Derivatization of ophiobolin A and cytotoxicity toward breast and glioblastoma cancer stem cells: Varying the ketone and unsaturated aldehyde moieties.

To gain further insights into the importance of the unsaturated 1,4-ketoaldehyde moiety of ophiobolin A (OpA) for the potency and selectivity observed toward cancer stem cells, several derivatives were synthesized through controlled reduction and oxidations of the unsaturated aldehyde and ketone moieties. Structure elucidation of these new OpA derivatives was achieved through detailed NMR studies and comparison to OpA and known isolated congeners possessing variations in these regions. The relative stereochemistry of the newly generated stereocenters was determined by coupling constants in conjunction with conformational analyses (DFT) of the synthetic derivatives.

Girolline is a sequence context-selective modulator of eIF5A activity.

Natural products have a long history of providing probes into protein biosynthesis, with many of these compounds serving as therapeutics. The marine natural product girolline has been described as an inhibitor of protein synthesis. Its precise mechanism of action, however, has remained unknown.

Non-Genotoxic and Environmentally Relevant Lower Molecular Weight Polycyclic Aromatic Hydrocarbons Significantly Increase Tumorigenicity of Benzo[]pyrene in a Lung Two-Stage Mouse Model.

The World Health Organization has classified air pollution as a carcinogen, and polycyclic aromatic hydrocarbons (PAHs) are major components of air particulates of carcinogenic concern. Thus far, most studies focused on genotoxic high molecular weight PAHs; however, recent studies indicate potential carcinogenicity of the non-genotoxic lower molecular weight PAHs (LMW PAHs) that are found in indoor and outdoor air pollution as well as secondhand cigarette smoke. We hypothesize that LMW PAHs contribute to the promotion stage of cancer when combined with benzo[]pyrene (B[]P), a legacy PAH.

Radical Reactions with Chiral Acylammonium Salts: Synthesis of Functionalized δ-Lactams through Giese-Initiated Organocascades.

Enantioselective Giese reactions employing chiral α,β-unsaturated acylammonium salts and subsequent diastereoselective trapping followed by lactamization deliver optically active δ-lactams. Alkyl iodides bearing tosylamides undergo radical initiation using triethylborane at low temperatures to provide carbon-centered radicals to initiate the described organocascade. Subsequent diastereoselective inter- or intramolecular trapping of the incipient α-radical leads to highly functionalized, enantioenriched mono- and bicyclic δ-lactams (up to 99:1 er, > 19:1 dr) bearing up to three stereogenic centers.

DMDA-PatA mediates RNA sequence-selective translation repression by anchoring eIF4A and DDX3 to GNG motifs.

Small-molecule compounds that elicit mRNA-selective translation repression have attracted interest due to their potential for expansion of druggable space. However, only a limited number of examples have been reported to date. Here, we show that desmethyl desamino pateamine A (DMDA-PatA) represses translation in an mRNA-selective manner by clamping eIF4A, a DEAD-box RNA-binding protein, onto GNG motifs.