The genus Phryna, which belongs to the Caryophyllaceae family, is represented in Turkey only by Phryna ortegioides. It is a monotypic and endemic taxon in Turkey [1]. The chemical composition and biological activity have so far not been investigated. Thus, this study seeks to characterize the chemical composition and antioxidant potential of this plant for the first time. The lipophilic fractions of P. ortedioides showed antioxidant activity in a concentration-dependent way, in general with different behaviors for all fractions. The dichloromethane fraction (DF) showed the highest total antioxidant activity with a value of 91.27 r 2.47%, while the methanol fraction exhibited weak activity (18.07 r 1.35%). The Phryna crude extract (PCE) from the ethyl acetate fraction (EF) and the butanol fraction (BF) showed meaningful antioxidant activity close to that of butylated hydroxyanisole (BHA) and vitamin E (Vit-E).In conclusion, the DF fraction and its subfractions demonstrated higher antioxidant activity than that of polar fractions. Information about the chemical composition and antioxidant activity of P. ortegioides has not been reported so far. In this study, we aimed to identify the chemical composition of the lipophilic fractions of P. ortegioides, an endemic species growing in Turkey. The volatile components in 17 subfractions of the active dichloromethane fractions were analyzed by gas chromatography-mass spectroscopy (GC-MS). The total antioxidant activity of the polar and nonpolar fractions was determined by the ferric thiocyanate method.A summary of the chemical composition of the lipophilic fractions showing the relative amounts of fatty acids, and their distribution among the subfractions obtained by column chromatography is given in Table 1. Separation by column chromatography of the dichloromethane fraction affected the different chemical compositions and fatty acid proportions as reported in Table 1. To the best of our knowledge, the effect of fractionation on fatty acid and volatile composition is investigated for the first time in P. ortegioides. As can be seen in Table 1, analysis of the fatty acid composition indicated that, of the total of 17 subfractions from the dichloromethane fractions, palmitic acid was the major compound with a value of 39.5% of total fatty acids in all subfractions followed by arachidic, stearic, linoleic, oleic, D-linolenic, myristic, and behenic acids, which constitute 15. 96, 13.35, 9.86, 9.45, 7.68, 2.65 and 1.55% of total fatty acids, respectively. These results are in agreement with previous reports stating the fatty acid compositions of different higher plants of the same family [2][3][4].The total of 17 subfractions from the dichloromethane fraction was characterized by the presence of a high proportion of saturated fatty acids (SFAs) with a value of 73.01%, followed by polyunsaturated fatty acids (PUFAs) and monounsaturated fatty acids (MUFAs), representing 17.53 and 7.46%, respectively.Linoleic and linolenic acids were determined as 17.54% of all subfractions. With...