Research explorer
Every record states its study design, sample size where reported, key finding and limitations. Where an identifier could not be verified, the entry links to a Europe PMC title search instead of asserting a PMID.
96 matching records
Notes that public independent data on hydroxypinacolone retinoate are limited relative to retinol and retinoic acid.
Limitations — Review highlighting an evidence gap rather than reporting new results.
Pooled analysis reported increased hair count versus placebo across multiple randomised trials.
Limitations — Regulated medicine; outcomes measured over 16-48 weeks; discontinuation reverses gains.
Concludes that derivative-specific human evidence is thinner than for L-ascorbic acid, with conversion efficiency the main open question.
Limitations — Review of heterogeneous small studies; identifier not verified during curation.
Reported comparable improvement in wrinkle and pigmentation scores between bakuchiol and retinol, with less scaling and stinging reported for bakuchiol.
Limitations — Single centre, 12 weeks, no vehicle arm, so both may reflect regression to the mean.
Pooled analysis reported reductions in melasma severity scores, with substantial heterogeneity between studies.
Limitations — High heterogeneity, varied vehicles and concentrations, mostly small trials.
Concludes that human topical data remain limited and heterogeneous despite consistent antioxidant activity in cell models.
Limitations — Review of small, mostly non-randomised studies; identifier not verified during curation.
Summarises the NAD salvage route in which nicotinamide is converted by NAMPT and NMNAT enzymes to NAD+, supporting redox and signalling functions.
Limitations — Review of mechanism, largely non-cutaneous; does not evaluate topical delivery.
Summarises concentration-dependent behaviour of urea, humectant at low percentages and keratolytic at higher percentages.
Limitations — Narrative review without quantitative synthesis.
Summarises evidence that skin expresses melatonin-pathway enzymes and receptors, and that melatonin scavenges reactive species in cutaneous models.
Limitations — Review; controlled cosmetic endpoints in humans are sparse.
Summarises melatonin receptor expression in skin and reported antioxidant and mitochondrial protective activity.
Limitations — Review; topical human endpoints sparse; identifier not verified during curation.
Reported direct retinoic acid receptor binding for the ester, in contrast to retinol which requires cutaneous conversion.
Limitations — Binding assays only; no controlled human comparison against retinol; identifier not verified during curation.
Reported similar pigmentation improvement between the two acids, with fewer irritation events in the mandelic acid arm.
Limitations — Small, unblinded, investigator-graded; identifier not verified during curation.
Reported faster transepidermal water loss recovery with a ceramide-dominant formulation compared with a control emollient.
Limitations — Short duration; identifier not verified during curation.
Found supporting evidence only in cases of underlying biotin deficiency; no evidence of benefit in non-deficient individuals.
Limitations — Review of a small literature; few controlled trials exist.
Found that reported benefits cluster in patients with an underlying biotin deficiency, with no good evidence in unaffected people.
Limitations — Review of low-quality case series; identifier not verified during curation.
Establishes linoleate as required for omega-O-acylceramide formation, with PNPLA1 mediating the transfer step.
Limitations — Review of genetic and animal evidence; topical repletion effects less characterised.
Summarises long-standing topical use with limited modern controlled data on mechanism.
Limitations — Sparse controlled evidence; mechanism partly unresolved.
Reported improved hydration and reduced roughness with an allantoin-containing emollient, without isolating the ingredient.
Limitations — Multi-ingredient formulation prevents attribution; identifier not verified during curation.
Reported consistent reduction in inflammatory lesion counts versus vehicle, with dose-related local irritation.
Limitations — Heterogeneous trials and concentrations; identifier not verified during curation.
Summarises RAR/RXR heterodimer signalling as the transcriptional mechanism of retinoid action in epidermis and dermis.
Limitations — Narrative review; mechanistic focus without effect-size synthesis.
Summarises reported effects of GHK and GHK-Cu on matrix protein and antioxidant gene expression in cell and animal models.
Limitations — Review with substantial single-group authorship; human cosmetic endpoints sparse.
Describes squalene as readily oxidised in sebum, whereas the saturated squalane form is oxidation-resistant and functions as an emollient.
Limitations — Review; largely physicochemical rather than biological endpoints.
Summarises matrikine signalling in which collagen-fragment peptides are reported to stimulate matrix synthesis in fibroblast models.
Limitations — Review of pre-clinical work; human topical evidence limited; identifier not verified during curation.
Summarises declining CoQ10 with age and reported restoration of respiratory-chain activity in supplemented cell models.
Limitations — Review of cell and supplementation studies; topical penetration uncertain; identifier not verified during curation.
Summarises how hyaluronan fragment size determines CD44 signalling outcomes, with high and low molecular weight forms behaving differently.
Limitations — Mechanistic review; largely non-topical models.
Reported association between follicular SULT1A1 activity and clinical response to topical minoxidil.
Limitations — Observational association; identifier not verified during curation.
Reported retinoid-like changes in collagen and matrix gene expression without direct retinoic acid receptor binding.
Limitations — Cell and ex-vivo models, industry-affiliated; identifier not verified during curation.
Reported prolonged anagen-phase markers in cultured human hair follicles exposed to caffeine.
Limitations — Organ-culture model, small follicle numbers; identifier not verified during curation.
Reported increased corneometry readings shortly after application, attributed to a hygroscopic surface film.
Limitations — Short measurement window, no long-term barrier endpoints; identifier not verified during curation.
Reported rapid oxidative degradation of L-ascorbic acid at neutral pH, mitigated by low pH and antioxidant co-formulation.
Limitations — Formulation chemistry only; no biological endpoints.
Reported small improvements in wrinkle depth versus vehicle, with overlapping confidence intervals on several endpoints.
Limitations — Small effect size; identifier not verified; peptide not isolated from other actives in the formulation.
Reported increased anagen hair ratio and thick hair rate compared with control lotion.
Limitations — Small sample; industry-sponsored; identifier not verified during curation.
Reported no detectable increase in skin ageing over 4.5 years in the daily sunscreen group compared with discretionary use.
Limitations — Sunscreen formulation was not zinc-oxide-specific; outcome assessed by microtopography of the hand.
Reported reduced melasma severity scores with a kojic-acid-containing combination versus its comparator over 12 weeks.
Limitations — Combination product prevents attribution to kojic acid alone; identifier not verified during curation.
Reported no detectable increase in skin ageing in the daily-sunscreen group over 4.5 years, unlike the discretionary-use group.
Limitations — Broad-spectrum sunscreen rather than zinc oxide specifically; identifier not verified during curation.
Reported reduced plasmin-dependent signalling to melanocytes in co-culture after tranexamic acid exposure.
Limitations — Cell model; identifier not verified during curation.
Reported improved formulation stability for magnesium ascorbyl phosphate but slower and variable conversion to free ascorbate in skin models.
Limitations — Formulation and ex-vivo delivery only; no clinical endpoints.
Reported upregulation of collagen and decorin transcripts in fibroblast culture after GHK-Cu exposure.
Limitations — Cell culture only; author affiliation with peptide commercialisation; identifier not verified during curation.
Summarises filaggrin proteolysis as the source of pyrrolidone carboxylic acid and its contribution to corneocyte water binding.
Limitations — Review; does not evaluate topical sodium PCA products; identifier not verified during curation.
Characterises nicotinamide as a weak product inhibitor of PARP enzymes in cell-free assays.
Limitations — Biochemical assay; inhibitory concentrations far above physiological skin levels.
Reported increased corneometry-measured hydration and reduced wrinkle depth versus baseline over 8 weeks.
Limitations — Instrumental surrogate endpoints; identifier not verified during curation.
Reported reduced UV-induced MMP-9 expression in treated skin equivalents.
Limitations — Skin equivalent model; identifier not verified; human endpoints lacking.
Establishes CLEC7A/dectin-1 as the principal receptor for beta-1,3-glucans in innate immune recognition.
Limitations — Immunology review; cosmetic topical endpoints not addressed.
Reported SIRT1-associated changes in oxidative-stress markers in fibroblast culture after resveratrol exposure.
Limitations — In-vitro only, supraphysiological concentrations; identifier not verified during curation.
Summarises efficacy in melasma alongside reported risks including exogenous ochronosis and the resulting regulatory restrictions.
Limitations — Review; regulatory status varies by region and changes over time; identifier not verified during curation.
Describes lipophilic partitioning into sebaceous follicles and reduced corneocyte cohesion as the principal described mechanisms.
Limitations — Review; mechanistic detail at the protein level remains incomplete.
Reported that apparent SIRT1 activation by resveratrol depends on the fluorophore-labelled substrate used in the assay.
Limitations — Biochemical; cautions against over-interpretation of resveratrol as a direct sirtuin activator.
Reported increased collagen deposition and faster wound closure in a rodent model.
Limitations — Animal wound model; not equivalent to intact cosmetic use; identifier not verified.
Summarises reported collagen and matrix effects for asiaticoside and madecassoside across animal and cell models.
Limitations — Extracts vary in composition; mostly animal data; identifier not verified during curation.
Summarises preferential-hydration mechanisms by which ectoine stabilises membranes and proteins under stress.
Limitations — Biophysical review, not cutaneous; identifier not verified during curation.
Reported reduced IL-8 release and NF-kB reporter activity in stimulated keratinocytes exposed to purified avenanthramides.
Limitations — Purified compounds at defined concentrations, unlike commercial extracts; identifier not verified during curation.
Reported reduced water loss across model membranes attributed to a compatible, non-polar occlusive film.
Limitations — Model membranes, not human skin; identifier not verified during curation.
Demonstrates that filaggrin proteolysis by caspase-14 and downstream enzymes generates pyrrolidone carboxylic acid and urocanic acid.
Limitations — Ex-vivo/in-vitro; identifier not verified during curation.
Reported reduced sebocyte lipid accumulation with zinc salts, including 5-alpha reductase inhibition in cell assays.
Limitations — Cell model; identifier not verified; concentration relevance unclear.
Reported increased thick-hair ratio with topical adenosine, with associated FGF7 expression changes in dermal papilla cells.
Limitations — Small, largely single-centre; identifier not verified during curation.
Summarises evidence that AQP3 transports both water and glycerol, linking glycerol to stratum corneum hydration.
Limitations — Mechanistic review including mouse knockout data; identifier not verified during curation.
Reported improvement in fine wrinkling with topical retinol versus vehicle in older adults.
Limitations — Small sample; older cohort limits generalisation; identifier not verified during curation.
Reported counteraction of testosterone-suppressed hair shaft elongation in ex-vivo follicle culture.
Limitations — Organ culture; topical delivery to the follicle in vivo not established; identifier not verified.
Reported reduced UVA-induced signalling and membrane damage in ectoin-treated keratinocytes.
Limitations — Cell model; identifier not verified during curation.
Reported interference with SNARE complex assembly in a cell-free and neuronal model system.
Limitations — Non-cutaneous model; topical delivery to neuromuscular junctions not demonstrated; identifier not verified during curation.
Reported reduced UV-induced erythema and inflammatory infiltrate markers in biopsies from polyphenol-treated sites.
Limitations — Small, short-duration, single-centre; identifier not verified during curation.
Reported greater aqueous stability than L-ascorbic acid and glucosidase-dependent release of free ascorbate in skin homogenates.
Limitations — Homogenate model may overstate in-vivo conversion; identifier not verified during curation.
Summarises reported anti-inflammatory activity of avenanthramides alongside the occlusive and buffering effects of the whole extract.
Limitations — Review; extract composition is variable between products; identifier not verified during curation.
Summarises hydroquinone as historically the most effective topical depigmenting agent, with dose-related irritation and ochronosis concerns.
Limitations — Review; regulatory status varies widely by jurisdiction.
Reported improvements in several appearance endpoints including fine lines and skin texture over 12 weeks of use versus vehicle.
Limitations — Manufacturer-affiliated authorship; appearance endpoints partly investigator-graded.
Reported improved formulation stability and increased measured photoprotection for a C/E/ferulic combination on human skin.
Limitations — Very small sample; surrogate photoprotection endpoints; industry-affiliated.
Reported increased collagen I and fibronectin expression in treated fibroblast cultures.
Limitations — In-vitro; identifier not verified; no dermal delivery data.
Reported improvement in dryness and itch scores, with penetration of the polysaccharide into the upper epidermis described in accompanying imaging.
Limitations — Small sample, manufacturer-supported; identifier not verified during curation.
Reported dose-dependent reduction of melanin content in cultured melanocytes.
Limitations — In-vitro only; hydroquinone release in skin not quantified; identifier not verified.
Reported stronger tyrosinase inhibition for the alpha isomer than the beta isomer in enzyme assays.
Limitations — Enzyme assay only, no skin model; identifier not verified during curation.
Reported rapid decomposition to benzoic acid with radical-mediated, non-selective antibacterial activity and no observed resistance selection.
Limitations — Microbiological models; identifier not verified during curation.
Establishes the approximately equimolar ceramide/cholesterol/free fatty acid composition required for competent lamellar barrier structure.
Limitations — Review; ratio requirements derived largely from animal and ex-vivo models.
Reported modest improvement in photoaging scores versus vehicle on half-face assessment.
Limitations — Small sample; identifier not verified; subjective grading.
Reported reduced corneocyte cohesion and increased desquamation with salicylic acid exposure in isolated stratum corneum.
Limitations — Ex-vivo tissue only; identifier not verified during curation.
Reported modest improvement in photoageing severity scores versus vehicle over 12 weeks.
Limitations — Single trial, partly subjective endpoints; identifier not verified during curation.
Reported reduced hyperpigmentation with topical niacinamide, and reduced melanosome transfer to keratinocytes in an accompanying co-culture model.
Limitations — Small sample, short duration, split-face design without long-term follow-up.
Reported improvement in investigator-assessed photoaging scores on the vitamin C treated side.
Limitations — Very small sample; identifier not verified during curation; formulation stability not reported.
Aquaporin-3 null mice showed reduced stratum corneum glycerol and impaired hydration, restored by glycerol administration.
Limitations — Animal knockout model; identifier not verified during curation.
Reported interference with SNAP-25 dependent complex formation in a cell-free system.
Limitations — Cell-free system; cutaneous penetration to neuromuscular junctions not demonstrated.
Reported faster barrier recovery measured by transepidermal water loss compared with vehicle after sodium lauryl sulfate challenge.
Limitations — Experimental irritation model; identifier not verified during curation.
Reported faster recovery of transepidermal water loss after sodium lauryl sulfate irritation with dexpanthenol versus vehicle.
Limitations — Experimental irritation model rather than clinical disease; identifier not verified during curation.
Reported increased epidermal thickness and improved texture scores on the treated side after a series of glycolic acid applications.
Limitations — Small sample, investigator-graded endpoints; identifier not verified during curation.
Reported increased ceramide and free fatty acid synthesis in keratinocyte culture after niacinamide exposure.
Limitations — In-vitro only; concentrations may not reflect in-use exposure.
Reported increased procollagen I expression and reduced MMP-1 in biopsied retinoid-treated skin.
Limitations — Biopsy-based surrogate endpoints; identifier not verified during curation.
Reported measurable CoQ10 in epidermal layers and reduced oxidation markers after supplementation in vitro.
Limitations — In-vitro; identifier not verified during curation.
Summarises evidence that retinaldehyde is oxidised in skin to retinoic acid, with reported tolerability intermediate between retinol and tretinoin.
Limitations — Narrative review; identifier not verified during curation.
Reported preferential RAR-beta and RAR-gamma binding with associated changes in keratinocyte differentiation markers.
Limitations — Cell models only; identifier not verified during curation.
Reported reduced corneocyte cohesion and increased epidermal thickness after repeated glycolic acid application.
Limitations — Historical study; identifier not verified during curation; pH and concentration not standardised across arms.
Reported increased epidermal ceramide production after lactic acid exposure in a skin model.
Limitations — In-vitro; stereoisomer-specific effects incompletely characterised; identifier not verified.
Reported that only balanced ceramide/cholesterol/fatty acid mixtures accelerated barrier recovery; incomplete mixtures delayed it.
Limitations — Animal model; identifier not verified during curation.
Summarises reported tyrosinase inhibition and a described preference for abnormal, hyperactive melanocytes over normal ones.
Limitations — Review, largely pre-clinical mechanism; identifier not verified during curation.
Reported comparable lesion-count reduction with adapalene and tretinoin, with less irritation in the adapalene group.
Limitations — Acne endpoints only, not photoageing; identifier not verified during curation.
Characterises kojic acid inhibition of tyrosinase through chelation of active-site copper ions.
Limitations — Enzyme assay only; no cutaneous endpoints; identifier not verified.
Establishes ascorbate as an obligatory cofactor for prolyl and lysyl hydroxylases in collagen maturation.
Limitations — Nutritional/biochemical focus rather than topical cosmetic use.
Reported competitive tyrosinase inhibition with greater effect on hyperactive melanocytes than normal melanocytes.
Limitations — In-vitro; selectivity claim not confirmed in later human work; identifier not verified.
Reported statistically significant improvement in photoaging endpoints with tretinoin versus vehicle.
Limitations — Small sample; prescription-strength retinoid, not a cosmetic retinol.