HPLC-Based Activity Profiling for GABAA Receptor Modulators in Searsia pyroides Using a Larval Zebrafish Locomotor Assay.

A dichloromethane extract from leaves of potentiated gamma aminobutyric acid-induced chloride currents by 171.8 ± 54% when tested at 100 µg/mL in oocytes transiently expressing gamma aminobutyric acid type A receptors composed of s subunits. In zebrafish larvae, the extract significantly lowered pentylenetetrazol-provoked locomotion when tested at 4 µg/mL. Active compounds of the extract were tracked with the aid of HPLC-based activity profiling utilizing a previously validated zebrafish larval locomotor activity assay. From two active HPLC fractions, compounds  -  were isolated. Structurally related compounds  -  were purified from a later eluting inactive HPLC fraction. With the aid of H and C NMR and high-resolution mass spectrometry, compounds  -  were identified as analogues of anacardic acid. Compounds  -  led to a concentration-dependent decrease of pentylenetetrazol-provoked locomotion in the zebrafish larvae model, while  -  were inactive. Compounds  -  enhanced gamma aminobutyric acid-induced chloride currents in oocytes in a concentration-dependent manner, while  -  only showed marginal enhancements of gamma aminobutyric acid-induced chloride currents. Compounds , and have not been reported previously.