A complex alkaloid, paxilline occurs in the mycelium of the mold Penicillium
paxilli. The structure has been confirmed by X-ray crystallography. The crystals
are orthorhombic with space group P2 12 121 and a = 31.009, b = 11.522 and
c = 7.70 A.
Paxilline is an indole diterpene from fungi which potently and reversibly inhibits large conductance Ca2+-activated K+ (BKCa) channels, as shown in patch clamp (Ki = 1.9 nM) and whole smooth muscle cell studies (Ki = 35.7 nM). It also enhances the binding of charybdotoxin , a peptidyl neurotoxin, to BKCa channels. Paxilline is currently used to evaluate the role of BKCa channels in various cell processes and responses.
Potent blocker of high-conductance calcium-activated potassium (BKCa) channels
Paxilline is a tremorgenic mycotoxin isolated from species of Penicillium, Acremonium and Emericella. Paxilline selectively blocks high-conductance Ca2+-activated potassium channels and inhibits binding to the cerebellar inositol 1,4,5-triphosphate (InsP(3)) receptor.
ChEBI: Paxilline is an indole diterpene alkaloid with formula C27H33NO4 isolated from Penicillium paxilli. It is a potent inhibitor of large conductance Ca2(+)- and voltage-activated K(+) (BK)-type channels. It has a role as a mycotoxin, a Penicillium metabolite, an anticonvulsant, an Aspergillus metabolite, a potassium channel blocker, a genotoxin, a geroprotector and an EC 3.6.3.8 (Ca(2+)-transporting ATPase) inhibitor. It is an organic heterohexacyclic compound, a tertiary alcohol, a terpenoid indole alkaloid, an enone and a diterpene alkaloid.
Potent blocker of high-conductance Ca 2+ -activated K + (BK Ca ) channels. Binds to the α -subunit of BK Ca (K i = 1.9 nM for block of currents in α -subunit-expressing oocytes) and enhances binding of charybdotoxin to BK Ca channels in vascular smooth muscle. Also inhibits sarco/endoplasmic reticulum Ca 2+ -ATPase (IC 50 = 5-50 μ M).
This BKCa/KCa1.1) channel blocker (FW = 435.56 g/mol; CAS 57186-25-1; Solubility: 100 mM in DMSO), also named (2R,4bS,6aS,12bS,12cR,14aS)- 5,6,6a,7,12,12b,12c,13,14,14a-decahydro-4b-hydroxy-2-(1-hydroxy-1- methylethyl)-12b,12c-dimethyl-2H-pyrano[2'',3'': 5',6']benz[1',2':6,7]indeno [1,2-b]indol-3(4bH)-one, binds to the α-subunit of BKCa, exhibiting a Ki value of 1.9 nM in blocking currents in α-subunit-expressing oocytes and enhancing binding of to BKCa channels in vascular smooth muscle. (See Charybdotoxin) Paxilline also inhibits sarco/endoplasmic reticulum Ca2+-ATPase, IC50 = 5 - 50 μM.
Springer et ai., Tetrahedron Lett., 2531 (1975)
