In vitro activity: RGFP109 dose-dependently upregulates frataxin mRNA and protein levels in cultures of unstimulated peripheral blood mononuclear cells (PBMC) obtained from FRDA patients.

Kinase Assay:  Aconitase activities are determined by homogenization of mouse brain tissues on ice at 10% w/v in CellLytic MT Mammalian Tissue Lysis/Extraction buffer, followed by centrifugation at 800×g for 10 min at 4°C. Tissue lysates (50 μL) are then added to 200 μL of substrate mix (50 mM Tris/HCl pH 7.4, 0.4 mM NADP, 5 mM Na citrate, 0.6 mM MgCl2, 0.1% (v/v) Triton X-100 and 1U isocitrate dehydrogenase) and the reactions are incubated at 37°C for 15 min, followed by spectrophotometric absorbance measurements every minute for 15 min at 340 nm 37°C to determine the reaction slope. Aconitase activities of mouse brain tissues are then normalized to citrate synthase activities, which are determined using a citrate synthase assay kit.

Cell Assay:  The Ki values of RG2833 for HDAC1 and HDAC3 are 5.4 nM and 7.8 nM, respectively. RG2833 is highly active in the whole tested concentration range from 1 to 10 µM. Continuous incubation with RG2833 slows the increase in frataxin protein, and when the compound is removed, frataxin protein levels rapidly increased in the cells from patient P13. RG2833 produces significant increases in brain aconitase enzyme activity, together with reduction of neuronal pathology of the dorsal root ganglia (DRG).