Could essential oils enhance biopolymers performance for wound healing? A systematic review

Background: Millions of people in the world suffer from chronic wounds of different etiologies such as diabetic foot and leg ulcers, without solutions nowadays. Molecules obtained from plants offer an alternative to aid wound healing. Strong evidence about essential oils (EO) anti-inflammatory and antimicrobial properties is thoroughly described in literature and their chemical compositions are well characterized. More recently, EO effects in experimental wounds have begun to be analyzed. Aim: We aim to summarize the evidence of EO in experimental wounds, and the possibility of combining them with biopolymers commonly used in skin regeneration. Methods: Electronic databases such as ScienceDirect, PubMed and Scopus were used to search scientific contributions until March 2017, using relevant keywords. In a first step, literature focusing on EO and/or mono-or sesqui-terpenoids effects in rodent wounds was identified and summarized. In all cases, chemical structures and EO composition were detailed, as well as references to in vitro activities previously determined, e.g. antibacterial, antioxidant or anti-inflammatory. In a second step, scientific literature devoted to combine EO and biopolymers with the focus set on wound healing innovations, was collected and analyzed. Results: Treatments with EO from species of genders Lavandula, Croton, Blumea, Eucalyptus, Pinus, Cymbopogon, Eucalyptus, Cedrus, Abies, Rosmarinus, Origanum, Salvia and Plectranthus, have shown positive results in rodent wounds. All of these EO were mainly composed by monoterpenoids-thymol, 1,8-cineole, linalool-or monoterpenes, as limonene or pinenes. Experimental wounds in rodents have shown faster closure rate, better collagen deposition and/or enhanced fibroblasts proliferation. In blends with biopolymers, several EO combined with chitosan, alginate, gelatin or collagen, were processed to give active films or nanofibers, with antioxidant, anti-inflammatory or antimicrobial activities. Curiously, all of these works were carried out since 2010. Conclusions: There is significant evidence about the effectivity of EO as wound healers. The incorporation of EO into a polymer matrix that contributes to wound healing is still incipient. However, scientific based evidence of the EO incorporation in resorbable polymeric scaffolds was found and analyzed herein. In summary, EO-biopolymer dressings or scaffolds have become promising artifacts regarding wound treatments, especially in chronic wounds, where treating infection and inflammation are still important issues.