Peptide Glow Journal

Korean Peptide Serums: Three Labels Read, and the Pattern They Share

Three Korean peptide serums declare 6, 6 and 13 peptides. All three put niacinamide 5th or 6th and add adenosine, an ingredient Korean law recognises in anti-wrinkle cosmetics. Six of the 18 distinct peptide names have no PubMed record under that name.

Fiona G · Edited by Caroline S · Published 2026-10-04

Illustration: Three unbranded amber bottles with blank beige labels on a warm rose marble counter in morning light.
Illustration

"Korean peptide serum" is a searched phrase, but it is not a regulated product type: it means a peptide serum made by a South Korean brand. This page reads three of them from their brands' own ingredient lists and reports what they have in common. It does not rank them, and nobody on this site has used them.

Three labels, read on 4 October 2026

Serum Ingredients Peptides declared Peptide positions Niacinamide Adenosine
COSRX The 6 Peptide Skin Booster Serum 44 6 7–12 6th 37th
COSRX The Blue Peptide Bakuchiol Plump Glow Serum 39 6 11, 24, 25, 26, 29, 39 5th 21st
medicube Hyaluronic Multi Peptide PDRN Serum 53 13 33–35, 37–46 6th 15th

Three things recur:

  1. Many peptides per bottle. Six, six and thirteen, each listed as a blend.
  2. Niacinamide above every peptide. It is 5th or 6th on all three lists.
  3. Adenosine on every label. Its position varies, from 15th to 37th.

Under US labelling rules, ingredients above 1% must appear in descending order of amount, and those at or below 1% may follow in any order (21 CFR 701.3(f)(2)). None of the three brands states a peptide amount.

Why adenosine keeps appearing

South Korea's Cosmetics Act sorts certain claims into a regulated functional cosmetics category, with whitening, anti-wrinkle and UV-protection groups and a codex of authorised ingredients. A 2016 study by a Korean provincial public-health laboratory measured adenosine, alongside whitening ingredients, in 100 market samples of functional cosmetics and found the levels within the authorised concentrations (Jeon et al., International Journal of Cosmetic Science, PMID 26564311).

That is the likeliest reason a Korean "anti-ageing" serum carries adenosine next to its peptides: it is an ingredient the Korean system recognises for that claim. The labels do not state the reason, and the peptides themselves are not what the regulated claim rests on.

The peptides, name by name

The three serums declare 18 distinct peptide INCI names between them, plus two (tripeptide-1, dipeptide-2) whose names also match longer ones in a literature search, so their counts would mislead. We searched PubMed for each name as a quoted phrase on 4 October 2026 and read PubMed's "phrase not found" warning.

Peptide (INCI name) In which serum PubMed records under this name
Acetyl hexapeptide-8 (Argireline) COSRX 6 Peptide; COSRX Blue; medicube 25
Copper tripeptide-1 (GHK-Cu) all three 10
Palmitoyl tetrapeptide-7 medicube 6
Palmitoyl tripeptide-8 COSRX 6 Peptide 5
Palmitoyl pentapeptide-4 (Matrixyl) medicube 5
Hexapeptide-11 medicube 5
Nonapeptide-1 medicube 4
Oligopeptide-1 medicube 3
Palmitoyl tripeptide-1 medicube 3
Oligopeptide-68 COSRX 6 Peptide 2
Palmitoyl hexapeptide-12 medicube 2
Acetyl tetrapeptide-3 medicube 1
sh-Polypeptide-121 COSRX 6 Peptide 0 (not found)
Dipeptide diaminobutyroyl benzylamide diacetate (SYN-AKE) COSRX 6 Peptide; COSRX Blue 0 (not found)
Acetyl hexapeptide-1 COSRX Blue 0 (not found)
Acetyl heptapeptide-4 COSRX Blue 0 (not found)
Acetyl octapeptide-3 (SNAP-8) COSRX Blue 0 (not found)
Arginine/lysine polypeptide medicube 0 (not found)

Six of the 18 return no record under their INCI name. That is a statement about the public literature under that name, not proof that no data exist: SYN-AKE and SNAP-8 are indexed under their trade names, which our SYN-AKE and SNAP-8 pages count, and suppliers hold unpublished studies. The best-documented peptide on all three labels, Argireline, has 25 records under its INCI name.

For comparison, a PubMed search for niacinamide and skin returned 144 records tagged as randomized controlled trials on the same day. On all three labels, niacinamide sits higher than every peptide.

What position shows, label by label

  • COSRX The 6 Peptide Skin Booster Serum lists its six peptides as one block at 7 to 12, directly after niacinamide. Our full analysis of it found that one of the six, sh-polypeptide-121, is a collagen fragment.
  • COSRX The Blue Peptide Bakuchiol Plump Glow Serum puts copper tripeptide-1, which the brand describes as "naturally blue-hued", at 11th. Its other five peptides sit from 24th to 39th, below adenosine (21st) and disodium EDTA (20th); bakuchiol, the other ingredient in its name, is 14th.
  • medicube Hyaluronic Multi Peptide PDRN Serum lists 13 peptide names from 33rd to 46th, after adenosine (15th), disodium EDTA (16th), sodium DNA (25th) and a collagen extract (36th). Its page leads with peptides and hyaluronic acid; by position, the hyaluronic-acid forms are spread from 10th to 53rd and the DNA sits above every peptide. Our PDRN serum census reads the DNA side of products like this one, and our medicube PDRN Pink Peptide Serum analysis covers the brand's other peptide serum.

How to read a Korean peptide serum label

  • Count the peptides, then find the first one. A long list of peptides in the second half of the label is not the same as one peptide near the top.
  • Look for niacinamide and adenosine. On these three labels they sit higher than most or all of the peptides, and both have larger published records.
  • Check the name against its literature. An unfamiliar INCI name with no published record is common in this category; our guide to reading a peptide ingredient list covers trade names and synonyms.

For the category as a whole, see our peptide serum guide and what peptides do for skin. For the expression-line peptides that recur on Korean labels, see Argireline and Matrixyl. For the copper peptide, see copper peptides.

Sources

  • COSRX, product pages for The 6 Peptide Skin Booster Serum and The Blue Peptide Bakuchiol Plump Glow Serum, ingredient lists, cosrx.com, read 4 October 2026.
  • medicube, Hyaluronic Multi Peptide PDRN Serum product page, ingredient list, medicube.us, read 4 October 2026.
  • Jeon JS et al. Simultaneous determination of water-soluble whitening ingredients and adenosine in different cosmetic formulations by HPLC-DAD. International Journal of Cosmetic Science 2016 (PMID 26564311).
  • PubMed E-utilities, 4 October 2026: each peptide INCI name above as a quoted phrase, with the quotedphrasesnotfound field read; niacinamide AND skin AND "randomized controlled trial"[pt] (144).
  • US Code of Federal Regulations, 21 CFR 701.3(f)(2).

Frequently asked questions

What makes a peptide serum 'Korean'?

Only the brand's origin; there is no regulated category. On the three labels we read, the shared pattern is a multi-peptide blend (6, 6 and 13 peptides) beside niacinamide near the top of the list and adenosine further down. Adenosine is one of the ingredients recognised in South Korea's regulated anti-wrinkle 'functional cosmetics' category, which helps explain why it recurs.

Why do Korean serums contain so many peptides?

The labels show it but do not explain it. Two of the three serums we read declare six peptides and one declares 13. Listing many peptides is a formulation and marketing choice; none of the three brands publishes the amount of any peptide, and in the 13-peptide serum every peptide sits in the second half of the list.

Why is adenosine in Korean peptide serums?

South Korea's Cosmetics Act treats anti-wrinkle products as functional cosmetics, a regulated category with authorised ingredients, and adenosine is among the ingredients a 2016 Korean market survey measured as authorised in it. All three serums we read declare adenosine. The peptides themselves are not what qualifies a product for that claim.

Are the peptides in Korean serums well studied?

Unevenly. Of 18 distinct peptide names across the three labels, six had no PubMed record under that name on 4 October 2026, and most of the rest had between one and ten. Acetyl hexapeptide-8 (Argireline) had the most, with 25 under that name. Niacinamide, on all three labels above the peptides, has a far larger trial record.

Is a Korean peptide serum different from any other peptide serum?

Not by ingredient class: the peptides on these labels — Argireline, copper tripeptide-1, palmitoyl pentapeptide-4 (Matrixyl) — are the same ones used by Western brands. The differences on the labels we read are the number of peptides listed and the recurring adenosine.