Design and synthesis of novel 3-substituted-indole derivatives as selective H3 receptor antagonists and potent free radical scavengers.

A series of novel 3-substituted-indole derivatives with a benzyl tertiary amino moiety were designed, synthesized and evaluated as H3 receptor antagonists and free radical scavengers for Alzheimer's disease therapy. Most of these synthesized compounds exhibited moderate to potent antagonistic activities in CREs driven luciferase assay. In particular, compound 2d demonstrated the most favorable H3 receptor antagonistic activity with the IC50 value of 0.049µM. Besides, it also displayed high binding affinity to H3 receptor (Ki=4.26±2.55nM) and high selectivity over other three histamine receptors. Moreover, 2d and other two 3-substituted indole derivatives 1d and 3d exerted potent ABTS radical cation scavenging capacities similar to melatonin. Above results illustrate that 2d is an interesting lead for extensive optimization to explore new drug candidate for AD therapy.

Identification and characterization of ZEL-H16 as a novel agonist of the histamine H3 receptor.

The histamine H3 receptor (H3R) has been recognized as a promising target for the treatment of various central and peripheral nervous system diseases. In this study, a non-imidazole compound, ZEL-H16, was identified as a novel histamine H3 receptor agonist. ZEL-H16 was found to bind to human H3R with a Ki value of approximately 2.07 nM and 4.36 nM to rat H3R. Further characterization indicated that ZEL-H16 behaved as a partial agonist on the inhibition of forskolin-stimulated cAMP accumulation (the efficacy was 60% of that of histamine) and activation of ERK1/2 signaling (the efficacy was 50% of that of histamine) at H3 receptors, but acted as a full agonist just like histamin in the guinea-pig ileum contraction assay. These effects were blocked by pertussis toxin and H3 receptor specific antagonist thioperamide. ZEL-H16 showed no agonist or antagonist activities at the cloned human histamine H1, H2, and H4 receptors and other biogenic amine GPCRs in the CRE-driven reporter assay. Furthermore, our present data demonstrated that treatment of ZEL-H16 resulted in intensive H3 receptor internalization and delayed recycling to the cell surface as compared to that of control with treatment of histamine. Thus, ZEL-H16 is a novel and potent nonimidazole agonist of H3R, which might serve as a pharmacological tool for future investigations or as possible therapeutic agent of H3R.

Synthesis and biological evaluation of new 4ß-anilino-4'-O-demethyl-4-desoxypodophyllotoxin derivatives as potential antitumor agents.

A series of new 4ß-anilino-4'-O-demethyl-4-desoxypodophyllotoxin derivatives were prepared and evaluated for their cytotoxicities against four human cancer cell lines including KB, KB/VCR, A549 and 95D. Most compounds showed better growth-inhibition activities against tested cell lines than that of etoposide (VP-16). Preliminary structure-activity relationships (SARs) were concluded and it indicated that the side chains substituted at 4ß position of podophyllotoxin significantly influenced the cytotoxic activity, especially for the drug resistance profile. In vivo studies of compound 26c on highly metastatic human lung cancer xenograft in nude mice showed that it can significantly inhibit tumor growth with administrating by oral route.