Noopept enantiomers

hey guys, i was reading the abstract to a few noopept studies and came across this "The results of molecular docking showed that Noopept (L-isomer), as well as its metabolite, L-isomer of N-phenyl-acetylprolyl, unlike its pharmacologically ineffective D-isomer, is able to bind to the active site of prolyl hydroxylase 2."

I haven't before seen before any mention of an L or D enantiomers of noopept and was wondering if anyone knew if the noopept we usually purchase from say nootropics depot is racemic or just a single enantiomer. Is it possible the difference in the function of each enantiomer could explain why some people have suggested that some noopept batches felt weaker than others?

Source: https://www.ncbi.nlm.nih.gov/pubmed/27099787