Crystalline ttx

From the ovaries of T. rubripes, TTX with a purity greater than 60% was prepared, and from the xanthid crab Zosimus aeneus, STX with a purity greater than 80% was prepared by solvent partitioning, activated charcoal treatment, and Bio-Gel P-2 (Bio-Rad Laboratories, Inc., Hercules, CA, USA) and Bio-Rex 70 (Bio-Rad) column chromatography according to the previously reported method [37 (link)], and used for the intrarectal TTX/STX administration experiment. Crystalline TTX (Wako Pure Chemical Industries Ltd., Tokyo, Japan) and an aqueous solution of STX purified from the xanthid crab Z. aeneus were used as external standards for the toxin quantification analyses described below.

The LLC-PK₁ cell line (ECACC number 86121112, Lot: 13G014) was purchased from DS Pharma Biomedical company (Osaka, Japan). High-glucose Dulbecco’s modified Eagle’s medium (DMEM), non-essential amino acid (NEAA) solution, and antibiotic-antimycotic solution (penicillin-streptomycin-amphotericin B suspension) were purchased from Wako Pure Chemical Industries (Osaka, Japan). Fetal bovine serum (FBS) was purchased from HyClone Laboratories (Logan, UT, USA). Crystalline TTX was purchased from Wako Pure Chemical Industries; in addition to its use in the experiments, it was used as a standard for liquid chromatography-tandem mass spectrometry (LC-MS/MS) analyses. Transport inhibitors l-carnitine, tetraethylammonium chloride (TEA), p-aminohippuric acid (PAH), probenecid, 1-methyl-4-phenylpyridinium iodide (MPP+), oxaliplatin, cefalexin, and cimetidine were purchased from Wako Pure Chemical Industries. All other chemicals were of reagent-grade quality.