Design and Synthesis of Photoaffinity Probe Candidates for the GABA-gated Chloride Channel

In order to characterize binding sites of insecticidal compounds on GABA gated chloride channel, new photoaffinity probe candidates based on 5e-t-butyl-2e-[4-（substituted-propynyl）phenyl]-1,3-dithiane for the noncompetitive blocker （NCB） site of the γ-aminobutyric acid （GABA）-gated chloride channel were designed and synthesized, and their potency as an inhibitor on NCB was measured by 4＇-ethynyl-4-n-[2,3-^3H2]-propylbicycloorthobenzoate （^3H EBOB） assay. The synthesized compounds showed high inhibition activities with half maximum inhibition concentrations （IC50） of lower than 35 nmol/L and were very stable in binding conditions as well photoreacted quickly at 300 nm light. These new compounds are expected to be good photoaffinity labeling probes if radioisotope iodine is incorporated.

Chemical proteomics reveals ligustilide targets SMAD3,inhibiting collagen synthesis in aortic endothelial cells

Atherosclerosis is a persistent inflammatory state,while vascular endothelial fibrosis is one of the primary causes of atherosclerosis development.Although ligustilide(Lig) was shown to exert obvious antiatherogenic effects in previous studies,its precise mechanism has not been deeply discussed.In this paper,we designed a Lig-derived photoaffinity labelling(PAL) probe to identify potential therapeutic targets of Lig via chemical proteomics approach.Mothers against decapentaplegic homologue 3(SMAD3),a signal transmitter of transforming growth factor-β(TGF-β) which promotes the development of vascular fibrosis,was identified as a potential target of Lig.Lig suppressed the phosphorylation and nuclear translocation of SMAD3 by blocking the interaction between SMAD3 and TGF-β receptor 1,thereby inhibiting the collagen synthesis process.Hence,developing a novel SMAD3 inhibitor may present a promising therapeutic option for preventing vascular fibrosis.

Chemical proteomics combined with metabonomics reveals berberine targets NDUFV1 of complex Ⅰ in the respiratory chain to regulate energy metabolism

Berberine(BBR) is the primary alkaloid compound of the heat-clearing traditional Chinese medicine Huanglian(Coptis chinensis) and exerts regulatory effects on energy metabolism. However, the specific targets and molecular mechanisms are not clear. In this paper, the BBR-affected energy metabolism pathway was screened by nontargeted metabolomics, and a BBR-derived photoaffinity labeled(PAL) probe was designed to identify potential targets via a chemical proteomics approach. NDUFV1, a subunit of complex Ⅰ on mitochondria, was identified as a potential target of BBR. In the respiratory chain, BBR suppressed the activity of complex Ⅰ, reduced the electrochemical potential in the mitochondrial intermembrane and inhibited the generation of ATP and heat via competitive binding with NDUFV1. The results illustrated the underlying mechanism of BBR in the downregulation of energy metabolism.