Polybia-CP

The incidence of life-threatening invasive fungal infections increased significantly in recent years. However, the antifungal therapeutic options are very limited. Antimicrobial peptides are a class of potential lead chemical for the development of novel antifungal agents. Antimicrobial peptide polybia-CP was purified from the venom of the social wasp Polybia paulista. In this study, we synthesized polybia-CP and determined its antifungal effects against a series of Candidian species. Our results showed that polybia-CP has potent antifungal activity and fungicidal activity against the tested fungal cells with a proposed membrane-active action mode. In addition, polybia-CP could induce the increase of cellular reactive oxygen species production, which would attribute to its antifungal activity. In conclusion, the present study suggests that polybia-CP has potential as an antifungal agent or may offer a new strategy for antifungal therapeutic option.

With the increasing emergence of resistant microbes toward conventional antimicrobial agents, there is an urgent need for the development of antimicrobial agents with novel action mode. Antimicrobial peptides (AMPs) are believed to be one kind of ideal alternatives. However, AMPs can be easily degraded by protease, which limited their therapeutic use. In the present study, D-amino acid substitution strategy was employed to enhance the stability of polybia-CP. We investigated the stability of peptides against the degradation of trypsin and chymotrypsin by determining the antimicrobial activity or determining the HPLC profile of peptides after incubation with proteases. Our results showed that both the all D-amino acid derivative (D-CP) and partial D-lysine substitution derivative (D-lys-CP) have an improved stability against trypsin and chymotrypsin. Although D-CP takes left-hand α-helical conformation and D-lys-CP loses some α-helical content, both of the D-amino acid-substituted derivatives maintain their parental peptides' membrane active action mode. In addition, D-lys-CP showed a slight weaker antimicrobial activity than polybia-CP, but the hemolytic activity decreased greatly. These results suggest that D-CP and D-lys-CP can offer strategy to improve the property of AMPs and may be leading compounds for the development of novel antimicrobial agents.

The wasp venom-derived antimicrobial peptide polybia-CP has been previously shown to exhibit potent antimicrobial activity, but it is also highly toxic. Previously, using a physicochemical-guided peptide design strategy, we reversed its toxicity while preserving and even enhancing its antibacterial properties. Here, we report on several additional unanticipated biological properties of polybia-CP and derivatives, namely their ability to target Plasmodium sporozoites and cancer cells. We leverage a physicochemical-guided approach to identify features that operate as functional hotspots making these peptides viable antiplasmodial and anticancer agents. Helical content and net positive charge are identified as key structural and physicochemical determinants for antiplasmodial activity. In addition to helicity and net charge, hydrophobicity-related properties of polybia-CP and derivatives were found to be equally critical to target cancer cells. We demonstrate that by tuning these physicochemical parameters, it is possible to design synthetic peptides with enhanced submicromolar antiplasmodial potency and micromolar anticancer activity. This study reveals novel and previously undescribed functions for Polybia-CP and analogs. Additionally, we demonstrate that a physicochemical-guided rational design strategy can be used for identifying functional hotspots in peptide molecules and for tuning structure-function to generate novel and potent new-to-nature therapies.