Anti-Inflammatory and Anti-Acne Effects of Hamamelis virginiana Bark in Human Keratinocytes

Abstract

Cutibacterium acnes (C. acnes) is recognized as one of the main triggers of the cutaneous inflammatory response in acne vulgaris, a chronic skin disorder with a multifactorial origin. Witch hazel (Hamamelis virginiana L.) is a plant widely used for skin inflammatory conditions, with some preliminary anti-inflammatory evidence on the skin, but lacking data on acne conditions. This study aimed to evaluate the effect of a glycolic extract from Hamamelis virginiana bark (HVE) versus C. acnes-induced inflammation in human keratinocytes (HaCaT). Phytochemical investigations of HVE identified hamamelitannin (HT) and proanthocyanidins as the most abundant compounds (respectively, 0.29% and 0.30% w/wextract). HVE inhibited C. acnes-induced IL-6 release (IC50: 136.90 μg/mL), by partially impairing NF-κB activation; however, no antibacterial or antibiofilm activities were found. In addition, HVE showed greater anti-inflammatory activity when TNF-α was used as a proinflammatory stimulus (IC50 of 38.93 μg/mL for IL-8 release), partially acting by antioxidant mechanisms, as shown for VEGF inhibition. The effects of HVE are primarily based on the proanthocyanidin content, as HT was found inactive on all the parameters tested. These results suggest further investigations of HVE in other inflammatory-based skin diseases.

Unveiling the Ability of Witch Hazel (Hamamelis virginiana L.) Bark Extract to Impair Keratinocyte Inflammatory Cascade Typical of Atopic Eczema

“…We previously reported that the glycolic extract included in the present study (HVE) mainly contains HT (0.30%) and oligomeric proanthocyanidins (0.29%) [ 13 ]; however, pure HT (until 10 μM, roughly corresponding to 5 μg/mL) was not able to explain the inhibitory activity of HVE against C. acnes or TNF-α-induced inflammation in human keratinocytes, thus suggesting the importance of oligomeric proanthocyanidins.…”

“…In our previous research on the anti-inflammatory activity of HVE in HaCaT cells, we observed the promising inhibitory effects of hamamelis glycolic extract on several TNF-α-induced mediators [ 13 ]. Cytokines belonging to the IL-17 family are known to regulate epithelial barrier homeostasis during infections, but also to contribute in autoimmune processes, in which TNF-α plays a crucial role (for a review on the topic, refer to Pappu et al [ 30 ]).…”

“…The latter experiments also represented a valuable method to exclude that HVE may act through cytotoxic mechanisms, since the number of living cells was not significantly different from the control. The direct interference with cell viability, in the absence of IL-4 challenge, was already excluded by our previous MTT experiments [ 13 ].…”

“…HT was purchased from PhytoLab GmbH & Co. KG (Vestenbergsgreuth, Germany). We previously characterized HVE, which contains HT (0.3%) and galloylated proanthocyanidins (0.29%) as main polyphenolic compounds [ 13 ]. The STAT6 inhibitor (S6I) (compound AS1517499, Merck Life Science, Milan, Italy), apigenin (A) (Phytolab GmbH & Co. KG, Vestenbergsgreuth, Germany) and epigallocatechin-3-O-gallate (EGCG) (Phytolab GmbH & Co. KG) were used as reference compounds.…”

“…Despite the broad use of Hamamelis virginiana in topical preparations, studies involving keratinocytes are rare. We recently published an in vitro study, suggesting for the first time that a tannin-rich extract from Hamamelis virginiana may contribute to counteract skin inflammation during C. acnes infection; however, the contribution of HT was excluded [ 13 ].…”