Phytochemical characterization of different yarrow species (Achillea sp.) and investigations into their antimicrobial activity

Abstract

Various Achillea species are rich in bioactive compounds and are important medicinal plants in phytotherapy. In the present study, Achillea millefolium L., Achillea moschata Wulfen, and Achillea atrata L. were compared with respect to their phenolic profile and antibacterial activity against gram-positive bacteria strains (Staphylococcus, Propionibacterium). Particular focus was given to A. atrata, which has hardly been studied so far. Based on the metabolite profile, A. atrata exhibited more similarities to A. moschata than to A. millefolium. The former two only differed in the occurrence of four compounds. The flavonols syringetin-3-O-glucoside and mearnsetin-hexoside, not reported for an Achillea species before, have been detected in A. atrata and A. moschata. All Achillea species reduced growth of the tested bacteria. A. atrata demonstrated highest activity against Propionibacterium acnes and Staphylococcus epidermidis, both being involved in the pathogenesis of acne vulgaris. Furthermore, A. atrata has a pronounced anti–methicillin-resistant Staphylococcus aureus potential. Bioassay-guided fractionation revealed that only the most polar fraction of A. moschata displayed antimicrobial activity, which was attributed to phenolics such as apigenin, centaureidin, and nevadensin, being present in high amounts in A. atrata. Thus, this alpine species shows promising antimicrobial activity and might be a potential source for developing novel dermal/topical drugs.

Comparison of the Phenolic Compound Profile and Antioxidant Potential of Achillea atrata L. and Achillea millefolium L.

“…The highest anti-radical capacity of the extracts was found in the ethyl acetate fractions of both species. The phytochemical comparison of these two Achillea species confirmed the findings of our previous study [34], indicating the differences in the occurrence of major phenolic components of aerial parts to be marginal. In contrast, the amounts of individual phenolic compounds appear to be species-specific.…”

“…Regardless of the species, the fractionation and subsequent phytochemical characterization revealed that luteolin, apigenin, nevadensin, and centaureidin were detected exclusively in the corresponding ethyl acetate fractions. A correlation between the contents of these phenolic compounds and an increased antimicrobial activity has already been demonstrated in our previous study [34]. It is also conceivable that an increased antioxidant capacity goes along with the occurrence of these four compounds, which are known as effective DPPH radical scavengers [37][38][39].…”

“…In order to meet the high demand for herbal medicines and to provide evidence for documented ethnobotanical applications of medicinal plants, the identification of further potential health-promoting plant species and the exploration of correlations between chemical composition and bioactivity is of utmost importance. To the best of our knowledge, only three studies on the bioactivity of A. atrata, also considering the identification of individual components, have been reported so far [32][33][34]. In contrast to these investigations, our studies report for the first time the characterization of the phenolic compound profile and antioxidant activity of the alpine species A. atrata, together with a comparison of the respective traits of A. millefolium originating from the same habitat, to exclude any impact of edaphic and climatic factors.…”

“…Acetone was removed from the filtrates in vacuo by rotovaporation at 34 • C. The resulting aqueous phases were subsequently extracted with ethyl acetate (2 × 200 mL) and n-butanol (2 × 200 mL). The respective phases were evaporated to dryness to yield 0.71 g residue of the ethyl acetate extract from each species as well as 0.37 g (A. atrata) and 0.71 g (A. millefolium) residue of n-butanol extract [34,41]. In parallel to this consecutive extraction with different solvents, 4 g of comminuted A. atrata and A. millefolium plant material were extracted twice with 80 mL acetone/water (8:2; v/v) under exclusion of light for 24 h to obtain a total compound extract.…”

“…The software Agilent Chemstation (Rev. B.01.03 SR1) (Agilent, Waldbronn, Germany) and Bruker Daltonik esquire control (Version 6.1) (Bruker Daltonik GmbH, Bremen, Germany) were used for data acquisition and processing [34,41].…”