Phytosterol and γ-Oryzanol Conjugates: Synthesis and Evaluation of their Antioxidant, Antiproliferative, and Anticholesterol Activities

J Nat Prod. 2018 Oct 26;81(10):2212-2221. doi: 10.1021/acs.jnatprod.8b00465. Epub 2018 Oct 17.

Abstract

Fifteen new multifunctional conjugates were designed and synthesized by chemically linking the steroidal framework of natural occurring γ-oryzanol and γ-oryzanol-derived phytosterols to a wide range of bioactive natural compounds (fatty acids, phenolic acids, amino acids, lipoic acid, retinoic acid, curcumin, and resveratrol). Starting from γ-oryzanol, which is the main component of rice bran oil, this study was aimed at assessing if the conjugation strategy might enhance some γ-oryzanol bioactivities. The antioxidant activity was evaluated through three different mechanisms, namely, DPPH-scavenging activity, metal-chelating activity, and β-carotene-bleaching inhibition. Measurement of the in vitro cell growth inhibitory effects on three different human cancer cellular lines was also carried out, and the potential hypocholesterolemic effect was studied. Compounds 10 and 15 displayed an improved antioxidant activity, with respect to that of γ-oryzanol. Compounds 2, 6, and 12 exerted an antiproliferative activity in the low micromolar range against HeLa and DAOY cells (GI50 < 10 μM). As for the claimed hypocholesterolemic effect of γ-oryzanol, none of the synthesized compounds inhibited the 3-hydroxy-3-methylglutaryl-coenzyme A reductase, a key enzyme in cholesterol biosynthesis.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Anticholesteremic Agents / chemical synthesis*
  • Anticholesteremic Agents / pharmacology*
  • Antineoplastic Agents, Phytogenic / chemical synthesis*
  • Antineoplastic Agents, Phytogenic / pharmacology*
  • Antioxidants / chemical synthesis*
  • Antioxidants / pharmacology*
  • Cell Line, Tumor
  • Cell Proliferation / drug effects
  • Chelating Agents / chemistry
  • Free Radical Scavengers / chemical synthesis
  • Free Radical Scavengers / pharmacology
  • Humans
  • Molecular Structure
  • Oryza / chemistry
  • Phenylpropionates / chemistry*
  • Phenylpropionates / pharmacology*
  • Phytosterols / chemistry*
  • Phytosterols / pharmacology*
  • Plant Oils / chemistry
  • beta Carotene / chemistry

Substances

  • Anticholesteremic Agents
  • Antineoplastic Agents, Phytogenic
  • Antioxidants
  • Chelating Agents
  • Free Radical Scavengers
  • Phenylpropionates
  • Phytosterols
  • Plant Oils
  • beta Carotene
  • gamma-oryzanol