Effects of Different Garlic-derived Allyl Sulfides on Peroxidative Processes and Anaerobic Sulfur Metabolism in Mouse Liver Małgorzata B. Iciek, 1 * Danuta Kowalczyk-Pachel, 1 Inga Kwiecień 2 and Magdalena B. Dudek 3 1 Chair of Medical Biochemistry, Jagiellonian University Medical College, Kopernika 7, 31-034 Kraków, Poland 2 Chair and Department of Pharmaceutical Botany, Jagiellonian University Medical College, Medyczna 9, 30-688 Kraków, Poland 3 Laboratory of Pharmacological Screening, Department of Pharmacodynamics, Jagiellonian University Medical College, Medyczna 9, 30-688 Kraków, Poland Biological activity of garlic has been attributed to organosulfur compounds, most of all to oil-soluble allyl sulfides, such as diallyl sulfide (DAS), diallyl disulfide (DADS) and diallyl trisulfide (DATS). This study evaluated the ef- fectiveness of garlic-derived allyl sulfides in influencing peroxidative processes, levels of thiols and sulfane sulfur and its metabolic enzymes in normal mouse liver cells. Various allyl sulfides (DAS, DADS and DATS) dissolved in corn oil were given intraperitoneally to mice for 10 days. After sacrificing the mice, biochemical assays were performed in liver homogenates and in plasma in order to establish liver function. All allyl sulfides under study had a beneficial effect in the mouse liver since they decreased reactive oxygen species and malondialdehyde levels and increased glutathione S-transferase activity and non-protein sulfhydryl group level. Moreover, DADS and DATS elevated total sulfane sulfur pool and activity of sulfane sulfur biosynthetic enzymes. The increase in sulfane sulfur level entailed augmentation of its antioxidant and regulatory capacities. Garlic-derived allyl sul- fides exhibited antioxidant action in the liver and elevated anaerobic cysteine metabolism leading to the forma- tion of sulfane sulfur-containing compounds. Thus, DADS and DATS showed beneficial action in the liver, which can be used for protection of normal liver cells during chemotherapy or for alleviation of liver damage. Copyright © 2011 John Wiley & Sons, Ltd. Keywords: garlic; diallyl sulfide; diallyl disulfide; diallyl trisulfide; sulfane sulfur; sulfurtransferases. INTRODUCTION Biological activity of garlic (Allium sativum) has been attributed to organosulfur compounds (OSC; Corzo- Martinez et al., 2007; Iciek et al., 2009). When garlic cloves are cut or crushed, alliin is transformed to allicin in an alliinase-catalyzed reaction. Allicin is an unstable compound that is decomposed to oil-soluble allyl sulfides, such as diallyl sulfide (DAS), diallyl disulfide (DADS) and diallyl trisulfide (DATS) (Scheme 1; Lanzotti, 2006). Many laboratory studies have confirmed antibacter- ial, antifungal, immunostimulating and antioxidant properties of garlic (Corzo-Martinez et al., 2007; Iciek et al., 2009). In recent years, garlic has received increas- ing interest due to its potential therapeutic efficacy in cardiovascular diseases and anticancer properties. Des- pite many studies on the therapeutic potential of garlic, metabolic fate and mechanisms of biological activity of garlic-derived sulfur compounds have not been eluci- dated in detail. It is commonly accepted that for humans garlic is perfectly safe and does not cause adverse reactions. Garlic has been reported to exhibit antioxidant po- tential but some sources reported indigestion after consumption of larger amounts of garlic (Amagase, 2006). Higher doses of raw garlic have been shown to be toxic (Banerjee et al., 2003), especially garlic con- sumption by dogs and cats causes toxic effects (Cope, 2005). The more sulfur atoms in a polysulfide molecule, the stronger biological activity and the greater toxicity. Our studies showed a higher toxicity of DATS com- pared with DAS or DADS. For this reason, in the present studies it was decided to lower DATS dose be- cause of death cases in the group receiving 350 mmol DATS/kg b.w. Our interest in allyl polysulfides stems also from the fact that DATS and higher polysulfides contain sulfane sulfur in their structure. Sulfane sulfur is characterized by a 0 or 1 oxidation state and by always binding to an- other sulfur atom. Sulfane sulfur is extraordinarily chemically reactive and fulfills regulatory and antioxi- dant functions (Iciek and Wlodek, 2001). In this study, the effect of garlic-derived allyl sulfides on anaerobic cysteine metabolism yielding sulfane-sul- fur-containing compounds and on peroxidative pro- cesses in livers was investigated in healthy mice. The aim of these experiments was to compare the action of different sulfides, of which DATS contains sulfane sulfur and DADS can be isomerized to sulfane-sulfur-contain- ing thiosulfoxide, but DAS lacks sulfane sulfur. It should be remembered that normal liver cells show intense anaerobic cysteine metabolism yielding sulfane- sulfur-containing compounds: thiosulfate, thiocysteine and thiocystine (Scheme 2; Wlodek et al., 1993). Diallyl trisulfide is a trisulfide, like thiocystine, whereas allyl * Correspondence to: Malgorzata Iciek, Chair of Medical Biochemistry, Jagiellonian University Medical College, Kopernika 7, PL 31–034 Kraków, Poland. E-mail: miciek@cm-uj.krakow.pl PHYTOTHERAPY RESEARCH Phytother. Res. (2011) Published online in Wiley Online Library (wileyonlinelibrary.com) DOI: 10.1002/ptr.3572 Copyright © 2011 John Wiley & Sons, Ltd. Received 31 January 2011 Revised 26 April 2011 Accepted 29 April 2011