Μελέτη αντιξειδωτικής και αντιμικροβιακής δράσης εκχυλισμάτων φυτών των οικογενειών Asteraceae και Geraceae που φυτέυονται στην Κύπρο

Abstract

In the present study we studied the composition of phenolic compounds, the antioxidant capacity and the antimicrobial activity of plant extracts from Achillea millefolium, Artemisia absinthium, Santolina chamaecyparisus and Stevia rebaudiana of the Asteraceae family and Pelargonium purpureum of the Geraniaceae family. Collected fresh plant samples were dried at room temperature and extracted with solvents ranging from high to intermediate polarity (water, methanol, acetone and ethyl-acetate). Identification and classification of phenolic compounds was carried out with photometric techniques, while their antioxidant capacity was determined using the Ferric Reducing Antioxidant Power method. In addition, the antimicrobial activity of the aforementioned extracts was studied against two plant pathogenic (Clavibacter michiganensis subsp. michiganensis and Xanthomonas campestris pv. campestris) and three food-borne bacteria (Enterococcus faecalis, Escherichia coli and Staphylococcus aureus) using a chromatographic method (p-iodonitrotetrazolium violet) and their minimum inhibitory concentration (MIC) was calculated. The highest concentration of total phenolic compounds were received when water was used as a solvent. Furthermore, the aqueous solvents presented the highest total antioxidant activity among all plants species. More specifically, A. absinthium presented the highest concentration of total phenolic compounds. The highest concentration of hydroxycinnamic acid derivatives was found in the polar extracts of S. rebaudiana and the extracts of intermediate polarity of P. purpureum. The highest content of flavonoids was observed in A. absinthium, while S. rebaudiana demonstrated high concentrations of polar flavonoids. Regarding the antimicrobial activity, the ethyl-acetate extract of A. absinthium had the lowest MIC value for both plant pathogenic bacteria. On the other hand, the acetone extract of A. millefolium demonstrated the best antimicrobial activity solely on S. aureus, among all studied food-borne pathogens.