Background <p>Sesquiterpenoids show potential as therapeutics against metabolic dysfunction-associated steatotic liver disease (MASLD). <i>Vernonia solanifolia</i> Benth. has been traditionally used to treat abdominal pain and enteritis. However, the anti-steatotic effect of <i>V. solanifolia</i> and its chemical principles have not been illustrated.</p> Methods <p>The structures of new compounds were determined through extensive spectroscopic analysis including 1D/2D nuclear magnetic resonance (NMR), high-resolution electrospray ionization mass spectrometry, ultraviolet and infrared. Especially, the structure of compound <b>6</b> was further verified by single crystal X-ray diffraction, and the relative and absolute configurations of compounds <b>1</b>–<b>5</b> and <b>7</b>–<b>9</b> were resolved with the help from density-functional theory-NMR and time-dependent density-functional theory-electronic circular dichroism calculation. The lipid-lowering activity was evaluated on palmitic acid/oleic acid (P/O)-treated AML12 hepatocytes. The biological evaluation was performed using Nile Red staining, flow cytometry, commercial kits, and Western blotting.</p> Results <p>Nine new sesquiterpenoid dimers and their co-occurring monomers (<b>1</b>–<b>9</b>) were identified from the leaves of <i>V. solanifolia</i>. A unique 10/5/6/5/7 pentacyclic ring system is exemplified in compounds <b>1</b> and<b> 2</b>. These compounds were constructed from a germacranolide and a 4,5-<i>seco</i>-guaianolide monomer through an unprecedented spiro cyclohexene ring. The first examples of germacrane-guaiane and guaiane-xanthane heterogeneous dimers are shown in compounds <b>3</b> and <b>4</b>, respectively, which also possess a spiro cyclohexene ring linkage. A guaianolide dimer featuring a rare C-13/C-13ʹ linkage is exhibited in compound <b>5</b>. The plausible biosynthetic pathways for compounds <b>1</b> and <b>5</b> were proposed. The isolates were tested for their lipid-lowering effect on P/O-treated AML12 hepatocytes, and the results showed that compound <b>3</b> significantly reduced lipid content in hepatocytes by triggering the AMP-activated protein kinase/acetyl-CoA carboxylase/peroxisome proliferator-activated receptor <i>γ</i> coactivator-1<i>α</i>&#xa0;signaling pathway.</p> Conclusion <p>Five homo- and hetero-dimeric sesquiterpenoids with unprecedented skeletons were characterized from <i>V. solanifolia</i>, together with four new co-occurring monomers. It’s the first time to report the lipid-lowering activity of sesquiterpenoids from this genus, which might be developed as lead compounds against MASLD.</p>

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Homo- and hetero-dimeric sesquiterpenoids with unprecedented skeletons and their co-occurring monomers from Vernonia solanifolia with anti-liver steatotic potential

  • Yue Yang,
  • Fei Zhou,
  • Chang-Qiang Ke,
  • Sheng Yao,
  • Ligen Lin,
  • Chunping Tang,
  • Yang Ye

摘要

Background

Sesquiterpenoids show potential as therapeutics against metabolic dysfunction-associated steatotic liver disease (MASLD). Vernonia solanifolia Benth. has been traditionally used to treat abdominal pain and enteritis. However, the anti-steatotic effect of V. solanifolia and its chemical principles have not been illustrated.

Methods

The structures of new compounds were determined through extensive spectroscopic analysis including 1D/2D nuclear magnetic resonance (NMR), high-resolution electrospray ionization mass spectrometry, ultraviolet and infrared. Especially, the structure of compound 6 was further verified by single crystal X-ray diffraction, and the relative and absolute configurations of compounds 15 and 79 were resolved with the help from density-functional theory-NMR and time-dependent density-functional theory-electronic circular dichroism calculation. The lipid-lowering activity was evaluated on palmitic acid/oleic acid (P/O)-treated AML12 hepatocytes. The biological evaluation was performed using Nile Red staining, flow cytometry, commercial kits, and Western blotting.

Results

Nine new sesquiterpenoid dimers and their co-occurring monomers (19) were identified from the leaves of V. solanifolia. A unique 10/5/6/5/7 pentacyclic ring system is exemplified in compounds 1 and 2. These compounds were constructed from a germacranolide and a 4,5-seco-guaianolide monomer through an unprecedented spiro cyclohexene ring. The first examples of germacrane-guaiane and guaiane-xanthane heterogeneous dimers are shown in compounds 3 and 4, respectively, which also possess a spiro cyclohexene ring linkage. A guaianolide dimer featuring a rare C-13/C-13ʹ linkage is exhibited in compound 5. The plausible biosynthetic pathways for compounds 1 and 5 were proposed. The isolates were tested for their lipid-lowering effect on P/O-treated AML12 hepatocytes, and the results showed that compound 3 significantly reduced lipid content in hepatocytes by triggering the AMP-activated protein kinase/acetyl-CoA carboxylase/peroxisome proliferator-activated receptor γ coactivator-1α signaling pathway.

Conclusion

Five homo- and hetero-dimeric sesquiterpenoids with unprecedented skeletons were characterized from V. solanifolia, together with four new co-occurring monomers. It’s the first time to report the lipid-lowering activity of sesquiterpenoids from this genus, which might be developed as lead compounds against MASLD.