Rastogi S, Shukla Y, Paul BN, Chowdhuri DK, Khanna SK, Das M.
Protective effect of Ocimum sanctum on 3-methylcholanthrene,
7,12-dimethylbenz(a)anthracene and aflatoxin B1 induced skin
tumorigenesis in mice.
Toxicol Appl Pharmacol. 2007 Jun 22
Industrial Toxicology Research Centre, Mahatma Gandhi Marg,
P.O. Box 80, Lucknow-226001, India.
A study on the protective effect of alcoholic extract of the
leaves of Ocimum sanctum on 3-mthylcholanthrene (MCA),
7,12-dimethylbenzanthracene (DMBA) and aflatoxin B1 induced skin
tumorigenesis in a mouse model has been investigated. The study
involved pretreatment of mice with the leaf extract prior to
either MCA application or tetradecanoyl phorbol acetate (TPA)
treatment in a two-stage tumor protocol viz a viz, DMBA/TPA and
Aflatoxin B1/TPA. The results of the present study indicate that
the pretreatment with alcoholic extract of the leaves of O.
sanctum decreased the number of tumors in MCA, DMBA/TPA and
Aflatoxin B1/TPA treated mice. The skin tumor induced animals
pretreated with alcoholic extract led to a decrease in the
expression of cutaneous gamma-glutamyl transpeptidase (GGT) and
glutathione-S-transferase-P (GST-P) protein. The
histopathological examination of skin tumors treated with leaf
extract showed increased infiltration of polymorphonuclear,
mononuclear and lymphocytic cells, decreased ornithine
decarboxylase activity with concomitant enhancement of
interleukin-1beta (IL-1beta) and tumor necrosis factor-alpha (TNF-alpha)
in the serum, implying the in vivo antiproliferative and
immunomodulatory activity of leaf extract. The decrease in
cutaneous phase I enzymes and elevation of phase II enzymes in
response to topical application of leaf extract prior to MCA,
Aflatoxin B1, DMBA/TPA and Aflatoxin B1/TPA treatment indicate
the possibility of impairment in reactive metabolite(s)
formation and thereby reducing skin carcinogenicity.
Furthermore, pretreatment of leaf extract in the carcinogen
induced animals resulted in elevation of glutathione levels and
decrease in lipid peroxidation along with heat shock protein
expression, indicating a scavenging or antioxidant potential of
the extract during chemical carcinogenesis. Thus it can be
concluded that leaf extract of O. sanctum provides protection
against chemical carcinogenesis in one or more of the following
mechanisms: (i) by acting as an antioxidant; (ii) by modulating
phase I and II enzymes; (iii) by exhibiting antiproliferative
activity.
PMID: 17669454
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