Wound healing can be delayed following colonization and infection with the common bacterium Pseudomonas aeruginosa. While multiple therapies are used for their treatment, these are ineffective, expensive, and labour-intensive. Thus, there is an enormous unmet need for the treatment of infected wounds. Cinnamaldehyde, the major component of cinnamon oil, is well known for its antimicrobial properties. Herein, we investigated the effects of sub-inhibitory concentrations of cinnamaldehyde in the virulence of P. aeruginosa. We also assessed its healing potential in P. aeruginosa-infected mouse skin wounds and the mechanisms involved in this response. Sub-inhibitory concentrations of cinnamaldehyde reduced P. aeruginosa metabolic rate and its ability to form biofilm and to cause haemolysis. Daily topical application of cinnamaldehyde on P. aeruginosa-infected skin wounds reduced tissue bacterial load and promoted faster healing. Lower interleukin-17 (IL-17), vascular endothelial growth factor (VEGF) and nitric oxide levels were detected in cinnamaldehyde-treated wound samples. Blockage of transient receptor potential ankyrin 1, the pharmacological target of cinnamaldehyde, abrogated its healing activity and partially reversed the inhibitory actions of this compound on VEGF and IL-17 generation. We suggest that topical application of sub-inhibitory concentrations of cinnamaldehyde may represent an interesting approach to improve the healing of P. aeruginosa-infected skin wounds.

Severe wounds result in large lesions and/or loss of function of the affected areas. The treatment of wounds has challenged health professionals due to its complexity, especially in patients with chronic diseases (such as diabetes), and the presence of pathogens such as Staphylococcus aureus and Pseudomonas aeruginosa. Taking this into consideration, the development of new therapies for wound healing requires immediate attention. Ethnopharmacological studies performed in different countries have shown the use of several plants from the Asteraceae family as wound-healing agents. Evidences gained from the traditional medicine have opened new ways for the development of novel and more efficient therapies based on the pharmacological properties of these plants. In this article, we discuss the literature data on the use of Asteraceae plants for the treatment of wounds, based on the ethnopharmacological relevance of each plant. Special attention was given to studies showing the mechanisms of action of Asteraceae-derived compounds and clinical trials. Ageratina pichinchensis (Kunth) R.M. King and H. Rob. and Calendula officinalis L. preparations/compounds were found to show good efficacy when assessed in clinical trials of complicated wounds, including venous leg ulcers and foot ulcers of diabetic patients. The compounds silibinin [from Silybum marianum (L.) Gaertn.] and jaceosidin (from Artemisia princeps Pamp.) were identified as promising compounds for the treatment of wounds. Overall, we suggest that Asteraceae plants represent important sources of compounds that may act as new and efficient healing products.