Chemical Speciation Influences Comparative Activity of Selenium-Enriched Garlic and Yeast in Mammary Cancer Prevention

J Agric Food Chem. 2000 Jun;48(6):2062-70. doi: 10.1021/jf000051f.

Abstract

A recent human intervention trial showed that daily supplementation with selenized yeast (Se-yeast) led to a decrease in the overall cancer morbidity and mortality by nearly 50%; past research has also demonstrated that selenized garlic (Se-garlic) is very effective in mammary cancer chemoprevention in the rat model. The goal of this study was to compare certain biological activities of Se-garlic and Se-yeast and to elucidate the differences based on the chemical forms of selenium found in these two natural products. Characterization of organic selenium compounds in yeast (1922 microg/g Se) and garlic (296 microg/g Se) was carried out by high-performance liquid chromatography with inductively coupled plasma mass spectrometry or with electrospray mass spectrometry. Analytical speciation studies showed that the bulk of the selenium in Se-garlic and Se-yeast is in the form of gamma-glutamyl-Se-methylselenocysteine (73%) and selenomethionine (85%), respectively. The above methodology has the sensitivity and capability to account for >90% of total selenium. In the rat feeding studies, supplementation of Se-garlic in the diet at different levels consistently caused a lower total tissue selenium accumulation when compared to Se-yeast. On the other hand, Se-garlic was significantly more effective in suppressing the development of premalignant lesions and the formation of adenocarcinomas in the mammary gland of carcinogen-treated rats. Given the present finding on the identity of selenomethionine and gamma-glutamyl-Se-methylselenocysteine as the major form of selenium in Se-yeast and Se-garlic, respectively, the metabolism of these two compounds is discussed in an attempt to elucidate how their disposition in tissues might account for the differences in cancer chemopreventive activity.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Adenocarcinoma / chemically induced
  • Adenocarcinoma / prevention & control
  • Animals
  • Anticarcinogenic Agents / therapeutic use*
  • Carcinogens
  • Female
  • Garlic / therapeutic use*
  • Humans
  • Mammary Neoplasms, Experimental / chemically induced
  • Mammary Neoplasms, Experimental / prevention & control*
  • Phytotherapy*
  • Plants, Medicinal*
  • Precancerous Conditions / chemically induced
  • Precancerous Conditions / prevention & control
  • Rats
  • Rats, Sprague-Dawley
  • Selenium Compounds / therapeutic use*
  • Sodium Selenite / therapeutic use
  • Yeasts*

Substances

  • Anticarcinogenic Agents
  • Carcinogens
  • Selenium Compounds
  • Sodium Selenite