Exposure to marine benthic dinoflagellate toxins may lead to mitochondrial dysfunction.

Even though marine dinoflagellates are important primary producers, many toxic species may alter the natural equilibrium of aquatic ecosystems and even generate human intoxication incidents, as they are the major causative agents of harmful algal blooms. In order to deepen the knowledge regarding benthic dinoflagellate adverse effects, the present study aims to clarify the influence of Gambierdiscus excentricus strain UNR-08, Ostreopsis cf. ovata strain UNR-03 and Prorocentrum lima strain UNR-01 crude extracts on rat mitochondrial energetic function and permeability transition pore (mPTP) induction. Our results, expressed in number of dinoflagellate cell toxic compounds tested in a milligram of mitochondrial protein, revealed that 934 cells mg prot-1 of G. excentricus, and 7143 cells mg prot-1 of both O. cf. ovata and P. lima negatively affect mitochondrial function, including by decreasing ATP synthesis-related membrane potential variations. Moreover, considerably much lower concentrations of dinoflagellate extracts (117 cells mg prot-1 of G. excentricus, 1429 cells mg prot-1 of O. cf. ovata and 714 cells mg prot-1 of P. lima) produced mPTP-induced swelling in Ca2+-loaded isolated mitochondria. The present study clearly demonstrates the toxicity of G. excentricus, O. cf. ovata and P. lima extracts at the mitochondrial level, which may lead to mitochondrial failure and consequent cell toxicity, and that G. excentricus always provide much more severe effects than O. cf. ovata and P. lima.