Comparative chemical and biomolecular profiles of two Achillea species and their potential for the treatment of skin disorders

This work reports on the study of Achillea millefolium L. and Achillea erba-rotta subsp. moschata (Wulfen) I. Richardson (syn. Achillea moschata), two species belonging to the genus Achillea (Asteraceae family), to test their potential activity for the treatment of skin disorders. Despite their different geographical distribution (A. millefolium is common in Eurasia and North America, while A. erba-rotta subsp. moschata is endemic to the Alps) both species are known for their traditional use as medicinal and food plants. Although this is not their first traditional use, they have long been used as ingredients for skin healing and skin care. A. millefolium, whose extracts are also included in the EU list of cosmetic ingredients (CosIng), is already known for its beneficial properties for the skin and is used in several cosmetic products, while less information is available on A. erba-rotta subsp. moschata (1,2,3). For this project, different samples of the aerial parts of both species were collected in northwestern Italy and purchased from local sellers. Chemical profiling (HPLC-PDA-MS/MS) of the hydroalcoholic extracts and biomolecular characterization (DNA barcoding), of the DNA purified from the dried leaves, were performed to identify useful tools for the discrimination of the two species, when used in dried and fragmented form. The potential application of the extracts in skin care was evaluated by testing their inhibitory effect on two enzymes involved in skin whitening and rejuvenation (tyrosinase and elastase), as well as on several strains of microorganisms that can cause skin-related infections. Moreover, a human fibroblast cell line was treated with a concentration range (0-1000 μg/ml) of the different extracts and cell viability was evaluated by the MTT assay. The hydroalcoholic extracts of the two species are qualitatively similar and rich in polyphenols, including phenolic acids (e.g. chlorogenic acid) and flavonoids (e.g. quercetin, apigenin derivatives), in agreement with literature data (1,2). Nevertheless, a statistical analysis (Principal Component Analysis) performed on the quantitative data of the main components allowed their differentiation, which is confirmed by the biomolecular analysis of the two species. Both extracts showed an interesting tyrosinase and elastase inhibitory activity with a 10-15% enzymatic inhibition at a concentration of 16 μg/mL. Achillea extracts also showed interesting results in inhibiting the growth of Staphylococcus aureus, Candida albicans and Candida tropicalis, displaying cytotoxicity only for concentrations equal to or above 500 μg/ml, as indicated by the analysis of human fibroblast cell viability. The hydroalcoholic extracts from the aerial parts of A. millefolium and A. erba-rotta subsp. moschata can therefore be considered good candidates for the cosmetic and health sectors, also supporting their traditional use in the treatment of skin diseases.