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Hydrophobic active pharmaceutical ingredients (APIs) are often difficult to deliver effectively because of formulation limitations. Nanosuspensions of such drugs may be used to increase bioavailability and offer a variety of delivery options including injection, inhalation, oral, and transdermal. Microfluidics reaction technology (MRT) was used successfully to produce submicrometer API suspensions via a continuous process that involves solvent/antisolvent crystallization. As proof of concept, nanosuspensions of norfloxacin (NFN), an antibacterial agent, were produced varying the key parameters of the technology. The nanosuspensions had narrow particle size distributions and median particle sizes in the range of 170−350 nm. The particle size depends on the supersaturation ratio and energy dissipation expressed as processing pressure. However, the particle size was found to be insensitive to the presence of the surfactant used. The crystalline structure of NFN was not affected by the mixing intensity but by the solvent/antisolvent system. This “bottom up” process for creating nanosuspensions was compared to a “top down” process, in which NFN nanosuspensions were created as a result of particle size reduction. It was found that the “bottom up” process was substantially more efficient and resulted in smaller particles than the “top down” process. MRT is based on an impinging jet reactor design with jet velocities and energy dissipation that is orders of magnitude higher than those of conventional impinging jet reactors. The technology provides precise control of the feed rates and the subsequent location and intensity of mixing of the reactants. It may be the best choice economically due to its process intensification character that minimizes energy requirements and the proven scalability of the reactor. [ABSTRACT FROM AUTHOR]

Tyrosyl-DNA phosphodiesterase 1 (Tdp1) is an enzyme that catalyzes the hydrolysis of 3′-phosphotyrosyl bonds. Such linkages form in vivo when topoisomerase I (Top1) processes DNA. For this reason, Tdp1 has been implicated in the repair of irreversible Top1−DNA covalent complexes. Tdp1 inhibitors have been regarded as potential therapeutics in combination with Top1 inhibitors, such as the camptothecin derivatives, topotecan, and irinotecan, which are used to treat human cancers. Using a novel high-throughput screening assay, we have identified the C21-substituted progesterone derivative, NSC 88915 (1), as a potential Tdp1 inhibitor. Secondary screening and cross-reactivity studies with related DNA processing enzymes confirmed that compound 1possesses specific Tdp1 inhibitory activity. Deconstruction of compound 1into discrete functional groups reveals that both components are required for inhibition of Tdp1 activity. Moreover, the synthesis of analogues of compound 1has provided insight into the structural requirements for the inhibition of Tdp1. Surface plasmon resonance shows that compound 1binds to Tdp1, whereas an inactive analogue fails to interact with the enzyme. On the basis of molecular docking and mechanistic studies, we propose that these compounds are competitive inhibitors, which mimics the oligonucleotide−peptide Tdp1 substrate. These steroid derivatives represent a novel chemotype and provide a new scaffold for developing small molecule inhibitors of Tdp1. [ABSTRACT FROM AUTHOR]

A fluorescence anisotropy (FA) competition-based Shc Src homology 2 (SH2) domain-binding was established using the high affinity fluorescein isothiocyanate (FITC) containing peptide, FITC-NH-(CH2)4-CO-pY-Q-G-L-S-amide (8; Kd= 0.35 μM). Examination of a series of open-chain bis-alkenylamide containing peptides, prepared as ring-closing metathesis precursors, showed that the highest affinities were obtained by replacement of the original Gly residue with Nα-substituted Gly (NSG) “peptoid” residues. This provided peptoid−peptide hybrids of the form “Ac-pY-Q-[NSG]-l-amide.” Depending on the NSG substituent, certain of these hybrids exhibited up to 40-fold higher Shc SH2 domain-binding affinity than the parent Gly-containing peptide (IC50= 248 μM) (for example, for N-homoallyl analogue 50, IC50= 6 μM). To our knowledge, this work represents the first successful example of the application of peptoid−peptide hybrids in the design of SH2 domain-binding antagonists. These results could provide a foundation for further structural optimization of Shc SH2 domain-binding peptide mimetics. [ABSTRACT FROM AUTHOR]

A 4-aminopiperidine-4-carboxylic acid residue was placed in the pTyr1 position of a Grb2 SH2 domain-binding peptide to form a general platform, which was then acylated with a variety of groups to yield a library of compounds designed to explore potential binding interactions, with protein features lying below the D strand. The highest affinities were obtained using phenylethyl carbamate and phenylbutyrylamide functionalities. [ABSTRACT FROM AUTHOR]