(1S*,3R*,5S*,7S*)-4,4,8,8-Tetrachloro-1-isopropyl-5-methyltricyclo[5.1.0.03,5]octane

The title compound, C12H16Cl4, is a derivative of the natural product 1-isopropyl-4-methylcyclohexa-1,4-diene, and represents a diastereomer with two trans-fused cyclopropane rings. Both enantiomers are present in the non-centrosymmetric polar space group Pna21. The central cyclohexane ring is planar within 0.02 (1) Å. The C atoms of dichloromethylene groups deviate from this plane by 1.19 (1) and −1.26 (1) Å, whereas the isopropyl and methyl groups are oriented more equatorially, deviating by 0.71 (1) and −0.87 (1) Å, respectively

Inhibition of T Cell Receptor Activation by Semi-Synthetic Sesquiterpene Lactone Derivatives and Molecular Modeling of Their Interaction with Glutathione and Tyrosine Kinase ZAP-70

A variety of natural compounds have been shown to modulate T cell receptor (TCR) activation, including natural sesquiterpene lactones (SLs). In the present studies, we evaluated the biological activity of 11 novel semi-synthetic SLs to determine their ability to modulate TCR activation. Of these compounds, α -epoxyarglabin, cytisinyl epoxyarglabin, 1 β ,10 α -epoxyargolide, and chloroacetate grosheimin inhibited anti-CD3-induced Ca2+ mobilization and extracellular signal-regulated kinase 1/2 (ERK1/2) phosphorylation in Jurkat T cells. We also found that the active SLs depleted intracellular glutathione (GSH) in Jurkat T cells, supporting their reactivity towards thiol groups. Because the zeta-chain associated tyrosine kinase 70 kDa (ZAP-70) is essential for TCR signaling and contains a tandem SH2 region that is highly enriched with multiple cysteines, we performed molecular docking of natural SLs and their semi-synthetic derivatives into the ZAP-70 binding site. The docking showed that the distance between the carbon atom of the exocyclic methylene group and the sulfur atom in Cys39 of the ZAP-70 tandem SH2 module was 3.04–5.3 Å for active compounds. Furthermore, the natural SLs and their derivatives could be differentiated by their ability to react with the Cys39 SH-group. We suggest that natural and/or semi-synthetic SLs with an α -methylene- γ -lactone moiety can specifically target GSH and the kinase site of ZAP-70 and inhibit the initial phases of TCR activation