Tier 4 — mechanistic

Dietary fisetin supplementation protects against alcohol-induced liver injury in mice

Sun Q, Zhang W, Zhong W, Sun X, Zhou Z
Alcoholism: Clinical and Experimental Research 2016 Volume 40, issue 10, pages 2076-2084

Bibliography

PubMed
PMID 27575873
PubMed Central
PMC5742867
DOI
10.1111/acer.13172
Funding
United States National Institutes of Health grants R01AA020212 and 2R01AA018844.
Competing interests
No competing interests were declared in the manuscript.

Study snapshot

DesignControlled animal feeding study using the Lieber-DeCarli liquid diet model of alcoholic liver disease, with biochemical, histological and immunoblot endpoints.
ModelMale C57BL/6J mice pair-fed a Lieber-DeCarli control or ethanol liquid diet for four weeks.
Samplen=6 per group (control, ethanol-alone, ethanol+fisetin).
InterventionDietary fisetin supplementation at 10 mg/kg/day alongside a stepwise Lieber-DeCarli ethanol diet (ethanol content increased from 3.2% to 4.2% w/v over the study); weekly ethanol (3 g/kg) or isocaloric dextrin gavage.
Duration4 weeks of pair-feeding.
EndpointsHepatic lipid accumulation (histology, triglycerides, free fatty acids); Plasma ALT and AST activity; Plasma and hepatic ethanol and acetaldehyde levels; Hepatic aldehyde dehydrogenase (ALDH) activity; Oxidative stress markers: plasma hydrogen peroxide, hepatic superoxide (DHE staining), 4-hydroxynonenal, NADPH oxidase 4 (NOX4); Hepatic apoptosis (TUNEL, Fas, FasL, cleaved caspase-3); Lipid-metabolism proteins: plasma adiponectin, hepatic p-AMPK, ACOX1, CYP4A, MTTP

What the study showed, in plain terms

This is a controlled mouse feeding study, not a human trial. Mice were pair-fed a standard alcohol-liver-disease diet (the Lieber-DeCarli model) for four weeks, with or without a modest dose of dietary fisetin, to see whether fisetin protects the liver from alcohol-related damage.

Alcohol feeding caused the expected picture of early alcoholic liver disease: fat accumulation in the liver, raised liver enzymes (ALT, AST), oxidative stress, and increased liver cell death (apoptosis). Adding fisetin to the diet blunted all of these changes.

The proposed mechanism has two strands. First, fisetin appeared to help the liver clear alcohol and its breakdown products faster, by raising the activity of aldehyde dehydrogenase (ALDH), the enzyme that detoxifies the toxic acetaldehyde produced from alcohol. Second, fisetin reduced oxidative stress markers and a pro-oxidant enzyme called NOX4, which likely explains why alcohol-induced liver cell death was reduced.

This is preclinical mechanistic evidence for a protective effect of fisetin against alcohol-related liver injury. It does not establish a protective dose or benefit in people who drink alcohol, and should not be read as licence to combine fisetin supplementation with heavy drinking.

Key findings

  • Alcohol feeding caused visible hepatic lipid droplet accumulation and raised plasma ALT and AST; dietary fisetin supplementation (10 mg/kg/d) reduced lipid droplet size/number and attenuated the rise in ALT and AST.
  • Fisetin significantly reduced plasma and hepatic ethanol concentrations after alcohol exposure without affecting the expression of ethanol-oxidising enzymes (ADH, catalase, ALDH2, CYP2E1), while significantly increasing hepatic aldehyde dehydrogenase (ALDH) activity.
  • Fisetin suppressed alcohol-induced oxidative stress: it lowered plasma hydrogen peroxide, hepatic superoxide (DHE staining) and hepatic 4-hydroxynonenal, and attenuated the alcohol-induced rise in hepatic NADPH oxidase 4 (NOX4) without affecting SOD1, SOD2 or Gpx1 levels.
  • Fisetin reduced alcohol-induced hepatic apoptosis (fewer TUNEL-positive cells) and normalised the alcohol-induced rise in Fas, FasL and cleaved caspase-3.
  • Fisetin attenuated alcohol-induced hepatic steatosis by raising plasma adiponectin and hepatic p-AMPK, ACOX1 and CYP4A/MTTP protein levels, all pathways involved in fatty-acid oxidation and lipid export.
  • The authors conclude fisetin protects against alcohol-induced liver injury via accelerated ethanol/acetaldehyde clearance and inhibition of oxidative stress, and propose therapeutic potential for alcoholic liver disease.

What this study can and cannot tell us

This is a short (4-week), small-sample (n=6/group) mouse feeding study with no human data. The fisetin dose (10 mg/kg/d, dietary) is modest relative to some other fisetin animal studies, but its human-equivalent dose and long-term safety in the context of alcohol use have not been established.

The mechanism proposed — accelerated ethanol clearance via increased ALDH activity — is inferred from indirect measurements (ethanol/acetaldehyde tissue levels and enzyme activity assays) rather than direct flux studies, and the authors themselves note that a direct fisetin-ethanol chemical interaction has not been ruled out.

This paper should not be interpreted as evidence that fisetin permits safe or protected alcohol consumption; it is a mechanistic animal study of a controlled experimental alcohol-feeding model, not a human safety or interaction study.

Editorial review

Reviewed by the Biohack Blueprint research team

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Dr. Khaled Mahmoud, MBBChCritical Care Medicine, Longevity Science & Editorial Direction Dr. Amr Yasser, PhDCardiometabolic, Musculoskeletal, Gut & Bioavailability Dr. Abdulla Mostafa, PhDCellular Senescence, Neurological, Mitochondrial & Brain-Ageing Biology