Effect of the antioxidant N-acetylcysteine on the depuration of the amnesic shellfish poisoning toxin, domoic acid, in the digestive gland of the king scallop

Domoic acid (DA) is a potent neurotoxin produced by worldwide distributed diatoms of the genus Pseudo-nitzchia (PSN) and is responsible for Amnesic Shellfish Poisoning (ASP) in humans. King scallop Pecten maximus, a bivalve species of high commercial interest, is regularly subjected to blooms of Pseudo-nitzschia sp., thus accumulating and retaining high levels of DA for extended periods, leading to prolonged fisheries and aquaculture closures and important economic losses following increasingly recurrent toxic PSN blooms. The underlying mechanisms behind this accumulation and long toxin retention remain poorly understood so far. Fishermen and the aquaculture industry ask for methods to accelerate DA depuration in contaminated scallops, which has led to investigate the effect of some substances such as the antioxidant N-Acetylcysteine (NAC), which was previously found to improve up to four-fold DA depuration in P. maximus adductor muscle. Our study investigated the potential of NAC to accelerate DA depuration in all scallop tissues, including the digestive gland (DG), where most of the toxin is accumulated. Twenty-four contaminated adult scallops were collected following a toxic P. australis bloom in the Bay of Brest (France) and half were treated with the antioxidant NAC (250 mg L−1) for 6 days. HPLC toxin quantification analyses did not revealed any significant differences in the DA burdens in the DG between treated scallops and the control group. DA amounts in the adductor muscle and gonads were below the HPLC detection limit in both groups. Our results revealed that NAC does not thus appear as a commercially suitable solution for fisheries and aquaculture industries as DA depuration enhancer in the tested conditions