Cyclotide-rich fractions containing nanofibers by electrospinning: preparation, characterization and examination of antimicrobial activity

In this study, antimicrobial nanofibers were produced with the mixtures of polyvinyl alcohol (PVA) and cyclotide-rich fractions by electrospinning method. After extraction, the first separation was carried out with C18 flash chromatography and then fractioned into five separate parts by reversed-phase high-pressure liquid chromatography (RP-HPLC). The molecular weights of cyclotides in each fraction were determined by quadrupole time-of-flight liquid chromatography-mass spectrometry (Q-TOF LC-MS). Cyclotide-rich fractions were mixed with 10% of PVA solution and nanofibers were produced from this biocomposite mixture by electrospinning method. The nanofibers were characterized by field emission scanning electron microscopy (FE-SEM), and it was observed that 100% peptide-containing nanofibers (cyclotide-rich fraction/10% PVA, w/v) had more regular fiber textures. The presence of the peptides in the nanofiber was also confirmed by analytical RP-HPLC, as the peptides in both peptide fractions and nanofiber solutions have the same retention times. The nanofibers produced with the fourth cyclotide-rich fraction showed activity against gram-positive bacteria (Bacillus cereus) in antimicrobial susceptibility test. As a result of these findings, cyclotide-containing nanofibers with antimicrobial activity can be produced for pharmaceutical research and development studies.