Ellagic acid embryoprotection in vitro: distribution and effects on DNA adduct formation.
Ellagic acid (EA) is a naturally occurring plant phenol that was recently demonstrated to protect cultured rat embryos from the embryotoxic effects of N-methyl-N-nitrosourea (MNU). The teratogenic mechanism of action of MNU, as well as other methylating agents, is debated: both cell death and mutation have been proposed. In some model systems, EA has been reported to selectively decrease the mutagenic DNA adduct O6-methylguanine (O6MG) when compared to the cytotoxic DNA adduct N7-methylguanine (N7MG). The present study was initiated to determine 1) the distribution of 14C-EA and 3H-MNU in the rat whole embryo culture model system and 2) the effects of EA on MNU-induced DNA adduct formation in this model system. 14C-EA (50 microM for 2 hr, known embryoprotective concentration; no MNU added) was used to demonstrate access of EA to the embryo within the 2 hr exposure period. The majority of EA (99.5%) remained in the media while tissue concentrations of 57.0 and 47.9 pmol/mg were attained in the yolk sacs and embryos, respectively. Similarly, MNU (75 microM for 1 hr, known effective concentration; no EA added) was distributed between the media, yolk sacs, and embryos at 99.7%, 73.7 and 112.9 pmol/mg, respectively. When non-radiolabeled EA (50 microM for 2 hr) was used to protect embryos prior to exposure to 3H-MNU (75 microM for 1 hr), the distribution of MNU in the model system was unchanged.(ABSTRACT TRUNCATED AT 250 WORDS)
Frank
A A
AA
College of Veterinary Medicine, Oregon State University, Corvallis 97331-4802.
Collier
J M
JM
Forsyth
C S
CS
Zeng
W
W
Stoner
G D
GD
D000014:Abnormalities, Drug-Induced / Q000517:prevention & control*; D000818:Animals; D004249:DNA Damage; D004610:Ellagic Acid / Q000493:pharmacokinetics / Q000627:therapeutic use*; D004622:Embryo, Mammalian / Q000737:chemistry / Q000187:drug effects*; D006147:Guanine / Q000031:analogs & derivatives / Q000032:analysis; D008770:Methylnitrosourea / Q000493:pharmacokinetics / Q000633:toxicity*; D009924:Organ Culture Techniques; D051381:Rats; D017207:Rats, Sprague-Dawley / Q000196:embryology; D012995:Solubility; D013723:Teratogens / Q000493:pharmacokinetics / Q000633:toxicity*; D015017:Yolk Sac / Q000737:chemistry
D013723:Teratogens; D004610:Ellagic Acid; D006147:Guanine; D008770:Methylnitrosourea; C008449:O-(6)-methylguanine