Description:
Aqueous extracts of Nigella sativa (Ranunculaceae), has been traditionally used for the
treatment of several ailments such as inflammations, liver disorders, and arthritis. Several
studies on N. sativa revealed antioxidant, anti-inflammatory, hepatoprotective and
antimutagenic activities. In this study the protective effects of aqueous extracts of Nigella
sativa were evaluated against four toxicants by ex vivo/in vitro treatment of rat hepatocytes.
Rats were supplied with N. sativa aqueous extracts instead of drinking water for two weeks
prior to hepatocyte isolation by collagenase in situ two step liver perfusion. Primary cultures
of hepatocytes from fed and unfed rats were established, and treated with benzo[a]pyrene
(B[a]P), 2,3-dimethoxy-1,4-naphthoquinone (DMNQ), N-methyl-N’-nitro-N-nitrosoguanidine
(MNNG), and tert-Butyl hydroperoxide (TBHP). Controls from both fed and unfed rats were
either untreated or treated with the solvent dimethylsulfoxide (DMSO). Thereafter, the treated
and control cultures were stimulated for proliferation, fixed and analyzed for cyto- and
genotoxic effects. Mitotic indices and the percentages of necrotic and apoptotic cells were
evaluated for cytotoxicity testing, while the percentages of micronucleated cells (MN) and the
frequency of chromosomal aberrations (CA) were analyzed as endpoints of genotoxicity.
Control cultures from extract fed rats showed a significant increase in the frequency of CA,
and the percentages of MN and necrotic cells as well as the mitotic indices, when compared to
controls from unfed rats, indicating potential cyto- and genotoxic as well as mitogenic effects
of N. sativa extracts by themselves. Furthermore, DMNQ treatment of cultures from fed rats
demonstrated a significant increase in CA and MN, and a reduction of the mitotic indices
compared to DMNQ treatment of cultures from unfed rats, which indicates an increased
susceptibility of hepatocytes to DMNQ. Additionally, in TBHP-treated cultures from fed rats
significantly increased percentages of MN were observed indicating an enhancement of its
toxicity. In contrast, MNNG-treated cultures from fed rats showed significantly reduced CA
compared to those from unfed rats, indicating a protective effect against this directly acting
mutagen. Finally treatment with B[a]P of cultures from fed rats did not influence any of the
parameters compared to unfed rats.
In conclusion, N. sativa extract constituents or their metabolites seem to render hepatocytes
sensitive to redox cycling agents, but induce potential protection from the clastogenic effects
of the directly acting mutagen MNNG.
Conference:
International conference: Molecular and physiological effects of bioactive food compounds
Location:
Vienna
Affiliation:
University of Salzburg
Date:
Wednesday, October 11, 2006
External Link: