Characterization of phenolic compounds and antioxidant activity of ethanolic extracts from flowers of Andryala glandulosa ssp. varia (Lowe ex DC.) R.Fern., an endemic species of Macaronesia region

Abstract

Andryala glandulosa spp. varia (Lowe ex DC.) R.Fern. (Asteraceae), is a small shrub that grows in mountains of Madeira Island, Fuerteventura and Lanzarote from Canary Islands. The flowerheads are used traditionally for the treatment of edemas and in homemade dermo-cosmetic preparations.In this paper the chemical composition of the extracts of this plant, used in folk medicine, and their antioxidant capacity were established; the presence of potentially harmful lactones, so commonly associated with related species used for the same purposes was also evaluated. A reversed-phase high-performance liquid chromatography method (RP-HPLC) coupled with diode-array detection (DAD) and electrospray ionization mass spectrometry (ESI/MSn) was used for the characterization of phenolic compounds in ethanol extracts of flowers from A. glandulosa spp. varia collected in Madeira Island. Total phenolic content (TPC) and total flavonoid content (TFC) were established and three assays (DPPH, ABTS and FRAP) were used to measure the antioxidant capacity of the dichloromethane and ethanol extracts.The dichloromethane extract of A. glandulosa contain long linear chain hydrocarbons and esters. In the alcoholic extracts, a total of 16 compounds were characterized based on their UV, mass spectra and HPLC retention time. Quinic acid and luteolin derivatives were found to be the main compounds. Quantification of caffeoylquinic acids (CQA) detected was performed by HPLC-DAD and 5-O-CQA and 3,5-O-diCQA were the major compounds (with values of 22.40±0.21 and 59.69±1.07mg/100g dried plant, respectively). Only the ethanol extract was active, revealing a high radical scavenging capacity and a moderate reducing potential.The potent antioxidant alcoholic extracts are composed mainly of hydroxycinnamic acid derivatives and flavonoids. The presence of sesquiterpene lactones was not detected. Since lactones are very common among related plants, like arnicas, and known to cause dermatitis and other unwanted effects, this can be an explanation for the preference for Andryala over other more easily available alternatives.