LDL oxidation: tomato oleoresin vs lycopene

From: Doug Skrecky (oberon@vcn.bc.ca)
Date: Thu Nov 22 2001 - 10:21:52 MST

  Lycopene synergistically inhibits LDL oxidation in
  combination with vitamin E, glabridin, rosmarinic acid, carnosic acid, or
  Antioxidants & Redox
  Signaling. 2(3):491-506, 2000 Fall.
  Several lines of evidence suggest that oxidatively modified low-density
  lipoprotein (LDL) is atherogenic, and that atherosclerosis can be attenuated
  by natural antioxidants, which inhibit LDL oxidation. This
  study was conducted to determine the effect of tomato
  lycopene alone, or in combination with other natural
  antioxidants, on LDL oxidation. LDL (100 microg of
  protein/ml) was incubated with increasing concentrations of
  lycopene or of tomato oleoresin (lipid extract of tomatoes
  containing 6% lycopene, 0.1% beta-carotene, 1% vitamin E,
  and polyphenols), after which it was oxidized by the addition of 5
  micromol/liter of CuSO4. Tomato oleoresin exhibited superior capacity to
  inhibit LDL oxidation in comparison to pure lycopene, by up
  to five-fold [97% vs. 22% inhibition of thiobarbituric acid reactive
  substances (TBARS) formation, and 93% vs. 27% inhibition of lipid peroxides
  formation, respectively]. Because tomato oleoresin also contains, in addition
  to lycopene, vitamin E, flavonoids, and phenolics, a
  possible cooperative interaction between lycopene and such
  natural antioxidants was studied. A combination of
  lycopene (5 micromol/liter) with vitamin E
  (alpha-tocopherol) in the concentration range of 1-10 micromol/liter resulted
  in an inhibition of copper ion-induced LDL oxidation that was significantly
  greater than the expected additive individual inhibitions. The synergistic
  antioxidative effect of lycopene with vitamin E was not
  shared by gamma-to-cotrienol. The polyphenols glabridin (derived from
  licorice), rosmarinic acid or carnosic acid (derived from rosemary), as well
  as garlic (which contains a mixture of natural antioxidants)
  inhibited LDL oxidation in a dose-dependent manner. When
  lycopene (5 micromol/liter) was added to LDL in combination
  with glabridin, rosmarinic acid, carnosic acid, or garlic, synergistic
  antioxidative effects were obtained against LDL oxidation induced either by
  copper ions or by the radical generator AAPH. Similar interactive effects
  seen with lycopene were also observed with beta-carotene,
  but, however, to a lesser extent of synergism. Because natural
  antioxidants exist in nature in combination, the in vivo
  relevance of lycopene in combination with other natural
  antioxidants was studied. Four healthy subjects were
  administered a fatty meal containing 30 mg of lycopene in
  the form of tomato oleoresin. The lycopene concentration in
  postprandial plasma was elevated by 70% in comparison to plasma obtained
  before meal consumption. Postprandial LDL isolated 5 hr after meal
  consumption exhibited a significant (p < 0.01) reduced susceptibility to
  oxidation by 21%. We conclude that lycopene acts
  synergistically, as an effective antioxidant against LDL oxidation, with
  several natural antioxidants such as vitamin E, the
  flavonoid glabridin, the phenolics rosmarinic acid and carnosic acid, and
  garlic. These observations suggest a superior antiatherogenic characteristic
  to a combination of different natural antioxidants over that
  of an individual one.

This archive was generated by hypermail 2b30 : Sat May 11 2002 - 17:44:20 MDT