| Size | Price | Stock | Qty |
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| 1mg |
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| 5mg |
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| Other Sizes |
| Targets |
Bacterial[1]
Parasin I does not target a specific host protein receptor. Instead, its primary target is the negatively charged phospholipid bilayer of microbial cell membranes. Through its amphipathic alpha-helical structure (typically adopting an alpha-helical conformation in membrane-mimetic environments), Parasin I binds to and disrupts the integrity of bacterial membranes, causing pore formation, loss of membrane potential, and leakage of cellular contents, ultimately leading to microbial cell death. The mechanism is reminiscent of other host defense peptides (HDPs) and offers a low propensity for resistance development. |
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| ln Vitro |
Parasin I TFA (1-100 uM) exhibits potent, broad-spectrum antimicrobial activity in vitro. It is effective against both Gram-positive bacteria (e.g., Staphylococcus aureus, MRSA, Listeria monocytogenes) and Gram-negative bacteria (e.g., Escherichia coli, Salmonella typhimurium, Pseudomonas aeruginosa). Minimum inhibitory concentration (MIC) values typically range from 1 to 10 uM. The peptide also shows antifungal activity against Candida albicans and other pathogenic fungi. Its mechanism of action is rapid, causing membrane permeabilization within minutes of contact. Parasin I is relatively non-toxic to mammalian cells at MIC concentrations.
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| ln Vivo |
In vivo, Parasin I has been evaluated in mouse models of bacterial infection. Systemic (intraperitoneal) or local (wound) administration of Parasin I (typically 1-5 mg/kg) reduces bacterial load in infected tissues and improves survival in models of peritonitis and sepsis. It is also effective in topical wound infection models, reducing bacterial colonization and accelerating wound healing. The peptide exhibits synergistic effects when combined with conventional antibiotics, potentially allowing for lower doses of both agents.
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| Enzyme Assay |
In a cell-free system, antimicrobial activity is assessed using membrane vesicle leakage assays. Large unilamellar vesicles (LUVs) composed of bacterial-mimetic phospholipids (e.g., 75% POPC/25% POPG, or E. coli lipid extract) are prepared and loaded with a self-quenching concentration of carboxyfluorescein (CF, 50 mM CF in 10 mM HEPES, pH 7.0). Parasin I TFA (1-50 uM) is added to a stirred cuvette containing CF-loaded LUVs (25 uM lipid) in 10 mM HEPES, 150 mM NaCl, pH 7.0. Fluorescence (ex/em = 490/520 nm) is continuously monitored for 5-10 minutes at room temperature. At the end of the experiment, Triton X-100 (0.1% final) is added to cause 100% leakage. The percent leakage at each time point is calculated as [(F_t - F0)/(F_Triton - F0)] × 100. Membrane disruption is quantified as the concentration of peptide required to induce 50% leakage (LC50). Alternatively, a SYTOX Green uptake assay (a DNA-binding dye that is excluded by intact membranes) is used: target bacteria (e.g., E. coli, 10⁶ CFU/mL in PBS) are mixed with 1 uM SYTOX Green and increasing concentrations of Parasin I TFA (0.1-50 uM). Fluorescence (ex/em = 504/525 nm) is measured every 1 minute for 30 min at 37degC. Antimicrobial activity against bacteria is assessed using standard CLSI microdilution methods.
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| Cell Assay |
For mammalian cytotoxicity, the MTT assay is performed: NIH3T3 fibroblasts or HaCaT keratinocytes are seeded in 96-well plates (1×10⁴ cells/well) and incubated for 24 h in DMEM + 10% FBS. The medium is replaced with fresh medium containing varying concentrations of Parasin I TFA (0.1-100 microM). After 24 h, MTT solution (0.5 mg/mL) is added to each well and incubated for 4 h at 37degC. The formazan crystals are dissolved in DMSO, and absorbance is measured at 570 nm. IC50 values are calculated. The selectivity index is calculated as IC50 (mammalian cells)/MIC (bacteria). Hemolytic activity is assessed as described for other AMPs.
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| Animal Protocol |
In a mouse peritonitis model: Female BALB/c mice (6-8 weeks, n=8-10 per group) are injected intraperitoneally with 1×10⁷ CFU of E. coli or S. aureus in 100 uL PBS. One hour post-infection, Parasin I TFA (0.1-5 mg/kg in 200 uL saline) is administered intraperitoneally (i.p.) or intravenously (i.v.). A control group receives an equal volume of saline. Survival is monitored for 7 days. At 6 or 24 h post-treatment, mice are euthanized, and peritoneal lavage fluid is collected to quantify bacterial CFU (plating on agar). Blood, liver, and spleen homogenates are also plated for bacterial load. Cytokine levels (TNF-alpha, IL-6, IL-1beta, MCP-1) are measured in serum by ELISA. In a topical wound infection model: An 8 mm full-thickness excisional wound is created on the dorsum of the mouse. The wound is inoculated with 5×10⁶ CFU S. aureus (MRSA strain). After 1 h, 50 uL of Parasin I TFA (0.1-1% w/v in sterile water) or vehicle is applied topically twice daily for 3 days. Wound area is measured with calipers. On day 3, mice are euthanized, and the wound tissue is excised, homogenized, and plated for CFU count. Histological sections (H&E, Gram stain) are prepared to evaluate infection and wound healing.
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| ADME/Pharmacokinetics |
Pharmacokinetics of Parasin I have not been extensively reported. As a 19-amino acid antimicrobial peptide, its plasma half-life is expected to be very short (<20 minutes) due to rapid proteolytic degradation. Renal clearance is also likely. For in vivo applications, frequent dosing or continuous infusion may be required. When administered intraperitoneally (1-5 mg/kg), detectable plasma levels occur within 5-15 minutes but decline rapidly. The peptide distributes widely but does not penetrate the blood-brain barrier. The TFA salt form is water soluble and stable in solution at 4degC for short-term use.
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| Toxicity/Toxicokinetics |
No detailed toxicology studies are publicly available for Parasin I TFA. In animal models, doses up to 10 mg/kg (i.p.) have been used without overt signs of acute toxicity. The primary safety concerns are mechanism-based and include potential hemolytic activity at high concentrations (typically >50 uM). Compared to the well-studied AMP melittin (a component of bee venom), Parasin I has significantly lower hemolytic activity. No evidence of nephrotoxicity or hepatotoxicity has been observed in short-term studies. Long-term toxicity and chronic exposure studies have not been conducted.
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| References | |
| Additional Infomation |
Parasin I is a research-grade peptide and has not been approved for any clinical application. It is part of a growing family of histone-derived antimicrobial peptides (also called "histone-derived peptides" or "HDPs") found in various species. The peptide is an important research tool for studying innate immunity mechanisms in fish and for developing new antimicrobial strategies, especially against antibiotic-resistant bacteria. The TFA salt form is the standard for commercial synthesis and provides handling stability. Store as lyophilized powder at -20degC for up to 2 years; reconstitute in sterile water or buffer and use within 24-48 hours when stored at 4degC.
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| Molecular Formula |
C82H154N34O24.XC2HF3O2
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| Molecular Weight |
2000.31 (free acid)
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| Related CAS # |
Parasin I;219552-69-9
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| Appearance |
White to off-white solid powder
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| HS Tariff Code |
2934.99.9001
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| Storage |
Powder -20°C 3 years 4°C 2 years In solvent -80°C 6 months -20°C 1 month Note: Please store this product in a sealed and protected environment, avoid exposure to moisture. |
| Shipping Condition |
Room temperature (This product is stable at ambient temperature for a few days during ordinary shipping and time spent in Customs)
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| Solubility (In Vitro) |
DMSO :~100 mg/mL
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| Solubility (In Vivo) |
Solubility in Formulation 1: ≥ 2.5 mg/mL (Infinity mM) (saturation unknown) in 10% DMSO + 40% PEG300 + 5% Tween80 + 45% Saline (add these co-solvents sequentially from left to right, and one by one), clear solution.
For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 25.0 mg/mL clear DMSO stock solution to 400 μL PEG300 and mix evenly; then add 50 μL Tween-80 to the above solution and mix evenly; then add 450 μL normal saline to adjust the volume to 1 mL. Preparation of saline: Dissolve 0.9 g of sodium chloride in 100 mL ddH₂ O to obtain a clear solution. Solubility in Formulation 2: ≥ 2.5 mg/mL (Infinity mM) (saturation unknown) in 10% DMSO + 90% (20% SBE-β-CD in Saline) (add these co-solvents sequentially from left to right, and one by one), clear solution. For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 25.0 mg/mL clear DMSO stock solution to 900 μL of 20% SBE-β-CD physiological saline solution and mix evenly. Preparation of 20% SBE-β-CD in Saline (4°C，1 week): Dissolve 2 g SBE-β-CD in 10 mL saline to obtain a clear solution. View More
Solubility in Formulation 3: ≥ 2.5 mg/mL (Infinity mM) (saturation unknown) in 10% DMSO + 90% Corn Oil (add these co-solvents sequentially from left to right, and one by one), clear solution. |
Calculation results
Working concentration： mg/mL；
Method for preparing DMSO stock solution： mg drug pre-dissolved in μL DMSO (stock solution concentration mg/mL). Please contact us first if the concentration exceeds the DMSO solubility of the batch of drug.
Method for preparing in vivo formulation:：Take μL DMSO stock solution, next add μL PEG300, mix and clarify, next addμL Tween 80, mix and clarify, next add μL ddH2O，mix and clarify.
(1) Please be sure that the solution is clear before the addition of next solvent. Dissolution methods like vortex, ultrasound or warming and heat may be used to aid dissolving.
(2) Be sure to add the solvent(s) in order.
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