Description_x000D_ Biochem/physiol Actions_x000D_ Octyl-(R)-2HG (Octyl-D-2HG) is a membrane-permeant precursor form of the oncometabolite D-2-hydroxyglutarate (D-2HG) produced by tumor cells due to mutations in the NADP+-dependent isocitrate dehydrogenase genes IDH1 and IDH2. D-2HG inhibits multiple α-ketoglutarate/α-KG-dependent dioxygenases by competing against α-KG binding. Cellular D-2HG delivery by Octyl-(R)-2HG treatment (1-50 mM) is shown to suppress demethylase activity (~148% H3K9me2 and ~310% H3K79me2 upregulation; 50 mM in U-87MG) as well as increase HIF-1α and decrease endostatin levels as a result of inhibiting α-KG-dependent dioxygenases prolyl hydroxylases (PHDs) and collagen prolyl-4-hydroxylase (C-P4H), respectively.