Structures of compounds 1–10 isolated from the DCM extract of S. longepedunculata bark

Examples of toxicological signs from morphological assessments of compounds isolated from S. longepedunculata on zebrafish larvae within the first 3, 24, and 48 h after treatment. (a) Larva exposed to 0.5% DMSO (control) is showing normal urogenital opening (in the dashed box) and normal heart (solid box) at 4 dpf 3 h postexposure, relative to (b) treated larva (compound 7, 9.4 μM) displaying abnormal urogenital opening (dashed box) and abnormal edema of the heart (solid box) at 4 dpf 3 h postexposure. (c) Control larva treated with 0.5% DMSO shows normal body axis (notochord) (arrow), somites [precursors to muscle tissue (solid box)], and swim bladder (solid box) at 5 dpf 24 h postexposure, relative to figure (d) where the treated larva (compound 7, 9.4 μM) displays abnormally curved body axis (notochord) (arrow), darkened tissues, suggestive of cell death (dashed box) and reduced swim bladder (solid box) at 5 dpf 24 h postexposure. (e) Larva as control (0.5% DMSO) shows no signs of darkened brain tissues, suggestive of cell death (dotted arrow), normal liver (dashed box), and normal yolk sac (solid box) at 6 dpf 48 h postexposure, compared to (f) treated larva (compound 4, 43.8 μM) showing darkened brain (dotted arrow), darkened liver (dashed box) indicating cell death, and edema of the yolk sac at 6 dpf 48 h postexposure. All scale bars are presented as 100 μm

Zebrafish behavioral assay showing inhibition of seizure-like paroxysms (a) and hypoactivity (b) of S. longepedunculata extracts and compounds after 30 min tracking period. The concentration of S. longepedunculata compounds and extracts used in both graphs (a,b) was equal to the MTC found after their toxicological evaluation in larval zebrafish (see Section 2.2). The final concentration of DMSO was 0.5% per well. (a) Average distance traveled (mm/30 min) by zebrafish larvae (y-axis) treated with PTZ + 0.5% DMSO (vehicle). Data normalized against the PTZ-control (final concentration 20 mM). (b) Average distance traveled (mm/30 min) by zebrafish larvae treated with 0.5% DMSO (y-axis). Data normalized against the DMSO control. Data were analyzed using two-way ANOVA with multiple comparisons. Results are expressed as means ± standard deviation (SD) of three to six separate experiments. Sample (n = 12), sample + PTZ (n = 12), PTZ (n = 8), fish water control (n = 8), and fish water + 0.5% DMSO (n = 8). n─represents the total number of larvae. **** = p < 0.0001, *** = p < 0.001, and ** = p < 0.01. * = <0.05, compared to controls; PTZ- or DMSO-treated larvae. Fish water and 0.5% DMSO were used as negative control (untreated larvae).