Syntheses and N-methyl-D-aspartate receptor antagonist pharmacology of fluorinated arylcycloheptylamines.

Selective uncompetitive antagonists of the phencyclidine (PCP) binding site of the N-methyl-D-aspartate receptor (NMDAR) are known to have therapeutic potential as anticonvulsants and neuroprotective agents. Several fluorinated molecules with each containing a cycloheptane ring were designed to probe the PCP pharmacophore and test the influence of fluorine substitution on NMDAR binding and in vivo efficacy. Syntheses and analyses of six novel compounds, 1-(4- fluorophenyl)cycloheptanamine (3), 1-(1-(4-fluorophenyl)cycloheptyl)piperidine (4), 1-(1-(4-fluorophenyl)cycloheptyl) pyrrolidine (5), 1-(3-fluorophenyl)cycloheptanamine (6), 1-(1-(3-fluorophenyl)cycloheptyl)piperidine (7), 1-(1-(3-fluorophenyl) cycloheptyl)pyrrolidine (8) and several related reference arylcyloalkylamines are described. Receptor binding was performed at the PCP site of NMDAR for each compound using [(3)H]-(+)-MK-801 displacement. Unexpectedly, the 3- fluoro- primary amine 6 had the greatest affinity of the series and these binding results support a different structure activity relationship (SAR) profile for arylcycloheptylamines when compared to arylcyclohexylamines like PCP. Five of the novel compounds have affinity (Ki) in the hundred nM (10(-7)) range. In addition, compounds 3, 5, 6, 7 and 8 were evaluated and found to exhibit neuroprotective effects from NMDA induced toxicity in vitro and compounds 6, 7 and 8 exhibited anticonvulsant activities in rats. An ED50 of 13.84 mg/kg was found for compound 6 in rat maximal electroshock (MES) test with a protective index (PI) of 3.66 against ataxia. These results support further investigation of the arylcycloheptylamine class.

Toxicity Studies on Novel N-Substituted Bicyclo-Heptan-2-Amines at NMDA Receptors.

Several novel norcamphor derivatives were designed and synthesized as uncompetitive NMDA receptor antagonists at the phencyclidine (PCP) binding site. Such compounds have potential as ligands for understanding and possibly the treatment of several neurodegenerative disorders and other glutamate-dependent disorders. We examined the toxic effects of the compounds as compared with memantine, an NMDA receptor antagonist that is FDA approved for treatment of Alzheimer's disease, by testing these compounds on two cell lines: MDCK (to mimic blood brain barrier) and N2a (a neuronal cell line). The compounds showed toxicity profiles similar to those of memantine i.e., dose dependence above 100 µM and IC50 values above 150 µM for each cell line. It is known that the serum level of memantine under therapeutic conditions in patients is about 1 µM, indicting these compounds could have acceptable therapeutic indexes. 2-Phenyl-N-(2-(piperidin-1-yl) ethyl)bicyclo[2.2.1]heptan-2-amine (5a) was found to possess acceptable toxicity profiles in both cell lines. Interestingly, this was the compound identified as a good lead in our previous studies based on binding and anticonvulsant (MES) activity studies. It has thus emerged as an excellent lead compound for further studies.

Syntheses and pharmacological evaluations of novel N-substituted bicyclo-heptane-2-amines at N-methyl-D-aspartate receptors.

Several novel norcamphor (bicycloheptane)-based compounds were designed and synthesized as non-competitive N-methyl-D-aspartate receptor antagonists at the phencyclidine binding sites. The heterocyclic ring was also varied to examine piperidine, pyrrolidine, and morpholine groups. We examined pharmacological activities of these compounds in vitro (binding studies) and in vivo (maximal electroshock test). Pharmacological evaluations revealed one of the compounds, 5a, to be a good lead, exhibiting moderate binding at N-methyl-D-aspartate receptors (IC(50) =7.86 µm; K(i) =5.28 µm), maximal electroshock neuroprotection activity at 100 mg/kg and acceptable toxicity profile.

Fluorinated molecules as drugs and imaging agents in the CNS.

The strategic use of fluorine substitution in drug discovery and drug development is well documented. The small size and high electronegativity of fluorine are among properties of this element that lend special advantages. Applications in drugs targeted to the central nervous system (CNS) have been particularly fruitful in addition to favorable properties seen in many peripherally acting drugs. Fluorine substitution can be used to solve problems unique to the CNS, such as blood brain barrier (BBB) penetration. Likewise, use of the positron emitting isotope, (18)F, provides a unique tool for non-invasive imaging and diagnoses in the CNS. In this review, fluorine in CNS drugs and drug discovery are discussed.

[Studies on chemical constituents from the bark of Morus macroura].

OBJECTIVE: To study the chemical constituents from the bark of Morus macroura. METHOD: The compounds were isolated with silica gel column chromatography and their structures were elucidated on the basis of chemical evidences and spectral analysis (IR, EI-MS, 1H-NMR, 13C-NMR). RESULT: Five compounds were identified as alpha-amyrin acetate (1), gult-5-en-3 beta-yl acetate (2), 3 beta-hydroxylup-20 (29)-en-28-oic acid (3), 3 beta-hydroxylup-12-en-28-oic acid (4), butyrospermol acetate (5).