Pyrimidines are heterocyclic six-membered nitrogen-containing carbon ring structures with uracil cytosine and thymine being the basal structures of ribose-containing nucleosides (uridine cytidine and thymidine respectively) or deoxyribose-containing deoxynucleosides and their corresponding ribonucleotides or deoxyribonucleotides.

Reference standards.The herbs of Ajuga ciliata Bunge.

BCATc Inhibitor 2 exhibited an IC50 of 0.8 microM in the hBCATc assays; it is an active and selective inhibitor.