Effects Of Diallyl Sulfide Research Articles

Chemoprevention of chemically induced skin tumor development by diallyl sulfide and diallyl disulfide.

Garlic and onion oil have been shown to inhibit chemically induced skin tumor development in mice. In the present study, the effects of diallyl sulfide and diallyl disulfide, oil-soluble constituents of garlic and onion, on 7,12-dimethylbenz(a)anthracene-induced and 12,O-tetradecanoylphorbol-13-acetate-promoted skin tumor formation were examined in SENCAR mice. Topical application of diallyl sulfide or diallyl disulfide significantly inhibited skin papilloma formation from the ninth week of promotion and significantly increased the rate of survival in the murine model. Our findings support earlier evidence that these naturally occurring compounds may be useful for the chemoprevention of certain types of tumors.

Inhibitory effects of diallyl sulfide on the metabolism and tumorigenicity of the tobacco-specific carcinogen 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) in A/J mouse lung

Diallyl sulfide (DAS), a component of garlic oil, has been shown to inhibit tumorigenesis by several chemical carcinogens. Our previous work demonstrated that DAS inhibited the metabolic activation of carcinogenic nitrosamines, including the tobacco-specific 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK), in rat lung and nasal mucosa microsomes. In the present study, the effects of DAS on the tumorigenicity and the metabolism of NNK in A/J mouse lung were examined. Female A/J mice at 7 weeks of age were pretreated with DAS (200 mg/kg body wt in corn oil, p.o) daily for 3 days. Two hours after the final DAS treatment, the mice were either given a single dose of NNK (2 mg/mouse, i.p.) and kept for an additional 16 weeks for determining the production of pulmonary tumors, or were killed immediately so as to measure the microsomal activity in metabolizing NNK. In comparison to the vehicle control group, DAS pretreatment significantly decreased the incidence of NNK-induced lung tumors (37.9 versus 100%) and the tumor multiplicity (0.6 versus 7.2 tumors/mouse). In pulmonary metabolism of NNK, DAS pretreatment reduced the rates of formation of keto aldehyde, keto alcohol, NNAL-N-oxide, and NNK-N-oxide by 70-90%. In addition, the formation of NNK oxidative metabolites from NNK in the liver microsomes from DAS-pretreated mice was remarkably reduced. DAS also inhibited the metabolism of NNK in mouse lung microsomes in vitro. These results demonstrate that DAS is an effective chemopreventive agent against NNK-induced lung tumorigenesis, probably by inhibiting the metabolic activation of NNK.

Modulation of N-nitrosomethylbenzylamine bioactivation by diallyl sulfide in vivo.

Diallyl sulfide (DAS), a major component of garlic oil, is an inhibitor of tumorigenesis by various metabolically activated carcinogens. In rats, pretreatment with DAS has been observed to suppress completely the induction of oesophageal neoplasms by N-nitrosomethylbenzylamine (NMBzA) (Wargovich et al. (1988) Cancer Res., 48, 6872-6875). This communication reports the effects of DAS on overall NMBzA metabolism and on DNA methylation of NMBzA in vivo under conditions equivalent to a single treatment of the chemoprevention assay. Male Fischer 344 rats received a single i.g. dose of DAS (200 mg/kg body wt) followed by an s.c. injection of [methyl-14C]NMBzA (3.5 mg/kg). In controls, exhalation of 14CO2 was complete within 5 h (t1/2max = 1.2 h), with 50% of the injected radioactivity recovered as 14CO2. When DAS was given 3 h prior to [methyl-14C]NMBzA, 49% of the injected radioactivity was released within 10 h (t1/2max = 3 h). When DAS was administered 18 h before the carcinogen, 42% of [methyl-14C]NMBzA was converted to 14CO2, with exhalation complete after 6 h (t1/2max = 1.8 h). We further examined the effects of acute doses of 10-200 mg/kg of DAS on DNA methylation by a single dose of NMBzA (3.5 mg/kg; survival time, 6 h) administered 3 h later. At 200 mg/kg, DAS inhibited the formation of O6-methyldeoxyguanosine (O6-MEdG) in oesophagus (-26%), nasal mucosa (-51%), trachea (-68%) and lung (-78%). In liver, levels of 7-MEdG were reduced by 43%. Decreases in DNA methylation were proportional to dose for > 25 mg/kg of DAS in oesophagus, liver and nasal mucosa, for 25-200 mg/kg in trachea and 10-50 mg/kg in lung. The dose-activity relationship for inhibition by DAS of DNA methylation by NMBzA suggests that short-term modulation of carcinogen bioactivation in situ contributes to but may not be sufficient for the chemo-prevention of nitrosamine tumorigenesis by DAS.

Inhibition of Benzoyl Peroxide-Mediated Tumor Promotion in 7,12-Dimethylbenz(a)anthracene-Initiated Skin of Sencar Mice by Antioxidants Nordihydroguaiaretic Acid and Diallyl Sulfide

Benzoyl peroxide (BPO), a free radical generating compound, is widely used in topical medications prescribed for acne vulgaris and in cosmetic products. It has been shown to possess tumor-promoting activity in murine skin initiated with chemical carcinogens such as 7,12-dimethylbenz(a)anthracene (DMBA). In the present study we assessed the effect of the antioxidants nordihydroguaiaretic acid (NDGA) and diallyl sulfide (DAS) against BPO-mediated tumor promotion in murine skin. Pretreatment of Sencar mice with NDGA and DAS prior to skin application of BPO resulted in a time- and dose-dependent inhibition of epidermal ODC induction caused by BPO. Tumor initiation was achieved by a single topical application of DMBA (10 micrograms/animal) to Sencar mice. Ten days later tumor promotion was begun by twice-weekly topical application of BPO (20 mg/animal). The anticarcinogenic effects of NDGA (25 mumol/mouse) and DAS (20 mumol/mouse) were evaluated by administering these agents topically 60 min prior to each BPO application. After 26 weeks on test, the number of benign papillomas/mouse were 0.10 +/- 0.07 and 2.15 +/- 0.30 in the NDGA and DAS pretreated group of animals as compared to 4.40 +/- 1.14 in animals receiving BPO alone. After 51 weeks on test, the number of squamous cell carcinomas/mouse were 0.00 +/- 0.00, 0.35 +/- 0.10 in the NDGA and DAS pretreated group of animals as compared to 0.65 +/- 0.12 in animals receiving BPO alone. From these data we suggest that the antioxidants NDGA and DAS can abrogate the tumor-promoting effects of BPO in murine skin and that NDGA is substantially more effective than DAS in this regard.