title: Discovery, isolation, and structural characterization of cyclotides from Viola sumatrana Miq.
abstract: Cyclotides are cyclic peptides from plants in the Violaceae, Rubiaceae, Fabaceae, Cucurbitaceae, and Solanaceae families. They are sparsely distributed in most of these families, but appear to be ubiquitous in the Violaceae, having been found in every plant so far screened from this family. However, not all geographic regions have been examined and here we report the discovery of cyclotides from a Viola species from South-East Asia. Two novel cyclotides (Visu 1 and Visu 2) and two known cyclotides (kalata S and kalata B1) were identified in V. sumatrana. NMR studies revealed that kalata S and kalata B1 had similar secondary structures. Their biological activities were determined in cytotoxicity assays; both had similar cytotoxic activity and were more toxic to U87 cells compared with other cell lines. Overall, the study strongly supports the ubiquity of cyclotides in the Violaceae and adds to our understanding of their distribution and cytotoxic activity.
authors.affiliation: Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD, 4072, Australia.|Department of Chemistry, Faculty of Science, Chulalongkorn University, Bangkok, 10330, Thailand.
authors.forename: Ploypat
authors.initials: P
authors.lastname: Niyomploy
authors.affiliation: Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD, 4072, Australia.
authors.forename: Lai Yue
authors.initials: LY
authors.lastname: Chan
authors.affiliation: Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD, 4072, Australia.
authors.forename: Aaron G
authors.initials: AG
authors.lastname: Poth
authors.affiliation: CSIRO Agriculture and Food, 306 Carmody Rd, St Lucia, QLD, 4067, Australia.
authors.forename: Michelle L
authors.initials: ML
authors.lastname: Colgrave
authors.affiliation: Department of Chemistry, Faculty of Science, Chulalongkorn University, Bangkok, 10330, Thailand.
authors.forename: Polkit
authors.initials: P
authors.lastname: Sangvanich
authors.affiliation: Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD, 4072, Australia.
authors.forename: David J
authors.initials: DJ
authors.lastname: Craik
mesh_terms: D002460:Cell Line; D003603:Cytotoxins / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology; D006801:Humans; D010456:Peptides, Cyclic / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology; D010940:Plant Proteins / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology; D017433:Protein Structure, Secondary; D032413:Viola / Q000737:chemistry*
chemical_list: D003603:Cytotoxins; D010456:Peptides, Cyclic; D010940:Plant Proteins
keywords: Viola plants; cyclic peptides; cyclotides; kalata B1; natural products