Determination of antioxidant properties of Rumex crispus and Scrophularia canina subsp . bicolor

Abstract: Methanol and ethyl acetate extracts of Rumex crispus L. and Scrophularia canina L. subsp. bicolor (SM.) Greuter were tested for their antioxidant activity using the DPPH method. Extracts were prepared from the above-ground parts of these plants. Significant antioxidant activity was determined for methanol (IC50: 4.16 μg/mL) and ethyl acetate (IC50: 8.71 μg/mL) extracts of Rumex crispus. Moreover, methanol (IC50: 60.78 μg/mL) and ethyl acetate (IC50: 149.33 μg/mL) extracts of Scrophularia canina subsp. bicolor (SM.) Greuter were shown to have important free radical scavenging antioxidant activity.


INTRODUCTION
The genus Rumex L. (Polygonaceae) consists of about 200 species growing worldwide and 23 species and 5 hybrids naturally growing in Turkey.Rumex crispus L. is a perennial plant, and its basal leaves are acute and narrowly lanceolate to oblanceolate [1,2].Various parts of Rumex species, including roots and fresh leaves, have been used in traditional medicine in Turkey.Rumex roots have important uses because of their laxative property.Decoctions prepared from the underground parts have been claimed to be therapeutically useful as cholagogue, tonic and laxative and for blood cleansing.Fresh leaves are used to treat eczema and also consumed as vegetable in Anatolia [3].
The name of Scrophularia comes from "scrofula", a kind of tuberculosis, since some species have been used for treatment of tuberculosis [4].In the flora of Turkey, Scrophularia is represented by 59 species, 23 of which are endemic.Some Scrophularia L. species, especially S. nodosa L. are used in folk medicine as a diuretic and for the treatment of wounds and hemorrhoids [5,6].Different species of the genus Scrophularia (Scrophulariaceae) have been used in traditional medicine to treat some diseases, including dermatosis and inflammatory affections [7].Besides that, some of Scrophularia species has shown anticancer and cell growth enhancing activities [8].
Contrary to Scrophularia canina L. subsp.bicolor (SM.)Greuter there have been reports on the antioxidant activity of Rumex crispus species.The leaves, seeds and fruits of Rumex crispus have been shown to have antioxidant activity [9][10].In the present study it is aimed to investigate the DPPH radical scavenging activity of methanol and ethyl acetate extracts prepared from Rumex crispus and Scrophularia canina subsp.bicolor.

Plant Material
Rumex crispus and Scrophularia canina subsp.bicolor were collected from Soma, Manisa.These plants were identified by Volkan Eroğlu and Hasan Yıldırım, respectively (Ege University, Faculty of Science).Voucher specimens are deposited in the Herbarium of the Department of Pharmacognosy, Faculty of Pharmacy, Ege University.
Above-ground parts of Rumex crispus and Scrophularia canina subsp.bicolor were powdered and 5 g powder of both plants were extracted with methanol and ethyl acetate (30 ml) three times.Extraction was followed by filtration and the filtrate was evaporated to dryness by a rotary evaporator.

Free Radical Scavenging Activity by DPPH Method
Radical scavenging activity of the extracts were determined using DPPH (2,2-diphenyl-1-picrylhydrazyl) method [11] with slight modification.Methanol and ethyl acetate extracts of Rumex crispus were tested within the range of 1.25 -20 µg/mL concentrations.DPPH radical scavenging activity of methanol extract of Scrophularia canina subsp.bicolor was performed within the range of 25-400 µg/mL concentrations.Antioxidant activity of ethyl acetate extract of Scrophularia canina subsp.bicolor was determined by using a concentration range of 50-800 µg/mL.DPPH solution was added to the extracts and the absorbance of the reaction mixture was measured at 517 nm after 30 minutes.Inhibition of free radical DPPH in percent (I %) was calculated and a sample concentration providing 50 % inhibition (IC50) was calculated by plotting inhibition percentages against different concentrations of samples.The experiments were carried out in triplicate.
In conclusion, all of the extracts prepared from Rumex crispus and Scrophularia canina subsp.bicolor have been found to possess antioxidant activity.Future studies, regarding the determination of the components responsible for the free radical scavenging activity may be carried out to clarify the antioxidant potentials of these plants.