Fatty acids of oil and antioxidant capacity of phenolics from fruits of 11 Cardueae (Carduoideae, Asteraceae) taxa from northeast Anatolia (Turkey)

Members of the tribe Cardueae have become a subject of major interest due to problems of their taxonomy and phylogeny, their possession of biologically active metabolites and their use in traditional medicine. The present study was conducted on 11 taxa of the tribe Cardueae collected from natural habitats in Turkey. In it we investigated the oil content of cypselae, fatty acid composition of the oil and the antioxidant capacity of phenolics from the cypselae. The results showed that the total oil content ranged from 1.45 to 9.28%. The main fatty acid was linoleic acid (C18:2n6; 44.36-70.49%), followed by oleic acid (C18:1n9; 11.41-23.71%), a situation which varied significantly among the taxa, as did the concentrations of different sums of fatty acids (PUFAs, 45.21-78.82%; SFAs, 6.53-14.06%; MUFAs, 12.21-41.40%). The total content of phenolic compounds (TPC; 428.17-752.14 mg/100 g of dry weight) and total flavonoid content (TF; 132.19-336.41 mg/100 g of dry weight) were in strong positive correlation with antioxidant capacity (range; micromol/g of dry weight) determined using DPPH (65.94-147.9), FRAP (32.32- 86.42), CUPRAC (41.04-92.91) and ORAC (22.11-51.24) assays. The data demonstrated that a higher content of phenolic compounds resulted in a higher antioxidant capacity, while a lower content resulted in a low antioxidant capacity. Relative proportions and quantities of fatty acids can be used as additional biochemical markers in taxonomy of the tribe. The present findings suggest that consumption of cypselae of those species that are rich in phenolic compounds and fatty acids may potentially be beneficial to human health by preventing chronic diseases caused by oxidative stress. © 2019 Institute of Botany and Botanical Garden Jevremovac, Belgrad