Design, synthesis, and biological activity of novel 1,4-disubstituted piperidine/piperazine derivatives as CCR5 antagonist-based HIV-1 entry inhibitors.

A series of novel 1,4-disubstituted piperidine/piperazine derivatives were designed, synthesized and evaluated for their in vitro activities against HIV-1 Bal (R5) infection in CEMX174 5.25M7 cells. A majority of these compounds showed potent anti-HIV-1 activities with IC(50) at nanomolar levels. N-(4-Fluoro-benzyl)piperazine analog B07 hydrochloride exhibited potency against HIV-1 activity similar to that of TAK-220 hydrochloride, but it had much better water solubility (25 mg/ml in phosphate sodium buffer at 25 °C) and oral bioavailability (56%) than TAK-220 hydrochloride (a solubility of 2 mg/ml and oral bioavailability of 1.4%). These results suggest that B07 hydrochloride may serve as a better lead for the development of new anti-HIV-1 therapies or microbicides for treatment and prevent of HIV-1 infection.

[Recent advances in study of antinociceptive conotoxins].

The Conus venom is secreted by the duct and theca of venom. Most of conotoxins are composed of 10-40 amino acid residues with several disulfide bridges. They can specifically target neurotransmitter receptors including nAChRs, calcium ion channels, sodium ion channels and potassium ion channels, etc. Some conotoxins, such as that target N-Ca2+ channels, nAChR alpha9alpha10 subtype, TTX-R Na+ channels or NMDA receptors, have potent antinociceptive activities, omega-MVIIA, an Ca2+ channels blocker was approved by FDA in December, 2004 for marketing. Because of lower molecular weight and high specificity, conotoxins are the powerful pharmacology tools and potent analgesics without addiction. This review briefly summarizes the research progress of antinociceptive conotoxins and addresses on their targets and structure-activity relationships.

Characterization of novel M-superfamily conotoxins with new disulfide linkage.

The M-superfamily with the typical Cys framework (-CC-C-C-CC-) is one of the seven major superfamilies of conotoxins found in the venom of cone snails. Based on the number of residues in the last Cys loop (between C4 and C5), M-superfamily conotoxins can be provisionally categorized into four branches (M-1, M-2, M-3, M-4) [Corpuz GP, Jacobsen RB, Jimenez EC, Watkins M, Walker C, Colledge C, Garrett JE, McDougal O, Li W, Gray WR, et al. (2005) Biochemistry44, 8176-8186]. Here we report the purification of seven M-superfamily conotoxins from Conus marmoreus (five are novel and two are known as mr3a and mr3b) and one known M-1 toxin tx3a from Conus textile. In addition, six novel cDNA sequences of M-superfamily conotoxins have been identified from C. marmoreus, Conus leopardus and Conus quercinus. Most of the above novel conotoxins belong to M-1 and M-2 and only one to M-3. The disulfide analyses of two M-1 conotoxins, mr3e and tx3a, revealed that they possess a new disulfide bond arrangement (C1-C5, C2-C4, C3-C6) which is different from those of the M-4 branch (C1-C4, C2-C5, C3-C6) and M-2 branch (C1-C6, C2-C4, C3-C5). This newly characterized disulfide connectivity was confirmed by comparing the HPLC profiles of native mr3e and its two regioselectively folded isoforms. This is the first report of three different patterns of disulfide connectivity in conotoxins with the same cysteine framework.

Effect of new O-superfamily conotoxin SO3 on sodium and potassium currents of cultured hippocampal neurons.

The effects of a new O-superfamily conotoxin SO3 on sodium and potassium currents were examined in cultured rat hippocampal neurons using the whole-cell patch clamp technique. SO3 caused a concentration-dependent, rapidly developing and reversible inhibition of sodium currents (I(Na)). The IC(50) value for the blockage of I(Na) was calculated to be 0.49 and the Hill coefficient was 1.7. Using electrophysiological and pharmacological protocols, transient A-type potassium currents (I(A)) and delayed rectifiers potassium currents (I(K)) were isolated. SO3 caused a concentration-dependent, and reversible inhibition of I(K). The IC(50) value for the blockage of I(K) was calculated to be 1.6 and the Hill coefficient was 0.6, with no significant effect on I(A). These results indicate that SO3 can selectively inhibit neuronal sodium and potassium currents.

Tricyclononene carboxamide derivatives as novel anti-HIV-1 agents.

By modifying the chemical structure of anti-orthopoxvirus compound ST-246, we designed and synthesized a series of tricyclononene carboxamide derivatives and tested their anti-HIV-1 activity and cytotoxicity. We found that benzoimidazol-containing compound 7g was highly effective in inhibiting HIV-1 R5 infection with an IC(50) value of 0.41 microM and a selectivity index of 292, but it exhibited no significant inhibitory activity on HIV-1 reverse transcriptase, integrase and protease. CoMFA was used to analyze structure-activity relationships with good predictive power (r(2) = 0.921; q(2) = 0.582). Moreover, the CoMFA model showed that the length of the molecule, the amide, and the amine moieties all played crucial roles in anti-HIV activity. These results suggest that 7g may serve as a lead for the development of novel anti-HIV-1 therapies.