Synthesis and biological activities of dibenzyl dipiperazine diquaternary ammonium salts

Unique spirocyclopiperazinium salt III: Further investigation of monospirocyclopiperazinium (MSPZ) salts as potential analgesics

Two novel classes of monospirocyclopiperazinium salts were designed, synthesized, and evaluated for their in vivo analgesic activities. Some interesting structure-activity relationships are revealed: (1) Spirocyclopiperazinium moiety is favorable to improve the analgesic activity; (2) The size and conformation of spirocyclopiperazinium moiety significantly affects the analgesic activity; (3) Phenylethyl group of 3d is a crucial pharmacophore. Among the compounds synthesized, 3d exhibited the most potent activity with low toxicity. Further antinociceptive mechanism studies of 3d showed that these compounds will be a new kind of analgesics.

Unique spirocyclopiperazinium salt. Part 4: Modification of dispirocyclopiperazinium (DSPZ) salts as analgesics

In order to improve the analgesic activity of lead compound 7a, two series of dispirocyclopiperazinium (DSPZ) salts 9a-h, 10a-e and compounds 14, 15 were synthesized and evaluated for their in vivo analgesic activity both by acetic acid induced writhing test and hot plate test. Compounds 9h, 14, and 15 exhibited better analgesic activities than 7a. Several important structure-activity relationships were revealed from this study: (1) the introduction of aryl group would obviously improve the activity; (2) it was favorable to enhance the analgesic activity and reduce the toxicity to incorporate alkyl group with suitable length in the molecule; (3) carbamate analogues displayed lower toxicity than carboxylic ester analogues; (4) hydroxylation and chlorination of lead compound could increase the analgesic activity in hot plate test.

Synthesis and analgesic activity of secondary amine analogues of pyridylmethylamine and positional isomeric analogues of ABT-594

A series of highly sterically hindered secondary amine analogues of pyridylmethylamine (7a-f, 8a-c) and positional isomeric analogues of ABT-594 (9a-c) were synthesized and evaluated for their in vivo analgesic activity. The compounds 7a and 7d show potent analgesic activity and lower toxicity. Some interesting structure-activity relationships have been revealed.

Synthesis and analgesic activity of hydrochlorides and quaternary ammoniums of epibatidine incorporated with amino acid ester

Hydrochloride derivatives 5a-c and quaternary ammonium derivatives 6a-c of epibatidine incorporated with amino acid ester were synthesized and evaluated for their in vivo analgesic activity and toxicity. Among all tested compounds, compound 6c has the most potent analgesic activity. The quaternary ammonium salts 6a and 6c showed better analgesic activity than the corresponding hydrochlorides 5a and 5c. Both 5a-c and 6a-c showed significantly lower toxicity than epibatidine itself.

Unique spirocyclopiperazinium salt. Part 2: synthesis and structure-activity relationship of dispirocyclopiperazinium salts as analgesics

Three series of spirocyclopiperazinium derivatives 5a-d, 6a-f and 17a-d were synthesized and evaluated for their in vivo analgesic activities. Compounds 5a, 17a and 17b exhibited excellent analgesic activity. Two important structure-activity relationships were observed from this study: (1) the quaternary ammonium functionality is a critical pharmacophore for analgesic activity; (2) it is important to adjust the lipophilic property of compounds to improve analgesic activity.

Unique spirocyclopiperazinium salt I: synthesis and structure-activity relationship of spirocyclopiperazinium salts as analgesics

Based on the structure of compound 3, two series of spirocyclopiperazinium derivatives 7a-n and 10a-h were synthesized and evaluated for their in vivo analgesic and sedative activities. Compounds 7f and 10c were discovered to exhibit excellent analgesic activity. Structure-activity relationships revealed that anion of the quaternary salt affected the analgesic and sedative activity significantly; the allyl group is a most effective group among the compounds 7a-n; the electron-released substitute on the aromatic ring is favorable to increase the analgesic activity.

Synthesis and biological activities of diquaternary dipiperazinium salts containing dithiocarboxyl groups

A series of diquaternary dipiperazinium salts containing dithiocarboxyl groups 6a-f and 9 were synthesized and evaluated for their analgesic and sedative activities. The result showed that the presence of two quaternary ammonium cations and the distance between them are very important for the activities of the salts. Compound 6b exhibited the best activities (at dose 2 mg/kg, analgesic, 57%; sedative, 59%) among compounds 6a-f. Compound 9 not only showed the most potent analgesic (85.4%, dose 1 mg/kg) and sedative (93.1%, dose 1 mg/kg) activities, but also exhibited anticancer activity against KB (68.7%, dose 10 microM).