title: Effect of diets fortified with tomatoes or onions with variable quercetin-glycoside content on azoxymethane-induced aberrant crypt foci in the colon of rats.
abstract: BACKGROUND
  Onion and tomato are vegetables widely consumed by humans and epidemiological studies show an inverse association between vegetable consumption and colon cancer risk; however, the effect on colon cancer of diets containing high levels of vegetables like onion and tomato are not clear.
  
  
  OBJECTIVE
  To investigate whether tomatoes and onions,with low or high quercetin-glycoside content, could reduce azoxymethane (AOM)-induced Aberrant Crypt Foci (ACF), preneoplastic lesions in the colon of rats.
  
  
  METHODS
  Male Fisher 344 rats were fed the following diets: a) high fat (HF) diet (control diet); b) HF diet containing 20 % (w/w) tomatoes with a low quercetin-glycoside content (final concentration in the diet: 5 mg/kg of quercetin aglycone equivalents); c) HF diet containing 20% (w/w) high quercetin-glycoside tomatoes (100 mg/kg final concentration of quercetin aglycone equivalents); d) HF diet containing 20 % (w/w) low quercetin-glycoside onions (14 mg/kg of quercetin aglycone equivalents in the diet); e) HF diet containing 20 % (w/w) high quercetin-glycoside onions (360 mg/kg quercetin aglycone equivalents in the diet). After 2 wks of feeding, all rats were treated twice, 1 wk apart, with AOM (12 mg/kg, s. c.). The dietary treatments continued until sacrifice, 7 wks after the first injection with AOM.
  
  
  RESULTS
  ACF induction did not vary in animals fed low or high quercetin-glycoside tomatoes relative to controls. On the contrary, rats fed 20% (w/w) onion-based diets, with low or high quercetin-glycoside content, showed an increase in number, multiplicity and "large" ACF compared to the control group (number of ACF/colon 145 +/- 15 (SE), 255 +/- 11 and 218 +/- 16 in controls, low and high-quercetin-glycoside groups, respectively; p < 0.01). Proliferative activity of the colon did not vary between animals fed control and high quercetin-glycoside tomato diet. The height of the crypts in normal mucosa of rats fed high quercetinglycoside onions was significantly increased compared to control rats (cells/emicrypt 38.4 +/- 1.2 (SE) and 41.3 +/- 0.6 in controls and high quercetin-glycoside onions group, p < 0.05).
  
  
  CONCLUSIONS
  None of the diets supplemented with onion or tomato with variable quercetin-glycoside content demonstrated a potential chemopreventive effect on ACF-induction by AOM in rats.
authors.affiliation: Dept. of Pharmacology, University of Florence, Viale Pieraccini 6, 50139, Florence, Italy. angelo.pietro@unifi.it
authors.forename: Angelo Pietro
authors.initials: AP
authors.lastname: Femia
authors.forename: Giovanna
authors.initials: G
authors.lastname: Caderni
authors.forename: Maura
authors.initials: M
authors.lastname: Ianni
authors.forename: Maddalena
authors.initials: M
authors.lastname: Salvadori
authors.forename: Elio
authors.initials: E
authors.lastname: Schijlen
authors.forename: Geoff
authors.initials: G
authors.lastname: Collins
authors.forename: Arnaud
authors.initials: A
authors.lastname: Bovy
authors.forename: Piero
authors.initials: P
authors.lastname: Dolara
mesh_terms: D000818:Animals; D016588:Anticarcinogenic Agents / Q000008:administration & dosage*; D001397:Azoxymethane / Q000633:toxicity; D002273:Carcinogens / Q000633:toxicity; D003110:Colonic Neoplasms / Q000139:chemically induced / Q000473:pathology / Q000517:prevention & control*; D004305:Dose-Response Relationship, Drug; D005527:Food, Fortified; D006027:Glycosides / Q000008:administration & dosage*; D018551:Solanum lycopersicum / Q000737:chemistry*; D008297:Male; D019697:Onions / Q000737:chemistry*; D011794:Quercetin / Q000008:administration & dosage*; D011897:Random Allocation; D051381:Rats; D011916:Rats, Inbred F344
chemical_list: D016588:Anticarcinogenic Agents; D002273:Carcinogens; D006027:Glycosides; D011794:Quercetin; D001397:Azoxymethane