Cyclopsychotride A, a biologically active, 31-residue cyclic peptide isolated from Psychotria longipes.

@article{Witherup1994CyclopsychotrideAA,
  title={Cyclopsychotride A, a biologically active, 31-residue cyclic peptide isolated from Psychotria longipes.},
  author={Keith M. Witherup and Michael Bogusky and Paul S. Anderson and Harri G. Ramjit and Richard W. Ransom and T Wood and Mohita Sardana},
  journal={Journal of natural products},
  year={1994},
  volume={57 12},
  pages={
          1619-25
        }
}
A preliminary characterization is provided of a naturally occurring cyclic peptide with interesting and potent biological activity. A 31-residue cyclic peptide, designated cyclopsychotride A [1], was obtained from the organic extract of the tropical plant, Psychotria longipes. Compound 1 inhibited [125I] neurotensin (NT) binding to HT-29 cell membranes (IC50 3 microM) and also stimulated increased levels of cytosolic Ca2+ in two unrelated cell lines that do not express NT receptors. The peptide… 
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