Bark and leaves: antioxidants and matrix protection in skin cells
LaboratoryLeaf and bark extractsHuman fibroblasts and keratinocytesCollagenase, hyaluronidase, elastase
Both extracts strongly reduce reactive oxygen species and pro-inflammatory cytokines. Only the bark extract clearly inhibits collagenase and elastase. Tannins dominate in both parts, the leaf adds flavonoids4.
A bark extract and its lead molecule, to qualify after passing through the microbiota
LaboratoryAqueous bark extract, hamamelitanninSkin microbiota ex vivoSkin cells and Staphylococcus aureus
The extract and hamamelitannin support keratinocyte migration in a lab test; the minimum inhibitory concentration against S. aureus is 0.5 mg/mL for the extract. But ellagic acid, the main metabolite formed by the skin microbiota, stimulates the release of inflammatory mediators by fibroblasts5.
A witch hazel formula tested ex vivo
LaboratoryFormula based on witch hazel extractsEx vivo skin modelsCytokines, barrier markers, oxidative stress
The formula reduces IL-6 and IL-8, improves barrier markers (loricrin, transglutaminase-1) and lowers the markers of UV-induced oxidative stress. Study by a manufacturer on a complete formula: it does not say what the extract does alone11.
A relatively weak antimicrobial activity
Clinical trial90% witch hazel distillate and 5% urea15 healthy volunteers, occlusion and extended flora test
The product shows significant antimicrobial activity in the extended flora test. Compared with chlorhexidine, that of witch hazel and urea remains relatively weak8.
Many in vitro and in vivo studies, few clinical trials
Review2025 reviewBark and leavesCosmetic and dermatological use
The review reports antimicrobial, antioxidant and UV and pollution protection activities, verified in vitro, in vivo and in limited clinical trials3.