title: Functional attenuation of human sperm by novel, non-surfactant spermicides: precise targeting of membrane physiology without affecting structure.
abstract: BACKGROUND
  We have attempted to identify structural, physiological and other targets on human sperm vulnerable to the spermicidal action of two novel series of non-detergent molecules, reported to irreversibly immobilize human sperm in <30 s, apparently without disrupting plasma membrane.
  
  
  METHODS
  Three sperm samples were studied. Scanning and transmission electron microscopy were used to assess structural aberrations of sperm membrane; plasma membrane potential and intracellular pH measurements (fluorometric) were used to detect changes in sperm physiology; reactive oxygen species (ROS, fluorometric) and superoxide dismutase activity (colorimetric) were indicators of oxidative stress; and sperm dynein ATPase activity demonstrated alterations in motor energy potential, in response to spermicide treatment. Post-ejaculation tyrosine phosphorylation of human sperm proteins (immunoblotting) was a marker for functional integrity.
  
  
  RESULTS
  Disulfide esters of carbothioic acid (DSE compounds) caused complete sperm attenuation at > or =0.002% concentration with hyper-polarization of sperm membrane potential (P < 0.001), intracellular alkalinization (P < 0.01), ROS generation (P < 0.05) and no apparent effect on sperm (n = 150) membrane structure. Isoxazolecarbaldehyde compounds required > or =0.03% for spermicidal action and caused disrupted outer acrosomal membrane structure, depolarization of membrane potential (P < 0.001), intracellular acidification (P < 0.01) and ROS generation (P < 0.01). Detergent [nonoxynol-9 (N-9)] action was sustainable at > or =0.05% and involved complete breakdown of structural and physiological membrane integrity with ROS generation (P < 0.001). All spermicides caused functional attenuation of sperm without inhibiting motor energetics. Unlike N-9, DSE-37 (vaginal dose, 200 microg) completely inhibited pregnancy in rats and vaginal epithelium was unchanged (24 h,10 mg).
  
  
  CONCLUSIONS
  The study reveals a unique mechanism of action for DSE spermicides. DSE-37 holds promise as a safe vaginal contraceptive. CDRI Communication No. 7545.
authors.affiliation: Division of Endocrinology, Central Drug Research Institute (CSIR), Lucknow 226 001, India.
authors.forename: Rajeev K
authors.initials: RK
authors.lastname: Jain
authors.forename: Ashish
authors.initials: A
authors.lastname: Jain
authors.forename: Rajeev
authors.initials: R
authors.lastname: Kumar
authors.forename: Vikas
authors.initials: V
authors.lastname: Verma
authors.forename: Jagdamba P
authors.initials: JP
authors.lastname: Maikhuri
authors.forename: Vishnu L
authors.initials: VL
authors.lastname: Sharma
authors.forename: Kalyan
authors.initials: K
authors.lastname: Mitra
authors.forename: Sanjay
authors.initials: S
authors.lastname: Batra
authors.forename: Gopal
authors.initials: G
authors.lastname: Gupta
mesh_terms: D000282:Administration, Intravaginal; D000818:Animals; D004220:Disulfides / Q000008:administration & dosage / Q000494:pharmacology; D004398:Dyneins / Q000378:metabolism; D005260:Female; D006801:Humans; D006863:Hydrogen-Ion Concentration; D066298:In Vitro Techniques; D008297:Male; D008564:Membrane Potentials / Q000187:drug effects; D008855:Microscopy, Electron, Scanning; D046529:Microscopy, Electron, Transmission; D017137:Nonoxynol / Q000008:administration & dosage / Q000494:pharmacology; D018384:Oxidative Stress / Q000187:drug effects; D011247:Pregnancy; D051381:Rats; D017382:Reactive Oxygen Species / Q000378:metabolism; D013081:Sperm Motility / Q000187:drug effects; D013089:Spermatocidal Agents / Q000008:administration & dosage / Q000494:pharmacology*; D013094:Spermatozoa / Q000187:drug effects* / Q000502:physiology* / Q000648:ultrastructure; D013482:Superoxide Dismutase / Q000378:metabolism
chemical_list: C519274:DSE-37 compound; D004220:Disulfides; D017382:Reactive Oxygen Species; D013089:Spermatocidal Agents; D017137:Nonoxynol; D013482:Superoxide Dismutase; D004398:Dyneins