Cyclotides from an extreme habitat: characterization of cyclic peptides from Viola abyssinica of the Ethiopian highlands

J Nat Prod. 2011 Apr 25;74(4):727-31. doi: 10.1021/np100790f. Epub 2011 Mar 24.

Abstract

As part of ongoing explorations of the structural diversity of cyclotides, the cyclotide content of a native violet of the East African highlands, Viola abyssinica (which grows at altitudes up to 3400 m), was studied. Six new cyclotides, vaby A-E (1-5) and varv E (6), were isolated and characterized by employing HPLC and MS techniques and quantitative amino acid analysis. Cyclotides 1-5 were found to have new sequences, and 1-3 have a further novel feature in their sequences, an alanine moiety in loop 2. Two of the cyclotides (1 and 4) also exhibited cytotoxic properties in a flourometric microculture cytotoxicity assay. The findings corroborate the hypothesis that investigating the cyclotide contents of violets growing in diverse environments is a promising approach for extending our knowledge of both the structural and biological diversity of cyclotides.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Antineoplastic Agents, Phytogenic / chemistry
  • Antineoplastic Agents, Phytogenic / isolation & purification*
  • Antineoplastic Agents, Phytogenic / pharmacology
  • Cyclotides / chemistry
  • Cyclotides / isolation & purification*
  • Cyclotides / pharmacology
  • Dose-Response Relationship, Drug
  • Drug Screening Assays, Antitumor
  • Ethiopia
  • Humans
  • Sequence Homology, Amino Acid
  • Viola / chemistry*

Substances

  • Antineoplastic Agents, Phytogenic
  • Cyclotides