<unk>  (PbTx), or<unk> s, are a suite of cyclic polyether compounds produced naturally by a species of dinoflagellate known as Karenia brevis.<unk> s are neurotoxins that bind to voltage-gated sodium channels in nerve cells, leading to disruption of normal neurological processes and causing the illness clinically described as neurotoxic shellfish poisoning (NSP). Although<unk> s are most well-studied in K. brevis, they are also found in other species of Karenia and at least one large fish kill has been traced to<unk> s in Chattonella.<unk>  A<unk>  B chemical structure<unk>  A<unk>  B subtypes<unk> -1 (PbTx-1) R = -CH2C(=CH2)CHO<unk> -7 (PbTx-7) R = -CH2C(=CH2)CH2OH<unk> -10 (PbTx-10) R = -CH2CH(-CH3)CH2OH<unk> -2 (PbTx-2) R = -CH2C(=CH2)CHO<unk> -3 (PbTx-3) R = -CH2C(=CH2)CH2OH<unk> -8 (PbTx-8) R = -CH2COCH2Cl<unk> -9 (PbTx-9) R = -CH2CH(CH3)CH2OH Other<unk> s:<unk> -5 (PbTx-5): like PbTx-2, but acetylated hydroxyl group in position 38.<unk> -6 (PbTx-6): like PbTx-2, but double bond 27-28 is epoxidated.<unk> -B was synthesized in 1995 by K. C. Nicolaou and coworkers in 123 steps with 91% average yield (final yield ~9·10−6) and in 2004 in a total of 90 steps with an average 93% yield for each step (0.14% overall). K. C. Nicolaou and coworkers reported their synthesis of<unk> -1 in 1998. In 2009, Michael Crimmins and co-workers reported their synthesis of<unk> -1 as well.
Brevetoxin
Bungarotoxin
Bukatoxin
Alpha-neurotoxin
Satratoxin-H
Agitoxin
Saxitoxin
Latrotoxin