title: ACS6, a Hydrogen sulfide-donating derivative of sildenafil, inhibits homocysteine-induced apoptosis by preservation of mitochondrial function.
abstract: BACKGROUND
  The hydrogen sulfide-releasing sildenafil, ACS6, has been demonstrated to inhibit superoxide formation through donating hydrogen sulfide (H2S). We have found that H2S antagonizes homocysteine-induced oxidative stress and neurotoxicity. The aim of the present study is to explore the protection of ACS6 against homocysteine-triggered cytotoxicity and apoptosis and the molecular mechanisms underlying in PC12 cells.
  
  
  METHODS
  Cell viability was determined by Cell Counting Kit-8 assay. Cell apoptosis was observed using the chromatin dye Hoechst 33258 and analyzed by Flow Cytometry after propidium iodide staining. Mitochondrial membrane potential was monitored using the fluorescent dye Rh123. Intracellular reactive oxygen species were determined by oxidative conversion of cell permeable 2',7'-dichlorfluorescein-diacetate to fluorescent 2',7'-dichlorfluorescein. The expression of cleaved caspase-3 and bcl-2 and the accumulation of cytosolic cytochrome c were analyzed by Western blot.
  
  
  RESULTS
  We show that ACS6 protects PC12 cells against cytotoxicity and apoptosis induced by homocysteine and blocks homocysteine-triggered cytochrome c release and caspase-3 activation. ACS6 treatment results in not only prevention of homocysteine-caused mitochondrial membrane potential (Δψ) loss and reactive oxygen species (ROS) overproduction but also reversal of Bcl-2 down-expression.
  
  
  CONCLUSIONS
  These results indicate that ACS6 protects PC12 cells against homocysteine-induced cytotoxicity and apoptosis by preservation of mitochondrial function though inhibiting both loss of Δψ and accumulation of ROS as well as modulating the expression of Bcl-2. Our study provides evidence both for a neuroprotective effect of ACS6 and for further evaluation of ACS6 as novel neuroprotectants for Alzheimer's disease associated with homocysteine.
authors.affiliation: Department of Physiology, Medical College, University of South China, Hengyang, 421001, Hunan, P.R. China.
authors.forename: Xiao-Qing
authors.initials: XQ
authors.lastname: Tang
authors.affiliation: Department of Physiology, Medical College, University of South China, Hengyang, 421001, Hunan, P.R. China.
authors.forename: Rong-Qian
authors.initials: RQ
authors.lastname: Chen
authors.affiliation: Department of Physiology, Medical College, University of South China, Hengyang, 421001, Hunan, P.R. China.
authors.forename: Yan-Kai
authors.initials: YK
authors.lastname: Ren
authors.affiliation: CTG Pharma, Milano, 20131, Italy.
authors.forename: Piero Del
authors.initials: PD
authors.lastname: Soldato
authors.affiliation: Department of Pharmaceutical Sciences "Pietro Pratesi", Università degli Studi di Milano, Milan, Italy.
authors.forename: Anna
authors.initials: A
authors.lastname: Sparatore
authors.affiliation: Department of Physiology, Medical College, University of South China, Hengyang, 421001, Hunan, P.R. China.
authors.forename: Yuan-Yuan
authors.initials: YY
authors.lastname: Zhuang
authors.affiliation: Department of Physiology, Medical College, University of South China, Hengyang, 421001, Hunan, P.R. China.
authors.forename: Hen-Rong
authors.initials: HR
authors.lastname: Fang
authors.affiliation: Department of Pathophysiology, Medical College,, University of south China, Hengyang, 421001, Hunan, P.R. China.
authors.forename: Chun-Yan
authors.initials: CY
authors.lastname: Wang