Effects of Gelidium amansii Extract on Lipid Metabolism and Mitochondrial Dysfunction in High-Fat Diet-Induced Hepatic Steatosis

다국어 초록 (Multilingual Abstract)

Non-alcoholic fatty liver disease (NAFLD), a representative metabolic liver
disorder induced by obesity, is characterized by excessive hepatic lipid accumulation,
elevated oxidative stress, and impaired mitochondrial function. These metabolic
abnormalities are accompanied by increased lipogenesis and suppressed lipolysis in
adipose tissue and Liver tissue, leading to disrupted lipid homeostasis, inflammation,
and hepatic fibrosis. Gelidium amansii, a red algae traditionally used as a raw material
for agar, has recently attracted attention as a marine-derived functional ingredient due
to its diverse bioactive components. This study aimed to evaluate the anti-obesity and
anti-steatosis effects of Gelidium amansii extract (GAE) and elucidate its underlying
molecular mechanisms using high-fat diet (HFD)-induced obese mice and cellular
models. GAE administration significantly reduced body weight gain and white adipose
tissue hypertrophy, decreased hepatic triglyceride accumulation, and normalized serum
AST and ALT levels without nephrotoxicity. Histological analyses revealed that GAE
alleviated hepatic lipid droplet accumulation, inflammatory cell infiltration, and
hepatocellular ballooning. GAE downregulated SREBP-1c and FAS, while
upregulating PPARα and CPT1A, indicating inhibition of lipogenesis and enhancement
of fatty acid β-oxidation. Furthermore, GAE reduced lipid peroxidation markers (4-
HNE and MDA), increased antioxidant enzyme SOD1, and decreased IL-6 and TNF-α
expression, demonstrating its antioxidative and anti-inflammatory effects. In addition,
GAE restored mitochondrial biogenesis through activation of the LKB1–AMPK–
SIRT1–PGC-1α–NRF1–TFAM pathway and enhanced mitophagy via the
PINK1/Parkin/LC3B axis, improving mitochondrial quality control and mitochondrial
homeostasis. It also reactivated PI3K/AKT signaling and inhibited the TGFβ1/Smad2/3 pathway, thereby suppressing COL1A1 expression and collagen deposition.
Overall, GAE effectively ameliorates obesity-induced NAFLD by regulating lipid
metabolism, attenuating oxidative stress and inflammation, restoring mitochondrial
function, and inhibiting hepatic fibrosis. LC–MS/MS analysis identified Porphyra-334,
a mycosporine-like amino acid (MAA), as a major active compound contributing to
these protective effects, highlighting the potential of GAE as a marine-derived
functional ingredient for the prevention and management of metabolic liver diseases.

목차 (Table of Contents)

• Abstracts
• 1. Introduction 1
• 2. Materials and methods 6
• 2.1. Reagents and antibodies 6
• 2.2. Preparation of Gelidium amansii extract 7
• 2.3. Animals study 7
• 2.4. Serum biochemical analysis 8
• 2.5. Hepatic MDA analysis 8
• 2.6. Hematoxylin and eosin staining 9
• 2.7. Immunohistochemical analysis 10
• 2.8. Masson’s Trichrome staining 10
• 2.9. Cell culture, differentiation, and treatment11
• 2.10. Cell viability assay 12
• 2.11. Oil Red O staining 12
• 2.12. Mitochondrial staining 13
• 2.13. Western blot analysis 13
• 2.14. Ultra-high performance liquid chromatography tandem mass spectrometry analysis for metabolite profiles 14
• 2.15. Statistical analysis 15
• 3. Results 16
• 3.1. GAE mitigates body weight gain and normalizes serum biochemical markers in HFD-fed mice 16
• 3.2. GAE attenuates adipocyte hypertrophy and modulates lipid metabolism associated proteins in the adipose tissue of HFD-induced mice 20
• 3.3. Effects of GAE on hepatic injury, lipid metabolic disorder, and oxidative stress in HFD-induced mice 25
• 3.4. Effects of GAE on mitochondrial biogenesis, function, and mitophagy signaling in the livers of HFD-induced mice 31
• 3.5. GAE suppresses hepatic fibrogenesis in HFD-fed mice by targeting the PI3K/AKT-dependent TGF-β1/Smad2/3 signaling cascade 36
• 3.6. GAE inhibits adipogenesis and modulates lipid metabolism related protein expression in 3T3-L1 adipocytes 39
• 3.7. Effects of GAE on lipid accumulation, oxidative stress, and expression of inflammation-related proteins in FFA-induced HepG2 cells 44
• 3.8. Effects of GAE on mitochondrial biogenesis, function, and mitophagy signaling in FFA-induced HepG2 cells 49
• 3.9. U-HPLC–MS/MS analysis for identification of Porphyra-334 in GAE 54
• 4. Discussion 57
• References 60
• 국문초록72