NP04634 prevents cell damage caused by calcium overload and mitochondrial disruption in bovine chromaffin cells

Abstract

Marine sponges are becoming a rich source of potential new medicines. NP04634 is a synthetic derivative of 11,19 dideoxyfistularin, a natural product of the Mediterranean sponge Aplysina cavernicola. We report the cytoprotective effects of this new compound in isolated bovine chromaffin cells exposed to cytotoxic stimuli that have been related to neuronal cell death, i.e. Ca2+ overload and mitochondrial dysfunction. Cell death was achieved by: (i) causing Ca2+ overload through voltage-dependent calcium channels by exposing the cells to 30 mM K+, 5 mM Ca2+ plus 0.3 µM FPL64176 (an L-type Ca2+-channel activator); (ii) incubating the cells with veratridine, causing cytosolic Ca2+ concentration ([Ca2+]c) oscillations and mitochondrial disruption; and (iii) blocking mitochondrial complexes I and V using a combination of 30 µM rotenone and 10 µM oligomycin. At 10 µM, NP04634 caused significant protection against 30K+/5Ca2+/FPL-induced toxicity. NP04634 caused a concentration-dependent reduction in [Ca2+]c induced by 70 mM K+ in cells loaded with Fluo-4; maximum blockade was 67% at 30 µM. Veratridine caused continuous [Ca2+]c oscillations that translated into 43.4 ± 2% cell death. In this model, NP04634 caused 42% and 67% protection at 3 and 10 µM, respectively. NP04634 reduced [Ca2+]c oscillations and mitochondrial depolarization caused by veratridine. NP04634 at 10 µM also protected against mitochondrial disruption caused by rotenone plus oligomycin. In conclusion, NP04634 is a novel compound of marine origin with cytoprotective properties that might have potential therapeutic implications under pathological circumstances involving Ca2+ overload and mitochondrial disruption, such as in certain neurodegenerative diseases and/or stroke.