Prequel Lucent-C 15% Vitamin C Serum Review | LEITIN

November 1, 2026

FORMULA NOTES / VITAMIN C

Prequel Lucent-C Brightening Vitamin C Serum

A closer look at 15% ascorbic acid, its supporting ingredients and who the formula might suit.

A formulation-based review

Full ingredient list (INCI)

water (aqua), propanediol, ascorbic acid, ethoxydiglycol, isopentyldiol, ferulic acid, ergothioneine, inulin, niacinamide, hydroxyacetophenone, aminomethyl propanol, 1,2-hexanediol, caprylyl glycol, mannitol

Source: Official product information, checked 1 November 2026. Check your packaging for formula changes.

Packaging image · Prequel

The focus

Dullness & uneven-looking tone

The format

30 mL aqueous serum

Price snapshot

US$23United States official store · checked 1 Nov 2026

Worth knowing

Brand advises against use on sensitive skin

Product	Formulation Rating	Value Rating	Overall Rating
PrequelLucent-C Brightening Vitamin C Serum15% L-ascorbic acid≈ A$32.67 · 30 mL	4.17★★★★★ ★★★★★Antioxidant ★★★★★Pigment Signalling ★★★★★Hydration	5★★★★★ converted priceA$10.89 per 10 mL; concentration-adjusted component uses 15% L-ascorbic acid.	4.59★★★★★

View the full comparison of 15 vitamin C serums

Vitamin C with ferulic acid and ergothioneine

Lucent-C takes a different supporting-antioxidant approach: 15% L-ascorbic acid sits alongside ferulic acid and ergothioneine, without listed vitamin E. Niacinamide, inulin and water-binding ingredients broaden the supporting design.

Who might it suit?

Dullness and uneven-looking tone: for someone seeking a disclosed ascorbic acid treatment.
A lightweight routine: suitable for people who prefer a thin serum under moisturiser.
Antioxidant-focused care: a supporting step alongside daily sunscreen, not a substitute for it.

The brand does not recommend this serum for sensitive skin. Introduce gradually and stop if persistent irritation develops. Official product information.

What does the 15% refer to?

The disclosed 15% refers to L-ascorbic acid, the unmodified form of vitamin C. It is not a combined vitamin C complex or a derivative percentage. Supporting ingredient levels are not all disclosed, so their concentrations cannot be calculated from INCI order. Official product information.

Listed pH: Approximately 3.2.

Ingredients grouped by function

Ingredients are grouped by their estimated primary role in this formula; some ingredients have more than one function.

Function	Ingredients	Role in formula
Function: Primary Actives	Ingredients: ascorbic acid, niacinamide	Role in formula: Ascorbic acid anchors antioxidant and tone support; niacinamide contributes a secondary skin-conditioning role.
Function: Antioxidants	Ingredients: ferulic acid, ergothioneine	Role in formula: Ferulic acid and ergothioneine provide complementary antioxidant roles.
Function: Humectants & Hydration Actives	Ingredients: propanediol, isopentyldiol, inulin, mannitol	Role in formula: Propanediol, isopentyldiol, inulin and mannitol support water binding and conditioning.
Function: Solvents	Ingredients: water (aqua), ethoxydiglycol	Role in formula: The aqueous solvent system supports dissolution and application.
Function: Preservatives & Antimicrobial Agents	Ingredients: hydroxyacetophenone, 1,2-hexanediol, caprylyl glycol	Role in formula: Multifunctional ingredients support preservation; hydroxyacetophenone also has antioxidant functions.
Function: pH Adjusters / Buffers	Ingredients: aminomethyl propanol	Role in formula: Adjusts the acidic formula’s pH.

The key ingredients, explained

Ingredient	What it contributes
Ingredient: L-ascorbic acid · 15%	What it contributes: The central antioxidant ingredient and a cofactor in collagen-related biology. Topical performance still depends on the vehicle and stability.
Ingredient: Ferulic acid	What it contributes: A complementary phenolic antioxidant. Inclusion supports the design rationale without proving the exact synergy of a different tested formula.
Ingredient: Ergothioneine	What it contributes: A distinct antioxidant with skin-model research; the exact concentration and finished-product contribution are not disclosed.
Ingredient: Niacinamide	What it contributes: Secondary tone and skin-conditioning rationale. Its presence does not establish the results of a known-percentage niacinamide product.
Ingredient: Inulin and mannitol	What it contributes: Supporting humectant and conditioning roles; no finished-product microbiome claim is inferred.

Ergothioneine adds a distinct antioxidant role

The formula combines ascorbic acid with two different antioxidant companions rather than simply repeating a C-and-E arrangement. Niacinamide contributes a plausible secondary tone and barrier-support role, but its undisclosed level does not justify transferring results from a known-percentage niacinamide trial. Inulin and mannitol support the water-based system; a prebiotic ingredient does not by itself demonstrate a changed skin microbiome.

Reading the claims carefully

The brand reports an eight-week study in 31 women, with instrumental assessments and participant questionnaires. It reports radiance findings at four weeks and firmness findings at eight weeks; the full protocol and comparator are not available in the summary. The official page advises use within three months of opening and says this high-potency serum is not intended for sensitive skin. Supporting active concentrations are not confirmed on the reviewed current page. Official product information.

What published vitamin C research tells us

These studies examined other formulations; they support ingredient rationale, not a claim that this serum has the same measured results.

Topical vitamin C and photoaged skin

A six-month placebo-controlled study of 5% vitamin C cream reported improvements in skin-surface and clinical measures. It used a different vehicle and concentration. Humbert et al., 2003.

Ascorbic acid and facial skin texture

A three-month split-face trial in 19 evaluable participants found improvements with another commercial serum versus vehicle. Its small sample and limited skin-type range constrain generalisation. Traikovich, 1999.

Our assessment

Lucent-C offers a disclosed ascorbic acid concentration with complementary ferulic acid and ergothioneine, plus niacinamide. At the comparison snapshot price of US$23 for 30 mL, it is approximately A$32.67, or A$10.89 per 10 mL. This gives it a 5-star Value Rating for its low converted product cost and disclosed 15% L-ascorbic acid, rather than proof that it delivers the best clinical results.

The AUD estimate uses the RBA exchange rate of 30 October 2026 and excludes shipping, import charges and currency fees. The brand’s sensitive-skin warning matters more than the appealing ingredient list if acidic products are poorly tolerated.

This serum earns an Overall Rating of 4.59 stars in our comparison of 15 ascorbic acid vitamin C serums.

Prices use the comparison snapshot of 1 November 2026; temporary promotions are excluded. Ratings are editorial assessments of formulation potential and value, not measured clinical outcomes.