Through high throughput screening and subsequent hit identification and optimization, we synthesized a series of 1-arylcarbonyl-6, 7-dimethoxyisoquinoline derivatives as the first reported potent and reversible GFAT inhibitors. SAR studies of this class of compounds indicated significant impact on GFAT inhibition potency by substitutions on the A-ring and C- ring. The ketone group was found to be necessary for high potency. Compound 28 ( ...