Table 1. Testing Various Selective HDAC Inhibitors as Activators of FXN Gene Transcription.

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Quantitative reverse transcriptase polymerase chain reaction was used to measure FXN messenger RNA levels after treatment with 10 μM compound in Friedreich ataxia lymphoid cells. Abbreviations: HDAC, histone deacetylase; PCR, polymerase chain reaction

Target/Class	Compound Structure	Ki or IC50	FXN transcription
HDAC1/2		Ki = 7 nM HDAC1 Ki = 2.5 μM HDAC3	Weakly active
HDAC3		Ki = 14 nM HDAC3 Ki = 148 nM HDAC1	Highly active
Class II		IC50 ∼ 1 μM class II HDACs	Inactive
Sirtuins		IC50 = 100 nM Sirt1 IC50 = 20 μM Sirt2 IC50 = 50 μM Sirt3	Inactive