Bioavailability profiling shows differences in OA, DTX1 and DTX2 toxins that justify their toxicity.

The marine toxins of the Okadaic acid (OA) group are natural compounds produced by dinoflagellates that enters the food chain by accumulating in seafood. They are responsible for Diarrhetic Shellfish Poisoning (DSP) events in humans over the world and therefore are also jointly named as Diarrhetic Shellfish Toxins (DSTs). The main objective of this study was to evaluate symptoms, toxicity, absorption, distribution, and elimination of OA, Dinophysistoxin-1 (DTX1), and Dinophysistoxin-2 (DTX2) at the sublethal dose of 90 µg toxin/kg bw administered through voluntary feeding to mice. The toxin comparison highlighted that OA and DTX1 induced more severe and specific symptoms such as diarrhea. After oral ingestion toxins were distributed through the entire organism being detected in liver, kidney, stomach, small and large intestine. Predominant excretion of the toxins was observed in feces, with OA exhibiting fast elimination, while DTX2 was showing prolonged excretion. The passage and accumulation of toxins in gastrointestinal organs instigated macroscopic damage in the stomach, small and large intestine that could persist up to 120 h. These findings highlight the importance of pharmacokinetic of sublethal doses of DSTs administered by voluntary feeding in their toxicity and their implication for public health.

Analytical and functional profiles of paralytic shellfish toxins extracted from Semele proficua and Senilia senilis from Angola.

Paralytic shellfish poisoning is a foodborne illness that typically derive from the consumption of shellfish contaminated with saxitoxin-group of toxins produced by dinoflagellates of the genus Gymnodinium, Alexandrium and Pyrodinium. N-sulfocarbamoyl, carbamate and dicarbamoyl are the most abundant. In 2007 and 2008 some episodes of PSP occurred in Angola where there is not monitoring program for shellfish contamination with marine biotoxins. Therefore, ten samples extracted from Semele proficua from Luanda Bay and Senilia senilis from Mussulo Bay, were analyzed by HPLC finding saxitoxin, decarbamoylsaxitoxin and other three compounds that have an unusual profile different to the known hydrophilic PSP toxins were found in different amounts and combinations. These new compounds were not autofluorescent, and they presented much stronger response after peroxide oxidation than after periodate oxidation. The compounds appear as peaks eluted at 2.5 and 5.6 min after periodate oxidation and 8.2 min after peroxide oxidation. Electrophysiological studies revealed that none of the three unknown compounds had effect at cellular level by decreasing the maximum peak inward sodium currents by blocking voltage-gated sodium channels. Thus, not contributing to PSP intoxication. The presence in all samples of saxitoxin-group compounds poses a risk to human health and remarks the need to further explore the presence of new compounds that contaminate seafood, investigating their activity and developing monitoring programs.