animals are divided into six groups of five animals each. Firstly, each group receive orally during seven days the following treatment: Group I: the mice do not receive any treatment (normal). Group II: the mice receive citral vehicle (0.1% Tween 80 solution). Groups III-V: the mice are pretreated with citral at doses of 125, 250, and 500 mg/kg, respectively. Group VI: the mice are pretreated with the hepatoprotective standard drug Silymarin (SLM) (200 mg/kg). After this time, the animals fasted for 8 h and then receive oral Acetaminophen on the seventh day at a dose of 250 mg/kg in Groups II-VI. Group I orally receive saline that contained 0.1% Tween 80 solution (Acetaminophen vehicle). The stock solution is used as the first concentration of 50 mg/mL and after that is diluted in 0.1% Tween 80 solution to prepare the solutions of 25 and 12.5 mg/mL. After 12 h of Acetaminophen administration, serum samples and liver tissue are collected followed by biochemistry and histological analysis.