Objective:

2

To explore the protective effect and mechanism of loganin

a iridoid glycoside isolated from

Corni Fructus

on carbon tetrachloride (CCl

4

)-induced acute liver injury (ALI) mice model and L-02 cells.

Methods:

2

ALI mice model was developed by an intraperitioneal injection of 0.3% CCl

4

. Thirty 8-week-old male C57BL/6 mice were randomly divided into 5 groups using a random number table

including control

model

loganin (40 and 80 mg/kg)

and silybin (100 mg/kg) groups (

n

=6). After 6 consecutive days of intragastric administration

serum levels of aspartate aminotransferase (AST) and alanine aminotransferase (ALT) were measured using an automatic biochemical analyzer. Hepatic pathological changes were observed by hematoxylin-eosin (HE) staining. Levels of interleukin (IL)-6 and tumor necrosis fact

or-α (TNF-α) in liver tissue were detected by enzyme-linked immunosorbent assay (ELISA). Superoxide dismutase (SOD) activity and malondialdehyde (MDA) contents were measured using biochemical kits. Mitochondrial ultrastructure and autophagosome formation were observed by transmission electron microscopy (TEM). Co-localization of mitophagy markers LC3 and TOMM20 were assessed by immunofluorescence (IF). Protein expressions of NOD-like receptor protein 3 (NLRP)3

LC3Ⅱ/LC3Ⅰ

p62

Beclin-1

Atg-7

Parkin

and PINK1 were determined by Western blot.

In vitro

an injury model was established in L-02 hepatocytes stimulated with CCl

4

. Cell viability was assessed by CCK-8 assay

and related mechanisms were evaluated using the aforementioned methods. Besides

CCl

4

-stimulated L-02 cells were intervened with NLRP3 shRNA or Mdivi-1.

Results:

2

Compared with the model group

pre-treatment with loganin (40 and 80 mg/kg) significantly reduced serum AST and ALT levels (

P

<

0.01)

alleviated pathological injuries such as swelling

necrosis

inflammatory infiltration

and lipid vacuolation in liver tissue. Loganin also markedly decreased the levels of IL-6 and TNF-α

increased SOD activity

and reduced MDA content in liver tissues (

P

<

0.05 or

P

<

0.01). Mechanistically

loganin up-regulated the ratios of LC3Ⅱ/LC3Ⅰ and expressions of Beclin-1

Atg-7

Parkin

and PINK1

while down-regulated p62 and NLRP3 protein expressions (

P

<

0.05).

In vitro

experiments further confirmed that loganin attenuated CCl

4

-induced injury in L-02 cells by enhancing mitophagy and inhibiting NLRP3 inflammasome activation

which was reversed by the mitophagy inhibitor Mdivi-1.

Conclusion:

2

Loganin protected against CCl

4

-induced ALI both

in vivo

and

in vitro

by suppressing the NLRP3 inflammasome and enhancing mitophagy.