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  • 1
    In: Toxins, MDPI AG, Vol. 12, No. 8 ( 2020-07-30), p. 484-
    Abstract: Antimicrobial peptides (AMPs) are promising therapeutic alternatives compared to conventional antibiotics for the treatment of drug-resistant bacterial infections. However, the application of the overwhelming majority of AMPs is limited because of the high toxicity and high manufacturing costs. Amphibian skin secretion has been proven to be a promising source for the discovery and development of novel AMPs. Herein, we discovered a novel AMP from the skin secretion of Odorrana schmackeri, and designed the analogues by altering the key factors, including conformation, net charge and amphipathicity, to generate short AMPs with enhanced therapeutic efficacy. All the peptides were chemically synthesised, followed by evaluating their biological activity, stability and cytotoxicity. OSd, OSe and OSf exhibited broad-spectrum antibacterial effects, especially OSf, which presented the highest therapeutic index for the tested bacteria. Moreover, these peptides displayed good stability. The results from scanning electron microscopy and transmission electron microscopy studies, indicated that brevinin-OS, OSd, OSe and OSf possessed rapid bactericidal ability by disturbing membrane permeability and causing the release of cytoplasmic contents. In addition, OSd, OSe and OSf dramatically decreased the mortality of waxworms acutely infected with MRSA. Taken together, these data suggested that a balance between positive charge, degrees of α-helicity and hydrophobicity, is necessary for maintaining antimicrobial activity, and these data successfully contributed to the design of short AMPs with significant bactericidal activity and cell selectivity.
    Type of Medium: Online Resource
    ISSN: 2072-6651
    Language: English
    Publisher: MDPI AG
    Publication Date: 2020
    detail.hit.zdb_id: 2518395-3
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  • 2
    In: Pharmaceutics, MDPI AG, Vol. 14, No. 3 ( 2022-03-10), p. 604-
    Abstract: Amphibian skin secretion is an ideal source of antimicrobial peptides that are difficult to induce drug resistance to due to their membrane-targeting mechanism as a new treatment scheme. In this study, a natural antimicrobial peptide Temporin-1CEh was identified by molecular cloning and mass spectrometry from the skin secretions of the Chinese forest frog (Rana chensinensis). Through the study of the structure and biological activity, it was found that Temporin-1CEh was a helical peptide from the Temporin family, and possessed good anti-Gram-positive bacteria activity through the mechanism of membrane destruction. Seven analogues were further designed to obtain broad-spectrum antimicrobial activity and higher stability in different physiological conditions. The results showed that T1CEh-KKPWW showed potent antibacterial activity with significantly increasing the activity against Gram-negative bacteria in vitro and in vivo with low haemolysis. In addition, T1CEh-KKPWW2 showed high sensitivity to the pH, serum or salts conditions, which applied a branched structure to allow the active units of the peptide to accumulate. Even though the haemolytic activity was increased, the stable antibacterial activity made this novel analogue meet the conditions to become a potential candidate in future antimicrobial and antibiofilm applications.
    Type of Medium: Online Resource
    ISSN: 1999-4923
    Language: English
    Publisher: MDPI AG
    Publication Date: 2022
    detail.hit.zdb_id: 2527217-2
    SSG: 15,3
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  • 3
    In: Biomedicines, MDPI AG, Vol. 8, No. 7 ( 2020-07-17), p. 225-
    Abstract: Bradykinin (BK) and bradykinin-related peptides (BRPs), which were identified from a diversity of amphibian skin secretions, exerted contractile and relaxing effects on non-vascular and vascular smooth muscle, respectively. Here, we report a novel bradykinin-related peptide with a molecular mass of 1890.2 Da, RVAGPDKPARISGLSPLR, which was isolated and identified from Ordorrana hejiangensis skin secretions, followed by a C-terminal extension sequence VAPQIV. The biosynthetic precursor-encoding cDNA was cloned by the “shotgun” cloning method, and the novel RR-18 was identified and structurally confirmed by high-performance liquid chromatography (HPLC) and tandem mass spectrometry (MS/MS). Subsequently, the myotropic activity of the synthetic replicate of RR-18 was investigated on the rat bladder, uterus, tail artery and ileum smooth muscle. The peptide was named RR-18 in accordance (R = N-terminal arginine, R = C-terminal arginine, 18 = number of residues). In this study, the synthetic replicates of RR-18 showed no agonist/antagonism of BK-induced rat bladder and uterus smooth muscle contraction. However, it displayed an antagonism of bradykinin-induced rat ileum contraction and arterial smooth muscle relaxation. The EC50 values of BK for ileum and artery, were 214.7 nM and 18.3 nM, respectively. When the tissue was pretreated with the novel peptide, RR-18, at the maximally effective concentration of bradykinin (1 × 10−6 M), bradykinin-induced contraction of the ileum and relaxation of the arterial smooth muscle was reduced by 50–60% and 30–40%, respectively. In conclusion, RR-18 represents novel bradykinin antagonising peptide from amphibian skin secretions. It may provide new insight into possible treatment options for chronic pain and chronic inflammation.
    Type of Medium: Online Resource
    ISSN: 2227-9059
    Language: English
    Publisher: MDPI AG
    Publication Date: 2020
    detail.hit.zdb_id: 2720867-9
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  • 4
    In: Microbial Pathogenesis, Elsevier BV, Vol. 153 ( 2021-04), p. 104795-
    Type of Medium: Online Resource
    ISSN: 0882-4010
    Language: English
    Publisher: Elsevier BV
    Publication Date: 2021
    detail.hit.zdb_id: 1471158-8
    SSG: 12
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  • 5
    In: Microbiology Spectrum, American Society for Microbiology, Vol. 9, No. 3 ( 2021-12-22)
    Abstract: Antimicrobial resistance has been an increasing public health threat in recent years. Antimicrobial peptides are considered as potential drugs against drug-resistant bacteria because they are mainly broad-spectrum and are unlikely to cause resistance. In this study, a novel peptide was obtained from the skin secretion of Agalychnis callidryas using the “shotgun” cloning method. The amino acid sequence, molecular weight, and secondary structure of Dermaseptin-AC were determined. The in vitro antimicrobial activity, hemolysis, and cytotoxicity of Dermaseptin-AC were evaluated. MICs and minimum bactericidal concentrations (MBCs) of Dermaseptin-AC against seven different bacterial strains ranged between 2 ∼ 4 μM and 2 ∼ 8 μM. The HC 50 (50% maximum hemolysis concentration) of Dermaseptin-AC against horse erythrocytes was 76.55 μM. The in vivo anti-MRSA effect was tested on immune-suppressed MRSA pneumonia in mice. Dermaseptin-AC showed anti-MRSA effects similar to the same dose of vancomycin (10 mg/kg body weight). Short-term (7 days of intraperitoneal injection, 10 mg/kg body weight) in vivo safety evaluation of Dermaseptin-AC was tested on mice. The survival rate during the 7-day injection was 80%. Dermaseptin-AC showed no obvious effect on the liver, heart, spleen, kidney, and blood, but did induce slight pulmonary congestion. The skin safety of Dermaseptin-AC was evaluated on wounds on the back skin of a rat, and no irritation was observed. IMPORTANCE In this study, we discovered a new antimicrobial peptide, Dermaseptin-AC, and studied its in vitro and in vivo antimicrobial activity. These studies provide some data for finding new antimicrobial peptides for overcoming antimicrobial resistance. Dermaseptin-AC showed strong broad-spectrum antibacterial activity and relatively low hemolysis, and was more cytotoxic to cancer cells than to normal cells. Dermaseptin-AC was active in vivo , and its anti-MRSA effect was similar to that of vancomycin when administered by intraperitoneal injection. Safety studies found that continuous injection of Dermaseptin-AC may cause mild pulmonary congestion, while there was no obvious irritation when it was applied to skin wounds. Chronic wounds are often accompanied by high bacterial burdens and, at the same time, antimicrobial resistance is more likely to occur during repeated infections and treatments. Therefore, developing Dermaseptin-AC to treat chronic wound infection may be an attractive choice.
    Type of Medium: Online Resource
    ISSN: 2165-0497
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2021
    detail.hit.zdb_id: 2807133-5
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  • 6
    In: Toxins, MDPI AG, Vol. 14, No. 4 ( 2022-04-12), p. 273-
    Abstract: The Bowman–Birk protease inhibitor (BBI) family is a prototype group found mainly in plants, particularly grasses and legumes, which have been subjected to decades of study. Recently, the discovery of attenuated peptides containing the canonical Bowman–Birk protease inhibitory motif has been detected in the skin secretions of amphibians, mainly from Ranidae family members. The roles of these peptides in amphibian defense have been proposed to work cooperatively with antimicrobial peptides and reduce peptide degradation. A novel trypsin inhibitory peptide, named livisin, was found in the skin secretion of the green cascade frog, Odorrana livida. The cDNA encoding the precursor of livisin was cloned, and the predicted mature peptide was characterized. The mature peptide was found to act as a potent inhibitor against several serine proteases. A comparative activity study among the native peptide and its engineered analogs was performed, and the influence of the P1 and P2′ positions, as well as the C-terminal amidation on the structure–activity relationship for livisin, was illustrated. The findings demonstrated that livisin might serve as a potential drug discovery/development tool.
    Type of Medium: Online Resource
    ISSN: 2072-6651
    Language: English
    Publisher: MDPI AG
    Publication Date: 2022
    detail.hit.zdb_id: 2518395-3
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  • 7
    In: Antibiotics, MDPI AG, Vol. 9, No. 5 ( 2020-05-10), p. 243-
    Abstract: Antibiotic resistance represents a tremendous contemporary clinical challenge. Given this challenge, antimicrobial peptides (AMPs) are regarded as one of the most promising new options for next-generation lead antibiotics. Here, we describe the antibacterial activities of a cationic peptide named DRP-AC4, obtained from frog skin secretion using shotgun cloning. Two modified peptides were derived by substituting the sequence of amino acids to complete the hydrophobic face (DRP-AC4b) and increase net charge (DRP-AC4a), respectively. The activity and cytotoxicity of these two peptides were compared. DRP-AC4a displayed significantly increased potency against bacteria compared to the natural peptide. It should be noted, however, that both analogue peptides demonstrated higher lytic ability than the natural peptide against the membranes of mammalian erythrocytes. At the same time, all three peptides displayed lower hemolytic activity compared to their antibacterial activity. Here, we demonstrate that AMPs have more complex activity mechanisms and faster bactericidal rates than traditional antibiotics, which may be one of the reasons why bacteria do not develop resistance to them. These discoveries provide interesting insights into the discovery and development of novel drugs from natural sources.
    Type of Medium: Online Resource
    ISSN: 2079-6382
    Language: English
    Publisher: MDPI AG
    Publication Date: 2020
    detail.hit.zdb_id: 2681345-2
    SSG: 15,3
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  • 8
    In: Antibiotics, MDPI AG, Vol. 10, No. 12 ( 2021-12-14), p. 1529-
    Abstract: Amphibian skin-derived antimicrobial peptides (AMPs) have attracted increasing attention from scientists because of their excellent bioactivity and low drug resistance. In addition to being the alternative choice of antibiotics or anticancer agents, natural AMPs can also be modified as templates to optimise their bioactivities further. Here, a novel dermaseptin peptide, t-DPH1, with extensive antimicrobial activity and antiproliferative activity, was isolated from the skin secretion of Phyllomedusa hypochondrialis through ‘shotgun’ cloning. A series of cationicity-enhanced analogues of t-DPH1 were designed to further improve its bioactivities and explore the charge threshold of enhancing the bioactivity of t-DPH1. The present data suggest that improving the net charge can enhance the bioactivities to some extent. However, when the charge exceeds a specific limit, the bioactivities decrease or remain the same. When the net charge achieves the limit, improving the hydrophobicity makes no sense to enhance bioactivity. For t-DPH1, the upper limit of the net charge was +7. All the designed cationicity-enhanced analogues produced no drug resistance in the Gram-negative bacterium, Escherichia coli. These findings provide creative insights into the role of natural drug discovery in providing templates for structural modification for activity enhancement.
    Type of Medium: Online Resource
    ISSN: 2079-6382
    Language: English
    Publisher: MDPI AG
    Publication Date: 2021
    detail.hit.zdb_id: 2681345-2
    SSG: 15,3
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  • 9
    In: Biology, MDPI AG, Vol. 9, No. 8 ( 2020-08-06), p. 209-
    Abstract: Antimicrobial peptides (AMPs) are a class of molecules that play an essential role in innate immune regulation. The Brevinin-1 family are AMPs that show strong pharmacological and antimicrobial potential. A novel peptide, B1A, was designed based on the primary structure of brevinin-1PLb and brevinin-1PLc. Subsequently, a synthesised replicate was subjected to a series of bioassays and was found to display antimicrobial activity. However, it also displayed high levels of haemolysis in a horse red blood cell haemolytic assay, suggesting potential toxicity. Therefore, we rationally designed a number of B1A analogues with aim of retaining antimicrobial activity, lowering toxicity, and to explore the structure–activity relationship of its N-terminus. B1A and its analogues still retained the “Rana Box” and the FLP-motif, which is a feature of this subfamily. However, the introduction of Lys and Trp residues into the peptide sequences revealed that antimicrobial activity of these analogues remained unchanged once the hydrophobicity and the charge reached the threshold. Hence, the idea that the hydrophobicity saturation in different situations is related to antimicrobial activity can be understood via the structure–activity relationship. Meanwhile, it could also be the starting point for the generation of peptides with specific antimicrobial activity.
    Type of Medium: Online Resource
    ISSN: 2079-7737
    Language: English
    Publisher: MDPI AG
    Publication Date: 2020
    detail.hit.zdb_id: 2661517-4
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  • 10
    In: Chemical Biology & Drug Design, Wiley, Vol. 97, No. 2 ( 2021-02), p. 273-282
    Abstract: As drug‐resistant bacteria have become a serious health problem and have caused thousands of deaths, finding new antibiotics has become an urgent research priority. A novel antimicrobial peptide, named Brevinin‐1H, was identified in the skin secretion of Amolops hainanensis through ‘shotgun’ cloning. It has broad‐spectrum antimicrobial activity against tested micro‐organisms and has anticancer cell activity. To improve its bioactivity and decrease its cytotoxicity, two structural analogues—Brevinin‐1Ha and Brevinin‐1HY—were designed based on the secondary structure of the natural peptide. Brevinin‐1HY, in which tyrosine substituted Pro 11 , had similar activity to the natural peptide against Gram‐negative bacteria and cancer cells, but showed a dramatic increase in haemolytic activity and cytotoxicity at its minimum inhibitory concentration. Brevinin‐1Ha, which transferred the Rana‐box from the C‐terminal to a central position, had significantly decreased haemolytic activity, but also in antimicrobial and anticancer activity. The present data suggest that increasing the proportion of α‐helix structure in an AMP can increase its target micro‐organism bioactivity to some extent.
    Type of Medium: Online Resource
    ISSN: 1747-0277 , 1747-0285
    URL: Issue
    Language: English
    Publisher: Wiley
    Publication Date: 2021
    detail.hit.zdb_id: 2216600-2
    SSG: 12
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