Synthesis, stability and mechanistic studies of potent anticryptococcal hexapeptides

Abstract

The growing incidents of cryptococcosis in immuno-compromised patients have created a need for novel drug therapies capable of eradicating the disease. The peptide-based drug therapy offers many advantages over the traditional therapeutic agents, which has been exploited in the present study by synthesizing a series of hexapeptides that exhibits promising activity against a panel of Gram-negative and Gram-positive bacteria and various pathogenic fungal strains; the most exemplary activity was observed against Cryptococcus neoformans. The peptides 3, 24, 32 and 36 displayed potent anticryptococcal activity (IC50 = 0.4 – 0.46 μg/mL, MIC = 0.63 – 1.25 μg/mL, MFC = 0.63 – 1.25 μg/mL), and stability under proteolytic conditions. Besides this, several other peptides displayed promising inhibition of pathogenic bacteria. The prominent ones include peptides 18–20, and 26 that exhibited IC50 values ranged between 2.1 – 3.6 μg/mL, MICs of 5 – 20 μg/mL and MBCs of 10 – 20 μg/mL against Staphylococcus aureus and methicillin-resistant S. aureus. The detailed mechanistic study on selected peptides demonstrated absolute selectivity towards the bacterial membranes and fungal cells by causing perturbations in the cell membranes, confirmed by the scanning electron microscopy and transmission electron microscopy studies.

The Meta-Position of Phe4 in Leu-enkephalin Regulates Potency, Selectivity, Functional Activity, and Signaling Bias at the Delta and Mu Opioid Receptors

“…Solid Phase Synthesis of Peptides: All peptides were synthesized using a rapid solid phase peptide synthesis protocol on an automated peptide synthesizer using an Fmoc protection strategy [34,35] and N,N′-diisopropylcarbodiimide and oxyma as the coupling reagents ( Figure 3B). Fmoc-Leu-Wang resin was utilized as a starting template for this synthetic protocol.…”

“…Peptides were synthesized using a solid phase peptide synthesis protocol using an Aapptec Focus XC automated peptide synthesizer coupled with a heating system using the Fmoc chemistry and Wang resin as solid support. 36 To prepare the resin for synthesis, a reaction vessel equipped with a sintered glass bottom was charged with Fmoc-Leu-Wang resin Cell culture and biased signaling assays. cAMP inhibition and β-arrestin 2 recruitment assays were performed as previously described.…”

“…Peptides were synthesized using a solid phase peptide synthesis protocol using an Aapptec Focus XC automated peptide synthesizer coupled with a heating system using the Fmoc chemistry and Wang resin as solid support [34]. To prepare the resin for synthesis, a Cell culture and biased signaling assays.…”

Investigation of α/γ hybrid peptide self‐assembled structures with antimicrobial and antibiofilm properties

“…The stability of peptides P1 to P3 was determined using the literature procedure . The peptide and proteolytic enzymes (trypsin, chymotrypsin, and proteinase K) were dissolved in buffer solution (pH 8.3) containing ammonium bicarbonate (0.1 M) and calcium chloride (0.1 mM) in a molar ratio of 0.5:100.…”

“…The stability of peptides P1 to P3 was determined using the literature procedure. 26 The peptide and proteolytic enzymes (trypsin, reported method. 27 The peptides were dissolved in phosphatebuffered saline (PBS) with 50% aqueous DMSO at 1 mg/mL with continuous heating until it was dissolved completely.…”