Functional verification technology for high-quality peptides: a scientific pathway from in vitro experiments to clinical applications

Introduction

The functional validation of peptides is a crucial step in their transition from the laboratory to the market. High quality peptides require rigorous in vitro experiments, animal experiments, and clinical trials to confirm their biological activity and safety. Starting from the three major stages of functional verification, this article analyzes the scientific path and technical points.

1、 In vitro experiment: preliminary screening of active peptide segments

cell experiment

Cell experiments are the fundamental step in verifying peptide function, evaluating its potential activity by detecting the effects of peptides on cell proliferation, migration, invasion, and gene expression. For example:

Antioxidant peptides: Using H2O2 induced HUVEC cell damage model, the effects of peptides on cell survival rate, SOD (superoxide dismutase) activity, and MDA (malondialdehyde) content were detected. For example, after treatment with silkworm pupa peptides, the cell survival rate increased by 40%, SOD activity doubled, and MDA content decreased by 50%.

Antimicrobial peptides: Using Staphylococcus aureus as a model, the antibacterial activity of peptides is evaluated through the minimum inhibitory concentration (MIC) test. For example, the MIC value of milk derived antimicrobial peptides is 16 μ g/mL, which is better than traditional antibiotics (such as ampicillin, MIC=32 μ g/mL).

Enzyme activity inhibition experiment

Design inhibition experiments targeting specific enzymes such as ACE and DPP-IV to validate the peptide's ability to lower blood pressure or blood glucose. For example:

ACE inhibitory peptide: The inhibition rate of the peptide on ACE enzyme activity was detected using carnitine histone leucine (HHL) as the substrate. For example, the ACE inhibition rate of cod bone peptide is 85%, and the IC50 (half maximal inhibitory concentration) is 0.5 mg/mL.

DPP-IV inhibitory peptide: Using glycyl prolyl p-nitroaniline (GP pNA) as the substrate, detect the inhibition rate of the peptide on DPP-IV enzyme activity. For example, the DPP-IV inhibition rate of soybean peptide is 70%, which is suitable for adjuvant treatment of diabetes.

Molecular docking simulation

Simulate the binding mode between peptides and target proteins (such as thrombin and TRPV1 channel) using molecular docking software (such as Discovery Studio) to predict their functional mechanisms. For example:

Antithrombotic peptide: Jade footed sea cucumber peptide SCp-1 tightly binds to the 10 amino acid residue sites of thrombin, with a binding energy (CDOCKER ENERGY) higher than that of hirudin fragment (HIRV2), confirming its strong anticoagulant activity.

Therapeutic peptide for osteoarthritis: C16A3GFOGER peptide matches the conformational changes of voltage receptors in TRPV1 channel, explaining its mechanism of promoting cartilage differentiation and inhibiting inflammation.

2、 Animal experiments: Verify in vivo activity and safety

acute toxicity test

Evaluate the safety of peptides by observing animals such as mice, high mortality rates, and organ damage through a single high-dose administration (e.g. 5000 mg/kg). For example:

Marine fish peptide: After oral administration of 5000 mg/kg to mice, there were no deaths within 7 days, and pathological sections of liver and kidney tissues showed no abnormalities, indicating extremely low acute toxicity (LD50>5000 mg/kg).

Subchronic toxicity test

By continuous administration (such as 90 days), animal blood biochemical indicators (such as ALT, AST, creatinine) and histopathological changes are detected to evaluate the long-term safety of peptides. For example:

Soy peptides: After continuous gavage of soy peptides in rats for 90 days, blood biochemical indicators were within the normal range, and there were no pathological changes in liver, kidney, and spleen tissues, indicating low subchronic toxicity.

Functional verification test

Design animal models for specific functions such as immune regulation and blood pressure lowering to validate the in vivo activity of peptides. For example:

Immune regulatory peptides: Using cyclophosphamide induced immune deficiency mice as a model, the effects of peptides on spleen index, lymphocyte proliferation, and cytokine levels (such as IL-2, IFN - γ) were detected. For example, after treatment with thymopentin, the spleen index of mice increased by 30%, the lymphocyte proliferation rate increased by 2 times, and the IL-2 level increased by 1.5 times.

Hypotensive peptides: Using spontaneously hypertensive rats (SHR) as a model, the effects of peptides on systolic blood pressure (SBP) and diastolic blood pressure (DBP) were detected. For example, after continuous gavage of cod bone peptide for 4 weeks, the SBP of SHR rats decreased by 25 mmHg and DBP decreased by 15 mmHg, which was equivalent to the effect of Captopril (positive control).

3、 Clinical Trials: A Key Leap from Animals to Humans

Phase I clinical trial: safety assessment

Recruit a small number of healthy volunteers (such as 20-50 people) to test the tolerance, pharmacokinetics (PK), and pharmacodynamics (PD) parameters of peptides through single and multiple administrations. For example:

Oral administration of collagen peptide: After a single oral administration of 5 g of collagen peptide by healthy volunteers, the concentration of hydroxyproline in plasma reached its peak within 2 hours (Cmax=10 μ g/mL), with a half-life (t1/2) of 4 hours and no adverse reactions (such as nausea and diarrhea).