1. We have reported previously that instant coffee contains ligands for opiate receptors with characteristics similar to those of opiate antagonists. 2. A concentrate of receptor-active ligands from instant coffee was prepared by serial treatments involving Amberlite XAD-2, flash chromatography and gel permeation chromatography. 3. Examination of the final concentrate by GC-MS showed the presence of a number of isomeric (iso)feruloylquinic acid lactones. 4. It is suggested that the synthesis and biological testing of each quinide isomer will establish which is responsible for the opiate receptor activity of instant coffee.
The 27-residue polypeptide omega-conotoxin GVIA (omega-CgTx), from the venom of the cone shell Conus geographus, blocks N-type neuronal calcium channels. It contains three disulphide bridges. We report here the synthesis and biological characterization of a series of analogues in which one disulphide has been replaced by substitution of appropriate Cys residues with Ser, viz. [Ser1,16]-omega -CgTx, [Ser8,19]-omega-CgTx, [Ser15,26)-omega-CgTx, [Ser16]-omega-CgTx8-27 and [Ser15]-omega-CgTx1-19. All syntheses were conducted manually using either Boc or Fmoc methodology. Deprotected peptides were oxidized to their bridged forms using either aerial oxidation or aqueous dimethyl sulphoxide. Peptides were purified using RP-HPLC, and their purity and identity were checked by RP-HPLC, capillary electrophoresis and mass spectrometry. Inhibition of neuronal N-type calcium channels was assessed as the inhibition of the twitch responses of rat vas deferens stimulated with single electrical pulses at 20 second intervals. None of these analogues was biologically active, suggesting that the disulphides play an important role in maintaining biological activity.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
customersupport@researchsolutions.com
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.