No abstract

Development of a gold-catalyzed tandem reaction of 1,7-diynes with both internal and external nucleophiles was realized, which constructed five chemical bonds, two rings, and two stereogenic centers in a single step. Based on the novel cascade transformation, we achieved a unified strategy toward the stereoselective total syntheses of C-15 oxygenated drimane-type sesquiterpenoids and their analogues, which provided the natural products kuehneromycin A, antrocin, anhydromarasmone, and marasmene as a proof-of-concept study.

Novel chitosan derivatives carrying linoleic acid (LA) as hydrophobic moieties and poly(beta-malic acid) (PMLA) as hydrophilic moieties (LA/PMLA double grafted chitosan, LMC) were synthesized. It self-assembled into nanoparticles of 190-350 nm in water, which carried negative surface charges in physiological pH. The critical aggregation concentration of the LMC deceased with an increase in the LA content. Paclitaxel (PTX) was loaded into the LMC nanoparticles with a high loading efficiency and the maximum loading capacity of 9.9 +/- 0.4%. PTX-LMC nanoparticles exhibited a sustained release within 24 h in pH 7.4 phosphate-buffered saline (PBS), and the release rate was affected by the LA content and PMLA length. Hemolysis and acute toxicity assessment indicated that the LMC nanoparticles were safe drug carriers for i.v. administration. Additionally, PTX-LMC showed significantly potent tumor inhibition efficacy relative to that of TAXOL in S-180 bearing mice. Therefore, the LMC nanoparticles could be an effective and safe vehicle for systemic administration of hydrophobic drugs, especially PTX.