Timosaponin B-II Ameliorates Palmitate-Induced Insulin Resistance and Inflammation via IRS-1/PI3K/Akt and IKK/NF-[Formula: see text]B Pathways

Am J Chin Med. 2016;44(4):755-69. doi: 10.1142/S0192415X16500415. Epub 2016 May 24.

Abstract

This study aimed to investigate the effect of timosaponin B-II (TB-II) on palmitate (PA)-induced insulin resistance and inflammation in HepG2 cells, and probe the potential mechanisms. TB-II, a main ingredient of the traditional Chinese medicine Anemarrhena asphodeloides Bunge, notably ameliorated PA-induced insulin resistance and inflammation, and significantly improved cell viability, decreased PA-induced production of tumor necrosis factor-[Formula: see text] (TNF-[Formula: see text]) and interleukin-6 (IL-6) levels. Further, TB-II treatment notably decreased malondialdehyde (MDA) and lactate dehydrogenase (LDH) levels, and improved superoxide dismutase (SOD) and nitric oxide (NO). TB-II also reduced HepG2 cells apoptosis. Insulin receptor substrate-1 (IRS1)/phosphatidylinositol 3-kinase (PI3K)/Akt and inhibitor of nuclear factor [Formula: see text]-B kinase (IKK)/NF-[Formula: see text]B pathways-related proteins, and IKK[Formula: see text], p65 phosphorylation, serine phosphorylation of insulin receptor substrate-1 (IRS-1) at S307, tyrosine phosphorylation of IRS-1, and Akt activation were determined by Western blot. Compared to model group, TB-II significantly downregulated the expression of p-NF-[Formula: see text]Bp65, p-IKK[Formula: see text], p-IRS-1, p-PI3K and p-Akt. TB-II is a promising potential agent for the management of palmitate-induced insulin resistance and inflammation, which might be via IR/IRS-1/PI3K/Akt and IKK/NF-[Formula: see text]B pathways.

Keywords: IKK/NF-B; IR/IRS-1/PI3K/Akt; Inflammation; Insulin Resistance; Timosaponin B-II.

MeSH terms

  • Hep G2 Cells
  • Humans
  • I-kappa B Kinase
  • Inflammation / drug therapy*
  • Inflammation / genetics
  • Inflammation / metabolism
  • Insulin Receptor Substrate Proteins / genetics
  • Insulin Receptor Substrate Proteins / metabolism*
  • Insulin Resistance*
  • Interleukin-6 / genetics
  • Interleukin-6 / metabolism
  • NF-kappa B / genetics
  • NF-kappa B / metabolism*
  • Nitric Oxide / metabolism
  • Palmitates / adverse effects*
  • Phosphatidylinositol 3-Kinases / genetics
  • Phosphatidylinositol 3-Kinases / metabolism*
  • Phosphorylation / drug effects
  • Proto-Oncogene Proteins c-akt / genetics
  • Proto-Oncogene Proteins c-akt / metabolism*
  • Saponins / pharmacology*
  • Signal Transduction / drug effects
  • Steroids / pharmacology*

Substances

  • Insulin Receptor Substrate Proteins
  • Interleukin-6
  • NF-kappa B
  • Palmitates
  • Saponins
  • Steroids
  • timosaponin B-II
  • Nitric Oxide
  • Phosphatidylinositol 3-Kinases
  • Proto-Oncogene Proteins c-akt
  • I-kappa B Kinase