Synthetic Peptide Purification via Solid-Phase Extraction with Gradient Elution: A Simple, Economical, Fast, and Efficient Methodology.

A methodology was implemented for purifying peptides in one chromatographic run via solid-phase extraction (SPE), reverse phase mode (RP), and gradient elution, obtaining high-purity products with good yields. Crude peptides were analyzed by reverse phase high performance liquid chromatography and a new mathematical model based on its retention time was developed in order to predict the percentage of organic modifier in which the peptide will elute in RP-SPE. This information was used for designing the elution program of each molecule. It was possible to purify peptides with different physicochemical properties, showing that this method is versatile and requires low solvent consumption, making it the least polluting one. Reverse phase-SPE can easily be routinely implemented. It is an alternative to enrich and purified synthetic or natural molecules.

Synergistic bactericide and antibiotic effects of dimeric, tetrameric, or palindromic peptides containing the RWQWR motif against Gram-positive and Gram-negative strains.

Dimeric and tetrameric peptides derived from LfcinB (20-25): RRWQWR, LfcinB (20-30): RRWQWRMKKLG, LfcinB (17-31): FKARRWQWRMKKLGA, or the palindromic sequence LfcinB (21-25)Pal: RWQWRWQWR were obtained by means of the SPPS-Fmoc/tBu methodology. The antibacterial activity of these molecules was evaluated against Escherichia coli (ATCC 25922 and ATCC 11775), Staphylococcus aureus (ATCC 25923), Enterococcus faecalis (ATCC 29212), and Pseudomonas aeruginosa (ATCC 27853). The dimer LfcinB (20-25)2: (RRWQWR)2K-Ahx, the tetramer LfcinB (20-25)4: (RRWQWR)4K2-Ahx2-C2, and the palindromic sequence LfcinB (21-25)Pal exhibited the highest antibacterial activity against the tested bacterial strains. In all cases, the antibacterial activity was dependent on peptide concentration. The polyvalent molecules LfcinB (20-25)2 and LfcinB (20-25)4 exhibited bacteriostatic and bactericidal activity against E. coli, P. aeruginosa, and S. aureus strains; additionally, this dimer and this tetramer combined with ciprofloxacin exhibited a synergistic antibacterial effect against E. coli ATCC 25922 and P. aeruginosa, respectively. Furthermore, the peptides LfcinB (20-30)4, LfcinB (20-25)4, and LfcinB (21-25)Pal combined with vancomycin exhibited a synergistic antibacterial effect against S. aureus and E. faecalis, respectively. This study showed that polyvalent peptides derived from LfcinB exhibit significant antibacterial activity, suggesting that these peptides could have a therapeutic application. Furthermore, our results suggest that polyvalent peptide synthesis could be considered as an innovative and viable strategy for obtaining promising antimicrobial molecules.