First report of borbotoxin occurrence in Brazilian Prorocentrum borbonicum isolates: LC-MS/MS detection and preliminary structural insights.

Borbotoxin is an emergent biotoxin produced by Prorocentrum borbonicum and other related dinoflagellates. This toxin is known to produce neuromuscular effects in animal models and may pose risks to human health, although its molecular structure is still unknown. Strains of Prorocentrum borbonicum isolated from the northeastern Brazilian coast were analyzed by reversed phase liquid chromatography coupled to tandem mass spectrometry. Cell pellets were extracted with methanol and water with the aid of an ultrasonic bath. Multiple reaction monitoring mode was used to search for borbotoxin A and B using mass data from literature. Putative peaks with close mass were found in two algal cell extracts. Experiments with the ion trap produced MS2 spectra in agreement with previous studies. Due to the absence of analytical standards, high mass spectrometry resolution was used to confirm the masses and the occurrence of borbotoxin was thus demonstrated. To the best of our knowledge, this is the first report of borbotoxin occurrence in Brazil. Further studies will be conducted to propose a definite structure to this relatively unknown marine biotoxin.