The CERT antagonist HPA-12: first practical synthesis and individual binding evaluation of the four stereoisomers

The first unified synthetic route to the four enantiopure HPA-12 stereoisomers in multi-gram scale is reported based on Crystallization-Induced Asymmetric Transformation (CIAT) technology. This preparative stereoselective synthesis allowed the unprecedented comparative evaluation of HPA-12 stereoisomers regarding their interaction with the CERT START domain. In vitro binding assay coupled to in silico docking approach indicate a possible interaction for the four derivatives. The first TR-FRET homogeneous-phase assay was developed to quantify their binding to the START domain, allowing complete determination of HPA-12 EC₅₀. Results indicate that not only the (1R,3S) lead to the strongest binding, but that both 1R and 3S stereocenters similarly contribute to extent of recognition This automated homogenous assay further opens up promising prospect for the identification of novel potential CERT antagonist by means of high throughput screening.

Synthesis and in vitro antiproliferative activity of amido and amino analogues of the marine alkaloid isogranulatimide

Marine organisms have proven to be a promising source of new compounds with activity against tumor cell lines. Granulatimide and isogranulatimide are marine alkaloids that have been shown to inhibit checkpoint kinase 1 (Chk1), a key protein in the DNA damage response and an emerging target for anticancer therapeutics. Here, we describe the synthesis and preliminary evaluation of amido and amino analogues of isogranulatimide. The new derivatives were prepared in three steps from 2-imidazol-1-yl-1H-indol-5-ylamine. Two of the compounds synthesized exhibited more potent in vitro antiproliferative activity (single-digit micromolar concentration range), by at least one log of magnitude, than the natural product isogranulatimide when evaluated in six human tumor cell lines: non-small-cell lung cancer (A549), colon cancer (LoVo), breast cancer (MCF7), oligodendroglioma (Hs683), glioblastoma (U373), and melanoma (SKMEL28). The mechanism of action of these derivatives remains to be elucidated, given that they did not significantly inhibit Chk1, however these compounds are easily synthesized and exhibit potent anticancer activity and are thus worthy of further study.

Genetic and epigenetic changes involving (retro)transposons in animal hybrids and polyploids

Transposable elements (TEs) are discrete genetic units that have the ability to change their location within chromosomal DNA, and constitute a major and rapidly evolving component of eukaryotic genomes. They can be subdivided into 2 distinct types: retrotransposons, which use an RNA intermediate for transposition, and DNA transposons, which move only as DNA. Rapid advances in genome sequencing significantly improved our understanding of TE roles in genome shaping and restructuring, and studies of transcriptomes and epigenomes shed light on the previously unknown molecular mechanisms underlying genetic and epigenetic TE controls. Knowledge of these control systems may be important for better understanding of reticulate evolution and speciation in the context of bringing different genomes together by hybridization and perturbing the established regulatory balance by ploidy changes. See also sister article focusing on plants by Bento et al. in this themed issue.

Reactive Ion Etching of Polymer Films

The need for nanometer-sized features in integrated circuits calls for the use of dry-etching techniques using glow-discharge plasmas. The reactive ion etching (RIE) mode in which there is a large difference in potential between the gas phase and the solid surface yields particularly desirable, straight-walled etched structures. The design of processes and materials for RIE requires a knowledge of the effects of operating variables on various parameters. In the present work, the parameter emphasized is the etch rate. A novel aspect of the apparatus used incorporates a laser interferometer for in situ measurements of etch rate. Some observations on operating variables are: i. Chamber pressure is more critical when a fluoride-oxygen plasma is used than when oxygen alone is used. This is due to polymer deposition that occurs with the former along with etching. 2. The etch rate in the oxygen/RIE mode is almost the arithmetic sum of the oxygen/plasma mode together with the nitrogen/RIE mode except at low incident power levels where etch rate with oxygen/RIE is much greater than the sum of the other two. 3. Aromatic polymers etch more slowly than aliphatic polymers. 4. The oxygen/RIE rate of polyvinylchloride, PVC, decreases on addition of a compatible organotin compound. A 1:1 mixture of PVC with a tin compound etches at i/10 the rate of PVC alone.