In vitro activity: ANA-12 binds directly and selectively to TrkB and inhibits processes downstream of TrkB without altering TrkA and TrkC functions. In nnr5 PC12-TrkB cells, ANA-12 prevents brain-derived neurotrophic factor (BDNF)-induced neurite outgrowth at concentrations as low as 10 nM. In DRG neurons, ANA-12 eliminates the effect of BDNF on increasing inward current.

Kinase Assay: Maxisorp ELISA 96-well plates are coated with various concentrations of Trk BECD -Fc, 20 mg/ml BSA, or 1 mg/mL IgG-Fc (polyclonal anti-TrkB) in a carbonate buffer (pH 9.6) overnight at 4°C. Plates are saturated with 0.5% BSA in PBS for 2 hours at room temperature and extensively washed in PBS-Tween 0.05%. Bodipy–ANA-12 is then incubated in 0.5% PBS-BSA for 1 hour at room temperature before the addition of BDNF in 0.5% PBS-BSA for another hour. After extensive washes in PBS-Tween 0.05%, the amount of bodipy–ANA-12 bound is quantified by fluorescence at 520 ± 10 nm. Detectability range for extrapolation analysis is assessed by coating ELISA plates with bodipy–ANA-12 and reading fluorescence at 520 ± 10 nm.

Cell Assay:  Modulation of neurite outgrowth by molecules is assessed in nnr5 PC12–TrkB, –TrkA, and –TrkC cells after addition of BDNF (1 nM), NGF (2 nM), and NT-3 (10 nM), respectively. The number of cells bearing neurites longer than 2 cells in diameter in each counting field is microscopically determined (2 fields per well, 3 wells per condition). Counting is performed blind each 24 hours for 3 days.