Description

Technical Parameters

Introduction

peptides

product-1400-1400

Products Description

#### Introduction

Delta Sleep-Inducing Peptide (DSIP) is a neuroactive peptide composed of 9 amino acids. It was first isolated and discovered from rabbit cerebrospinal fluid in 1977 and was named for its ability to significantly promote slow-wave sleep (SWS). In addition to regulating sleep, DSIP also has neuroprotective, antioxidant, and metabolic regulation functions. This article will systematically explain DSIP and its derivatives from the aspects of structural classification, physicochemical properties, color characteristics, advantages and application fields.

### 1. Structural classification and characteristics of DSIP

#### 1. **Natural DSIP (natural type)**

- **Structural characteristics**:

The sequence is **Trp-Ala-Gly-Gly-Asp-Ala-Ser-Gly-Glu** (molecular weight ≈ 849.88 Da), with a linear structure, containing hydrophilic amino acids (such as Asp, Glu) and hydrophobic residues (such as Trp).

- **Physical and chemical properties**:

- **Solubility**: Easily soluble in water (>10 mg/mL) and polar solvents (such as DMSO), stable in pH 7.0 buffer.

- **Stability**: Easily degraded by proteases (half-life of about 15 minutes), requires low temperature (-20℃) storage.

- **Color**: The pure product is white or off-white lyophilized powder.

- **Advantages**:

- High biocompatibility, no obvious toxicity.

- Directly involved in the regulation of sleep-wake cycle, clear mechanism of action.

- **Application limitations**:

Rapid metabolism in the body, frequent administration required; weak membrane permeability, limiting application in the central nervous system.

#### 2. **Synthetic modified DSIP analogs**

Through chemical modification to enhance stability, prolong half-life or improve bioavailability, they are mainly divided into the following subcategories:

##### **(1) Cyclic DSIP**

- **Structural modification**:

The peptide chain is cyclized by introducing disulfide bonds or amide bonds, such as cyclization of the C-terminus and the N-terminus.

- **Physical and chemical properties**:

- **Stability**: Significantly improved resistance to enzymatic degradation (half-life extended to several hours).

- **Solubility**: Slightly lower than the natural type, the formula needs to be optimized (such as adding co-solvents).

- **Color**: White crystals, no significant difference from the natural type.

- **Advantages**:

- Prolong the duration of drug effect and reduce the frequency of administration.

- Enhance the ability to penetrate the blood-brain barrier.

##### **(2) D-amino acid replacement DSIP**

- **Structural modification**:

Replace some L-amino acids with D-configuration (such as D-Ala replacing L-Ala) to reduce enzyme recognition sites.

- **Physical and chemical properties**:

- **Stability**: Plasma stability is improved by 2-3 times.

- **Solubility**: Similar to the natural type, good water solubility.

- **Color**: White powder, which may be slightly yellow due to the degree of modification.

- **Advantages**:

- Enhanced resistance to protease degradation, suitable for oral administration research.

##### **(3) Lipid-modified DSIP**

- **Structural modification**:

Connect fatty acid chains (such as palmitic acid) at the end of the peptide chain to enhance membrane permeability.

- **Physical and chemical properties**:

- **Solubility**: Lipid solubility is improved, and liposomes or nanoparticles can be made.

- **Stability**: The half-life in the blood is extended to 4-6 hours.

- **Color**: Due to lipid components, it may be milky white.

- **Advantages**:

- Improves transdermal or blood-brain barrier efficiency, suitable for local administration (such as transdermal patches).

### 2. Functional classification and pleiotropic advantages

#### 1. **Sleep regulation DSIP**

- **Core function**:

Activates the GABAergic system, promotes delta wave (slow wave) sleep, and improves insomnia and circadian rhythm disorders.

- **Clinical advantages**:

Compared with traditional sedatives, it has no addictive and next-day sleepiness side effects.

#### 2. **Neuroprotective DSIP derivatives**

- **Function extension**:

Reduces cerebral ischemia or Alzheimer's disease damage by scavenging free radicals and inhibiting neuroinflammation (such as regulating IL-6).

- **Representative modification**:

Antioxidant groups (such as glutathione) conjugated DSIP to enhance free radical neutralization ability.

#### 3. **Metabolism regulation DSIP**

- **Mechanism of action**:

Regulate insulin sensitivity and lipid metabolism related genes (such as PPARγ), improve metabolic indicators of obesity and diabetes models.

- **Application potential**:

Combined with GLP-1 analogs to develop dual-target metabolic syndrome therapeutic drugs.

### 3. Comprehensive analysis of physical and chemical properties

#### 1. **Molecular weight and structural characteristics**

- **Natural DSIP**: 849.88 Da, containing 3 negative charges (Asp, Glu), isoelectric point ≈ 4.5.

- **Modified derivatives**: molecular weight range 900-1500 Da, charge characteristics vary due to modification groups.

#### 2. **Solubility and formulation development**

- **Water solubility**: natural type > cyclized type > lipidated type.

- **Preparation form**: lyophilized powder (injection), liposomes (transdermal), sustained-release microspheres (implantation).

#### 3. **Stability and Storage Conditions**

- **Temperature sensitivity**: Activity loss <10% when stored at 4℃ for 1 week, stable for more than 1 year at -20℃.

- **Photosensitivity**: It is recommended to store in the dark, especially derivatives containing Trp are prone to photooxidation.

### 4. Color characteristics and quality control

- **Natural and most synthetic DSIP**: White or off-white, no significant color difference when purity ≥95%.

- **Specially modified derivatives**:

- **Fluorescently labeled DSIP** (such as FITC labeling): Yellow or green powder.

- **Metal complex** (such as Cu-DSIP): May appear light blue (copper ion chelation).

- **Impurity influence**: Oxidation or degradation products may cause yellowing, and HPLC is required to monitor purity.

### 5. Application fields and future directions

#### 1. **Medical field**

- **Sleep disorders**: Development of nasal spray or sublingual tablet form.

- **Neurodegenerative diseases**: targeted delivery system (such as exosomes loaded with DSIP).

#### 2. **Cosmetics**

- **Anti-aging ingredients**: using antioxidant function, added to anti-wrinkle essence.

#### 3. **Research tools**

- **Labeled DSIP**: used for receptor localization and signaling pathway research.

#### 4. **Challenges and prospects**

- **Delivery bottleneck**: development of brain-targeted nanocarriers.

- **Long-acting**: polyethylene glycol (PEG) modification to extend circulation time.

### Conclusion

DSIP is a multifunctional peptide, and its natural form and synthetic derivatives have their own characteristics in structure, properties and applications. Through rational design and modification, DSIP is expected to play a greater role in neuroscience, metabolic diseases and personalized medicine. Future research needs to focus on improving stability, optimizing delivery systems and expanding multi-target synergistic effects to unleash its clinical potential.