Synthesis of alamandine glycoside analogs as new drug candidates to antagonize the MrgD receptor for pain relief

Two series of putatively brain-penetrant alamandine glycosides have been prepared for screening against the MrgD receptor. The first series retains the initial six residues of the alamandine sequence (ARVYIHP) as the peptide message, replacing the C-terminal proline (P) with several serine (S) glycosides at the C-terminus to produce glycoside addresses. In the second series, steric bulk was altered to modify the peptide message- the N-terminal alanine (A) residue was substituted with glycine (G); D-alanine (a); nor-valine (norV); D-nor-valine (D-norV); valine (V); and D-nor-valine (v), keeping the C-terminal serine-beta-D-glucoside (S-Glc) glycoside address constant. All the peptides and glycopeptides were synthesized as their C-terminal amides. The purity of native alamandine and its eleven selected derivatives were each confirmed using analytical HPLC. Also, the molecular weight and chemical composition were confirmed using mass spectroscopy. The MrgD receptor expression was evaluated in rationally chosen human cell lines, A549 and HEK 293. Both cell lines showed the presence of the MrgD receptor around 35 kDa, as confirmed by western blot analysis. The effect of varying concentrations of some alamandine derivatives on cell viability was evaluated on HEK 293 and A549 cell lines. [GRAPHICS] .

Automated summary

Two series of brain-penetrant alamandine glycosides were prepared and screened against the MrgD receptor. Structural modifications were made to the peptide message and glycoside addresses to create different variants. The purity and chemical composition of the compounds were confirmed, and the expression of the MrgD receptor was evaluated in human cell lines. The effects of the alamandine derivatives on cell viability were assessed.