Effects of a Synthetic Analog of Polycavernoside A on Human Neuroblastoma Cells

Abstract

Background: Polycavernoside A is a glycosidic marine toxin first extracted from the red alga Polycavernosa tsudai in 1991 when 3 people died after the ingestion of this food. Polycavernoside A is an interesting molecule because of its complex macrolide structure and strong bioactivity. However, the target site of this toxin has not been characterized. Methods: We studied the effects of a synthethic analog of polycavernoside A on human neuroblastoma cells by measuring changes in membrane potential with bis-oxonol and variations in intracellular calcium levels with fura-2. Fluorescent phalloidin was utilized for assaying activity on actin cytoskeleton. Results: Data showed that this polycavernoside A analog induced a membrane depolarization and an increase in cytosolic calcium levels. Conclusion: These results provide the first insight into the mode of action of polycavernoside A, suggesting that: i) this toxin triggers an initial extracellular calcium entry neither produced across L-type voltage-gated calcium channels nor activation of muscarinic receptors ii) there is a depolarization induced by the toxin and due to the extracellular calcium entry.

Specific and dynamic detection of palytoxins by in vitro microplate assay with human neuroblastoma cells

“…PLT effects were comparatively tested in two cellular models: a rat hepatic cell line (Clone 9) widely used in metabolic studies [24] and human neuroblastoma BE-(2)-M17 cells, excitable cells with a great reference potential for the toxicity evaluation of many compounds [25,26]. In this case, we took advantage of the ease of obtaining cells from a cell line compared with the laborious isolation procedure of erythrocytes for the delayed HNA [7].…”

Synthetic efforts on the road to marine natural products bearing 4-O-2,3,4,6-tetrasubstituted THPs: an update

“… 12 Pharmacological studies developed with a synthetic derivative of 2a (in which the middle double bond of the lateral triene moiety was replaced by an alkyne group), gave a hint about the mechanism of action of this neurotoxin, suggesting that polycavernosides evokes a cytosolic calcium influx and a membrane potential depolarization. 39 Keeping in mind the aforementioned stimulant molecular architecture and potent toxic bioactivities, it was reasonable that synthetic strategies were developed to attain polycavernosides in the laboratory. The first total synthesis of 2a performed by Murai's group in 1998 allowed the unambiguous establishment of its absolute stereochemistry.…”

Production of Functionally Active Palytoxin-like Compounds by Mediterranean <i>Ostreopsis cf. siamensis</i>

“…Neuroblastoma cells were incubated in a thermostated chamber with the standard salt solution containing 5 nM bis-oxonol for 10 min at 37ºC. Fluorescence recordings were performed with a Nikon Diaphot microscope with epifluorescence optics (Nikon 40x immersion fluor objective) at the wavelengths 490 nm excitation and 530 nm emission [61,62]. Results are expressed as relative fluorescence as in Louzao et al [63].…”

“…Calcium measurements were made with the same microscope as above. Fluorescent images were collected by dual excitation wavelengths at 340 and 380 nm, and a wavelength emission at 530 nm with a Lambda 10-2 Sutter Instrument Co equipment [61,62]. Data are expressed as normalized ratio by dividing the fura-2 340/380 ratio at time t with respect to the 340/380 ratio at the baseline.…”