β-cyano-L-Alanine

β-cyano-L-Alanine (BCA) is a reversible inhibitor of the H₂S-synthesizing enzyme CTH (CSE). BCA blocks H₂S synthesis activity in rat liver preparations with an IC₅₀ value of 6.5 μM and increases blood pressure in anaesthetized rats induced with hemorrhagic shock by inhibiting endogenous H₂S synthesis. BCA at 50 mg/kg blocked both L-cysteine- and LPS-induced hyperalgesia in rats. Hydrogen sulfide (H₂S) is a naturally-occurring gasotransmitter with vasodilator and inflammatory modulating activity. H₂S is synthesized naturally in a range of mammalian tissues principally by the activity of two enzymes, CTH (cystathionine γ lyase CSE) and cystathionineβ synthetase (CBS).