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Recovery & Healing

Thymosin Beta-4 Fragment (TB-4 FRAG)

Formula: C16H27N5O8Sequence: Ac-Ser-Asp-Lys-Pro

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Written by Peptok Research
Reviewed by Medical Advisory BoardLast updated: Jan 2026

Quick Stats

Evidence Strength1/10 (Low)

Based on number and quality of indexed studies

Community Popularity0/10 (Low)

Based on search volume and community interest

Legal Status

⚖️ Not FDA-approved

Type

Recovery & Healing

Route

Subcutaneous injection

Half-life

~4-5 minutes (rapidly cleaved by ACE)

Medical Disclaimer

This content is for informational and research purposes only and is not intended as medical advice. Always consult with a qualified healthcare professional before making decisions about peptide use or any medical treatment. Individual results may vary.

Overview

TB4-Frag (Thymosin Beta-4 Fragment) is a smaller version of the naturally occurring peptide Thymosin Beta-4, used to promote healing. It's only a short sequence of the full TB-4 peptide. Some research suggests it may enhance neurogenesis.

Quick Summary

  • 🧬
    What it is:TB4-Frag (Thymosin Beta-4 Fragment) is a smaller version of the naturally occurring peptide Thymosin Beta-4, used to promote healing.
  • 🎯
    Primary use:Recovery & Healing applications — see benefits section for details.
  • 📊
    Evidence level:Preliminary — Mostly anecdotal or very early-stage research (1 indexed papers)
  • Bottom line:Very early research phase. Approach with appropriate caution; long-term safety is unknown.

TB4-Frag is a short peptide derived from the larger Thymosin Beta-4 (TB-4) molecule. While TB-4 has a wide range of purported benefits, TB4-Frag focuses on a specific section thought to be responsible for certain regenerative effects. It's a synthetic peptide, meaning it's created in a lab to mimic a naturally occurring sequence.

TB4-Frag is a fragment consisting of amino acids 17-23 of the TB-4 peptide. TB-4 itself is a 43 amino acid peptide that's found in high concentrations in wound fluid. Some studies suggest that TB4-Frag retains some of the parent peptide's beneficial properties, potentially offering a more targeted approach.

One area of interest is TB4-Frag's potential impact on brain health. Some researchers believe it can support neurogenesis, the creation of new neurons in the brain. This is particularly interesting in areas like the hippocampus, which is vital for memory and learning.

How TB4-Frag (Thymosin Beta-4 Fragment) Works

TB4-Frag's mechanism of action is still being researched, but several key pathways are believed to be involved. It is thought to interact with actin, a protein crucial for cell structure and movement. By binding to actin, TB4-Frag may promote cell migration and wound healing.

Another potential mechanism involves increased neurogenesis. Animal studies suggest that TB4-Frag may stimulate the growth of new neurons, particularly in the hippocampus. The exact pathways involved are not fully understood, but it's hypothesized that TB4-Frag may influence the expression of genes related to neuronal growth and survival.

It is also thought to interact with calmodulin-sensitive cAMP phosphodiesterase. This enzyme plays a role in regulating cyclic AMP (cAMP) levels within cells. cAMP is a signaling molecule involved in various cellular processes, including inflammation, cell growth, and differentiation. By interacting with this enzyme, TB4-Frag may indirectly influence these processes.

Finally, TB4-Frag may exert some of its effects through anti-inflammatory actions. While the exact mechanisms are still being investigated, it's plausible that TB4-Frag can modulate the activity of immune cells and reduce the production of pro-inflammatory cytokines. This could contribute to its potential wound-healing and neuroprotective properties.

What the Research Actually Shows

Wound Healing:

  • Evidence Grade: Preliminary (Animal studies only)
  • While TB4-Frag is often associated with wound healing, most direct evidence comes from research on the full TB-4 peptide. TB4-Frag is theorized to retain some of these properties due to its actin-binding domain. Further research is needed to confirm this.

Neurogenesis and Cognitive Function:

  • Evidence Grade: Preliminary (Animal studies only)
  • A study published in Neuroscience in 2015 found that TB4-Frag increased hippocampal neurogenesis and facilitated spatial memory in mice (Kim et al., 2015). This suggests a potential for cognitive enhancement, but these findings need to be replicated in human trials. The study specifically showed improved performance in a Morris water maze test, a common assessment of spatial learning and memory in rodents.

Anti-inflammatory Effects:

  • Evidence Grade: Preliminary (In vitro and animal studies)
  • Research suggests that TB4-Frag may possess anti-inflammatory properties. While the exact mechanisms are not fully understood, it's hypothesized that TB4-Frag can modulate the activity of immune cells and reduce the production of pro-inflammatory cytokines. This could contribute to its potential wound-healing and neuroprotective properties.

Interaction with Calmodulin-Sensitive cAMP Phosphodiesterase:

  • Evidence Grade: Preliminary (In vitro)
  • A study in Neurochemical Research (Voelter et al., 1995) investigated the interaction of TB4-Frag with calmodulin-sensitive cAMP phosphodiesterase from the hypothalamus. The research provides evidence that TB4-Frag interacts with this enzyme, which plays a role in regulating cyclic AMP (cAMP) levels within cells. This suggests a possible mechanism by which TB4-Frag may influence cellular processes related to inflammation, cell growth, and differentiation.

TB4-Frag (Thymosin Beta-4 Fragment) vs. TB-500

TB-500 is often confused with TB4-Frag, but they are not the same. TB-500 is not actually Thymosin Beta-4. TB-500 is a fragment of Thymosin Beta-4, but it's a synthetic peptide called Ac-LKKTETQ. TB-500 is a 43 amino acid peptide. TB4-Frag is a shorter sequence of TB-4.

Both TB-500 and TB4-Frag are being investigated for their potential regenerative properties, but they may work through slightly different mechanisms due to their different structures. TB-500's larger size may allow it to interact with a broader range of targets in the body, while TB4-Frag's smaller size may offer more targeted effects.

Both peptides are thought to promote wound healing by influencing cell migration and reducing inflammation. However, TB4-Frag has received more attention for its potential neuroprotective effects, particularly in the hippocampus. Some research suggests that TB4-Frag may stimulate neurogenesis and improve cognitive function, while TB-500's effects on the brain are less well-defined.

TB-500 is typically administered systemically, meaning it circulates throughout the body. TB4-Frag can also be administered systemically, but some researchers are exploring the possibility of more localized delivery to target specific tissues or organs.

Ultimately, the choice between TB-500 and TB4-Frag depends on the specific goals and needs of the individual. More research is needed to fully understand the differences between these two peptides and determine their optimal applications.

The Honest Limitations

The primary limitation of TB4-Frag research is the lack of human clinical trials. Most of the available evidence comes from animal studies and in vitro experiments. While these studies provide valuable insights into the potential mechanisms of action and therapeutic applications of TB4-Frag, they cannot be directly extrapolated to humans.

Another limitation is the relatively small number of studies specifically focused on TB4-Frag. Much of the research on Thymosin Beta-4 has focused on the full-length peptide, TB-4. While TB4-Frag is believed to retain some of the beneficial properties of TB-4, more research is needed to confirm this and to fully understand its unique effects.

The long-term effects of TB4-Frag are also unknown. Most studies have only evaluated the short-term effects of the peptide. It's unclear whether TB4-Frag is safe and effective for long-term use.

Finally, the optimal dosage and administration route for TB4-Frag are still being investigated. Different studies have used different dosages and administration routes, making it difficult to compare results and to establish clear guidelines for use.

Combine TB4-Frag with BPC-157 for Enhanced Healing

TB4-Frag and BPC-157 are sometimes used together to promote healing, based on preliminary evidence. While TB4-Frag may support neurogenesis and reduce inflammation, BPC-157 is believed to enhance angiogenesis (the formation of new blood vessels) and protect tissues from damage.

Combining these two peptides may provide a synergistic effect, promoting faster and more complete recovery from injuries. However, it's important to note that this combination is based on anecdotal evidence and theoretical considerations. There are currently no clinical trials that have specifically evaluated the combined effects of TB4-Frag and BPC-157. Before using this combination, it's essential to consult with a healthcare professional and to carefully consider the potential risks and benefits. Use a peptide dosage calculator to determine the appropriate dose for each.

Benefits & Evidence

Anti-fibrotic (prevents scarring)

Moderate Evidence

1 studies · 0 human trials

Anti-inflammatory

Preliminary

1 studies · 0 human trials

Cardiovascular protection

Preliminary

1 studies · 0 human trials

Stem cell mobilization

Preliminary

1 studies · 0 human trials

Kidney protection

Preliminary

1 studies · 0 human trials

Hematopoietic regulation

Preliminary

1 studies · 0 human trials

Who Uses Thymosin Beta-4 Fragment (TB-4 FRAG)?

Athletes with injuries

Moderate

Accelerates tendon, ligament, and muscle repair

Post-surgery recovery

Preliminary

May improve wound healing and tissue regeneration

Chronic pain sufferers

Preliminary

Anti-inflammatory effects reported in animal studies

Active fitness enthusiasts

Anecdotal

Faster recovery between training sessions

Not recommended if:

Pregnant or nursing, history of hormone-sensitive cancers, active autoimmune conditions, or pediatric patients. Always consult a physician before starting any peptide protocol.

Dosage Guide

Protocol by Experience Level

ExperienceDoseFrequencyCycleRoute
Beginner100 mcgDaily or EOD4–6 wks, 2 wks offSubQ injection
Intermediate300 mcgDaily4–6 wks, 2 wks offSubQ injection
Advanced500 mcgDaily (split dose)4–6 wks, 2 wks offSubQ injection

Standard Protocol

100-500 mcg per day

Notes

Rapidly degraded by ACE (angiotensin-converting enzyme). ACE inhibitor medications will increase endogenous Ac-SDKP levels. This peptide may partly explain the anti-fibrotic benefits of ACE inhibitors.

Route

Subcutaneous injection

Half-life

~4-5 minutes (rapidly cleaved by ACE)

Molecular Weight

417.41 g/mol

Disclaimer

This information is for educational purposes only. Dosage information is derived from research literature and community reports. Always consult a qualified healthcare provider before using any peptide.

What the Community Reports

Community data coming soon

We're aggregating Reddit discussions for Thymosin Beta-4 Fragment (TB-4 FRAG).

Safety Profile

Regulatory Status

Not FDA-approved. Research chemical.

Common

  • Very few reported
  • Injection site irritation
  • Theoretical blood pressure effects (ACE pathway)

Rare

  • Dizziness
  • Headache

Serious

No serious adverse events reported in available literature.

Pregnancy: ❌ Not recommended — no safety dataKnown Interactions: 3 documented stacks
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Research

Mechanism of Action

Ac-SDKP inhibits TGF-β/Smad signaling, the primary pathway driving tissue fibrosis. It prevents fibroblast differentiation into myofibroblasts (the cells that produce scar tissue). It also inhibits inflammatory cell recruitment, suppresses collagen deposition, and promotes angiogenesis. In hematopoiesis, it keeps bone marrow stem cells in a quiescent state, protecting them from damage during chemotherapy.

Search Volume Trend

Rank #33
12 months agoPresent
Review2012

Ac-SDKP: the suppressor of fibrosis

Hypertension · Peng H, et al.

Common Stacks

Peptides frequently combined together for synergistic effects.

BPC-157

Recovery & Healing

Complements systemic healing with localized tissue repair

TB-500

Recovery & Healing

Synergistic tissue repair — BPC-157 handles GI/tendons while TB-500 targets systemic healing

GHK-Cu

Longevity & Anti-Aging

Skin/collagen synergy — anti-aging and wound healing

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