Synthesis and Characterization of Synthetic Neurotoxins

PnTX A, PnTX G, and the ketamine analogue (PnTX AK) were prepared by total synthesis as described herein. Detailed procedures and spectral data are presented in Supporting Information. Samples of synthetic PnTX A, PnTX G and PnTX AK were dissolved in ethanol and diluted in physiological solutions. The total ethanol concentration in the test solution did not exceed 0.15%. All physical data for synthetic PnTX A, PnTX AK, and PnTX G, including ¹H and ³C NMR spectroscopy, high-resolution mass spectrometry (HRMS), HPLC, and optical rotation data showed both compounds to be of high purity and identical to natural samples. [¹²⁵I]α-Bungarotoxin ([¹²⁵I]α-BTX) (210–250 Ci 3 mmol^–1), ((±)-[³H]epibatidine (55 Ci•mmol^–1), andN-methyl-[³H]scopolamine methyl chloride ([³H]NMS) (78 Ci•mmol^–1) were purchased from Perkin-Elmer (Courtaboeuf, France). All other chemicals were obtained from Sigma–Aldrich (Saint Quentin Fallavier, France) or other usual sources.