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A study was conducted to characterize a series of alpha-helical C-capping auxiliaries supporting various chain lengths based on alkyldiamines and monoguanylated diamines. A sedimentation equilibrium ultracentrifugation analysis was carried out on a peptide to show that is was monomeric in nature. Results indicated that D-Arginine can be effectively incorporated at any position within a peptide or protein sequence.

The nucleation and extension of a conformation from an arranged template region by a disordered alpha-amino acid-based region achieved by using templates, lead to alpha-helices and beta-sheet structures. The porphyrin, pyridine- and bipyridine-based templates cause alpha-helical folding. Small cyclic and acyclic templates are utilized for obtaining the folded state. Beta-turn mimics are responsible for the folding of the peptide fragments into beta-sheet structure. A beta-turn template substitutes the i+1 and i+2 residues of a beta-turn.

The preparation of four 6,6'-bis(acylamino)-2,2'-bipyridine-based amino acids involves the coordination of Cu(II) complexes. The coordination replaces the i + 1 and i + 2 residues of the beta-turn in the amino acids. The four 6,6'-bis(acylamino)-2,2'-bipyridine-based amino acids consist of several peptides with amino acids incorporated at different levels.

Abstract Background The recently approved anti-AIDS drug rilpivirine (TMC278, Edurant) is a nonnucleoside inhibitor (NNRTI) that binds to reverse transcriptase (RT) and allosterically blocks the chemical step of DNA synthesis. In contrast to earlier NNRTIs, rilpivirine retains potency against well-characterized, clinically relevant RT mutants. Many structural analogues of rilpivirine are described in the patent literature, but detailed analyses of their antiviral activities have not been published. This work addresses the ability of several of these analogues to inhibit the replication of wild-type (WT) and drug-resistant HIV-1. Results We used a combination of structure activity relationships and X-ray crystallography to examine NNRTIs that are structurally related to rilpivirine to determine their ability to inhibit WT RT and several clinically relevant RT mutants. Several analogues showed broad activity with only modest losses of potency when challenged with drug-resistant viruses. Structural analyses (crystallography or modeling) of several analogues whose potencies were reduced by RT mutations provide insight into why these compounds were less effective. Conclusions Subtle variations between compounds can lead to profound differences in their activities and resistance profiles. Compounds with larger substitutions replacing the pyrimidine and benzonitrile groups of rilpivirine, which reorient pocket residues, tend to lose more activity against the mutants we tested. These results provide a deeper understanding of how rilpivirine and related compounds interact with the NNRTI binding pocket and should facilitate development of novel inhibitors.

Non‐nucleoside reverse transcriptase inhibitors (NNRTIs) inhibit reverse transcription and block the replication of HIV‐1. Currently, NNRTIs are usually used as part of a three‐drug combination given to patients as antiretroviral therapy. These combinations involve other classes of anti‐HIV‐1 drugs, commonly nucleoside reverse transcriptase inhibitors (NRTIs). However, attempts are being made to develop two‐drug maintenance therapies, some of which involve an NNRTI and an integrase strand transfer inhibitor. This has led to a renewed interest in developing novel NNRTIs, with a major emphasis on designing compounds that can effectively inhibit the known NNRTI‐resistant mutants. We have generated and tested novel rilpivirine (RPV) analogs. The new compounds were designed to exploit a small opening in the upper right periphery of the NNRTI‐binding pocket. The best of the new compounds, 12, was a more potent inhibitor of the NNRTI‐resistant mutants we tested than either doravirine or efavirenz but was inferior to RPV. We describe the limitations on the modifications that can be appended to the "upper right side" of the RPV core and the effects of substituting other cores for the central pyrimidine core of RPV and make suggestions about how this information can be used in NNRTI design. [ABSTRACT FROM AUTHOR]

Understanding the chemical mechanisms at play in atomic layer deposition (ALD) is critical for effective process development and expansion of ALD into more complex classes of materials. In this work, a mechanistic study of iron oxide deposited by ALD using tert‐butylferrocene and ozone as reactants is performed. Iron oxide ALD using ozone is a useful model system for mechanistic studies due to the prevalence of ozone‐based ALD processes and the uses of iron oxide in ternary and quaternary metal oxides. Results show that saturation conditions require significantly greater exposures of both reactants than is typically reported in the literature, and growths per cycle of greater than one monolayer of Fe2O3 per cycle are observed and explained. A growth mechanism is proposed whereby increased ozone exposure results in uptake of superstoichiometric oxygen into the film. X‐ray characterizations reveal the presence of excess oxygen stored near the surface of films deposited with larger ozone exposures and show that increased ozone exposures cause crystalline domain rearrangement and conversion of the film from the γ‐maghemite phase to the α‐hematite phase. The mechanism described here has implications for the wider class of ozone‐based ALD processes, and potential applications of this growth phenomenon are discussed. [ABSTRACT FROM AUTHOR]

Introduction: Transporters comprising the blood-brain barrier complicate delivery of many therapeutics to the central nervous system. The present study ascertained whether the natural product botryllamide G is viable for in vivo inhibition of ABCG2 using lapatinib as a probe for ABCB1 and ABCG2-mediated efflux from the brain. Methods: Wild-type and Mdr1a/Mdr1b (-/-) mice were treated with botryllamide G and lapatinib ("doublet therapy"), and while a separate cohort of wild-type mice was treated with botryllamide, tariquidar and lapatinib ("triplet therapy"). Results: Botryllamide G demonstrates biphasic elimination with a rapid distribution, decreasing below the in vitro IC50 of 6.9 µM within minutes, yet with a relatively slower terminal half-life (4.6 h). In Mdr1a/Mdr1b (-/-) mice, doublet therapy resulted in a significant increase in brain lapatinib AUC at 8 h (2058 h*ng/mL vs 4007 h*ng/mL; P =.031), but not plasma exposure (P =.15). No significant differences were observed after 24 h. Lapatinib brain exposure was greater through 1 h when wild-type mice were administered triplet therapy (298 h*pg/mg vs 120 h*pg/mg; P <.001), but the triplet decreased brain AUC through 24 h vs. mice administered lapatinib alone (2878 h*pg/mg vs 4461hr*ng/mL; P <.001) and did not alter the brain:plasma ratio. Conclusions: In summary, the ABCG2 inhibitor, botryllamide G, increases brain exposure to lapatinib in mice lacking Abcb1, although the combination of botryllamide G and tariquidar increases brain exposure in wild-type mice only briefly (1 h). Additional research is needed to find analogs of this compound that have better pharmacokinetics and pharmacodynamic effects on ABCG2 inhibition. [ABSTRACT FROM AUTHOR]