title: Equol: a comparison of the effects of the racemic compound with that of the purified S-enantiomer on the growth, invasion, and DNA integrity of breast and prostate cells in vitro.
abstract: It has been postulated that the R- and S-equol enantiomers have different biological properties given their different binding affinities for the estrogen receptor. S-(-)equol is produced via the bacterial conversion of the soy isoflavone daidzein in the gut. We have compared the biological effects of purified S-equol to that of racemic (R and S) equol on breast and prostate cancer cells of varying receptor status in vitro. Both racemic and S-equol inhibited the growth of the breast cancer cell line MDA-MB-231 (> or = 10 microM) and the prostate cancer cell lines LNCaP (> or = 5 microM) and LAPC-4 (> or = 2.5 microM). The compounds also showed equipotent effects in inhibiting the invasion of MDA-MB-231 and PC-3 cancer cells through matrigel. S-equol (1, 10, 30 microM) was unable to prevent DNA damage in MCF-7 or MCF-10A breast cells following exposure to 2-hydroxy-4-nonenal, menadione, or benzo(a)pyrene-7,8-dihydrodiol-9,10-epoxide. In contrast, racemic equol (10, 30 microM) prevented DNA damage in MCF-10A cells following exposure to 2-hydroxy-4-nonenal or menadione. These findings suggest that racemic equol has strong antigenotoxic activity in contrast to the purified S-equol enantiomer implicating the R-, rather than the S-enantiomer as being responsible for the antioxidant effects of equol, a finding that may have implications for the in vivo chemoprotective properties of equol.
authors.affiliation: Northern Ireland Centre for Food and Health, University of Ulster, Coleraine, Northern Ireland. pj.magee@ulster.ac.uk
authors.forename: Pamela J
authors.initials: PJ
authors.lastname: Magee
authors.forename: Marian
authors.initials: M
authors.lastname: Raschke
authors.forename: Claudia
authors.initials: C
authors.lastname: Steiner
authors.forename: Julie G
authors.initials: JG
authors.lastname: Duffin
authors.forename: Beatrice L
authors.initials: BL
authors.lastname: Pool-Zobel
authors.forename: Tuija
authors.initials: T
authors.lastname: Jokela
authors.forename: Kristiina
authors.initials: K
authors.lastname: Wahala
authors.forename: Ian R
authors.initials: IR
authors.lastname: Rowland
mesh_terms: D000970:Antineoplastic Agents / Q000737:chemistry / Q000494:pharmacology*; D001943:Breast Neoplasms / Q000473:pathology*; D002455:Cell Division / Q000187:drug effects; D045744:Cell Line, Tumor; D020552:Comet Assay; D004249:DNA Damage / Q000187:drug effects; D004273:DNA, Neoplasm / Q000187:drug effects* / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D060754:Equol; D005260:Female; D006801:Humans; D007529:Isoflavones / Q000737:chemistry / Q000494:pharmacology*; D008297:Male; D048789:Phytoestrogens / Q000737:chemistry / Q000494:pharmacology*; D011471:Prostatic Neoplasms / Q000473:pathology*; D011960:Receptors, Estrogen / Q000378:metabolism; D013237:Stereoisomerism
chemical_list: C007610:4',7-dihydroxy-3,4-dihydroisoflavone; D000970:Antineoplastic Agents; D004273:DNA, Neoplasm; D007529:Isoflavones; D048789:Phytoestrogens; D011960:Receptors, Estrogen; D060754:Equol; C004742:daidzein