Cell-based impedance spectroscopy for probing inhibitory effects of steroids and ergostane/lanosta-related compounds

Electric cell substrate impedance sensing (ECIS) was used for probing inhibitory effects on Spodoptera frugiperda Sf9 insect cells exposed to five synthesized steroid compounds. The results were compared to the levels obtained using three ergostane-related steroids and five lanosta-related triterpenes purified from the fruiting bodies of Antrodia camphorata. The half-inhibition concentration (ECIS50), the level of 50% inhibition of the resistance response, was determined from the response function to establish inhibitory effects of the different compounds. Significant effects on inhibition as probed by impedance spectroscopy were noticed because of slight changes in chemical structure. Only two of the synthesized compounds, 24(R,S)-5 alpha-lanost-8-ene-3,24,25-triol and 5 alpha-lanost-8-ene-3,7,11-trione, showed inhibitory effects which were much less significant compared to the A. camphorata steroids. The ECIS50 values were 150-250 mu M, similar to the value for the least inhibitory lanosta-related triterpene. This noninvasive measurement in combination with Sf9 insect cells has been proven as a simple and reliable tool for screening inhibition/cytotoxicity and designing steroid-related compounds.