A new series of cyclic antimicrobial peptides (AMPs) containing D/L-α-amino acids have been designed and characterized by spectroscopic techniques. Newly synthesized cyclic peptides were tested for antibacterial and antifungal activities in the hopes of discovering novel clues that may be used to create effective anti-microbial medicine. Those cyclic AMPs demonstrated good antibacterial activity against Escherichia coli, Pseudomonas aeruginosa and Staphylococcus aureus and that was comparable to reference drug Imipenem, as well as good antifungal activity against microbial strains Aspergillus Flavus, Candida Albicans and Candida GlabarataI that was comparable to reference drug Miconazole. In continuous, molecular docking study of the targeted cyclic peptides revealed that they exhibited promising binding interaction networks with DNA gyrase and lanosterol-14 alpha demethylase, which showed the correlation between biologic activity and docking score of the synthesized analogs.

A new series of dipeptide derivatives with 5-chloro-thiophene-2-carboxylic acid conjugates have been designed and synthesized using solid-phase peptide synthesis. The synthesized dipeptide derivatives were characterized by using spectroscopic tools, like 1H and 13C NMR, IR, and mass and elemental analysis. Additionally, the obtained target dipeptide derivatives were evaluated for in vitro antimicrobial activity. The antibacterial activity of the target compounds was evaluated against four bacteria (two Gram-positive; Streptococcus pyogenes and Staphylococcus aureus, two Gram-negative; Escherichia coli and Pseudomonas aeruginosa). The screened analogs showed good antibacterial activity. Noteworthily, among them, Thiophene-Tyr-Arg-OH derivative exhibited excellent activity against Escherichia coli (MIC=15 µg/mL) as compared to standard drug ampicillin. The antifungal activity was evaluated against two fungi (Aspergillus niger and Candida albicans). The screened analogs also showed good antifungal activity.