Abstract

Rosa species are widely distributed in Turkey.  Ethanolic extracts from flowers and leaves of R. horrida, one of the 25 species of Rosa used as a traditional Turkish medicine as tonic, diuretic, expectorant, stomachic and for the treatment of dyspepsia, diarrhea and nephritis were tested in vitro for their ability to scavenge DPPH^·, ABTS^·+ and superoxide radicals, reduce Fe (III) to Fe (II) and to inhibit peroxidation of phophatidylcholine liposomes induced with ascorbate/Fe (III) in order to establish a relashionship between their antioxidant potency and the content of phenolic compounds. Flowers and leaves extracts showed high DPPH radical scavenging activity as shown by the lowest value of EC₅₀, indicating the strong hydrogen-donating ability. The extracts showed similar metal chelation ability in Fe²⁺-ferrozin test, reducing power and ability to scavenge ABTS^·+ radical cation as shown by the small differences of the EC₅₀ values, since the EC₅₀ values were found to be highest in TBA test, suggesting that the extracts were less effective in protection of liposomes from lipid peroxidation. The activities correlated well with total phenolic and flavonoid contents, indicating that the extracts may play an important role in chemical protection from oxidative damage by possessing endogenious antioxidants, such as phenolics and flavonoids.

Key words: Rosa horrida, leaves, flowers, polyphenol content, antioxidant potential.

Abbreviation

Abbrevations: ABTS, 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt; BHA, butylated hydroxyanisol; CE, catechin equivalents; DPPH, 2,2-diphenyl-1-picryl-hydrazyl; DW, dry weight; EC, extractable compounds; EC₅₀, the effective concentration at which the antioxidant activity is 50%; EDTA, ethylenediamine tetraacetic acid; GAE, gallic acid equivalents; MDA, malondialdehyde; PC, total phenolics; ROS, reactive oxygen species; SD, standart deviation; TBARS, thiobarbituric acid reactive substances; TEAC,trolox equivalent antioxidant coefficient; TRAP, total radical antioxidant potentials.