Regulation of oxidative stress–mediated apoptosis by diallyl sulfide in DMBA-exposed Swiss mice
Authors: N Kalra
Y Shukla
S Srivastava
S Prasad
Journal: Human & experimental toxicology (2008)
Discipline: PHARMACOLOGY & TOXICOLOGY
Keywords: Diallyl sulfide; apoptosis; oxidative stress; antioxidant enzymes; lipid peroxidation
Affiliations: Proteomics Laboratory, Indian Institute of Toxicology Research, Mahatma Gandhi Marg, Lucknow, India.

Abstract:  Diallyl sulfide, a sulfur-containing volatile compound present in garlic (Allium sativum), exerts anticarcinogenic activity in various rodent tumor models. In the present study, apoptosis-inhibiting effects of diallyl sulfide against a carcinogenic polycyclic aromatic hydrocarbon, 7,12-dimethyl benz(a)anthracene (DMBA), in Swiss albino mice were observed. The animals were given either 250 microg/mouse or 500 mug/mouse of diallyl sulfide for 1 week after a single intragastric dose of 7,12-dimethyl benz(a)anthracene (50 mg/kg body weight). Results showed that diallyl sulfide supplementation effectively protects against 7,12-dimethyl benz(a)anthracene-induced oxidative stress, characterized by restored antioxidant enzyme levels (up to 64%) and lipid peroxidation (up to 25%). Flow cytometric analysis showed a reduction in apoptotic cell population in hypodiploid region in diallyl sulfide-supplemented animals. Inhibition of apoptosis was preceded by decrease in reactive oxygen species levels and restoration of mitochondrial transmembrane potential followed by decreased DNA fragmentation. In 7,12-dimethyl benz(a)anthracene-exposed animals, downregulation approximately 30%) of antiapoptotic Bcl-2 and upregulation (approximately 60%) of pro-apoptotic Bax proteins were observed. These alterations were restored significantly by diallyl sulfide supplementation, indicating inhibition of apoptosis. Thus, these results show that diallyl sulfide provides protection against oxidative damage induced by 7,12-dimethyl benz(a)anthracene in mouse liver and may be an effective chemopreventive and therapeutic agent by modulating expression of cell-growth regulatory proteins. 

Retracted: No

PubPeer comments:
  Figure 5 Western blot and its densitometric analysis of (A) Bcl-2 and (B) Bax expression in mouse liver in different groups [untreated control (C), DMBA alone (D), 250 u00b5g mouse DAS + DMBA (L+D), DMBA + 500 u00b5g mouse DAS (H+D), 500 u00b5g mouse DAS alone (S)]. Equal loading was confirmed by reprobing the membrane with u03b2-actin.  (A) displays remarkable rectangular discontinuity around the 4th lane (emphasised with an enhanced-contrast version). There is also the concern of how 6 lanes of u03b2-actin are supposed to control for 5 lanes of Bcl-2. ![file] In (B), the horizontal and vertical discontinuities are everywhere. The Bax slice looks like a headline-letter ransom note. ![file] , 
  Figure 4 Effect of DAS on DNA fragmentation. Isolated DNA from liver was run by agarose gel (0.8%) electrophoresis. Ladder formation was observed in DMBA-treated tissue (lane 3), whereas slight ladders were observed in both 250 u00b5g mouse (lane 4) and 500 u00b5g mouse DAS (lane 5) supplemented animals. DNA fragmentation was also not observed in untreated (lane 2) and DAS (500 u00b5g mouse)-treated (lane 6) mouse liver. Lane 1 showing marker DNA. Very sharp edges between some of the lanes. Emphasised in lighter version at the right. ![file] The  marker DNA lane also appears in Figures 7A and 7B of  Induction of apoptosis by lupeol and mango extract in mouse prostate and LNCaP cells [(Prasad et al 2007)] . ![] , 
  Figure 2 Effect of DAS in hepatic cell death. DMBA treatment showing increased sub G1 peak (2), which is decreased by treatment with 250 u00b5g mouse (3) and 500 u00b5g mouse (4) DAS in a dose-depended manner, whereas no sub G1 peak was observed in untreated control (1). PI fluorescence was measured using a flow cytometer with FL-2 filter and were expressed as histogram. I am intrigued by the peculiar glitches in these histograms. ![file] There are unsought-for similarities with the white-anted histograms of Fig 4 A ( Effect of lupeol and mango pulp extract (MPE) on apoptosis. Mouse prostate of testosterone treated ) from  Induction of apoptosis by lupeol and mango extract in mouse prostate and LNCaP cells [(Prasad et al 2007)] : ![] What happens if we superimpose, say, Fig 2(3) over Fig 4 (A Testosterone + MPE)? Or 2(2) over 4 (A Testosterone)? ![file] ,