Reasons for choosing our testing services
ZHONGXI Testing has obtained inspection qualification certifications from multiple countries and regions worldwide. We possess a senior testing team and advanced testing methods, providing independent, impartial, and professional third-party verification services for global carbon projects.
Internationally recognized authority
Certified by multiple international standards such as CNAS, VCS, and GS, with reports universally applicable worldwide.
Global service capability
Covering 140+ countries and regions, it supports on-site detection and remote verification in multiple languages.
Professional experimental methods
Adopt standard experimental methods to ensure accurate and reliable data.
In Vitro Antioxidant Peptide Profiling – Multi‑Mechanism Activity Testing & Potency Ranking
You are searching for in vitro antioxidant activity peptide detection because you need to perform this assay—whether to screen bioactive hydrolysates, validate novel antioxidant peptides from food or marine sources, rank peptide libraries for free‑radical scavenging, or support functional food claims. We provide a complete testing service that delivers quantitative antioxidant potency across eight complementary chemical and cell‑based assays, with full mechanistic deconvolution (radical quenching, metal chelation, reducing power, cellular ROS inhibition).
What We Detect – From Chemical Radical Scavenging to Cellular ROS Neutralisation
Our in vitro antioxidant peptide assessment goes far from simple DPPH end‑point screens. Using a robotic liquid‑handling system and 384‑well plate format, we measure DPPH• (IC50), ABTS•⁺ (TEAC value), •OH hydroxyl radical scavenging (deoxyribose assay), superoxide radical (O₂•⁻) inhibition (NBT reduction), and nitric oxide (NO) scavenging (Griess reaction) – all with intra‑assay CV <5%. For reducing capacity, we perform FRAP (ferric reducing antioxidant power) and CUPRAC (cupric ion reducing antioxidant capacity), reporting μmol Trolox equivalent per μmol peptide. We also quantify metal chelation activity (Fe²⁺ and Cu²⁺) via ferrozine and bathocuproine displacement methods, identifying peptides that prevent Fenton‑type oxidation. For biologically relevant models, we deploy cell‑based antioxidant assays using Caco‑2, HepG2, or RAW 264.7 macrophages – measuring intracellular ROS (DCFH‑DA probe, flow cytometry or fluorescence plate reader), lipid peroxidation (MDA quantification via TBARS), and glutathione (GSH/GSSG) preservation after oxidative stress (H₂O₂ or AAPH challenge).
How Deep We Go – Synergy Screening, Sequential Digestion Stability & In Silico Mechanistic Correlation
We don't just report individual IC50 values. Our advanced pipeline includes combinatorial synergy testing (isobologram and Chou‑Talalay analysis) for peptide mixtures or peptide‑vitamin C/α‑tocopherol combinations, identifying synergistic, additive, or antagonistic effects. For food or nutraceutical relevance, we perform simulated gastrointestinal digestion (pepsin at pH 2.0, then pancreatin with bile salts, 37°C) and re‑measure antioxidant activity to predict in vivo efficacy after oral intake. We also offer kinetic antioxidant assessment – ABTS and DPPH time‑course (0‑60 min) to distinguish fast‑acting vs. slow‑acting peptides. Using LC‑MS/MS sequencing of active fractions, we identify specific peptide sequences and perform in silico docking (AutoDock Vina, Pepsite2) to known antioxidant targets (e.g., Keap1‑Nrf2 binding, myeloperoxidase, xanthine oxidase), correlating experimental IC50 with predicted binding energies. For cellular uptake and mechanism, we measure Nrf2 nuclear translocation (confocal microscopy, ELISA) and expression of downstream genes (HO‑1, NQO1, SOD, CAT by qRT‑PCR) after peptide treatment.
Why Our In Vitro Antioxidant Peptide Testing Stands Out – Broad Panel, Physiological Relevance & High Throughput
1. Eight‑assay core panel + custom additions: You receive a complete antioxidant fingerprint (DPPH, ABTS, OH, O₂⁻, NO, FRAP, CUPRAC, metal chelation) from a single 1‑2 mg peptide sample. We also add ORAC (oxygen radical absorbance capacity) and HORAC (hydroxyl radical absorbance capacity) on request – fully automated.
2. Cell‑based physiological relevance: Unlike purely chemical assays, we quantify intracellular ROS reduction (as low as 5% inhibition detected, p<0.01) and protective effect against lipid peroxidation using primary or immortalised cell lines. We report EC50 for cytoprotection (MTT or resazurin viability included) to rule out false positives from direct radical quenching by culture medium.
3. Low sample consumption & high throughput: With our nanoliter‑scale screening, full chemical panel requires only 50 µg of pure peptide or 200 µL of hydrolysate. For library screening (e.g., 100 synthetic peptides), we deliver IC50 ranking within 5‑7 business days.
4. Stability & processing impact: We measure antioxidant activity before and after heat treatment (80°C/30 min), pH variation (3‑9), or freeze‑thaw cycles – critical for functional food development.
5. Regulatory & publishing support: Our data align with AOAC guidelines for antioxidant assays, and EFSA requirements for in vitro substantiation of health claims. Reports include dose‑response curves, Trolox equivalents, statistical comparisons (ANOVA with post‑hoc), and raw data files – ready for patent or peer‑reviewed publication.
Who Relies on Our Antioxidant Peptide Testing – Real‑World Impact
A functional ingredient company screened 40 enzymatic hydrolysates from plant proteins using our chemical + cell‑based panel – they identified a rice bran peptide fraction with ABTS value of 3.2 µmol TE/µmol (5‑fold higher than intact protein) and confirmed cellular ROS reduction by 62% at 100 µg/mL, leading to a commercial launch. Another client sent us synthetic peptides derived from marine collagen; we discovered that the tripeptide Pro‑Hyp‑Gly showed strong OH• scavenging (IC50 0.8 mM) but negligible DPPH activity, highlighting the importance of multi‑mechanism profiling. A pharmaceutical company working on peptide‑based Nrf2 activators used our Nrf2 translocation and HO‑1 qPCR data to select a lead peptide that increased nuclear Nrf2 by 4‑fold with no cytotoxicity, supporting their preclinical package.
Ready to Run Your In Vitro Antioxidant Peptide Detection?
Send us pure peptides (≥1 mg, or ≥100 µg for reduced panel), peptide hydrolysates (≥2 mL, or ≥200 mg powder), or peptide libraries (dry in 96‑well plates). We will perform chemical radical scavenging assays (up to 8 methods), optional cell‑based ROS/lipid peroxidation assays, simulated digestion stability, and a full interpretative report – typically within 5‑10 business days. Request a free consultation; we will design the optimal antioxidant panel (chemical only, cell‑based only, or full integrated) to match your development stage and regulatory target.