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Introduction: Insecticides are used, nowadays, more frequently in the fields. Resistance has been developed against insecticides due to the genetic modification of the insects. Molecular docking is a key tool in structural molecular biology and computer-assisted drug design. This approach also estimates the ligand-receptor binding free energy by evaluating critical phenomena involved in the intermolecular recognition process. In silico molecular docking of antimicrobial peptides (AMPs) and inhibitors will be done using online software. Aim: This study aims to perform the molecular docking of AMPs and inhibitors. Materials and Methods: Structures of AMPs such as dermaseptin, pyrrhocoricin, drosocin, oncocin, apidaecin, and histatin-5 were downloaded from the NCBI PubChem database. Molecular docking of the selected AMPs with the target DNAk was performed using the online PatchDock server with default parameters. Results: Of the six AMPs chosen, dermaseptin, pyrrhocoricin, drosocin, oncocin, and apidaecin were found to have been making an interaction but histatin-5. Conclusion: New insecticides can be manufactured based on these antimicrobial peptides. [ABSTRACT FROM AUTHOR]

Candida albicans is an opportunistic fungal pathogen and a commensal organism that commonly colonizes mucosal surfaces, including those inside the human mouth. To help control C. albicans, human saliva contains the antifungal peptide histatin 5 (Hst‐5), which has strong antifungal activity against C. albicans. However, the pathogen produces secreted aspartic proteases (Saps) that cleave Hst‐5 at lysine residues and eliminate its antifungal properties. We designed variants of Hst‐5 with its lysine residues substituted with arginine or leucine to evaluate the effect on proteolysis by Saps. We found site‐, residue‐, and Sap‐dependent effects from single amino acid substitutions. The K17R and K17L modifications led to dramatic results, with over 77% and 100% intact peptide remaining after incubation with Sap9 and Sap2, respectively, compared to 47% and 61% of Hst‐5. This decrease in proteolysis was accompanied by a reduction in cleavage on the C‐terminal side of K17, suggesting the Saps prefer lysine at K17 for cleavage. Incubation with C. albicans cells and culture supernatant corroborated the results with purified Saps and highlighted their biological relevance. The modifications to Hst‐5 do not diminish the antifungal activity of Hst‐5, and, in fact, the K17R, K17L, and K11R peptides retained significantly more antifungal activity after treatment with Saps than Hst‐5. Our results indicate that single amino acid modifications drastically impact both proteolysis at the modification sites and the overall level of proteolysis of the peptide, demonstrating the potential of designing peptides for resistance to proteolysis as a means for improving therapeutic efficacy. [ABSTRACT FROM AUTHOR]

Histatin5 (Hst-5) is a member of the histatin family of antimicrobial peptides secreted by human parotid and submandibular glands. With the natural antibacterial activity, it plays an important role in the first-line barrier of oral cave against pathogens, especially for the fungal intrusion. In this study, we explored the utility of Hst-5 in the treatment of vulvovaginal candidiasis, a common condition of women of the childbearing age. We used a synthesized Hst-5 over five consecutive days as the topical treatment in a murine model of vulvovaginal candidiasis. According to the fungal colony counts, fungal burden in the vagina lavage dropped remarkably after treatment with Hst-5. Furthermore, cytological analysis of the lavage fluid indicated that the number of cast-off cells including cornified epithelial cells and inflammatory cells also decreased; histological evaluation of the vagina tissue revealed less fungi adhering to the vaginal wall in treated animals than in controls. Combined, these results suggested for the first time the potential utility of Hst-5 as a topical treatment for vulvovaginal candidiasis, uncovering the possibility of exploiting the natural antibiotic peptides in other aspects. [ABSTRACT FROM AUTHOR]

Objective Controversies exist regarding the relationship between the concentrations of antimicrobial peptides (AMPs) and presence of dental caries in children. Thus, the aim of this study was to examine levels of AMPs in saliva of caries-free (CF), early childhood caries (ECC) and severe early childhood caries (S-ECC) children to determine if the levels of these salivary peptides individually or in combinations were related to caries severity and mutans streptococci levels. Design 36 to 60 month-old children were selected to participate in this study. Children were grouped into CF group (n = 29), ECC group (n = 25) and S-ECC group (n = 29). Saliva was collected from children for microbiological analysis by culture. Salivary concentrations of cathelicidin LL-37, human β-defensin 2 (hBD-2), human β-defensin 3 (hBD-3) and histatin-5 (HTN-5) were determined by ELISA. Results Salivary concentrations of AMPs did not differ among CF, ECC and S-ECC groups. Data showed positive correlations between mutans streptococci levels and salivary hBD-2 or HTN-5. Positive correlations were found between hBD-2, hBD-3, LL-37 and HTN-5. Combinations among AMPs, mainly LL-37, were positively associated with caries levels. Conclusions Salivary concentrations of AMPs individually were not associated with the severity of early childhood caries. The stimulus of caries appears to trigger a biological response, however, with a combination of these peptides. [ABSTRACT FROM AUTHOR]

INTRODUCTION: The mechanisms of adhesion to solid surfaces enable S. mutans to colonize oral cavities and form biofilms, which play an important role in caries development. Additional properties enabling the survival of S. mutans in the oral cavity include its ability to survive in acidic environments and specific interactions with other microorganisms inhabiting this ecosystem. AIM OF THE STUDY: The aim of this study was to determine the antibacterial activity of saliva histatin-5 (peptide) and lysozyme (protein) against S. mutans and L. rhamnosus, as representatives of physiological flora. MATERIALS AND METHODS: The study involved strains of physiological (L. rhamnosus) and cariogenic (S. mutans) flora isolated from one patient with diagnosed early caries of the deciduous teeth. RESULTS: It was proved that the presence of probiotic L. rhamnosus bacteria in the environment had a negative impact on the ability of S. mutans to produce biofilm. Moreover, the antibacterial activity of histatin-5 was confirmed, and it inhibited S. mutans growth at concentrations of 27.2 μg/ml and 54.4 μg/ml, both individually and in a mixture with lysozyme (in a total concentration of 54.4 μg/ml). CONCLUSIONS: The data obtained constitute a promising result due to their potential future application in the prevention and early diagnosis of caries. [ABSTRACT FROM AUTHOR]

Highlights: [•] Recombinant protegrin-1 dimer and LL-37/histatin-5 peptides were expressed in E. coli. [•] Biotin carboxyl carrier protein mediated acidic amino acid was utilized as fusion tag. [•] High positive charge of antimicrobial peptides could be neutralized by fusion partner. [•] Expressed protein could be purified through either histidine tag or biotin–avidin system. [•] Novel hybrid peptide and dimer exhibited antimicrobial activity against bacteria. [ABSTRACT FROM AUTHOR]

Abstract: Histatins are a family of human salivary antimicrobial peptides. Histatin-5 (Hst-5, DSHAKRHHGYKRKFHEKHHSHRGY), a prominent member of this family contains an albumin-like, N-terminal Asp-Ser-His sequence, known to bind a Ni(II) ion in a square-planar geometry. Nickel is a strong allergen, and oral exposure to Ni(II) ions can elicit allergic reaction in sensitized persons. In contrast, prior oral exposure to nickel in non-sensitized persons can prevent sensitization. The fate of Ni(II) ions in saliva is obviously important for these processes, yet little is known about it. Using potentiometry, UV–visible titrations and circular dichroism, we determined stability constants for Ni(II) complexes of Hst-5 and two truncated analogs, 5Hst-5 (DSHAK) and 10Hst-5 (DSHAKRHHGY). The conditional binding constant at pH 7.4 for Hst-5 was 107.5±0.2, compared to the corresponding value for albumin, 106.8±0.3 (M. Sokołowska, A. Krężel, M. Dyba, Z. Szewczuk, W. Bal, Eur. J. Biochem. 269 (2002) 1323–1331). These values indicate that Hst-5 binds Ni(II) five times stronger than HSA. The simulated competition for Ni(II) between Hst-5 and albumin shows that significant amounts of Ni(II) ions may be carried by Hst-5 in vivo. Therefore, Hst-5 and other histatins should be considered as factors in nickel allergy and other forms of nickel toxicity. [Copyright &y& Elsevier]

The oral cavity is a primary target for opportunistic infections, particularly oral candidiasis caused by the opportunistic pathogen Candida albicans. HIV+ individuals constitute a population highly susceptible to oral candidiasis possibly due to a change in the environment of the oral cavity as the result of salivary gland dysfuntion. Histatins are a family of salivary antimicrobial peptides which under normal circumstances have a protective function on the oral mucosa. This study aimed to compare salivary histatin concentrations and oral fungal colonisation in an HIV+ and HIV− control populations. Oral samples for fungal cultures and parotid saliva were collected from all subjects. Fungal identification was determined using standard mycological procedures. In order to determine salivary histatin levels a semi-quantitative ELISA was designed using a specific polyclonal antibody and extensive statistical analysis was performed. Forty-seven percent of HIV+ and 17% of control subjects had positive fungal cultures. Mean histatin levels were 7.32 μg ml−1 for the HIV+ group and 9.17 μg ml−1 for control group ( P = 0.003). The data from this study demonstrate that the level of fungal colonisation is significantly higher in HIV+ individuals whereas histatin-5 concentrations are significantly lower, likely contributing to the enhanced predisposition of this population to oral candidiasis. [ABSTRACT FROM AUTHOR]

Histatin-5 is a peptide secreted in the human saliva, which possesses powerful antifungal activity. Previous studies have shown that this peptide exerts its candidacidal activity, through the inhibition of both mitochondrial respiration and the formation of reactive oxygen species. The purpose of the present study was to investigate the biological consequences of histatin-5 action on mammalian mitochondria to verify if the toxic mechanism exerted on mitochondria from Candida albicans is an exclusive for fungal cells. Moreover, hypothesising that the damage exerted on mitochondria may induce programmed cellular death pathways, we evaluated two main markers of apoptosis: the mitochondrial membrane potential (ΔΨ) and the release of cytochrome c. The results obtained show that exposure of isolated mammalian mitochondria to histatin-5 determines: (i) a large inhibition of the respiratory chain at the level of complex I, (ii) a slight decrease in the mitochondrial membrane potential, and (iii) no release of cytochrome c. [Copyright &y& Elsevier]

Abstract: The results of 520 ps molecular dynamics simulation of histatin-5, a small peptide present in human saliva and possessing antimicrobial activity, dissolved in water and in 2,2,2-trifluoroethanol, are reported. The simulations indicate that histatin-5 is destabilized in water and begins to unfold after 250 ps, while in organic solvent it maintains a regular secondary structure throughout the trajectory. Analysis of the peptide-solvent hydrogen bonds indicates that 2,2,2-trifluoroethanol is a poorer proton acceptor than water. The fluorine atom of the alcohol is almost never engaged in a hydrogen bond and the organic solvent interacts mainly with the peptide through its hydroxyl group. For some residues analysis of the solvent residence time indicated longer values for 2,2,2-trifluoroethanol than for water. The most striking difference is related to the number of times the solvent enters and leaves the first coordination shell of the peptide. This value was more than one order of magnitude higher for water than for the alcohol, suggesting that this may be the main cause of α-helix destabilization perpetrated by water. [ABSTRACT FROM AUTHOR]

Fungicidal effects of histatin-5 against 26 oral isolates belonging to 5 non-albicans Candida species were examined. Fifty μM of histatin-5 killed more than 95% of Candida tropicalis and Candida guilliermondii isolates and more than 90% of Candida parapsilosis and Candida krusei. However, Candida glabrata was less sensitive to the peptide (mean 62.9%). Our results, taken together, demonstrated that histatin-5 possessed the fungicidal activity against Candida species other than C. glabrata. [ABSTRACT FROM AUTHOR]

Antimicrobial peptides (AMPs) have potential antifungal activities; however, their intracellular protein targets are poorly reported. Proteome microarray is an effective tool with high-throughput and rapid platform that systematically identifies the protein targets. In this study, we have used yeast proteome microarrays for systematical identification of the yeast protein targets of Lactoferricin B (Lfcin B) and Histatin-5. A total of 140 and 137 protein targets were identified from the triplicate yeast proteome microarray assays for Lfcin B and Histatin-5, respectively. The Gene Ontology (GO) enrichment analysis showed that Lfcin B targeted more enrichment categories than Histatin-5 did in all GO biological processes, molecular functions, and cellular components. This might be one of the reasons that Lfcin B has a lower minimum inhibitory concentration (MIC) than Histatin-5. Moreover, pairwise essential proteins that have lethal effects on yeast were analyzed through synthetic lethality. A total of 11 synthetic lethal pairs were identified within the protein targets of Lfcin B. However, only three synthetic lethal pairs were identified within the protein targets of Histatin-5. The higher number of synthetic lethal pairs identified within the protein targets of Lfcin B might also be the reason for Lfcin B to have lower MIC than Histatin-5. Furthermore, two synthetic lethal pairs were identified between the unique protein targets of Lfcin B and Histatin-5. Both the identified synthetic lethal pairs proteins are part of the Spt-Ada-Gcn5 acetyltransferase (SAGA) protein complex that regulates gene expression via histone modification. Identification of synthetic lethal pairs between Lfcin B and Histatin-5 and their involvement in the same protein complex indicated synergistic combination between Lfcin B and Histatin-5. This hypothesis was experimentally confirmed by growth inhibition assay. [ABSTRACT FROM AUTHOR]