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 :

Range : 5 to 100 µMDADS (diallyl sulfide)DADSO (allicin)SAC (S-allyl cystein)AM (allyl mercaptan)

In vitro evaluation of antigenotoxic properties of garlic compoundsin 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.

Undamaged DNA Broken DNA = comet

Genotoxic compound

Pre-treatment studies : cells are treated first with the garlic compound and then with the pro-mutagen

Hypothesis : inhibition or induction of xenobiotic metabolizing enzymes

Garlic compound Pro-mutagen

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

Garlic compound + mutagen

Mutagens : benzopyrene (BaP) aflatoxin B1 (AFB1) nitrosodimethylamine (NDMA)

Mutagens : hydrogen peroxide (H2O2) methyl methane sulfonate (MMS) 4-nitrosoquinoline oxide (4-NQO)

PROTOCOLS

P450 1AP450 1A, 3AP450 2E1

RESULTS

Pre-treatment studies

DADS DADSO SACAM

NDMA n.d. n.d. n.d.

AFB1 ()

BaP

n.d.

: inhibition of the genotoxicity() : slight inhibition - : no effectn.d. : not determined

: inhibition of the genotoxicity() : slight inhibition() :slight increase - : no effect

Co-treatment studies

()

DADS DADSO SACAM

H2O2

4-NQO

MMS

()

()

RESULTS

% o

f D

NA

alte

ratio

ns

0

20

40

60

80

100

120

H202 5 µM 25 µM 50 µM 100µM

Effects of S-allylcystein on H2O2 genotoxicity in HepG2 cells

RESULTS

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

Studied material :

Garlic powder «  0 kg/ha SO4 »

Garlic powder «  100 kg/ha SO4  »

Garlic powder «  200 kg/ha SO4  »

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

4 5 6 7

5 % garlic powder

Sacrifice

Liver DNA damageevaluation

(comet test)

intraperitoneal injection of

a genotoxic agent : AFB1 NDMA(4 hours before sacrifice)

Group C : control diet

SA : Garlic 0 kg/ha SO4

SB : Garlic 100 kg/ha

SC : Garlic 200 kg/ha

60 Wistar male rats

PROTOCOL

weeks

RESULTS

0

1

2

3

4

5

6

7

C SA SB SC C SA SB SC C SA SB SC

**

*

(control) +AFB1

+NDMA

DN

A d

amag

e (

OT

M)

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