Fatty acid ester metabolites of gymnodimine in shellfish collected from China and in mussels (Mytilus galloprovincialis) exposed to Karenia selliformis

Abstract

Marine shellfish exposed to the microalgae Karenia selliformis can accumulate gymnodimines (GYM). Shellfish samples collected from Beihai City in Guangxi Autonomous Region, and Ningde City in Fujian Province, in the South China Sea, as well as mussels Mytilus galloprovincialis fed on K. selliformis under laboratory conditions were analyzed. Gymnodimines and various fatty acid ester metabolites were detected in the clam Antigona lamellaris and pen shell Atrina pectinata, while no esters were found in the oyster Crassostrea sp. and the gastropod Batillaria zonalis despite positive detection of free GYM in both species. When present, the predominant acyl esters observed were 18:0-GYM-A and 20:1-GYM-A. Under laboratory conditions GYM-A was accumulated and metabolized to fatty acid esters in mussels exposed to K. selliformis, with 16:0-GYM-A and 20:1-GYM-A as the major variants. A novel compound with the same accurate mass as GYM-A and its 16:0 fatty acid ester were observed in the experimental mussels but was not present in the microalgal strain to which mussels were exposed. No significant differences of reactive oxygen species (ROS) levels and antioxidant enzymes were found between mussels fed on K. selliformis or GYM-free microalgae Isochrysis galbana. This suggests the accumulation of GYM and its metabolites does not significantly impact the physiological status of mussels. While it is currently not proven that GYM affects human health, risk assessments should consider the presence of GYM esters in naturally contaminated shellfish as part of exposure analysis. Please note that this is an author-produced PDF of an article accepted for publication following peer review. The definitive publisher-authenticated version is available on the publisher Web site.

Development of an Efficient Extraction Method for Harvesting Gymnodimine-A from Large-Scale Cultures of Karenia selliformis

“…The GYM-A producing strain of K. selliformis (GM94GAB) used in this study was isolated from the Gulf of Gabes, Tunisia [19]. The K. selliformis culture method was described in our previous study [8]. In brief, the strain was cultured in sterile-filtered (0.45 µm membrane, Xingya, Shanghai, China) seawater before enrichment with an f/2 medium without silicate.…”

“…Extracellular toxins in culture medium were enriched by an Oasis ® HLB SPE cartridge (3 cc, 60 mg, Waters, Medford, MA, USA) as described in our previous study [8]. The cartridge was activated and conditioned with 100% MeOH (3 mL) and 20% MeOH (3 mL), respectively.…”

“…Similar to other phycotoxins, a high content of GYMs can accumulate in bivalve mollusks, including in scallops, mussels, oysters, and clams. Shellfish samples contaminated by Toxins 2021, 13, 793 2 of 14 GYMs have been reported in China [8,9], Europe [10,11], Lebanon [12], Mexico [13] and India [14]. Even though a regulatory limit for GYMs in shellfish has not been adopted due to lack of knowledge regarding their toxicological effects on human health, this toxin group has been evaluated by EFSA [15].…”

Chemodiversity of Brevetoxins and Other Potentially Toxic Metabolites Produced by Karenia spp. and Their Metabolic Products in Marine Organisms

“…However, only the 18:0 esters of GYM-B and GYM-C were specifically identified, with respective ID number of #135 and # ID136 (Figure 15). Some of the GYM-A fatty acids conjugates were also identified in shellfish collected in the South China Sea [41]. Clam (Antigona lamellaris) and pen shell (Atrina pectinata) profiles were different.…”

“…For both, individual analogs have been reported worldwide (Figure 1), whereas data are lacking for the other groups of metabolites produced by Karenia spp. [10,[20][21][22][23][24][25][26][27][30][31][32][33][35][36][37][38][39][40][41][42][43][44][45][46][47]. Several BTXs known to be produced by Karenia spp.…”