Brevetoxins: Looks colourful but it is harmful

Toxic dinoflagellate Karenia brevis (K. brevis), a species of phytoplankton produces lipid-soluble polyether neurotoxins known as brevetoxins. Karenia brevis produces at least nine brevetoxins, grouped according to their backbone structures (types A and B). Brevetoxins can be found in red tides (HABs) which are caused by toxic dinoflagellate Karenia brevis, during a red tide event, toxins are concentrated in seawater droplets that turn into aerosols ⁶. The red tides can occur worldwide in favourable conditions but for the past 20 years the west coast of Florida has faced these blooms on a near-annual basis ².

Offhore winds can carry aerosolized brevetoxins towards onshore ¹. Humans can be exposed either through eating a contaminated shellfish or through inhaling aerosolized brevetoxins ⁵. A concentration of brevetoxins in the aerosols ranging from <0.5 to 108 ng/m³ have been measured during an active red tide blooms period. People with asthma appear to be more vulnerable to aerosolized particles ³. They are also neurotoxic and a respiratory-tract irritant causing membrane depolarization.

Fish killing by brevetoxins up to 100 tons of fish per day have been estimated during an active blooms period. A value of 2.5 × 10⁶ cells/l is the typical concentration causing fish mortality ⁷.

Like other marine algae, K. brevis which produces brevetoxins also requires nutrients to grow. The sources of these nutrients are not fully understood yet, but they are thought to be originate both naturally and anthropogenically ⁴.

Figure 1. Backbone structures of Brevetoxins; (a) Brevetoxins A (b) Brevetoxins B

 

CAS No: Brevetoxins A: 98112-41-5, Brevetoxins B: 79580-28-2

SMILES:

Brevetoxins A: CC1CC2C(CC(=O)O2)OC3CC4C(CC(C5C(O4)CC=CCC6C(O5)CC=CC7C(O6)CCCC8C(O7)(CC9C(O8)CC2C(O9)C(CC(O2)CC(=C)C=O)O)C)C)OC3(C1)C

Brevetoxins B:

CC1CC2C(CC3(C(O2)CC4C(O3)C(=CC(=O)O4)C)C)OC5C1OC6CC7C(CC8C(O7)(CC=CC9C(O8)CC1C(O9)CC2C(O1)(C(CC(O2)CC(=C)C=O)O)C)C)(OC6(CC5)C)C

 

Result: Don’t dare to go near

References:

[1] Abraham, W. M., Bourdelais, A. J., Ahmed, A., Serebriakov, I., & Baden, D. G. (2005). Effects of inhaled brevetoxins in allergic airways: Toxin-allergen interactions and pharmacologic intervention. Environmental Health Perspectives, 113(5), 632–637. https://doi.org/10.1289/ehp.7498

[2] Alcock, F. (2007). An Assessment of Florida red tide: Causes, Consequences and Management Strategies. Marine Policy, (August), 46.

[3] Fleming L.E., B. Kirkpatrick, L.C. Backer, J.A. Bean, A. Wanner, A. Reich, D. Dalpra, J. Zaias, Y.S. Cheng, R. Pierce, J. Naar , W.M. Abraham, and D.G. Baden. 2007.
Aerosolized red-tide toxins (brevetoxins) and asthma. Chest 131(1):187-194

[4] Hogland, P., Jin, D., Beet, A., Kirkpatrick, B., Reich, A., Ullman, S., Fleming L.E., Kirkpatrick, G., (2014). The human health effects of Florida red tide (FRT) blooms: an expanded analysis. Environ Int. 2014 Jul;68:144-53. doi: 10.1016/j.envint.2014.03.016. Epub 2014 Apr 14.

[5] Kirkpatrick, B., Fleming, L. E., Backer, L. C., Bean, J. A., Tamer, R., Kirkpatrick, G., … Baden, D. G. (2006). HARMFUL emergency room respiratory diagnoses admissions. Water, 5(5), 526–533. https://doi.org/10.1016/j.hal.2005.09.004.Environmental

[6] Landsberg JH. The effects of harmful algal blooms on aquatic organisms. Rev. Fish. Sci. 2002;10:113–390.

[7] Quick, JA.; Henderson, GE. Effects of Gynmodinium breve red tides on fishes and birds: a preliminary report on behavior, anatomy, hematology and histopathology. In: Ambroski, RL.; Hood, MA.; Miller, RR., editors. Proceedings of the Gulf regional symposium on diseases of aquatic animals. Louisiana State University; Louisiana Sea Grant: 1974. p. 85-113.

 

Figures:

Brevetoxins structure: https://pubchem.ncbi.nlm.nih.gov/compound/Brevetoxin

Karenia brevis and red tides: https://www.google.com/