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Inhibitors of the voltage-gated sodium channel NaV1.7 are being investigated as pain therapeutics due to compelling human genetics. We previously identified NaV1.7-inhibitory peptides GpTx-1 and JzTx-V from tarantula venom screens. Potency and selectivity were modulated through attribute-based positional scans of native residues via chemical synthesis. Herein, we report JzTx-V lead optimization to identify a pharmacodynamically active peptide variant. Molecular docking of peptide ensembles from NMR into a homology model-derived NaV1.7 structure supported prioritization of key residues clustered on a hydrophobic face of the disulfide-rich folded peptide for derivatization. Replacing Trp24 with 5-Br-Trp24 identified lead peptides with activity in electrophysiology assays in engineered and neuronal cells. 5-Br-Trp24 containing peptide AM-6120 was characterized in X-ray crystallography and pharmacokinetic studies and blocked histamine-induced pruritis in mice after subcutaneous administration, demonstrating systemic NaV1.7-dependent pharmacodynamics. Our data suggests a need for high target coverage based on plasma exposure for impacting in vivo end points with selectivity-optimized peptidic NaV1.7 inhibitors.

A series of mansonone F (MF) derivatives were designed and synthesized. These compounds were found to be strong inhibitors for topoisomerases, with much more significant inhibition for topoisomerase II rather than topoisomerase I. The best inhibitor showed 20 times stronger anti-topoisomerase II activity than a positive control Etoposide. The cytotoxic activity of these MF derivatives was evaluated against human cancer cell lines CNE-2 and Glc-82, which showed that these compounds were potent antitumor agents. The structure–activity relationships (SARs) study revealed that o-quinone group and pyran ring are important for their cytotoxic activity.

Silver metal nanocrystals with passivating ligand shells of dodecanethiol were synthesized by a one-phase wet chemical method. Postsynthesis thermochemical processing, known as digestive ripening, was used to focus the size distribution from a very broad distribution to 5.6 ± 0.4 nm. Chemical analysis of the final Ag nanocrystals showed a metallic core with a densely packed ligand shell. No oxidation was observed despite the entirely aerobic conditions. The size distribution was found to change most dramatically after the two steps proceeding digestive ripening, namely, ligand exchange and precipitation. Imaging also showed that the digestive ripening mechanism of Ag nanocrystals could be significantly different than that for Au, and involved a competitive silver thiolate side product. This synthesis was optimized to produce Ag nanocrystals with little to no silver thiolate materials.

The Ala(1)-Gly(28) glycopeptide fragment (28) of EPO was prepared by chemical synthesis as a single glycoform. Key steps in the synthesis include attachment of a complex dodecasaccharide (7) to a seven amino acid peptide via Lansbury aspartylation, native chemical ligation to join peptide 19 with the glycopeptide domain 18, and a selective desulfurization at the ligation site to reveal the natural Ala(19). This glycopeptide fragment (28) contains both the requisite N-linked dodecasaccharide and a C-terminal (alpha)thioester handle, the latter feature permitting direct coupling with a glycopeptide fragment bearing N-terminal Cys(29) without further functionalization.

Five new stilbene oligomers, laetevirenol A-E (4-8), were isolated from Parthenocissus laetevirens, together with three known stilbene oligomers (2, 3, and 9). The structures of the new compounds were elucidated by spectroscopic analysis, including 1D and 2D NMR experiments. Afterward the absolute configurations were determined. Biomimetic transformations revealed a possible biogenetic route, where stilbene trimers were enzymatically synthesized for the first time. In addition, their antioxidant activities were evaluated by 1,1-diphenyl-2-picrylhydrazyl (DPPH) assay. The results showed that stilbene oligomers with an unusual phenanthrene moiety exhibited much stronger antioxidant activities. Thus, the photocatalyzed cyclization of stilbenes was supposed to be an antioxidant activity promoting transformation, which was hypothesized to play a role in the antioxidative defense system of the plant.

Apoptolidins A−D are microbial secondary metabolites shown to be selectively cytotoxic against several cancer cell lines and noncytotoxic against normal cells. Total syntheses of apoptolidinones A and D are reported. The efficient synthetic strategy leading to the apoptolidinones features construction of the common 20-membered macrolactone by an intramolecular Suzuki reaction and stereocontrolled aldol reactions establishing the C19/C20 and C22/C23 stereocenters. In contrast to apoptolidin A, the aglycones apoptolidinone A and D were shown to be noncytotoxic when evaluated against human lung cancer cells (H292).

A novel, highly stereoselective synthesis of an azaspirocyclic core, which contains four stereogenic carbons consistent with structures of natural halichlorine and pinnaic acid, is presented. Lipase PS-catalyzed selective acylation, asymmetric methylation on the alpha-methylene of the bicyclic lactone, and an asymmetric Michael addition of the tertiary nitro cyclopentane were concisely used to conquer the challenging problem of successfully constructing the C9 quarternary carbon center with complete stereocontrol. The spiropiperidine ring was formed by reduction of the delta-nitroketone, intramolecular condensation, and then highly stereoselective reduction of the cyclic nitrone with NaBH(4). This spirocyclic core is a key intermediate in Danishefsky's synthesis of pinnaic acid and halichlorine.

A synthesis of EPO 22–37 glycopeptide ( 1 ), presenting the N-linked dodecasaccharide of erythropoietin, is described.

A comprehensive account of the development of a synthetic strategy leading to the apoptolidinones A and D is provided. Key transformations include diastereoselective aldol reactions under substrate control and an intramolecular Suzuki cross‐coupling leading to the formation of a 20‐membered macrolactone. Finally, C27 glycosylation of the synthetic aglycone is achieved using whole cells of the apoptolidin‐ producing microorganism. Overall, this work demonstrates the synthetic power of chemical synthesis in combination with whole cell‐assisted glycosylation to access complex natural products and their derivatives.

A synthesis of EPO 114-166 glycopeptide (1), presenting the O-linked glycophorin of erythropoietin, is described.

A pathway has been devised, wherein a phenolic ester of a C-terminal peptide is ligated with an N-terminal peptide through two consecutive acyl migrations. In the first transacylation, the C-terminus is transferred from a phenol to a newly liberated ortho-thiol function. Subsequently, the acyl group is transported to a proximal benzylamine through a six-membered transition state.

[reaction: see text] A good regio- and stereoselectivity was observed for the PdCl2-catalyzed cyclocarbonylation of 2-alkynols with CuCl2 affording (Z)-alpha-chloroalkylidene-beta-lactones. The highly optically active (Z)-alpha-chloroalkylidene-beta-lactones could be easily prepared from the readily available optically active propargylic alcohols. The Pd(II)-catalyzed cyclocarbonylation of 2-alkynols with CuBr2 was also studied. Although the yields of (Z)-alpha-bromoalkylidene-beta-lactones were low, due to the relatively higher activity of the C-Br bond, the coupling reactions of (Z)-alpha-bromoalkylidene-beta-lactones were quite smooth to afford the corresponding products in high yields. A rationale for this reaction is discussed.

[reaction: see text] The PdCl2-catalyzed cyclocarbonylation reaction of propargylic amines with CuCl2 and benzoquinone afforded (E)-alpha-chloroalkylidene-beta-lactams in moderate to good yields. The formation of the corresponding Z-isomers or five-membered products was not observed. The reaction of the readily available optically active propargylic amines provides a convenient synthesis of the corresponding (E)-alpha-chloroalkylidene-beta-lactams with high ee values. The structure and the stereochemistry of the products were established by the X-ray single-crystal diffraction study of (E)-6d and (E)-6e, which indicates that the stereoselectivity in this reaction is different from what was observed with propargylic alcohols. A rationale for this reaction was proposed.

4-Halo-5-hydroxyfuran-2(5H)-ones were synthesized via the efficient sequential halolactonization-hydroxylation reaction of 4-aryl-2,3-allenoic acids with I(2) or CuX(2) (X = Br or Cl) in moderate to good yields. The structures of the products were established by the X-ray single-crystal diffraction study of 3-methyl-4-iodo-5-phenyl-5-hydroxyl-2(5H)-furanone (2a). A rationale for this reaction was discussed based on some brief mechanistic study.

Endomorphin-1 (Tyr-Pro-Trp-Phe-NH2, EM-1), an effective analgesic, was efficiently synthesized by a combination of enzymatic and chemical methods. Peptide Boc-Trp-Phe-NH2 was synthesized with a high yield of 97.1% by the solvent-stable protease WQ9-2 in a 20% methanol medium. The maximum concentration (141 g L−1) of Boc-Trp-Phe-NH2 was obtained with an economical molar ratio of the substrate of 1 : 1. The products crystallized and separated from the substrates without purification, followed by the removal of the Boc group with trifluoroacetic acid to generate Trp-Phe-NH2. Using the efficient mixed carbonic anhydride method, Boc-Tyr-Pro-OH was synthesized chemically. The tetrapeptide Boc-Tyr-Pro-Trp-Phe-NH2 was synthesized with a yield of 84.5% by another organic solvent-tolerant protease, PT121, from Boc-Tyr-Pro-OH and Trp-Phe-NH2 in an organic–aqueous biphasic system and was extracted with ethyl acetate, shifting the equilibrium of the synthesis. EM-1 was obtained by removal of the Boc group from Boc-Tyr-Pro-Trp-Phe-NH2 in a high yield of 91% due to the free protection of the side-chain of the Tyr phenolic hydroxy group. After a one-step purification in the final step by using high speed countercurrent chromatography (HSCCC), EM-1 was obtained with a purity greater than 99.8%. The chemo-enzymatic synthesis of EM-1 proved to be efficient, productive, with minimal side-chain protection and simple purification, thus greening the synthesis of the peptide.