Rossini Gian Paolo, Hess Philipp
Università di Modena e Reggio Emilia, Dipartimento di Scienze Biomediche, Italy.
EXS. 2010;100:65-122. doi: 10.1007/978-3-7643-8338-1_3.
Phycotoxins are natural metabolites produced by micro-algae. Through accumulation in the food chain, these toxins may concentrate in different marine organisms, including filter-feeding bivalves, burrowing and grazing organisms, herbivorous and predatory fish. Human poisoning due to ingestion of seafood contaminated by phycotoxins has occurred in the past, and harmful algal blooms (HABs) are naturally occurring events. Still, we are witnessing a global increase in HABs and seafood contaminations, whose causative factors are only partially understood. Phycotoxins are small to medium-sized natural products and belong to many different groups of chemical compounds. The molecular mass ranges from approximately 300 to over 3000 Da, and the compound classes represented include amino acids, alkaloids and polyketides. Each compound group typically has several main compounds based on the same or similar structure. However, most groups also have several analogues, which are either produced by the algae or through metabolism in fish or shellfish or other marine organisms. The different phycotoxins have distinct molecular mechanisms of action. Saxitoxins, ciguatoxins, brevetoxins, gambierol, palytoxins, domoic acid, and, perhaps, cyclic imines, alter different ion channels and/or pumps at the level of the cell membrane. The normal functioning of neuronal and other excitable tissues is primarily perturbed by these mechanisms, leading to adverse effects in humans. Okadaic acid and related compounds inhibit serine/threonine phosphoprotein phosphatases, and disrupt major mechanisms controlling cellular functions. Pectenotoxins bind to actin filaments, and alter cellular cytoskeleton. The precise mechanisms of action of yessotoxins and azaspiracids, in turn, are still undetermined. The route of human exposure to phycotoxins is usually oral, although living systems may become exposed to phycotoxins through other routes. Based on recorded symptoms, the major poisonings recognized so far include paralytic, neurotoxic, amnesic, diarrheic shellfish poisonings, ciguatera, as well as palytoxin and azaspiracid poisonings.
藻毒素是微藻产生的天然代谢产物。通过食物链的积累，这些毒素可能会在不同的海洋生物中浓缩，包括滤食性双壳贝类、穴居和草食性生物、食草和食肉鱼类。过去曾发生过因食用受藻毒素污染的海鲜而导致的人体中毒事件，有害藻华是自然发生的现象。然而，我们正在目睹全球范围内有害藻华和海鲜污染事件的增加，其致病因素仅得到部分了解。藻毒素是中小型天然产物，属于许多不同的化合物类别。分子量范围从大约300到超过3000道尔顿，代表的化合物类别包括氨基酸、生物碱和聚酮化合物。每个化合物组通常基于相同或相似的结构有几种主要化合物。然而，大多数组也有几种类似物，它们要么由藻类产生，要么通过鱼类、贝类或其他海洋生物的代谢产生。不同的藻毒素具有不同的分子作用机制。石房蛤毒素、雪卡毒素、短裸甲藻毒素、冈比亚毒素、刺尾鱼毒素、软骨藻酸，以及可能的环亚胺，会在细胞膜水平改变不同的离子通道和/或泵。神经元和其他可兴奋组织的正常功能主要受到这些机制的干扰，从而对人体产生不良影响。冈田酸及相关化合物会抑制丝氨酸/苏氨酸磷酸蛋白磷酸酶，并破坏控制细胞功能的主要机制。pectenotoxins与肌动蛋白丝结合，并改变细胞骨架。而耶氏毒素和azaspiracids的确切作用机制仍未确定。人体接触藻毒素的途径通常是口服，尽管生物系统可能通过其他途径接触藻毒素。根据记录的症状，迄今为止确认的主要中毒类型包括麻痹性、神经毒性、失忆性、腹泻性贝类中毒、雪卡毒素中毒，以及刺尾鱼毒素和azaspiracid中毒。
