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Protection of garlic against carcinogen genotoxicity. Anne-Marie Le Bon , Christine Belloir, Varsha Singh. Milestones :. In vitro evaluation of the antigenotoxic properties of garlic compounds in HepG2 cells
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Protection of garlic against carcinogen genotoxicity Anne-Marie Le Bon , Christine Belloir, Varsha Singh Milestones : In vitro evaluation of the antigenotoxic properties of garlic compounds in HepG2 cells Evaluation of the antigenotoxic properties of garlic extracts in tissues of rat
The studied molecules were : DADS (diallyl sulfide) DADSO (allicin) SAC (S-allyl cystein) AM (allyl mercaptan) Range : 5 to 100 µM Genotoxic compound Broken DNA = comet Undamaged DNA In vitro evaluation of antigenotoxic properties of garlic compounds in HepG2 cells Objectives : to assess if garlic compounds prevent DNA alterations induced by mutagenic compounds in a human cell line, HepG2 cells. DNA alterations were measured using the comet test.
Garlic compound +mutagen PROTOCOLS Pre-treatment studies : cells are treated firstwith the garlic compound and then with the pro-mutagen Garlic compound Pro-mutagen Hypothesis : inhibition or induction of xenobiotic metabolizing enzymes Mutagens : benzopyrene (BaP) aflatoxin B1 (AFB1) nitrosodimethylamine (NDMA) P450 1A P450 1A, 3A P450 2E1 Co-treatment studies : cells are treated with both the garlic compound and the direct-acting mutagen at the same time Hypothesis : scavenging of mutagenic compounds Mutagens : hydrogen peroxide (H2O2) methyl methane sulfonate (MMS) 4-nitrosoquinoline oxide (4-NQO)
DADS DADSO AM SAC BaP () AFB1 n.d. n.d. n.d. n.d. NDMA RESULTS Pre-treatment studies : inhibition of the genotoxicity () : slight inhibition - : no effect n.d. : not determined
SAC DADS DADSO AM () H2O2 MMS () () 4-NQO RESULTS Co-treatment studies : inhibition of the genotoxicity () : slight inhibition () :slight increase - : no effect
120 100 80 % of DNA alterations 60 40 20 0 H202 5 µM 25 µM 50 µM 100µM RESULTS Effects of S-allylcystein on H2O2 genotoxicity in HepG2 cells
CONCLUSIONS Garlic sulfur compounds prevent genotoxicity induced by direct- and indirect-acting compounds DADS and AM can act throught both mechanisms : modulation of EMX and scavenging DADS is more efficient than AM DADS and SAC act rather by scavenging genotoxic compounds The metabolites of DADS, DADSO and AM, could be the effective compounds in vivo
In vivo evaluation of antigenotoxic properties of garlic extracts in rats Objectives : to assess if garlic ingestion prevent DNA alterations induced by genotoxic compounds in rat liver Studied material : Garlic powder « 0 kg/ha SO4 » Garlic powder « 100 kg/ha SO4 » Garlic powder « 200 kg/ha SO4 »
5 6 7 4 5 %garlic powder PROTOCOL intraperitoneal injection of a genotoxic agent : AFB1 NDMA (4 hours before sacrifice) 60 Wistar male rats weeks Sacrifice Group C : control diet SA : Garlic 0 kg/ha SO4 SB : Garlic 100 kg/ha SC : Garlic 200 kg/ha Liver DNA damage evaluation (comet test)
7 6 5 * 4 * DNA damage (OTM) * 3 2 1 0 C SA SB SC C SA SB SC C SA SB SC + NDMA + AFB1 (control) RESULTS Effects of garlic ingestion on DNA damage in rat liver (5 rats / group) *: significantly different from the group C (Dunnett ’s test, p < 0.05)
CONCLUSIONS Garlic powders are not genotoxic by themselves. Garlic powder ingestion reduce liver DNA damage induced by AFB1. No statistical difference was observed between fertilisation levels. Mechanims of action : induction of CYP 1A and/or GST ? A slight reduction of NDMA genotoxicity was observed but this effect was not significant. Mechanims of action : inhibition of CYP 2E1 ? To be done shortly : colon study (preliminary studies in progress)
WP 6 Cancer : General conclusion Metabolism of DADS almost elucidated, proposition of a scheme of the metabolic pathway. In vivo after garlic powder administration to rats, we observed a modulation of hepatic enzymes involved in carcinogen activation or detoxication. Sulfur compounds prevent the genotoxicity of carcinogens in a human cell-line. They act by scavenging ultimate metabolites and/or by modulating the activity of carcinogen metabolizing enzymes
WP 6 Cancer : Deliverables DH. 8:In vitro metabolism of diallyl disulfide, ajoene and allicin (P12) : done, publication in progress DH. 9: In vitro effects of sulphur compounds on human P450 iso-enzymes (P12) : done DH. 10: In vitro evaluation of the anti-genotoxic properties of garlic compounds in HepG2 cells (P12) : done DH.13: In vivo metabolism of diallyl disulfide (P12) : done, publication submitted DH. 14: Effects of garlic extracts on carcinogen-metabolising enzymes (P12) : done, publication in progress DH. 15: In vivo evaluation of the antigenotoxic properties of garlic extracts in rats (P12) : in progress