Recent
studies have shown that modified human lactoferrin 20–31
fragment, named HLopt2, possesses antibacterial and antifungal activity.
Thus, we decided to synthesize and evaluate the biological activity
of a series of conjugates based on this peptide and one of the antimicrobials
with proven antibacterial (ciprofloxacin, CIP, and levofloxacin, LVX)
or antifungal (fluconazole, FLC) activity. The drugs were covalently
connected to the peptide via amide, methylenecarbonyl moieties, or
a disulfide bridge. The antibacterial and antifungal activities were
evaluated under Clinical and Laboratory Standard Institute (CLSI)
recommended conditions or in a low-salt brain–heart infusion
diluted medium (BHI1/100). Results showed that conjugation
of the peptide with the drug increased its antimicrobial activity
up to 4-fold. Under CLSI-recommended conditions, all the compounds
revealed rather low efficiency. Among conjugates, the highest antibacterial
activity was recorded for the CIP-Cys-S-S-HLopt2-NH2 (III). In BHI1/100, which had lower differentiating
properties, all of the conjugates revealed low MIC and MMC (minimum
inhibitory and microbicidal concentrations) values. The disulfide
bridge used as a linker in the most active conjugate (III) upon incubation with S. aureus cells is reduced,
releasing constituent peptide and CIP-Cys. In addition, we showed
that its fluorescently labeled analogue and constituent peptide are
able to be internalized into both C. albicans and S. aureus cells. Moreover, the invaluable advantage
of the presented conjugates was their low toxicity to mammalian cells
and very low hemolytic activity. The current research can form a solid
basis for further in vivo studies and drug development.
Matriptase-2 plays a pivotal role in keeping iron concentrations within a narrow physiological range in humans. The opportunity to reduce matriptase-2 proteolytic activity may open a novel possibility to treat iron overload diseases, such as hereditary hemochromatosis and thalassemia. Here, we present 23 new analogues of trypsin inhibitor SFTI-1 designed to inhibit human matriptase-2. Influence of the modifications Gly1Lys, Ile10Arg, and Phe12His, as well as the introduction of Narg in P1 or P1 and P4 positions were examined. Selected peptides were further analyzed, together with previously reported peptides, for their inhibitory activity against related human proteases, that are, matriptase-1, plasmin, thrombin and trypsin. A highly potent inhibitor of matriptase-2, the bicycylic [Arg , Arg , His ]SFTI-1, with a K value of 15 nm was obtained.
Infections of Candida spp. etiology are frequently treated with azole drugs. Among azoles, the most widely used in the clinical scenario remains fluconazole (FLC). Promising results in treatment of dangerous, systemic Candida infections demonstrate the advantages of combined therapies carried out with combinations of at least two different antifungal agents. Here, we report five conjugates composed of covalently linked FLC and cell penetrating or antimicrobial peptide: TP10-7-NH2, TP10-NH2, LFcinB(2-11)-NH2, LFcinB[Nle1,11]-NH2, and HLopt2-NH2, with aspects of design, chemical synthesis and their biological activities. Two of these compounds, namely FLCpOH-TP10-NH2 and FLCpOH-TP10-7-NH2, exhibit high activity against reference strains and fluconazole-resistant clinical isolates of C. albicans, including strains overproducing drug transporters. Moreover, both of them demonstrate higher fungicidal effects compared to fluconazole. Analysis performed with fluorescence and scanning electron microscopy as well as flow cytometry indicated the cell membrane as a molecular target of synthesized conjugates. An important advantage of FLCpOH-TP10-NH2 and FLCpOH-TP10-7-NH2 is their low cytotoxicity. The IC90 value for the human cells after 72 h treatment was comparable to the MIC50 value after 24 h treatment for most strains of C. albicans. In reported conjugates, FLC was linked to the peptide by its hydroxyl group. It is worth noting that conjugation of FLC by the nitrogen atom of the triazole ring led to practically inactive compounds. Two compounds produced by us and reported herein appear to be potential candidates for novel antifungal agents.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.