Coronaridine, an iboga type alkaloid, inhibits the wnt signaling pathway by decreasing β-catenin expression[1].

Coronaridine (0-40 μM; 24 hours) is against non-cancer cells with IC50 values >40 μM. It agaisnt wnt-dependent cells with IC50 values of 10.4, 11.6 and 24.4 μM for SW480, HCT116 and DLD1cells, respectively[1].
Coronaridine (0-40 μM; 24 hours) inhibits β-catenin expression, but the protein levels of p-β--catenin at Ser33, Ser37, and Thr41 and p-β-catenin at Ser 45 [p-b-catenin (S45)] are unchanged[1].
In whole-cell patch clamp recordings,Catharanthine (1-300 μM) are respectively co-applied with GABA at concentrations corresponding to the EC30 value for each receptor subtype. Both congeners potentiated different GABAARs in a concentration-dependent manner[2].
At higher concentrations, however, Catharanthine starts to inhibit GABA-activated currents due to the reduced amplitude and rebound current, where the threshold concentration depended on the receptor subtype (e.g., >30 μM for hα1β2; >100 μM for hα1β2γ2 and hα2β2γ2). The PAM activity of Catharanthine's are depended on the receptor subtype: hα1β2 (4.6±0.8 μM), >hα2β2γ2 (12.6±3.8 μM), hα1β2γ2 (14.4 ± 4.6 μM)[2].

[1]. Kensuke Ohishi, et al. Coronaridine, an iboga type alkaloid from Tabernaemontana divaricata, inhibits the Wnt signaling pathway by decreasing β-catenin mRNA expression. Bioorg Med Chem Lett. 2015 Sep 15;25(18):3937-40.
[2]. Hugo R Arias, et al. Coronaridine congeners potentiate GABA A receptors and induce sedative activity in mice in a benzodiazepine-insensitive manner. Prog Neuropsychopharmacol Biol Psychiatry. 2020 Jul 13;101:109930