title: Microwave-assisted extraction of cyclotides from Viola ignobilis.
abstract: Cyclotides are an interesting family of circular plant peptides. Their unique three-dimensional structure, comprising a head-to-tail circular backbone chain and three disulfide bonds, confers them stability against thermal, chemical, and enzymatic degradation. Their unique stability under extreme conditions creates an idea about the possibility of using harsh extraction methods such as microwave-assisted extraction (MAE) without affecting their structures. MAE has been introduced as a potent extraction method for extraction of natural compounds, but it is seldom used for peptide and protein extraction. In this work, microwave irradiation was applied to the extraction of cyclotides. The procedure was performed in various steps using a microwave instrument under different conditions. High-performance liquid chromatography (HPLC) and matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) results show stability of cyclotide structures on microwave radiation. The influential parameters, including time, temperature, and the ratio of solvents that are affecting the MAE potency, were optimized. Optimal conditions were obtained at 20 min of irradiation time, 1200 W of system power in 60 °C, and methanol/water at the ratio of 90:10 (v/v) as solvent. The comparison of MAE results with maceration extraction shows that there are similarities between cyclotide sequences and extraction yields.
authors.affiliation: Medicinal Plants and Drugs Research Institute, Shahid Beheshti University, Evin, Tehran, Iran.
authors.forename: Mohsen
authors.initials: M
authors.lastname: Farhadpour
authors.affiliation: Department of Chemistry, Faculty of Basic Sciences, Azarbaijan Shahid Madani University, Tabriz, Iran.
authors.forename: Hossein
authors.initials: H
authors.lastname: Hashempour
authors.affiliation: Department of Chemistry, Alzahra University, Vanac, Tehran, Iran.
authors.forename: Zahra
authors.initials: Z
authors.lastname: Talebpour
authors.affiliation: Medicinal Plants and Drugs Research Institute, Shahid Beheshti University, Evin, Tehran, Iran.
authors.forename: Nazanin
authors.initials: N
authors.lastname: A-Bagheri
authors.affiliation: Medicinal Plants and Drugs Research Institute, Shahid Beheshti University, Evin, Tehran, Iran.
authors.forename: Mozhgan Sadat
authors.initials: MS
authors.lastname: Shushtarian
authors.affiliation: Center for Physiology and Pharmacology, Medical University of Vienna, 1090 Vienna, Austria.
authors.forename: Christian W
authors.initials: CW
authors.lastname: Gruber
authors.affiliation: Medicinal Plants and Drugs Research Institute, Shahid Beheshti University, Evin, Tehran, Iran. Electronic address: a-ghassempour@sbu.ac.ir.
authors.forename: Alireza
authors.initials: A
authors.lastname: Ghassempour
mesh_terms: D000595:Amino Acid Sequence; D002851:Chromatography, High Pressure Liquid; D047169:Cyclotides / Q000032:analysis* / Q000302:isolation & purification; D008872:Microwaves; D008969:Molecular Sequence Data; D010936:Plant Extracts / Q000737:chemistry* / Q000302:isolation & purification; D016415:Sequence Alignment; D052616:Solid Phase Extraction; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D032413:Viola / Q000737:chemistry*
chemical_list: D047169:Cyclotides; D010936:Plant Extracts
keywords: Cyclopeptides; Microwave-assisted extraction; Vigno cyclotides; Viola ignobilis; Violaceae