title: New circulin macrocyclic polypeptides from Chassalia parvifolia.
abstract: Four new macrocyclic polypeptides were isolated and identified from an extract of the tropical tree Chassalia parvifolia. Circulins C-F are 29-30 amino acid cyclic peptides in which the entire primary amino acid chain is covalently cyclized via peptide bonds. Their structures were deduced from a combination of FABMS analyses, N-terminal Edman degradation, endoproteinase digestion, and amino acid analyses. All the peptides share a high degree of sequence homology and contain six cysteine residues forming three intramolecular disulfide bridges. Circulins C-F inhibited the cytopathic effects of in vitro HIV-1 infection with EC(50) values of 50-275 nM.
authors.affiliation: Laboratory of Drug Discovery Research and Development, Developmental Therapeutics Program, Division of Cancer Treatment and Diagnosis, National Cancer Institute, Frederick Cancer Research and Development Center, Frederick, MD 21702-1201, USA.
authors.forename: K R
authors.initials: KR
authors.lastname: Gustafson
authors.forename: L K
authors.initials: LK
authors.lastname: Walton
authors.forename: R C
authors.initials: RC
authors.lastname: Sowder
authors.forename: D G
authors.initials: DG
authors.lastname: Johnson
authors.forename: L K
authors.initials: LK
authors.lastname: Pannell
authors.forename: J H
authors.initials: JH
authors.lastname: Cardellina
authors.forename: M R
authors.initials: MR
authors.lastname: Boyd
mesh_terms: D000478:Alkylation; D000595:Amino Acid Sequence; D000900:Anti-Bacterial Agents / Q000032:analysis* / Q000302:isolation & purification / Q000494:pharmacology; D019380:Anti-HIV Agents / Q000032:analysis* / Q000302:isolation & purification / Q000494:pharmacology; D002851:Chromatography, High Pressure Liquid; D047169:Cyclotides; D003545:Cysteine / Q000032:analysis; D015497:HIV-1 / Q000187:drug effects; D006801:Humans; D008826:Microbial Sensitivity Tests; D008969:Molecular Sequence Data; D010084:Oxidation-Reduction; D018547:Plant Stems / Q000737:chemistry; D010946:Plants, Medicinal / Q000737:chemistry*; D016339:Spectrometry, Mass, Fast Atom Bombardment; D013648:Tasmania
chemical_list: D000900:Anti-Bacterial Agents; D019380:Anti-HIV Agents; D047169:Cyclotides; C011198:circulin; D003545:Cysteine