Discovery, stereospecific characterization and peripheral modification of 1-(pyrrolidin-1-ylmethyl)-2-[(6-chloro-3-oxo-indan)-formyl]-1,2,3,4-tetrahydroisoquinolines as novel selective κ opioid receptor agonists.

A novel series of 1-(pyrrolidin-1-ylmethyl)-2-[(3-oxo-indan)-formyl]-1,2,3,4-tetrahydroisoquinoline derivatives maj-3a-maj-3u were synthesized and evaluated in vitro for their binding affinity at κ-opioid receptors. Maj-3c displayed the highest affinity for κ-opioid receptors (Ki = 0.033 nM) among all the compounds evaluated. Furthermore, all four stereoisomers of compound 3c were prepared, and (1S,18S)-3c was identified as the most potent (Ki = 0.0059 nM) κ-opioid receptor agonist among the four stereoisomers. Maj-3c produced significant antinociception (ED50 = 0.000406 mg kg(-1)) compared to U-50,488H and original BRL 52580 in the acetic acid writhing assay, but its strong sedative effect (ED50 = 0.000568 mg kg(-1)) observed in the mouse rotation test reduced its druggability. To minimize the central nervous system side effects, a series of hydroxyl-containing analogs of maj-3c were synthesized, and maj-11a was found to be a potent κ-opioid receptor agonist (Ki = 35.13 nM). More importantly, the dose for the sedative effect (ED50 = 9.29 mg kg(-1)) of maj-11a was significantly higher than its analgesic dose (ED50 = 0.392 mg kg(-1)), which made it a promising peripheral analgesic candidate compound with weak sedative side effects.

[Technology study on extraction and purification of alkaloid from Stemona japonica].

OBJECTIVE: In order to obtain the optimal conditions for separating the alkaloids from the extract of Stemona japonica by selecting appropriate cation exchange resins. METHODS: Seven types of cation exchange resins were evaluated in separating efficiency with measuring the adsorption ratio and eluting ratio of total alkaloids as indices, and the content of total alkaloids from Stemona japonica was determined as an index by spectrophotometry to choose the optimal technological parameters. RESULTS: The optimal result of extraction was obtained as Stemona japonica shattered into thick powder, adding eight times amount of 90% alcohol and refluxing and extracting for 3 h (totally extracting for 3 times). Each gram of D004 cation exchange resin could absorb 0.5003 mg of the total alkaloid, and the desorption ratio was 68.45%. The transfer rate of total alkaloids was 58.70%. the product purity of alkaloids was up to 70%. CONCLUSION: The D004 cation exchange resin can be used for purificating total alkaloids from Stemona japonica and the established procedure is simple and feasible.