Representatives of Mnemosyne Pharmaceuticals Inc. have cooperated with scholars overseas to identify novel GluN2A antagonists MPX-004 and MPX-007 as new pharmacological tools to study the physiology of NMDA receptors containing the GluN2A subunit. In their article they seek to define the high potency and selectivity of their GluN2A probes upon targeted NMDA receptors with GluN2A subunits. The authors of this study expect that MPX-004 and MPX-007 should provide improved pharmacological tools to examine GluN2A physiology and function in neuropsychiatric and developmental illnesses.

To inspect structure-activity relationship of MPX-004 and MPX-007 with GluN2A, the researchers chose to prepare calcium activity assays containing HEK cells expressing human GluN2A, B, and D. GluN2A NMDA receptor activity would be evaluated through observation of glutamate/glycine-induced increases in intracellular calcium concentration rendered quantifiable by fluorescent calcium indicator Fluo-8^®. These structure-activity values would be compared among MPX-004, MPX-007 and their 2010 predecessor, TCN-201, which MPX-004 and MPX-007 are analogs of. Their findings indicated that TCN-201 exhibited less inhibitory activity on all NMDA receptors used in the assays than MPX-004 and MPX-007 did, and that both MPX compounds were able to completely halt GluN2A-induced calcium responses, while minimally affecting GluN2B and D activity, demonstrating proof of the improved potency and selectivity of MPX-004 and MPX-007 over TCN-201.

Another probe that also proved effective during this experiment was Fluo-8^®, which enabled fluorescent microplate readers to accurately distinguish between events of minimal calcium activity and heavier calcium responses. This is due to Fluo-8^®'s intense and sensitive fluorescent signal upon chelation with calcium. Another advantage of using Fluo-8^® over other calcium dyes is its enhanced loading properties, as shown by the description of the screening assays within the study. Fluo-8^® has been optimized to be less temperature-dependent, allowing for its efficient and convenient incubation with HEK cells at room temperature for 30 minutes, according to the article. Validating MPX-004 and MPX-007 has also established Fluo-8^® as a robust and valuable tool in pharmacological studies considering calcium interaction.