Garlic oil polysulfides: H2S- and O2-independent prooxidants in buffer and antioxidants in cells.
The health benefits of garlic and other organosulfur-containing foods are well recognized and have been attributed to both prooxidant and antioxidant activities. The effects of garlic are surprisingly similar to those of hydrogen sulfide (H2S), which is also known to be released from garlic under certain conditions. However, recent evidence suggests that polysulfides, not H2S, may be the actual mediator of physiological signaling. In this study, we monitored formation of H2S and polysulfides from garlic oil in buffer and in human embryonic kidney (HEK) 293 cells with fluorescent dyes, 7-azido-4-methylcoumarin and SSP4, respectively and redox activity with two redox indicators redox-sensitive green fluorescent protein (roGFP) and DCF. Our results show that H2S release from garlic oil in buffer requires other low-molecular-weight thiols, such as cysteine (Cys) or glutathione (GSH), whereas polysulfides are readily detected in garlic oil alone. Administration of garlic oil to cells rapidly increases intracellular polysulfide but has minimal effects on H2S unless Cys or GSH are also present in the extracellular medium. We also observed that garlic oil and diallyltrisulfide (DATS) potently oxidized roGFP in buffer but did not affect DCF. This appears to be a direct polysulfide-mediated oxidation that does not require a reactive oxygen species intermediate. Conversely, when applied to cells, garlic oil became a significant intracellular reductant independent of extracellular Cys or GSH. This suggests that intracellular metabolism and further processing of the sulfur moieties are necessary to confer antioxidant properties to garlic oil in vivo.
Indiana University School of Medicine-South Bend Center, South Bend, Indiana; and Department of Biological Sciences, University of Notre Dame, Notre Dame, Indiana.
Eric R
ER
DeLeon
Indiana University School of Medicine-South Bend Center, South Bend, Indiana; and.
Yan
Y
Gao
Indiana University School of Medicine-South Bend Center, South Bend, Indiana; and Department of Biological Sciences, University of Notre Dame, Notre Dame, Indiana.
Evelyn
E
Huang
Indiana University School of Medicine-South Bend Center, South Bend, Indiana; and olson.1@nd.edu.
Kenneth R
KR
Olson
D000498:Allyl Compounds / Q000737:chemistry* / Q000494:pharmacology*; D000975:Antioxidants / Q000737:chemistry / Q000378:metabolism; D002021:Buffers; D002468:Cell Physiological Phenomena / Q000187:drug effects; D057809:HEK293 Cells; D006801:Humans; D006862:Hydrogen Sulfide / Q000737:chemistry* / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D016877:Oxidants / Q000737:chemistry / Q000378:metabolism; D010084:Oxidation-Reduction; D010100:Oxygen / Q000737:chemistry / Q000378:metabolism; D013440:Sulfides / Q000737:chemistry* / Q000378:metabolism* / Q000494:pharmacology*
D000498:Allyl Compounds; D000975:Antioxidants; D002021:Buffers; D016877:Oxidants; D013440:Sulfides; C038491:allyl sulfide; C032915:polysulfide; D010100:Oxygen; D006862:Hydrogen Sulfide
allium; dialyltrisulfide; polysulfides