a potent protein phosphatase 1A and 2A inhibitor.

Polyether derivative of C-38 fatty acid, C₄₄H₆₈O₁₃, from the microorganism Prorocentrum lima.

• Molecular Weight : 805.0 Da.
  
  
• Solubility in : chloroform, ethanol, methanol, acetone, ethyl acetate and DMSO; not soluble in water.
  
  
• Purity min. : 95 %. (HPLC)
  
  
• Physical Form : white photosensitive solid.
  
  
• Chemical Name : 9,10-Deepithio-9,10-didehydroacanthifolicin.
  
  
• Biological Activity : Very potent inhibitor of protein phosphatases-1 (PP1) and -2A (PP2A) that also stimulates the phosphorylation of many proteins [2]. 1 nM completely inhibits PP2A, IC50 ~0.1 nM. IC50 = 10-15 nM for PP1. IC50 = 5 µM for PP2B; 10 µM have no effect on PP2C [4].
  Causes a durable contraction of isolated vascular smooth muscles from human umbilical arteries (0.1-100 µM) and rabbit aorta (10 µM), indicating that myosin P-light chain phosphorylation is increased [1-2].
  Causes Diarrhetic Shellfish Poisoning (DSP), probably by stimulating the phosphorylation of proteins that control sodium secretion by intestinal cells [2]. Powerful tumour promoter. In two-stage carcinogenesis experiments on mouse skin, is of comparable potency to agents like phorbol esters, which exert their effects by activating protein kinase C [2].
  It reproduces the effects of Insulin on glucose transport in adipocytes [1].
  Diffuses through the cell membrane.
  
  
• Toxicity (LD₅₀) : mice (i.v.): 192 µg/kg [3]
  mice (i.p.): 192 µg/kg [2]
  
  
• Storage recommendations : Stable when kept dry, in a dark place; store at -20 °C; in solution, keep at -20°C; stable in methanol; stable in media/saline solutions for 1 experiment.
  Safety recommendations:
  Supposed tumour promoter: avoid skin contact, do not inhale.
  
  
• CAS Reg. No. : 78111-17-8
  
  
• RTECS No. : AA8227800
  
  
• Bibliography :
  
  1. Haysted et al., "Effects of the tumour promoter okadaic acid on intracellular protein phosphorylation and metabolism." Nature (1989). 337:78-81
  2. Cohen et al., "Okadaic acid: a new probe for the study of cellular regulation." TIBS (1990). 15:98-102
  3. Shibata et al., "Contractile Effects of Okadaic Acid, a novel Ionophore-Like Substance from Black Sponge, on Isolated Smooth Muscles Under the Condition of Ca Deficiency." J. Pharmacol. Exp. Therap. (1982). 233(1):135-143
  4. Cohen et al., FEBS Letters (1989). 250:596-600