Carnosic acid in topical rosemary extract enhances skin repair via TRPA1 activation
Emmanuel Rapp, Jiayi Pang, Borna Saeednia, Stephen Marsh Prouty, Christopher A. Reilly, Thomas H. Leung
Emmanuel Rapp, Jiayi Pang, Borna Saeednia, Stephen Marsh Prouty, Christopher A. Reilly, Thomas H. Leung
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Research Article Dermatology Inflammation

Carnosic acid in topical rosemary extract enhances skin repair via TRPA1 activation

Abstract

Mammalian skin wounds typically heal with a scar, characterized by fibrotic tissue that disrupts original tissue architecture and function. Therapies that limit fibrosis and promote regenerative healing remain a major unmet clinical need. Rosemary extract, particularly in the form of topical oils and creams, has gained widespread public attention for its purported wound-healing properties. However, its efficacy and mechanism of action remain poorly understood. We show in adult wound healing mouse models that an ethanol-based rosemary extract accelerates the speed of wound healing and mitigates fibrosis. Mechanistically, we identify that carnosic acid, a major bioactive component of rosemary leaves, activates the transient receptor potential ankyrin 1 (TRPA1) nociceptor on cutaneous sensory neurons to enhance tissue regeneration. Mice lacking TRPA1 in sensory neurons do not exhibit these pro-regenerative responses, confirming its role as a critical mediator. Together, these findings suggest that topical rosemary extract may represent an effective and accessible therapeutic approach to improve skin repair outcomes.

Authors

Emmanuel Rapp, Jiayi Pang, Borna Saeednia, Stephen Marsh Prouty, Christopher A. Reilly, Thomas H. Leung

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Figure 3

Topical carnosic acid cream promotes cutaneous mouse ear wound regeneration.

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Topical carnosic acid cream promotes cutaneous mouse ear wound regenerat...
(A) Representative photographs of vehicle control cream-, rosemary cream-, or carnosic acid cream-treated WT ears. Dotted circle represents original 2 mm hole punch size. Black scale bar represents 2 mm. (B) Percentage of wound closure in vehicle control cream- (solid black line, n = 12), rosemary cream-treated (solid green line, n = 12), or carnosic acid cream-treated (dotted red line, n = 14) WT mouse ears. Two-way ANOVA. (C) H&E-stained representative tissue sections from vehicle control cream- and carnosic acid cream-treated WT mouse ears. Distance between opposing cartilage endplates is marked. Black scale bar represents 0.5 cm. (D) Bar plot quantifying cartilage endplate distance in between control- and carnosic acid cream-treated WT mouse ears (C = control, CA = carnosic acid). Student’s t test 2-tailed and unpaired. (E) Representative H&E-stained or PSR-stained images of WT mouse ears treated with vehicle control cream, rosemary cream, or carnosic acid cream. (F) Bar plot quantifying fibrosis by PSR stain at the wound edge tissue from vehicle control cream-, rosemary cream-, or carnosic acid cream-treated WT mouse ears (C = control, R = rosemary, CA = carnosic acid). Student’s t test 2-tailed and unpaired. Data are presented as mean ± SEM. **P < 0.01, ****P < 0.0001.