Atsuattenone, a novel ishwarane derivative from Piper attenuatum, mitigates hepatic lipid accumulation by modulating PPARα pathway and lipolytic enzymes.

BACKGROUND

Non-alcoholic fatty liver disease (NAFLD) is a major metabolic disorder lacking effective pharmacological therapy. Medicinal plants represent valuable sources of hepatoprotective agents. Piper attenuatum Buch.-Ham. has been used traditionally for liver ailments, yet its potential against NAFLD remains unknown.

PURPOSE: To isolate and characterize bioactive metabolites from P. attenuatum and evaluate their effects on hepatic lipid accumulation and related molecular pathways.

METHODS

Bioassay-guided fractionation of the hexane extract of P. attenuatum stems afforded six compounds, including a novel ishwarane derivative, Atsuattenone. Structures were elucidated by NMR, MS, and single-crystal X-ray diffraction. Lipid accumulation and cell viability were assessed in linoleic acid-loaded HepG2 cells. Gene expression was analyzed by qRT-PCR, and molecular docking was performed against hepatocyte nuclear factor 4α (HNF4α) and peroxisome proliferator-activated receptor γ (PPARγ).

RESULTS

Atsuattenone markedly reduced intracellular triglyceride accumulation without cytotoxicity, while other isolates showed weak or adverse effects. qRT-PCR analysis revealed that Atsuattenone significantly downregulated PPARα and SREBP1 mRNA, while upregulating FABP4 and the lipolytic genes ATGL, HSL, and MGL. It also decreased AMPKα expression in a dose-dependent manner. Docking analysis indicated moderate affinity for HNF4α (-6.9 kcal/mol), a transcriptional regulator of PPARα, but weak binding to PPARγ (-5.5 kcal/mol), suggesting an indirect, non-classical regulatory mechanism.

CONCLUSION

P. attenuatum is identified as a new source of lipid-regulating metabolites. Atsuattenone acts as a promising natural modulator that attenuates steatosis by enhancing lipolytic gene expression, suppressing lipogenesis, and modulating HNF4α- and AMPKα-linked transcriptional pathways, offering potential for NAFLD prevention and therapy.