Synthesis and DNA-cleaving activity of lactenediynes conjugated with DNA-complexing moieties

AgNTf2-catalyzed formal [3 + 2] cycloaddition of ynamides with unprotected isoxazol-5-amines: efficient access to functionalized 5-amino-1H-pyrrole-3-carboxamide derivatives

A formal [3 + 2] cycloaddition between ynamides and unprotected isoxazol-5-amines has been developed in the presence of catalytic AgNTf2 in an open flask. By the protocol, a variety of functionalized 5-amino-1H-pyrrole-3-carboxamide derivatives can be obtained in up to 99% yield. The reaction mechanism might involve the generation of an unusual α-imino silver carbene intermediate (or a silver-stabilized carbocation) and subsequent cyclization/isomerization to build the significant pyrrole-3-carboxamide motif. The reaction features the use of an inexpensive catalyst, simple reaction conditions, simple work-up without column chromatographic purification for most of products and high yields.

Traceless Release of Alcohols Using Thiol-Sensitive Oxanorbornadiene Linkers

A class of ester-amide oxanorbornadiene (EA-OND) molecules was developed to release alcohol cargos by succinimide formation upon addition of a thiol reagent. The resulting ring-closed adducts undergo further fragmentation by retro-Diels-Alder reaction to release a furan moiety in a manner similar to oxanorbornadiene diesters. The rates of each of these fragmentation pathways in the same medium were found to be sensitive to the steric nature of the amide substituent. Alcohol release was much faster in protic solvents than in aprotic ones, suggesting that this system may be useful for rapid response to thiols in biological environments. Accordingly, the attachment and thiol-dependent release of cholesterol was characterized as an example of the manipulation of a drug-like cargo.

Enzymatically promoted release of organic molecules linked to magnetic nanoparticles

Magnetite-based magnetic nanoparticles have been successfully coupled to an organic system constituted of a fluorescent molecule, a tripeptide specifier and a spacer. The system is able to selectively release the fluorescent molecule upon targeted enzymatic hydrolysis promoted by a lysine/arginine specific protease.

Artemisinin-polypyrrole conjugates: synthesis, DNA binding studies and preliminary antiproliferative evaluation

Greater than the sum of its parts: Artemisinins are currently in phase I-II clinical trials against breast, colorectal and non-small-cell lung cancers. In an attempt to offer increased specificity, a series of hybrid artemisinin-polypyrrole minor groove binder conjugates are described. DNA binding/modelling studies and preliminary biological evaluation give insights into their mechanism of action and the potential of this strategy.

Optically active 1,3,4,4-tetrasubstituted β-lactams: synthesis and evaluation as tumor cell growth inhibitors

The in vitro cytotoxicity assays of several enantiopure (3S,4S)- and (3R,4R)-1,3,4,4-tetrasubstituted β-lactams derived from amino acids have shown that the (3S,4S)-4-benzyl-1-p-methoxybenzyl-3-methyl-4-methoxycarbonyl derivative 2a, obtained from Phe, displays significant activity, which is comparable to that of the anticancer drug Doxorubicin against HT29 cell lines. Modifications at positions 1 and 4 of the β-lactam ring led to identify the Tyr(2,6-ClBz) analogu 26d with similar activity data to those of 2a. The synthesis and SAR of all these tetrasubstituted β-lactams are reported here.