ABSTRACT: We present two new synthetic strategies to rigid multivalent scaffolds of the general structure 1 based on adamantane. Both routes start from arylated adamantane derivatives and give the target compounds 12 and 18 in 5 and 7 steps, respectively. These scaffolds have been designed for the assembly of multivalent binders for cell surface epitopes. The adamantane nucleus exposes three carboxylic acid groups in a well-defined tripodal geometry for conjugation of targeting ligands. In addition, an amino group at the fourth bridgehead position provides a flexible linker for attachment of effector molecules such as contrast agents, radiotracers, or cytotoxins without interfering with the cell binding process.
Project description:An efficient route to novel 1,3,5,7-tetrasubstituted derivatives of adamantane is described. This route starts from adamantane and gives the tetrafunctionalized derivative 9 in eight steps with an overall yield of 23%. These tetrahedrally shaped molecules possess three identical arms terminated by an activated carboxylic acid derivative and a protected amino function in the 1-position. We propose these tetravalent cage compounds such as 9 as scaffolds for the assembly of ligand/marker conjugates for studies of multivalent ligand receptor interactions. [reaction: see text]
Project description:Adamantyl groups are widely used in medicinal chemistry. However, metabolism limits their usage. Herein, we report the first systematic study of adamantyl ureas and diureas bearing substituents in bridgehead positions of adamantane and/or spacers between urea groups and adamantane group, and tested their effects on soluble epoxide hydrolase inhibitor potency and metabolic stability. Interestingly, the effect on activity against human and murine sEH varied in opposite ways with each new methyl group introduced into the molecule. Compounds with three methyl substituents in adamantane were very poor inhibitors of murine sEH while still very potent against human sEH. In addition, diureas with terminal groups bigger than sEH catalytic tunnel diameter were still good inhibitors suggesting that the active site of sEH opens to capture the substrate or inhibitor molecule. The introduction of one methyl group leads to 4-fold increase in potency without noticeable loss of metabolic stability compared to the unsubstituted adamantane. However, introduction of two or three methyl groups leads to 8-fold and 98-fold decrease in stability in human liver microsomes for the corresponding compounds.
Project description:Herein, the chemical synthesis and binding analysis of functionalizable rigid and flexible core trivalent sialosides bearing oligoethylene glycol (OEG) spacers interacting with spike proteins of influenza?A virus (IAV) X31 is described. Although the flexible Tris-based trivalent sialosides achieved micromolar binding constants, a trivalent binder based on a rigid adamantane core dominated flexible tripodal compounds with micromolar binding and hemagglutination inhibition constants. Simulation studies indicated increased conformational penalties for long OEG spacers. Using a systematic approach with molecular modeling and simulations as well as biophysical analysis, these findings emphasize on the importance of the scaffold rigidity and the challenges associated with the spacer length optimization.
Project description:Multivalent and multimodal imaging probes are rapidly emerging as powerful chemical tools for visualizing various biochemical processes. Herein, we described a bifunctional chelator (BFC)-based scaffold that can be used to construct such promising probes concisely. Compared to other reported similar scaffolds, this new BFC scaffold demonstrated two major advantages: (1) significantly simplified synthesis due to the use of this new BFC that can serve as chelator and linker simultaneously; (2) highly efficient synthesis rendered by using either click chemistry and/or total solid-phase synthesis. In addition, the versatile utility of this molecular scaffold has been demonstrated by constructing several multivalent/multimodal imaging probes labeled with various radioisotopes, and the resulting radiotracers demonstrated substantially improved in vivo performance compared to the two individual monomeric counterparts.
Project description:Cyclodextrin vesicles are versatile models for biological cell membranes since they provide a bilayer membrane that can easily be modified by host-guest interactions with functional guest molecules. In this article, we investigate the multivalent interaction of the lectin concanavalin A (ConA) with cyclodextrin vesicles decorated with mannose-adamantane conjugates with one, two or three adamantane units as well as one or two mannose units. The carbohydrate-lectin interaction in this artificial, self-assembled glycocalyx was monitored in an agglutination assay by the increase of optical density at 400 nm. It was found that there is a close relation between the carbohydrate density at the cyclodextrin vesicle surface and the multivalent interaction with ConA, and the most efficient interaction (i.e., fastest agglutination at lowest concentration) was observed for mannose-adamantane conjugates, in which both the cyclodextrin-adamantane and the lectin-mannose interaction is inherently multivalent.
Project description:Memantine hydrochloride is a medicine used for the treatment of Alzheimer's disease. A number of methods for the preparation of memantine hydrochloride have been reported. These procedures started from 1,3-dimethyl-adamantane by as many as using three or four reaction steps to produce memantine hydrochloride with overall yields ranging from 54 to 77%. In this article, a simple, concise two-step synthesis of memantine hydrochloride from 1,3-dimethyl-adamantane via N-formamido-3,5-dimethyl-adamantane with an improved overall yield of 83% was developed. In step 1, 3,5-dimethyl-adamantane was reacted with formamide and nitric acid to afford 1-formamido-3,5-dimethyl-adamantane in 98% yield, followed by hydrolysis of 1-formamido-3,5-dimethyl-adamantane with aq hydrochloride to give memantine hydrochloride in 85% yield. The procedure can be easily deployed at an industrial scale.
Project description:The crystal structure of the title adamantane derivative, C(12)H(18)O(3), has been determined by X-ray diffraction. The structure is stabilized by inter-molecular O-H?O hydrogen bonds, forming a chain.
Project description:Candidate structures for the global minima of adamantane clusters, (C10H16) N , are presented. Based on a rigid model for individual molecules with atom-atom pairwise interactions that include Lennard-Jones and Coulomb contributions, low-energy structures were obtained up to N = 42 using the basin-hopping method. The results indicate that adamantane clusters initially grow accordingly with an icosahedral packing scheme, followed above N = 14 by a structural transition toward face-centered cubic structures. The special stabilities obtained at N = 13, 19, and 38 are consistent with these two structural families, and agree with recent mass spectrometry measurements on cationic adamantane clusters. Coarse-graining the intermolecular potential by averaging over all possible orientations only partially confirm the all-atom results, the magic numbers at 13 and 38 being preserved. However, the details near the structural transition are not captured well, because despite their high symmetry the adamantane molecules are still rather anisotropic.
Project description:For over a decade virtually all A(H3N2) influenza viruses have been resistant to the adamantane class of antivirals. However, during the 2017 influenza season in Australia, 15/461 (3.3%) adamantane-sensitive A(H3N2) viruses encoding serine at residue 31 of the M2 protein were detected, more than the total number identified globally during the last 6 years. A return to wide circulation of adamantane-sensitive A(H3N2) viruses would revive the option of using these drugs for treatment and prophylaxis.
Project description:Adamantanes (amantadine and rimantadine) have been used to prevent and treat influenza A virus infections for many years; however, resistance to these drugs has been widely reported in the world. To investigate the frequency and distribution of M2 gene mutations in adamantane-resistant influenza variants circulated in the world between 1902 and 2013, 31251 available M2 protein sequences from different HA-subtype influenza A viruses (H1-H17) were analyzed and adamantane resistance-associated mutations were compared (L26F, V27A, A30T, A30V, S31N, G34E, and L38F). We find that 45.2% (n = 14132) of influenza A (H1-H17) viruses circulating globally were resistant to adamantanes, and the vast majority of resistant viruses (95%) bear S31N mutations. Whereas, only about 1% have V27A mutations and other mutations (L26F, A30T, G34E, and L38F) were extremely rare (their prevalence appeared to be < 0.2%). Our results confirm that H1, H3, H5, H7, H9, and H17 subtype influenza A viruses exhibit high-level resistance to adamantanes. In contrast, the appearance of adamantane-resistant mutants in H2, H4, H6, H10, and H11 subtypes was rare. However, no adamantane resistance viruses were identified among other HA subtypes (H8, H12-H16). Our findings indicate that the frequency and distribution of adamantane-resistant influenza variants varied among different HA subtypes, host species, years of isolation, and geographical areas. This comprehensive study raises concerns about the increasing prevalence of adamantane-resistant influenza A viruses and highlights the importance of monitoring the emergence and worldwide spread of adamantane-resistant variants.