Extended Data Fig. 3. TBG is safer than ibogaine.
(a) Unlike ibogaine, IBG and TBG do not induce bradycardia in larval zebrafish. Sertindole (SI) was used as a positive control. (b) Heatmaps are shown representing aggregate larval zebrafish locomotor activity per well compared to vehicle controls (pseudo-Z-score). Red and blue indicate higher and lower activity than the mean of vehicle controls, respectively, while white indicates activity within ± 1 SD from control. Stimuli applied over time are indicated under the heatmaps. Colors indicate bright LED light of respective colors, black traces represent the waveforms of acoustic stimuli, and gray vertical lines indicate physical tapping as secondary acoustic stimuli. (c) Confusion matrix for classification of compounds (200 μM) plus VEH and lethal controls. (d) Concentration–response curves are shown for treated zebrafish subjected to the battery of stimuli depicted in Extended Data 3b. Lower percentages indicate treatments that were more often classified as vehicle (blue) or lethal (red). The solid line denotes the median and the shading denotes a 95th percentile confidence interval calculated by bootstrap. N = 8 wells / condition (64 zebrafish / condition). Blue lines indicate that all compounds produce behavioral phenotypes more distinct from vehicle at higher concentrations. Red lines indicate that known toxins (e.g., PTZ, picrotoxin, endosulfan), known hERG inhibitors (sertindole, haloperidol, terfenadine), and iboga alkaloids (IBO, NOR) produce behavioral phenotypes more closely resembling a lethal phenotype as their concentrations are increased. Increasing concentrations of IBG or TBG do not produce lethal-like behavioral phenotypes. (e) Transgenic larval zebrafish expressing GCaMP5G were immobilized in agarose, treated with compounds, and imaged over time. The known seizure-inducing compound PTZ was used as a positive control. Ibogaine and TBG were treated at 50 μM (n = 2 per condition). (f) Proportion of viable and non-viable (malformed + dead) zebrafish following treatment with VEH and TBG (66 μM) for 5 dpf (Fisher’s exact test: p = 0.3864). Representative images of zebrafish treated with VEH and TBG (66 μM) for 2 and 5 dpf are shown. Scale bar = 2 mm. Exact N numbers for each experimental condition are reported in Supplementary Table 1. Specific statistical tests, information on reproducibility, and exact p values are reported in the Methods and Supplementary Table 1.