Rationally Designed α-Conotoxin Analogues Maintained Analgesia Activity and Weakened Side Effects

A lack of specificity is restricting the further application of conotoxin from Conus bullatus (BuIA). In this study, an analogue library of BuIA was established and virtual screening was used, which identified high α7 nicotinic acetylcholine receptor (nAChR)-selectivity analogues. The analogues were synthesized and tested for their affinity to functional human α7 nAChR and for the regulation of intracellular calcium ion capacity in neurons. Immunofluorescence, flow cytometry, and patch clamp results showed that the analogues maintained their capacity for calcium regulation. The results of the hot-plate model and paclitaxel-induced peripheral neuropathy model indicated that, when compared with natural BuIA, the analgesia activities of the analogues in different models were maintained. To analyze the adverse effects and toxicity of BuIA and its analogues, the tail suspension test, forced swimming test, and open field test were used. The results showed that the safety and toxicity of the analogues were significantly better than BuIA. The analogues of BuIA with an appropriate and rational mutation showed high selectivity and maintained the regulation of Ca²⁺ capacity in neurons and activities of analgesia, whereas the analogues demonstrated that the adverse effects of natural α-conotoxins could be reduced.