Aminoalkoxyfluorenones and aminoalkoxybiphenyls: DNA binding modes.

Many evidences suggest that DNA-drug interaction in the minor groove and the intercalation of drugs into DNA may play critical roles in antiviral, antimicrobial, and antitumor activities. As a continuous effort to develop novel antiviral agents, the series of planar fluorenone (3a-7d) were synthesized and used along with nonplanar biphenyls (11a-d) for the comparative analysis of their interaction with DNA. The chemical structure of new compounds was confirmed by 1H NMR, 13C NMR and mass spectra as well as elemental analysis. DNA affinity of 3a-7d and 11a-d was evaluated by ethidium bromide displacement assay. Affinity constant (lgKa) of 3a-7d was found to be approximately two orders of magnitude higher than constants of corresponding 11a-d. The molecular docking of aminoalkoxybiphenyls (11a-d) into minor grove of five different nucleotide sequences (d(CCIICICCII), d(CGCGTTAACGCG), d(CGCGATATCGCG), d(GGCCAATTGG), d(GGATATATCC)) demonstrated their binding capacity to the specific DNA site. The linear least squares fitting technique was successfully applied to derive an equation describing the relationship between lgKa and SF.

Preparation and Characterization of Lipophilic Doxorubicin Pro-drug Micelles.

Micelles have been successfully used for the delivery of anticancer drugs. Amphiphilic polymers form core-shell structured micelles in an aqueous environment through self-assembly. The hydrophobic core of micelles functions as a drug reservoir and encapsulates hydrophobic drugs. The hydrophilic shell prevents the aggregation of micelles and also prolongs their systemic circulation in vivo. In this protocol, we describe a method to synthesize a doxorubicin lipophilic pro-drug, doxorubicin-palmitic acid (DOX-PA), which will enhance drug loading into micelles. A pH-sensitive hydrazone linker was used to conjugate doxorubicin with the lipid, which facilitates the release of free doxorubicin inside cancer cells. Synthesized DOX-PA was purified with a silica gel column using dichloromethane/methanol as the eluent. Purified DOX-PA was analyzed with thin layer chromatography (TLC) and (1)H-Nuclear Magnetic Resonance Spectroscopy ((1)H-NMR). A film dispersion method was used to prepare DOX-PA loaded DSPE-PEG micelles. In addition, several methods for characterizing micelle formulations are described, including determination of DOX-PA concentration and encapsulation efficiency, measurement of particle size and distribution, and assessment of in vitro anticancer activities. This protocol provides useful information regarding the preparation and characterization of drug-loaded micelles and thus will facilitate the research and development of novel micelle-based cancer nanomedicines.

The medicinal chemistry of 5-HT6 receptor ligands with a focus on arylsulfonyltryptamine analogs.

Arylsulfonyl analogs of aminopyrimidines (e.g. Ro 04-6790; 2), aminopyridines (e.g. Ro 63-0563; 3), 1-phenylpiperazines (e.g. SB-271046; 4), and tryptamines (e.g. MS-245; 5) were described as the first examples of selective 5-HT(6) receptor antagonists only ten years ago. Today, hundreds of compounds of seemingly diverse structure have been reported. The early antagonists featured an arylsulfonyl group leading to the wide notspread assumption that an arylsulfonyl moiety might be critical for binding and antagonist action. With respect to the arylsulfonyltryptamines, it seems that neither the "arylsulfonyl" nor the "tryptamine" portion of these compounds is essential for binding or for antagonist action, and some such derivatives even display agonist action. The present review describes many of the currently available 5-HT(6) receptor ligands and, unlike prior reviews, provides a narrative of the thinking (where possible) that led to their design, synthesis, and evaluation. The arylsulfonyltryptamines are also used as the structural basis of attempts to relate various structure-types to one another to afford a better understanding of the overall structural requirements for 5-HT(6) receptor binding.

Binding of sulfonyl-containing arylalkylamines at human 5-HT6 serotonin receptors.

Various sulfonyl-containing compounds (e.g. sulfonamides, sulfones) bind at human 5-HT6 serotonin receptors, but it has been difficult relating the binding mode(s) of such agents to one another, even though many possess a common SO2 moiety, to identify a common pharmacophore model(s). On the basis of the hypothesis that an ergoline-type conformation might be important for the binding of some sulfonamide-containing arylalkylamines, we prepared for examination at h5-HT6 receptors a series of compounds, including phenylethylamines 6, pyrroloethylamine 7, and phenylpiperazines 9. The results (with Ki values ranging from about 1 nM to >1000 nM) suggest that many of these agents likely bind in a related fashion, and structure-affinity studies indicate that the benzenesulfonamide portion of the phenylethylamine and phenylpiperazine analogues can be "reversed", abbreviated to a sulfone, and moved to an adjacent position with relatively little impact on affinity. Although a benzenesulfonamide (or related arylsulfonamide) group might be common to various 5-HT6 ligands, there appears to be some latitude with regard to the specific constitution and location of the sulfonamide moiety even within the same arylalkylamine structural framework. A pharmacophore model is presented to account for some of the current findings.

Binding of amine-substituted N1-benzenesulfonylindoles at human 5-HT6 serotonin receptors.

An examination of several amine-substituted analogs of N(1)-benzenesulfonylindoles reveals that although they bind at human 5-HT(6) serotonin receptors with high affinity, they are likely to bind in a dissimilar manner.

Beta-oxygenated analogues of the 5-HT2A serotonin receptor agonist 1-(4-bromo-2,5-dimethoxyphenyl)-2-aminopropane.

Activation of 5-HT(2A) serotonin receptors represents a novel approach to lowering intraocular pressure. Because 5-HT(2A) serotonin receptor agonists might also produce undesirable central effects should sufficient quantities enter the brain, attempts were made to identify 5-HT(2) serotonin receptor agonists with reduced propensity to penetrate the blood-brain barrier. 1-(4-Bromo-2,5-dimethoxyphenyl)-2-aminopropan-1-ol (6), an analogue of the 5-HT(2) serotonin receptor agonist 1-(4-bromo-2,5-dimethoxyphenyl)-2-aminopropane (DOB; 1a) bearing a benzylic hydroxyl group, was identified as a candidate structure. Of the four optical isomers of 6, the 1R,2R-isomer (6d; K(i) = 0.5 nM) was found to bind at 5-HT(2A) receptors with an affinity similar to that of R(-)DOB (K(i) = 0.2 nM). Like R(-)DOB, 6d behaved as a partial agonist (efficacy ca. 50%) in a 5-HT(2)-mediated calcium mobilization assay. However, in an in vivo test of central action (i.e., stimulus generalization with rats as subjects), 6d was >15 times less potent than R(-)DOB. O-Methylation of 6d (i.e., 7d; 5-HT(2A) K(i) = 0.3 nM) resulted in an agent that behaved as a full (93% efficacy) agonist. Intraocular administration of 300 microg of 6d and 7d to ocular hypertensive monkeys was shown to reduce intraocular pressure by 20-27%. Given the route of administration (i.e., topical), and concentrations necessary to reduce intraocular pressure, compounds such as 6d should demonstrate minimal central effects at potentially useful therapeutic doses and offer useful leads for further development.

Behavioral and biochemical investigations of bupropion metabolites.

The stimulus effects of bupropion metabolites were examined in a drug discrimination procedure using (-)nicotine- and (+)amphetamine-trained rats. (+)- and (-)threohydrobupropion partially substituted in each group. R,R-hydroxybupropion produced vehicle-appropriate responding in (-)nicotine animals but, when given in combination with the training dose of (-)nicotine, resulted in an attenuated effect. S,S-Hydroxybupropion partially (66%) substituted for (-)nicotine. In (+)amphetamine-trained animals, S,S-hydroxybupropion (ED50=4.4 mg/kg) generalized completely and was similar in potency to bupropion (ED50=5.4 mg/kg). Bupropion and its metabolites lacked affinity for nicotinic acetylcholinergic receptors, but all antagonized (-)nicotine-induced 86Rb+ efflux in cells expressing alpha3beta4 nicotinic cholinergic receptors. S,S-Hydroxybupropion possessed affinity at the dopamine transporter comparable to bupropion, and was also found to bind at the norepinephrine transporter. Although it is unlikely that any metabolite isomer is chiefly responsible for the stimulus actions of bupropion, some probably play a role in the complex actions of this agent.