Search

Direct-acting cannabinoid receptor agonists are well known to reduce hyperalgesic responses and allodynia after nerve injury, although their psychoactive side effects have damped enthusiasm for their therapeutic development. Alternatively, inhibiting fatty acid amide hydrolase (FAAH) and monoacylglycerol lipase (MAGL), the principal enzymes responsible for the degradation of the respective endogenous cannabinoids, anandamide (AEA) and 2-arachydonylglycerol (2-AG), reduce nociception in a variety of nociceptive assays, with no or minimal behavioral effects. In the present study we tested whether inhibition of these enzymes attenuates mechanical allodynia, and acetone-induced cold allodynia in mice subjected to chronic constriction injury of the sciatic nerve. Acute administration of the irreversible FAAH inhibitor, cyclohexylcarbamic acid 3'-carbamoylbiphenyl-3-yl ester (URB597), or the reversible FAAH inhibitor, 1-oxo-1-[5-(2-pyridyl)-2-yl]-7-phenylheptane (OL-135), decreased allodynia in both tests. This attenuation was completely blocked by pretreatment with either CB(1) or CB(2) receptor antagonists, but not by the TRPV1 receptor antagonist, capsazepine, or the opioid receptor antagonist, naltrexone. The novel MAGL inhibitor, 4-nitrophenyl 4-(dibenzo[d][1,3]dioxol-5-yl(hydroxy)methyl)piperidine-1-carboxylate (JZL184) also attenuated mechanical and cold allodynia via a CB(1), but not a CB(2), receptor mechanism of action. Whereas URB597 did not elicit antiallodynic effects in FAAH(-/-) mice, the effects of JZL184 were FAAH-independent. Finally, URB597 increased brain and spinal cord AEA levels, whereas JZL184 increased 2-AG levels in these tissues, but no differences in either endo-cannabinoid were found between nerve-injured and control mice. These data indicate that inhibition of FAAH and MAGL reduces neuropathic pain through distinct receptor mechanisms of action and present viable targets for the development of analgesic therapeutics.

Two exceptionally concise total syntheses of (−)- and ent-(+)-vindoline are detailed enlisting a diastereoselective tandem [4 + 2]/[3 + 2] cycloaddition of a 1,3,4-oxadiazole. The unique reaction cascade assembles the fully functionalized pentacyclic ring system of vindoline in a single step that forms four C−C bonds and three rings while introducing all requisite functionality and setting all six stereocenters within the central ring including three contiguous and four total quaternary centers.

Fatty acid amide hydrolase (FAAH) degrades neuromodulating fatty acid amides including anandamide (endogenous cannabinoid agonist) and oleamide (sleep-inducing lipid) at their sites of action and is intimately involved in their regulation. Herein we report the discovery of a potent, selective, and efficacious class of reversible FAAH inhibitors that produce analgesia in animal models validating a new therapeutic target for pain intervention. Key to the useful inhibitor discovery was the routine implementation of a proteomics-wide selectivity screen against the serine hydrolase superfamily ensuring selectivity for FAAH coupled with systematic in vivo examinations of candidate inhibitors.

Efficient and unusually concise total syntheses of both enantiomers of the Aspidosperma alkaloids 4-desacetoxy-6,7-dihydrovindorosine (12) and minovine (1) are detailed. A tandem intramolecular Diels−Alder/1,3-dipolar cycloaddition reaction of the 1,3,4-oxadiazole 8, in which three new rings, four new C−C bonds, and five stereocenters are formed, is a key step in the sequence. The availability of optically active material permitted an assessment of the enantiomeric integrity of minovine and the source of its reported unusual optical rotation.

A summary of the qualitative and quantitative elements of a fluorescent intercalator displacement (FID) assay useful for establishing the DNA binding selectivity, affinity, stoichiometry, and binding site size and distinguishing modes of DNA binding is provided.

An efficient synthesis of two diastereomers of the chlorofusin cyclic peptide bearing either the l-Asn3/d-Asn-4 or d-Asn3/l-Asn4 stereochemistry is detailed. Four key subunits were prepared, sequentially coupled, and cyclized to provide the two diastereomeric macrocycles. The absolute stereochemistry at the asparagine residues 3 and 4 was assigned as l and d, respectively, by correlating the NMR data of the two diastereomers with that reported for the natural product.

We report the isolation of a heretofore unrecognized brain lipid that is present in cerebrospinal fluid of sleep-deprived cats. The molecule appears to be a long-chain base structurally related to sphingosine and sphinganine in which a second unsaturated bond has been introduced. An increase in the degree of unsaturation of a key membrane component is expected to have important physiological consequences.

Studies on the structural origin of the DNA alkylation selectivity of the antitumor antibiotic (+)-CC-1065 are detailed. The sites of alkylation of double-stranded DNA were examined for simple derivatives of 7-methyl-1,2,8,8a-tetrahydrocycloprop[1,2-c]pyrrolo[3,2-e]indol- 4(5H)-one (CPI), (+)-CC-1065, and agents incorporating the parent 1,2,7,7a-tetrahydrocycloprop[1,2-c]indol-4-one (CI) left-hand subunit. The CI subunit of the agents is a much more reactive alkylating agent than the natural CPI alkylation subunit of CC-1065. Consequently, simple derivatives of CI were found to alkylate double-stranded DNA under milder conditions than were simple derivatives of CPI, and the marked similarities in the CI and CPI DNA alkylation profiles illustrate that CI represents the minimum pharmacophore of CPI. Comparisons of the DNA alkylation profiles of (+)-N-butyloxycarbonyl-CPI, (+)-N-acetyl-CPI, and (+)-CC-1065 revealed distinctions in the CPI and (+)-CC-1065 sites of alkylation, whereas the incorporation of the reactive CI electrophile into an analog of CC-1065 (CI-CDPI2) (CDPI, N3-carbamoyl-1,2-dihydro-3H-pyrrolo[3,2-e]indole-7-carboxylic acid) provided an agent that possesses the characteristic CC-1065 DNA alkylation profile (site selectivity and relative site intensity). These observations suggest that the noncovalent binding selectivity of the agents may restrict the number of available DNA alkylation sites and play a productive role in controlling the sequence-selective alkylation by effectively delivering the electrophile to A + T-rich minor groove regions of DNA possessing accessible adenine N-3 alkylation sites. In turn, the noncovalent binding selectivity may be derived from preferential binding within the narrower, sterically more accessible A + T-rich minor groove of double-stranded DNA.

Key studies defining the DNA alkylation properties and selectivity of a new class of exceptionally potent, naturally occurring antitumor antibiotics including CC-1065, duocarmycin A, and duocarmycin SA are reviewed. Recent studies conducted with synthetic agents containing deep-seated structural changes and the unnatural enantiomers of the natural products and related analogs have defined the structural basis for the sequence-selective alkylation of duplex DNA and fundamental relationships between chemical structure, functional reactivity, and biological properties. The agents undergo a reversible, stereoelectronically controlled adenine-N3 addition to the least substituted carbon of the activated cyclopropane within selected AT-rich sites. The preferential AT-rich non-covalent binding selectivity of the agents within the narrower, deeper AT-rich minor groove and the steric accessibility to the alkylation site that accompanies deep AT-rich minor groove penetration control the sequence-selective DNA alkylation reaction and stabilize the resulting adduct. For the agents that possess sufficient reactivity to alkylate DNA, a direct relationship between chemical or functional stability and biological potency has been defined.