LZ1 is a synthetic peptide composed of 15 amino acids, studied primarily for antimicrobial activity and other biological responses observed in preclinical experiments. In scientific literature, this name refers to a specific molecule, not to a mixture of biological substances or a whole group of antimicrobial peptides.
Studies on LZ1 include laboratory experiments, cell cultures, and animal models. Among other things, its activity against acne-related bacteria, malaria-causing parasites, and pancreatic cancer cells was analyzed [1–3].
The results of these studies indicate interesting biological properties of the peptide. However, they do not confirm that LZ1 is an effective method of treating acne, malaria, or tumors in humans.
The name LZ1 itself is also important. This abbreviation is also used in publications concerning protein fragments unrelated to this peptide. Therefore, a proper interpretation of the studies requires first determining the molecular identity of the substance.
The article discusses the structure of LZ1, its chemical classification, the most important mechanisms studied experimentally, and the limitations of the current scientific evidence.
What is LZ1 peptide? Name, origin and identity
LZ1 is a short synthetic peptide with a defined amino acid sequence.
In antimicrobial research, this molecule is described by the sequence:
VKRWKKWWRKWKKWV-NH₂
This sequence represents a chain containing 15 amino acid residues and an amidated group at the C-terminal end.
The final modification is part of the chemical identity of the peptide. It should not be overlooked when comparing materials used in different experiments.
In the study on malaria LZ1, a peptide derived from studies on the venom dynamics of snakes was described. However, this does not mean that the material used in the experiments was crude venom or a mixture of proteins of animal origin.
The researchers used a synthetically produced peptide with a specific sequence [2].
Why the name LZ1 itself can lead to confusion?
The abbreviation LZ1 is not unique to the peptide in question.
For example, in a publication from 2003, the name LZ1 was used to describe the region of the leucine zipper associated with the regulation of potassium channels in mammals [4].
It is not the same molecule as the 15-amino acid antimicrobial peptide.
Combining such publications into a single analysis would lead to the incorrect attribution of biological properties.
Therefore, when reviewing the literature, it is necessary to check not only the name, but also:
- the amino acid sequence;
- final modifications;
- authors and year of publication;
- type of material being tested;
- the experimental model used;
- the biological mechanism under analysis.
Similar caution is needed when evaluating products labeled with the LZ1 name.
The label itself does not confirm that the material has exactly the same structure and composition as the substance used in the published study.
How is LZ1 classified – peptide, protein or mixture?
LZ1 is a synthetic peptide that is being studied for its antimicrobial activity.
It is not a large recombinant protein or an undefined peptide mixture.
Its basic characteristic is a short, defined chain of amino acids.
From a chemical classification point of view, LZ1 belongs to the group of peptides. However, the term „antimicrobial” describes the type of activity studied in the experiments.
These two concepts are not the same.
The chemical classification indicates what a molecule is. The functional classification refers to the effects observed in a specific research system.
Why is LZ1 classified as a cationic peptide?
The sequence of LZ1 contains numerous residues of lysine and arginine.
These amino acids have basic side groups that, under many biological conditions, can give the molecule a positive charge.
The structure also contains other tryptophan residues, whose aromatic and hydrophobic properties may be important for interactions with biological surfaces.
Such a combination of characteristics provides the basis for studying the interaction of LZ1 with cell membranes and other molecular structures.
However, this does not mean that all the effects of LZ1 result from a single mechanism of membrane damage.
It also does not confirm full selectivity towards the cells of microorganisms.
A peptide may exhibit a certain activity in one model, but a different activity in different experimental conditions.
Is LZ1 an antimicrobial drug?
The mere term „antimicrobial peptide” does not mean that the substance is an approved drug.
In the case of LZ1, this term refers to the results of laboratory and preclinical studies.
Activity against selected bacteria or other organisms is insufficient to establish clinical efficacy, safety, or appropriate therapeutic use.
Similarly, studies on cancer cells do not convert LZ1 into a confirmed anticancer drug.
Each potential application requires separate evidence.
The structure and chemical composition of LZ1 – what has been determined?
The basic structure of LZ1 is a linear chain of 15 amino acids with an amidated C-terminal end.
The amino acid sequence allows determining the order of the residues that make up the molecule.
However, it does not automatically describe all the properties of a particular laboratory sample.
Amino acid sequence and physicochemical properties
The presence of lysine, arginine and tryptophan suggests that electrostatic and hydrophobic effects may be important in the LZ1 studies.
However, the sequence alone is not sufficient to determine unequivocally:
- spatial structures in any environment;
- stability in various solutions;
- tendency to aggregation;
- behavior during storage;
- selectivity towards certain types of cells;
- activity in various biological systems.
These properties require direct measurements under appropriately defined conditions.
It should also not be assumed that the schematic illustration of the helical antimicrobial peptide represents the experimentally confirmed spatial structure of LZ1 in all environments.
How is the identity of the laboratory sample LZ1 confirmed?
A study on malaria described the synthetic production of LZ1 and its analytical characteristics using chromatography and mass spectrometry [2].
These methods help to assess the identity and properties of the material under study.
At the same time, the individual analytical parameters answer different questions.
| Parameter | What allows us to determine? | What doesn’t it confirm on its own? |
|---|---|---|
| Amino acid sequence | The order of residues in the intended molecule | Conformity of a specific sample with the declaration |
| The end of the C-terminal amino acid | Specified chemical modification | Its presence in any sample without proper analysis |
| Chromatographic purity | The proportion of detected components in the conditions of a given method | Absolute content of peptide and absence of all impurities |
| Composition of the formulation | Type of solvent, carrier and additional ingredients | Comparability with another product |
| Biological activity | The effect in a specific test | Clinical efficacy and acceptable risk in humans |
In the case of peptides, anti-ions, residual moisture, impurities, and the composition of the applied solution can also be important factors.
Therefore, the identical name of a substance does not automatically mean identical properties of the material.
More about the interpretation of qualitative studies of peptides can be read in the article The quality of Epitalon peptide – how to interpret the COA, the purity of the HPLC and the results of mass spectrometry?.
Studies on LZ1 – evidence involving humans, animals and cells
The available literature on LZ1 covers several different research areas.
Its antimicrobial properties, activity in malaria models, and effects in experimental models of pancreatic cancer were most often analyzed.
However, these are not studies of the same application.
The result obtained in the cultivation of bacteria does not constitute confirmation of the activity in a tumor model.
Similarly, anti-parasite activity does not allow for predicting efficacy in skin diseases.
Was LZ1 studied clinically in humans?
The review of the literature that forms the basis of this article did not identify a published intervention study in patients that would confirm the safety or clinical efficacy of the peptide with the discussed LZ1 sequence.
Searching for the name LZ1 in ClinicalTrials.gov revealed two records unrelated to this peptide, in which the abbreviation referred to the anatomical area of stimulation.
These results should not be considered as clinical studies of LZ1.
At the same time, the lack of an appropriate record in a specific search does not constitute proof that there are no unpublished, unrecorded, or otherwise unlisted studies.
It is also necessary to distinguish between studies that use human cells or plasma and intervention studies involving patients.
The experiment using human material may still be of a preclinical nature.
It does not allow for the independent assessment of therapeutic benefits, systemic exposure, or the effects of repeated administration of the substance to humans.
LZ1 in studies on bacteria associated with acne
One of the first directions of research on LZ1 was the activity against bacteria associated with acne.
A 2013 publication evaluated the activity of the peptide in laboratory conditions and in an experimental model of ear inflammation in mice [1].
What was shown in the 2013 study?
The researchers observed antibacterial activity of LZ1 and a reduction in selected indicators of bacterial load and inflammatory response in the model used.
The results indicated the possibility of further studying the peptide in the context of changes associated with acne-causing bacteria.
However, they did not confirm the effectiveness of acne treatment in humans.
The dog ear model does not reproduce all the elements of human disease, such as the variety of skin changes, the long-term course, or the response to a ready-made dermatological formulation.
Also, the laboratory concentration that inhibits bacterial growth is not a direct equivalent of the effectiveness of the product used in the patient.
Why did later studies show differences?
In a comparative study published in 2023, it was found that LZ1 had lower activity against Cutibacterium acnes than some previous results suggested.
Differences in cytotoxicity have also been observed depending on the cell model used [5].
This does not necessarily mean that the previous examination was wrong.
Discrepancies may arise, among other things, from different strains of bacteria, growing conditions, measurement methods, sample characteristics, or the definition of endpoints.
In older publications the name Propionibacterium acnes was used, while in more recent publications it is Cutibacterium acnes.
This change in nomenclature should be taken into account when searching for literature.
However, this does not mean that the results obtained for different strains and methods can be compared without further analysis.
LZ1 in malaria research
The next direction of research was the activity of LZ1 against the parasites that cause malaria.
In a 2019 publication, in vitro experiments were conducted with Plasmodium falciparum and studies were conducted on mice infected with Plasmodium berghei [2].
What results were observed?
The researchers described the antiparasitic activity of LZ1 in the experimental systems analyzed.
They also evaluated the metabolic processes occurring in infected erythrocytes.
Special attention was paid to the activity of pyruvate kinase and the production of ATP.
The results suggested a relationship between exposure to LZ1 and disturbances in certain energy processes in the model under study.
However, this does not mean that LZ1 positively increases energy production throughout the body.
In this case, metabolic processes associated with parasitic infection were analyzed.
Can LZ1 be considered an antimalarial drug?
Not based on these data.
In vitro studies and animal experiments do not allow determining the efficacy or safety in patients with malaria.
The differences between the species of parasites, the host's physiology, and exposure to the substance are important.
The results from 2019 provide the basis for further mechanistic studies, but do not confirm the equivalence of LZ1 with approved antimalarial drugs.
LZ1 in studies on pancreatic cancer
The studies published online in 2018 and then in the 2019 issue of the journal concerned the activity of LZ1 in pancreatic cancer models [3].
Cellular systems and experiments were used in mice.
The goal was to understand the biological activity of the peptide and the possible mechanisms responsible for the observed effects.
What role does nucleolin play?
The study analyzed the effect of LZ1 with nucleolin present on the surface of the cells.
Nucleolin is a protein involved in various cellular processes.
Under certain conditions, it can also occur on the surface of cells, which is the subject of research into potential molecular targets.
The researchers linked the experimental activity of LZ1 with its effect on the surface nucleolin and its subsequent degradation.
The activation of AMPK, the reduction of mTORC1 signaling, and the processes of autophagy were also analyzed [3].
Did LZ1 cause the death of cancer cells?
Antitumor effects associated with mechanisms involving autophagy were observed in the studied models.
Experiments interfering with the autophagy process provided additional evidence indicating its involvement in the observed response.
This reinforces the mechanistic interpretation of the results in a specific model.
However, it does not prove that LZ1 will selectively act on the cancer in the human body.
Questions remain regarding the delivery of the substance to tissues, its effects on healthy cells, systemic exposure, and safety.
Nor can it be argued on this basis that LZ1 prevents cancer or improves the treatment outcomes of patients with pancreatic cancer.
The mechanisms of action of LZ1 studied scientifically
LZ1 was analyzed in several different biological systems.
For this reason, one universal mechanism responsible for all observed effects should not be attributed to it.
A change in the activity of a specific protein, metabolite, or signaling pathway can indicate a mechanism of action.
However, it does not always confirm a direct causal relationship.
1. Antibacterial activity and inflammatory response
Studies related to acne evaluated the effect of LZ1 on bacterial growth and inflammatory response parameters, including selected cytokines [1].
The observed changes indicate activity in specific models.
However, they do not prove that LZ1 inhibits all types of skin inflammation.
It cannot also be assumed that every anti-inflammatory effect is the result of a direct interaction with the cells of the immune system.
Reducing the number of bacteria can limit the stimulus that triggers an inflammatory reaction.
In such a case, the decrease in certain inflammatory markers may be an indirect effect.
Distinguishing between direct and indirect action requires appropriately designed experiences.
2. Influence on the metabolism of infected erythrocytes
The study on malaria analyzed changes in the activity of pyroglutamate kinase and ATP production in infected red blood cells [2].
These results suggested the involvement of certain metabolic processes in response to LZ1.
However, they cannot be transferred to the metabolism of healthy human cells or presented as evidence of a general increase in cellular energy.
The significance is the type of cell, the presence of the parasite, the conditions of the experiment, and the direction of the observed change.
3. Nucleolin, AMPK and autophagy
In models of pancreatic cancer, the effect of LZ1 with surface nucleolin was studied, as well as the subsequent changes in intracellular signaling [3].
The processes analyzed included:
- binding of LZ1 to the surface nucleolin;
- degradation of nucleolin;
- activation of AMPK;
- reduction of mTORC1 pathway activity;
- the role of autophagy in cell death.
The results suggest a mechanistic relationship between these processes in the applied models.
However, they do not confirm that the same pathway will dominate in every tissue or in patients.
It is also not appropriate to describe these results with the general statement that LZ1 „replaces cells”.
In antimicrobial studies the goal was to limit the activity of bacteria, whereas in cancer models the death of cancer cells was analyzed.
These are different biological processes.
Restrictions on research into LZ1
The most important limitation of the current literature is the lack of sufficient clinical evidence to assess the efficacy and safety of LZ1 in humans.
The number of published experiences is not the only criterion for the quality of evidence.
Equally important is how closely the model corresponds to the actual clinical application.
Why preclinical studies do not confirm efficacy in humans?
Experiments on cells and animals allow testing of biological hypotheses.
However, they do not reproduce all the processes that occur in the human body.
The differences may concern, among other things, metabolism, the distribution of substances in tissues, the immune response, and tolerance.
Confirmation of clinical efficacy would require studies with appropriate endpoints, safety assessment and sufficient observation time.
Each proposed application of LZ1 would have to be evaluated separately.
Why can laboratory test results vary?
The activity of the peptide may depend on the experimental conditions.
Among other things, the strain of the pathogen, the type of cell, the preparation of the sample, the exposure time, and the method of measuring the effect are important.
A 2023 comparative study showed that the results regarding the activity of LZ1 may differ from previous observations [5].
Such discrepancies require methodological analysis and independent replication.
It is not necessary to choose only the most favorable outcome.
Does the favorable result of the hemolysis test confirm safety?
No.
The hemolysis test allows the evaluation of erythrocyte damage under certain experimental conditions.
It does not cover all possible adverse reactions.
It does not allow the individual to independently assess the risk of skin sensitization, chronic toxicity, the impact on fertility, or the consequences of systemic exposure.
Similarly, the cell viability test provides information about the response of a specific cell model.
It does not replace a full toxicological evaluation.
Does the formulation affect the interpretation of the results?
Yes.
Studies conducted on purified peptide do not automatically confirm the effectiveness of a ready-made cream, oral preparation, injection solution, or other formulation.
The composition of the product and the route of administration can influence the stability of the substance, its availability, and tissue exposure.
More about the importance of the delivery route can be read in the article Peptide injections and other routes of administration.
It cannot also be assumed that the mere presence of LZ1 on the label confirms equivalence with the material examined in the scientific publication.
Can the studies of other peptides confirm the effect of LZ1?
Not directly.
Peptides from the same research group or derived from similar biological structures may have different sequences and properties.
The results regarding another peptide can serve as the basis for a hypothesis.
However, they should not be counted as direct evidence of the effectiveness of LZ1.
Similarly, publications that use the abbreviation LZ1 for the leukinogenic region are not part of the same research set [4].
Most frequently asked questions about the LZ1 peptide
1. Does LZ1 mean a specific substance?
In antimicrobial studies discussed in this article, LZ1 stands for a specific peptide with the sequence VKRWKKWWRKWKKWV-NH₂. However, the acronym itself is not unambiguous, as it also appears in publications concerning regions of the protein unrelated to it. Therefore, when reviewing the literature, the sequence, chemical modifications, and context of the study must be compared. Only after this confirmation of identity does it become possible to properly combine the results of different publications [2,4].
2. What do the available studies on LZ1 confirm?
Available studies confirm the biological activity of LZ1 in specific preclinical models. These include antimicrobial experiments, studies of malaria parasites, and models of pancreatic cancer. These results indicate the possibility of further studies, but do not confirm the effectiveness of the treatment in humans. The effect obtained in cell culture or in animals should be interpreted in relation to the specific model and the measured parameter [3,5].
3. Is LZ1 a natural mixture of snake venom?
No. In the studies discussed, LZ1 is a synthetic peptide with a specific amino acid sequence. The description of its origin from studies on the venom dynamics of snakes refers to the history of developing the molecule, not to the necessity of obtaining it from raw venom. The synthetic material is not the same as a mixture of proteins and other biological components. The identity of LZ1 must be evaluated based on the sequence and analytical documentation [2].
4. Is LZ1 the same as the leucine zipper region LZ1?
No. The abbreviation LZ1 can refer to various molecular structures. In studies of potassium channels, it was used to label the leucine zipper region associated with the regulation of membrane proteins. This is not the 15-amino acid antimicrobial peptide described in this article. Such publications should not be combined with the activity studies of the LZ1 discussed herein, as they relate to other molecules and biological mechanisms [4].
5. Does the amidation of the C-terminal end have significance in the LZ1 studies?
Yes. The C-terminal end methylation is an element of the defined structure of LZ1 and should be taken into account when comparing samples. Sequences without information about the terminal modification may not fully describe the same chemical form. This does not automatically mean that each variant will exhibit different activity, but equivalence cannot be assumed without appropriate analytical and biological data [2].
6. Has it been proven that LZ1 treats acne in humans?
No. The studies discussed in this article did not demonstrate a confirmed clinical efficacy of LZ1 in patients with acne. Early experience included acne-related bacteria and an animal model. The observed antibacterial activity and changes in inflammatory parameters justify further studies, but do not replace the evaluation of skin changes, tolerability, durability of the response, and comparison with appropriate treatment in humans [1].
7. Does a lower concentration of bacteria that inhibits bacteria mean better acne treatment?
No. The concentration that inhibits bacterial growth is a laboratory parameter and not a direct measure of clinical efficacy. The formulation properties, the availability of the substance at the site of action, tolerance, and the actual impact on the disease are also important. The differences between the results of the LZ1 studies further show that a single value of activity should not be considered a universal indicator of efficacy [5].
8. Does the result of the LZ1 study in the malaria model mean efficacy in humans?
No. An experiment in mice infected with malaria parasites does not allow determining efficacy and safety in patients. Differences between parasite species, host organisms, and exposure conditions limit the direct transfer of results. The LZ1 study provides information on antiparasitic activity and possible metabolic mechanisms, but does not constitute a basis for replacing approved malaria treatment methods [2].
9. Do the LZ1 studies on pancreatic cancer confirm the anticancer effects in patients?
No. Studies have shown biological effects in cell and animal models, as well as indicated possible involvement of nucleolin and autophagy. However, they do not confirm improvement in the treatment outcomes for patients with pancreatic cancer. Studies regarding the delivery of the substance, selectivity towards tissues, safety, and actual therapeutic outcomes would be necessary to assess its potential clinical application [3].
10. Are human cell studies clinical trials?
No. Research using human cells remains preclinical research unless it involves interventions directly evaluated in the participants of the study. It can provide information about cellular activity, toxicity, or mechanisms of action, but does not allow for the determination of absorption, distribution, clinical benefits, or overall risk in humans independently. Therefore, the term „research using human cells” should not be equated with confirmed clinical efficacy.
11. Does low hemolysis mean that LZ1 is safe?
No. Low hemolysis indicates only limited damage to erythrocytes under the specific test conditions. It does not include all potential adverse effects, such as skin reactions, chronic toxicity, or effects on other organs. Comparative studies have also shown that cytotoxicity results may depend on the type of cells used. A comprehensive safety assessment requires many complementary methods and appropriate clinical data [5].
12. Does the activity of LZ1 after incubation in plasma confirm the half-life in humans?
No. Maintaining biological activity after incubation in plasma outside the body is not equivalent to measuring the pharmacokinetic half-life in humans. The body also factors in distribution, metabolism, elimination, and the method of detecting the intact molecule. Early plasma studies of LZ1 provide limited information about the substance’s behavior in a specific environment, but do not allow the determination of the duration of action or the dosing regimen [1].
13. Does one study, LZ1, confirm the effectiveness of any product containing this peptide?
No. The test result refers to specific material, formulation, and experimental conditions. Other solvents, concentrations, administration routes, or the presence of additional ingredients can affect the properties of the substance and the biological response. The mere inclusion of the name LZ1 on the label does not confirm compliance with the study sample in the publication. Any finished product requires appropriate evaluation of identity, composition, and declared properties.
14. Does LZ1 definitely not cause the development of antimicrobial resistance in microorganisms?
There is no basis for such a statement. Activity against the selected strain, even resistant to certain antibiotics, does not prove that microorganisms cannot develop resistance to LZ1 during repeated exposure. Assessing such a risk requires appropriately designed long-term studies and analyses of changes in susceptibility. The mere classification of LZ1 as an antimicrobial peptide does not guarantee the absence of resistance.
15. Why can different laboratories obtain different results from the LZ1 test?
Differences may result from the used bacterial strains, cell models, material preparation methods, culture conditions, and methods of measuring activity. A comparative study from 2023 showed discrepancies compared to previous observations. One result should not be automatically considered correct, and the other erroneous. The most important is to compare methods, experimental conditions, and the possibility of independent replication of results [5].
16. Does the presence of LZ1 in the research substance catalogue mean approval for human use?
No. Placing LZ1 in the supplier’s catalog merely means that the material is offered in a specific commercial category. It does not confirm the approval of the medicinal product, clinical efficacy, or safety. Regulatory status should be determined based on the official records regarding the specific product, indication, and jurisdiction. Commercial availability does not replace such verification.
17. What studies could strengthen the scientific evidence regarding LZ1?
Independent replication of experiments, consistent analytical characterization of samples, studies of appropriate formulations, and well-designed clinical trials would be of greatest importance. Any proposed application, for example dermatological, antiparasitic, or anti-cancer, would require separate evaluation of efficacy and safety. Additional mechanistic studies may expand knowledge, but will not replace the immediate confirmation of clinical benefits.
Applications
LZ1 is a defined synthetic peptide with a 15-amino acid sequence and an amidated C-terminal end.
In preclinical studies, its activity against acne-related bacteria, malaria parasites, and pancreatic cancer cells was analyzed.
The results indicate several interesting research directions, including antimicrobial activity, metabolic changes, and processes related to autophagy.
However, this does not mean that LZ1 has been proven to have therapeutic efficacy in humans.
The available data leave important questions regarding the repeatability of results, biological selectivity, safety, pharmacokinetics, and the properties of ready-made formulations.
It is also important to distinguish the LZ1 peptide from other structures described with the same abbreviation.
The most substantiated claim is that LZ1 is a subject of preclinical research, and not a substance with a confirmed clinical application in the diseases in question.
Disclaimer
The article is purely educational and scientifically informative in nature. It does not constitute medical advice, therapeutic recommendations, dosage instructions, formulation preparation, or the use of LZ1 peptide.
Laboratory and animal studies do not confirm the safety or efficacy of products containing LZ1 in humans. Any potential clinical application requires separate studies and appropriate regulatory assessment.
References
- Zhang, Z., Mu, L., Tang, J., Duan, Z., Wang, F., Wei, L., Rong, M., & Lai, R. (2013). A small peptide with therapeutic potential for inflammatory acne vulgaris. PLOS ONE, 8(8), Article e72923. https://doi.org/10.1371/journal.pone.0072923
- Fang, Y., He, X., Zhang, P., Shen, C., Mwangi, J., Xu, C., Mo, G., Lai, R., & Zhang, Z. (2019). In vitro and in vivo antimalarial activity of LZ1, a peptide derived from snake cathelicidin. Toxins, 11(7), Article 379. https://doi.org/10.3390/toxins11070379
- Xu, C., Wang, Y., Tu, Q., Zhang, Z., Chen, M., Mwangi, J., Li, Y., Jin, Y., Zhao, X., & Lai, R. (2019). Targeting surface nucleolin induces autophagy-dependent cell death in pancreatic cancer via AMPK activation. Oncogene, 38(11), 1832–1844. https://doi.org/10.1038/s41388-018-0556-x
- Tian, L., Coghill, L. S., MacDonald, S. H., Armstrong, D. L., & Shipston, M. J. (2003). Leucine zipper domain targets cAMP-dependent protein kinase to mammalian BK channels. Journal of Biological Chemistry, 278(10), 8669–8677. https://doi.org/10.1074/jbc.M211661200
- Ramata-Stunda, A., Boroduskis, M., Kaktina, E., Patetko, L., Kalnenieks, U., Lasa, Z., Rubina, M., Strazdina, I., Kalnins, G., & Rutkis, R. (2023). Comparative evaluation of existing and rationally designed novel antimicrobial peptides for treatment of skin and soft tissue infections. Antibiotics, 12(3), Article 551. https://doi.org/10.3390/antibiotics12030551