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Centella asiatica extract
Centella is studied in skincare for hydration and the response of skin to irritation. In a small four-week study, extract-containing creams and hydrogels improved hydration and water-loss measurements and reduced redness after an experimental challenge. The interesting question is which preparation produced those effectsโnot whether every product called โcicaโ is the same.
A plant with a wider home than its skincare reputation
Centella asiatica is a perennial in the Apiaceae family. Kew records a broad native range across the Caucasus and tropical and subtropical parts of the Old World, extending to eastern Australia and the western Pacific. Its association with particular skincare traditions should not be confused with a single botanical homeland or the origin of every commercial crop.
[2]Four related molecules help explain its identity
Four characteristic centellosides are asiatic acid, madecassic acid, asiaticoside and madecassoside. The first pair are triterpenoid cores; the second pair carry attached sugar chains. Madecassic acid and madecassoside also have an additional hydroxyl group compared with their corresponding asiatic relatives.
In 2022, investigators compared 50 plant accessions grown under the same conditions for six generations. The amounts of these four constituents still varied substantially. The plant name therefore does not imply one universal molecular ratio.
[3]โGlycoside,โ without a chemistry background
A glycoside has a sugar group chemically joined to a non-sugar part. The attached sugar is part of the molecule, rather than an extra sweetener mixed into it. Joining those parts changes molecular size and the way the molecule interacts with water and other surroundings. It does not let us predict a skincare result just from the name.
The term aglycone describes the non-sugar portion. It is useful for understanding why names that look almost identical can refer to different compounds. โAsiatic acidโ and โasiaticosideโ are related, but they are not interchangeable labels.
A 2024 plant-biochemistry study identified enzymes that attach the second glucose and then rhamnose in the sugar chains of asiaticoside and madecassoside. This shows how precisely a plant builds these molecules. It is a biosynthesis finding, not a demonstration that applying an extract activates the same pathway in human skin.
[7]Extract, liquid carrier and isolated constituent
A cosmetic extract can include a delivery liquid as well as the material drawn from the plant. One documented Centella grade contains botanical concentrate dissolved in glycerin and water. Those accompanying ingredients are part of what is added to a moisturizer; the stock liquid is not pure centellosides.
This helps explain why a percentage of โextractโ is incomplete without its meaning. A large amount of a dilute liquid and a smaller amount of a concentrated dry fraction may supply quite different quantities of plant compounds. The technical description identifies a form of ingredient, not the efficacy of every cream containing it.
[4]Similarly, an isolated constituent such as madecassoside is narrower than a broad extract. A leaf water, a dried plant powder and a concentrated triterpenoid fraction also retain their own identities. It is more helpful to understand these as different preparations than to arrange them on a simplistic ladder from โnaturalโ to โprocessed.โ Processing may change composition without automatically making an ingredient better or worse.
Three human investigations, three different questions
Ratz-ลyko and colleagues followed 25 volunteers using creams and hydrogels with two extract levels on their forearms. After four weeks, the higher-level preparations gave the strongest results. The redness test used methyl nicotinate to provoke a controlled response.
Limits of the first investigation
Randomization and blinding were not clearly reported. The extraction process and starting material do not establish a final dose of each centelloside. A temporary challenge on forearms is also different from persistent facial sensitivity or a diagnosed skin condition.
A 2021 double-blind study involved 30 Indonesian batik workers with dry skin but no clinical contact dermatitis. They used either a Centella cream or a ceramide cream on hands and arms for four weeks. Both groups improved on hydration measurements, with no significant difference between the preparations in the reported comparison.
No significant difference is not proof of equivalence
This was a small occupational-skin study, not a formal demonstration that the ingredients work identically. The abstract does not supply the full extract composition or concentration. Different within-group changes also do not establish that one cream was superior on every barrier measure.
A 2026 trial randomized 80 adults with rosacea; 75 completed four weeks. A cream containing Centella, ceramide NP and panthenol was compared with a different basic moisturizer. Both groups also received oral minocycline. The combination cream produced greater hydration improvement and favorable redness changes; between-group water-loss differences were not significant.
What the combination trial actually establishes
It investigated adjunctive skincare during treatment, not Centella alone. The single-blind study had baseline age and redness differences, compared different complete formulas and was industry-funded. Five participants withdrew with possibly product-related reactions. It offers a useful formulation-level result without proving that any cica serum treats rosacea.
Follow the comparison, not just the headline
A before-and-after improvement asks whether a group changed. A comparison against a matched base asks whether adding the extract made a difference. A comparison of two different complete creams asks which preparation performed differently in that setting. These designs can all be informative, but they cannot answer exactly the same question.
The practical meaning of the research
Centellaโs appeal is not a single magic constituent. It is a family of chemically interesting preparations with some direct human evidence for hydration and irritation-related outcomes. The strongest interpretation keeps composition, vehicle and study setting connected. That gives the positive findings room to be useful without stretching them into claims about every extract, every skin condition or guaranteed tolerability.
Sources to explore
- Ratz-ลyko et al. (2016): Centella creams, hydrogels and skin measurements
- Kew: Centella asiatica identity and distribution
- Kunjumon et al. (2022): four centellosides across plant accessions
- Centella extract technical identity: botanical concentrate and liquid carrier
- Anggraeni et al. (2021): moisturizers in batik workers with dry skin
- Controlled moisturizer study in rosacea (2026)
- Han et al. (2024): enzymes that assemble Centella sugar chains
