Investigation for the cyclization efficiency of linear tetrapeptides: Synthesis of tentoxin B and dihydrotentoxin

Synthesis and evaluation of catecholamine derivatives as amyloid-beta aggregation inhibitors

Effectively inhibition of amyloid β (Aβ) aggregation is considered an important method for treatment of the Alzheimer's disease. Herein, inspired by the ability of trans-clovamide to effectively inhibit Aβ aggregation, we synthesized a series of structurally related catecholamine derivatives and tested them as Aβ aggregation inhibitors using the Thioflavin T assay. The results show that they demonstrated a higher inhibitory rate against Aβ aggregation. Furthermore, these compounds exhibited high water solubilities and low cytotoxicities. Additionally, transmission electron microscopy images and dynamic light scattering of their Aβ aggregations were observed. Docking simulations revealed that the catechol moiety of the synthesized compounds can form hydrogen bonds with the key regions of Aβ and thereby inhibit Aβ aggregation.

Synthesis and biological evaluation of nectriatide derivatives, potentiators of amphotericin B activity

Nectriatide 1a, a naturally occurring cyclic tetrapeptide, has been reported to a potentiator of amphotericin B (AmB) activity. In order to elucidate its structure-activity relationships, we synthesized nectriatide derivatives with different amino acids in solution-phase synthesis and evaluated AmB-potentiating activity against Candida albicans. Among them, C-and N-terminal protected linear peptides were found to show the most potent AmB-potentiating activity.

Marine natural products

This review covers the literature published between January and December in 2018 for marine natural products (MNPs), with 717 citations (706 for the period January to December 2018) referring to compounds isolated from marine microorganisms and phytoplankton, green, brown and red algae, sponges, cnidarians, bryozoans, molluscs, tunicates, echinoderms, mangroves and other intertidal plants and microorganisms. The emphasis is on new compounds (1554 in 469 papers for 2018), together with the relevant biological activities, source organisms and country of origin. Reviews, biosynthetic studies, first syntheses, and syntheses that led to the revision of structures or stereochemistries, have been included. The proportion of MNPs assigned absolute configuration over the last decade is also surveyed.

The total synthesis of berberine and selected analogues, and their evaluation as amyloid beta aggregation inhibitors

The total synthesis of berberine and selected analogues. And their evaluation as amyloid β (Aβ) aggregation inhibitors is described. The key step in the synthesis, the assembly of the berberine framework, was accomplished using an intermolecular Heck reaction. Berberine analog 17 incorporating a tertiary amine moiety showed good anti Aβ aggregation activity, water solubility, and almost no toxicity to nerve cells.

Synthesis of endolides A and B: naturally occurring N-methylated cyclic tetrapeptides

Endolides A and B are naturally occurring, N-methylated, cyclic tetrapeptides possessing an unusual 3-(3-furyl)alanine amino acid and outstanding biological profiles. 1-Propanephosphonic anhydride (T3P) was used to mediate a solution-phase cyclisation reaction of the linear tetrapeptides, thus achieving the first syntheses of both endolides A and B. The stereoselectivity of the tetrapeptide cyclisation reactions was found to be reagent-controlled, and was independent of the C-terminal configuration of the linear peptide starting materials.