Antimicrobial peptide; The primary target of CA(1-7)M(2-9)NH₂ is believed to be the bacterial cytoplasmic membrane, where it is hypothesized to form ion channels that disrupt ionic homeostasis, leading to cell death. Alternative proposed mechanisms include detergent-like activity on the membrane or stimulation of autolysis. No specific IC50, Ki, or EC50 values are reported. [1]
The primary target is the bacterial cell membrane. Unlike traditional antibiotics that inhibit specific enzymes, this peptide acts via a non-receptor-mediated mechanism. It targets the anionic phospholipid bilayer of bacterial membranes, specifically interacting with the phosphate groups, leading to membrane depolarization and pore formation .

CA(1-7)M(2-9)NH₂ demonstrated broad-spectrum antibacterial activity against 111 clinical anaerobic isolates. The minimum inhibitory concentration (MIC) ranges, MIC50, and MIC90 were determined for various species. [1]
For Bacteroides fragilis (24 strains): MIC range 2–8 mg/L, MIC50 4 mg/L, MIC90 4 mg/L. [1]
For other B. fragilis group (14 strains): MIC range 2–4 mg/L, MIC50 4 mg/L, MIC90 4 mg/L. [1]
For Bacteroides spp. and Prevotella spp. (13 strains): MIC range 2–32 mg/L, MIC50 4 mg/L, MIC90 8 mg/L. [1]
For Fusobacterium nucleatum (6 strains): MIC range 2–4 mg/L, MIC50 2 mg/L, MIC90 4 mg/L. [1]
For Clostridium difficile (22 strains): MIC range 0.5–32 mg/L, MIC50 2 mg/L, MIC90 16 mg/L. [1]
For Clostridium perfringens (10 strains): MIC range 0.5–4 mg/L, MIC50 2 mg/L, MIC90 4 mg/L. [1]
For Propionibacterium spp. (9 strains): MIC range 4–8 mg/L, MIC50 4 mg/L, MIC90 8 mg/L. [1]
For Peptostreptococcus spp. (13 strains): MIC range 2 to >64 mg/L, MIC50 4 mg/L, MIC90 >64 mg/L. [1]
Ninety percent of strains of the B. fragilis group, fusobacteria, propionibacteria, and peptostreptococci were inhibited by 4 mg/L of the peptide. The antimicrobial activity was comparable to that of chloramphenicol. [1]
Quality control strains tested included E. coli ATCC 25922 (MIC 8 mg/L), S. aureus ATCC 29213 (MIC 32 mg/L), B. fragilis NCTC 9343 (MIC 8 mg/L), and C. perfringens ATCC 13124 (MIC 64 mg/L). [1]

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Melittin A (2-9) (0-64 mg/L, 48 h)-Cecropin A (1-7) acts on E. For E. Coli ATCC 25922, B. fragilis NCTC 9343, Staphylococcus aureus ATCC 29213, and C. pefringens ATCC 13124, the MIC values are 8 mg/L, 32 mg/L, 8 mg/L, and 64 mg/L, respectively[1].

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CA(1-7)M(2-9)NH2 demonstrates potent in vitro activity against multidrug-resistant bacteria. Against clinical isolates of Methicillin-resistant Staphylococcus aureus (MRSA), the MIC ranges are 1–16 μg/mL (MIC50 of 4 μg/mL). Against Acinetobacter baumannii, it shows even higher potency (MIC range 0.25–16 mg/L), outperforming its parent peptides cecropin A and melittin. It exhibits a rapid bactericidal effect, and synergy is observed when combined with beta-lactam antibiotics like amoxicillin-clavulanate and imipenem .

In vivo efficacy was demonstrated in a rabbit model of bacterial keratitis caused by Pseudomonas aeruginosa. Topical administration of the peptide (0.1% solution) significantly reduced clinical signs of inflammation and bacterial damage to the anterior segment compared to controls, showing efficacy comparable to gentamicin. This confirms its potential as a topical therapeutic agent .

The minimum inhibitory concentrations of one hybrid, CA(1--7)M(2--9)NH2, were compared with those of seven other antimicrobial agents against 111 clinical anaerobic strains; Bacteroides fragilis, 24 strains; other Bacteroides fragilis group, 14 strains; other Bacteroides species, 13 strains; Fusobacterium nucleatum, six strains; Clostridium difficile, 22 strains; Clostridium perfringens, 10 strains, Propionibacterium spp., nine strains; and anaerobic cocci, 13 strains. [1]

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Specific non-cellular binding assays for this peptide typically utilize Planar Lipid Bilayers (BLM) to study ion-channel formation. Peptides are added to the cis chamber (final conc. 0.1–1 μM), and voltage-dependent conductance is measured across the membrane to confirm pore-forming activity. Circular Dichroism (CD) spectroscopy is used to assess secondary structure; helicity is measured in the presence of membrane-mimetic solvents (e.g., 50% hexafluoro-2-propanol, HFIP) to confirm alpha-helical folding upon target interaction .

Standard antimicrobial susceptibility testing follows the microbroth dilution method recommended by CLSI (formerly NCCLS). Bacteria at ~5×10^5 CFU/mL are incubated with doubling dilutions of the peptide (0.125–128 μg/mL) in cation-adjusted Mueller-Hinton broth (CAMHB). Plates are read after 18–24h at 35°C to determine the Minimum Inhibitory Concentration (MIC). For cytotoxicity, time-kill assays involve sampling at 0, 1, 2, 4, and 24h post-exposure for colony counting .

An established rabbit model of Pseudomonas aeruginosa keratitis is used. New Zealand white rabbits are anesthetized, and the cornea is injected with bacteria. One hour later, treatment groups receive topical 0.1% peptide solution in PBS, while controls receive PBS alone. Clinical scores are assessed by slit lamp biomicroscopy (McDonald-Shadduck scale) at 6, 24, and 48h post-infection to quantify inflammation and corneal damage .

As a small peptide (MW: 1770.3 g/mol), CA(1-7)M(2-9)NH2 is rapidly metabolized. In silico predictions estimate a half-life of approximately 1.3 hours in mammalian reticulocytes (in vitro). It is expected to be unstable in serum due to protease degradation, necessitating frequent dosing or topical administration for therapeutic effect .

The retrieved data does not contain specific acute toxicity (LD50) or histopathology reports for this exact hybrid (157606-25-2). However, by design, this hybrid exhibits significantly less hemolytic activity compared to natural melittin. Safety data sheets classify it as "Not a hazardous substance or mixture" for research use. Further comprehensive toxicological evaluation is required .

[1]. Antianaerobic activity of a cecropin---melittin peptide. Clin Microbiol Infect. 1998 Apr;4(4):181-185.

Synthesis and characterization: The peptide was synthesized using solid-phase methods with Fmoc chemistry, purified by reverse-phase HPLC, and its mass verified by plasma desorption time-of-flight mass spectrometry. Peptide concentrations were estimated by absorption spectroscopy at 280 nm using the molar absorption coefficient for tryptophan (ε₂₈₀ = 5.6 × 10³ M⁻¹ cm⁻¹). [1]
Mechanism of action hypothesis: The peptide is hypothesized to form ion channels in the bacterial cytoplasmic membrane, disrupting ionic homeostasis and leading to cell death. Alternative mechanisms include detergent-like activity on the membrane or stimulation of autolysis. The study found no major differences in activity between Gram-positive and Gram-negative anaerobes, suggesting that the outer membrane of Gram-negative anaerobes does not serve as a barrier to this peptide. [1]
Clinical relevance: The authors suggest that the encouraging results, particularly against the B. fragilis group (which are important pathogens with increasing resistance), warrant further studies on these antimicrobial peptides. [1]

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Objective: Previous studies have shown that some small peptides containing melittin A and a portion of the melittin's amino acid sequence (15 amino acid residues) possess broad-spectrum antibacterial activity against aerobic microorganisms without adverse hemolytic properties. Understanding the effects of these hybrid peptides on anaerobic bacteria is also important. Methods: The minimum inhibitory concentration (MIC) of a hybrid peptide, CA(1-7)M(2-9)NH2, was compared with the MICs of seven other antibacterial agents against 111 clinical anaerobic bacterial strains. These strains included: 24 strains of Bacteroides fragilis; 14 strains of other Bacteroides fragilis groups; 13 strains of other Bacteroides species; 6 strains of Fusobacterium nucleatum; 22 strains of Clostridium difficile; 10 strains of Clostridium perfringens; 9 strains of Propionibacterium spp.; and 13 strains of anaerobic cocci. Results: 4 mg/L CA(1-7)M(2-9)NH2 inhibited 90% of the strains of Bacteroides fragilis, Fusobacterium, Propionibacterium, and Peptostreptococcus, exhibiting antibacterial activity roughly equivalent to chloramphenicol. Conclusion: This study shows that the antibacterial spectrum of this cephalosporin-meetingin hybrid also includes anaerobic bacteria. [1]

C89H152N22O15

1770.2976

1769.18

157606-25-2

9833894

H-Lys-Trp-Lys-Leu-Phe-Lys-Lys-Ile-Gly-Ala-Val-Leu-Lys-Val-Leu-NH2; L-lysyl-L-tryptophyl-L-lysyl-L-leucyl-L-phenylalanyl-L-lysyl-L-lysyl-L-isoleucyl-glycyl-L-alanyl-L-valyl-L-leucyl-L-lysyl-L-valyl-L-leucinamide;

KWKLFKKIGAVLKVL; H-KWKLFKKIGAVLKVL-[NH2]

Typically exists as White to off-white solid at room temperature

10.72

22

21

63

126

3380

15

O=C([C@]([H])(C([H])([H])C([H])(C([H])([H])[H])C([H])([H])[H])N([H])C([C@]([H])(C([H])(C([H])([H])[H])C([H])([H])[H])N([H])C([C@]([H])(C([H])([H])[H])N([H])C(C([H])([H])N([H])C([C@]([H])([C@@]([H])(C([H])([H])[H])C([H])([H])C([H])([H])[H])N([H])C([C@]([H])(C([H])([H])C([H])([H])C([H])([H])C([H])([H])N([H])[H])N([H])C([C@]([H])(C([H])([H])C([H])([H])C([H])([H])C([H])([H])N([H])[H])N([H])C([C@]([H])(C([H])([H])C1C([H])=C([H])C([H])=C([H])C=1[H])N([H])C([C@]([H])(C([H])([H])C([H])(C([H])([H])[H])C([H])([H])[H])N([H])C([C@]([H])(C([H])([H])C([H])([H])C([H])([H])C([H])([H])N([H])[H])N([H])C([C@]([H])(C([H])([H])C1=C([H])N([H])C2=C([H])C([H])=C([H])C([H])=C12)N([H])C([C@]([H])(C([H])([H])C([H])([H])C([H])([H])C([H])([H])N([H])[H])N([H])[H])=O)=O)=O)=O)=O)=O)=O)=O)=O)=O)=O)N([H])[C@]([H])(C(N([H])[C@]([H])(C(N([H])[C@]([H])(C(N([H])[H])=O)C([H])([H])C([H])(C([H])([H])[H])C([H])([H])[H])=O)C([H])(C([H])([H])[H])C([H])([H])[H])=O)C([H])([H])C([H])([H])C([H])([H])C([H])([H])N([H])[H]

WMTUWZOBAVPERW-VZYQMWHSSA-N

InChI=1S/C89H152N22O15/c1-14-56(12)75(87(124)98-50-72(112)99-57(13)77(114)109-73(54(8)9)89(126)108-69(46-53(6)7)83(120)103-65(37-23-28-42-93)81(118)110-74(55(10)11)88(125)104-67(76(96)113)44-51(2)3)111-82(119)66(38-24-29-43-94)100-79(116)63(35-21-26-40-91)101-85(122)70(47-58-30-16-15-17-31-58)107-84(121)68(45-52(4)5)106-80(117)64(36-22-27-41-92)102-86(123)71(105-78(115)61(95)33-20-25-39-90)48-59-49-97-62-34-19-18-32-60(59)62/h15-19,30-32,34,49,51-57,61,63-71,73-75,97H,14,20-29,33,35-48,50,90-95H2,1-13H3,(H2,96,113)(H,98,124)(H,99,112)(H,100,116)(H,101,122)(H,102,123)(H,103,120)(H,104,125)(H,105,115)(H,106,117)(H,107,121)(H,108,126)(H,109,114)(H,110,118)(H,111,119)/t56-,57-,61-,63-,64-,65-,66-,67-,68-,69-,70-,71-,73-,74-,75-/m0/s1

(2S)-2,6-diamino-N-[(2S)-1-[[(2S)-6-amino-1-[[(2S)-1-[[(2S)-1-[[(2S)-6-amino-1-[[(2S)-6-amino-1-[[(2S,3S)-1-[[2-[[(2S)-1-[[(2S)-1-[[(2S)-1-[[(2S)-6-amino-1-[[(2S)-1-[[(2S)-1-amino-4-methyl-1-oxopentan-2-yl]amino]-3-methyl-1-oxobutan-2-yl]amino]-1-oxohexan-2-yl]amino]-4-methyl-1-oxopentan-2-yl]amino]-3-methyl-1-oxobutan-2-yl]amino]-1-oxopropan-2-yl]amino]-2-oxoethyl]amino]-3-methyl-1-oxopentan-2-yl]amino]-1-oxohexan-2-yl]amino]-1-oxohexan-2-yl]amino]-1-oxo-3-phenylpropan-2-yl]amino]-4-methyl-1-oxopentan-2-yl]amino]-1-oxohexan-2-yl]amino]-3-(1H-indol-3-yl)-1-oxopropan-2-yl]hexanamide

157606-25-2; Cecropin A (1-7)-Melittin A (2-9) amide; L-Leucinamide,L-lysyl-L-tryptophyl-L-lysyl-L-leucyl-L-phenylalanyl-L-lysyl-L-lysyl-L-isoleucylglycyl-L-alanyl-L-valyl-L-leucyl-L-lysyl-L-valyl-; Cecropin A (1-7)-Melittin A (2-9) amide trifluoroacetate salt; CHEMBL1214077;

2934.99.9001

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 (e.g. under nitrogen), avoid exposure to moisture and light.

Room temperature (This product is stable at ambient temperature for a few days during ordinary shipping and time spent in Customs)

DMSO : ~100 mg/mL (~56.5 mM)
H2O : ~10 mg/mL (~5.65 mM)

Note: Listed below are some common formulations that may be used to formulate products with low water solubility (e.g. < 1 mg/mL), you may test these formulations using a minute amount of products to avoid loss of samples.

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Injection Formulation 1: DMSO : Tween 80： Saline = 10 : 5 : 85 (i.e. 100 μL DMSO stock solution → 50 μL Tween 80 → 850 μL Saline)
*Preparation of saline: Dissolve 0.9 g of sodium chloride in 100 mL ddH ₂ O to obtain a clear solution.
Injection Formulation 2: DMSO : PEG300 ：Tween 80 : Saline = 10 : 40 : 5 : 45 (i.e. 100 μL DMSO → 400 μLPEG300 → 50 μL Tween 80 → 450 μL Saline)
Injection Formulation 3: DMSO : Corn oil = 10 : 90 (i.e. 100 μL DMSO → 900 μL Corn oil)
Example: Take the Injection Formulation 3 (DMSO : Corn oil = 10 : 90) as an example, if 1 mL of 2.5 mg/mL working solution is to be prepared, you can take 100 μL 25 mg/mL DMSO stock solution and add to 900 μL corn oil, mix well to obtain a clear or suspension solution (2.5 mg/mL, ready for use in animals).

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Injection Formulation 4: DMSO : 20% SBE-β-CD in saline = 10 : 90 [i.e. 100 μL DMSO → 900 μL (20% SBE-β-CD in saline)]
*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.
Injection Formulation 5: 2-Hydroxypropyl-β-cyclodextrin : Saline = 50 : 50 (i.e. 500 μL 2-Hydroxypropyl-β-cyclodextrin → 500 μL Saline)
Injection Formulation 6: DMSO : PEG300 : castor oil : Saline = 5 : 10 : 20 : 65 (i.e. 50 μL DMSO → 100 μLPEG300 → 200 μL castor oil → 650 μL Saline)
Injection Formulation 7: Ethanol : Cremophor : Saline = 10： 10 : 80 (i.e. 100 μL Ethanol → 100 μL Cremophor → 800 μL Saline)
Injection Formulation 8: Dissolve in Cremophor/Ethanol (50 : 50), then diluted by Saline
Injection Formulation 9: EtOH : Corn oil = 10 : 90 (i.e. 100 μL EtOH → 900 μL Corn oil)
Injection Formulation 10: EtOH : PEG300：Tween 80 : Saline = 10 : 40 : 5 : 45 (i.e. 100 μL EtOH → 400 μLPEG300 → 50 μL Tween 80 → 450 μL Saline)

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Oral Formulation 1: Suspend in 0.5% CMC Na (carboxymethylcellulose sodium)
Oral Formulation 2: Suspend in 0.5% Carboxymethyl cellulose
Example: Take the Oral Formulation 1 (Suspend in 0.5% CMC Na) as an example, if 100 mL of 2.5 mg/mL working solution is to be prepared, you can first prepare 0.5% CMC Na solution by measuring 0.5 g CMC Na and dissolve it in 100 mL ddH2O to obtain a clear solution; then add 250 mg of the product to 100 mL 0.5% CMC Na solution, to make the suspension solution (2.5 mg/mL, ready for use in animals).

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Oral Formulation 3: Dissolved in PEG400
Oral Formulation 4: Suspend in 0.2% Carboxymethyl cellulose
Oral Formulation 5: Dissolve in 0.25% Tween 80 and 0.5% Carboxymethyl cellulose
Oral Formulation 6: Mixing with food powders

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Note: Please be aware that the above formulations are for reference only. InvivoChem strongly recommends customers to read literature methods/protocols carefully before determining which formulation you should use for in vivo studies, as different compounds have different solubility properties and have to be formulated differently.

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 (Please use freshly prepared in vivo formulations for optimal results.)