Browsing by Author "Kirkan B."
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Item Onosma heterophyllum: Phenolic composition, enzyme inhibitory and antioxidant activities(Elsevier B.V., 2018) Ozer M.S.; Kirkan B.; Sarikurkcu C.; Cengiz M.; Ceylan O.; Atılgan N.; Tepe B.Onosma species have frequently been used for their colouring and dyeing properties in foods and medicinal preparations. The antioxidant and enzyme inhibitory activities of the ethyl acetate, methanol and water extracts of Onosma heterophyllum (Griseb.) are described. Phytochemical compositions of these extracts were also determined. The water extract showed not only remarkable antioxidant activity in all assays but also considerable inhibitory activity on tyrosinase and α-glucosidase (112.44 μmol KAEs/g dry plant and 984.36 μmol ACEs/g dry plant, respectively). The methanol extract exhibited the highest inhibitory activity on acetylcholinesterase (AChE) and α-amylase (79.18 μmol GALAEs/g dry plant and 10.42 μmol ACEs/g dry plant, respectively). Chromatographic analyses revealed that the water extract was found to be rich in phenolic and flavonoid contents. On the basis of the correlation coefficients calculated separately for all experimental parameter pairs, protocatechuic acid, p-hydroxybenzoic acid, syringic acid, p-coumaric acid and luteolin were found to be highly in correlation with the antioxidant and enzyme inhibitory activities. This study demonstrates that O. heterophyllum, contained in food preparations with various purposes for many years, could be used for the treatment of diabetes as well as its skin whitening effect. © 2017 Elsevier B.V.Item Chemical characterization and biological activity of Onosma gigantea extracts(Elsevier B.V., 2018) Sarikurkcu C.; Kirkan B.; Ozer M.S.; Ceylan O.; Atilgan N.; Cengiz M.; Tepe B.Onosma species have traditionally been used as laxative and anthelmintic agents as well as their uses in eye, blood diseases, bronchitis, abdominal pain, strangury, thirst, itch, leucoderma, fever, wounds, burns, piles, and urinary calculi. This study examines the investigation of biological activities of ethyl acetate, methanolic, and aqueous extracts from Onosma gigantea Lam. The extracts were evaluated for the antioxidant and enzyme inhibitory activities. Phenolic compounds in the extracts were also detected by RP-HPLC-DAD. The aqueous extract showed remarkable antioxidant activity in phosphomolybdenum [134.31 μmol trolox equivalents (TEs)/g air dry matter (adm)], chelating effect [32.97 μmol ethylenediaminetetraacetic acid (disodium salt) equivalents (EDTAEs)/g adm], radical scavenging [on DPPH (32.14 μmol TEs/g adm) and ABTS (58.68 μmol TEs/g adm)], and reducing power [CUPRAC (50.23 μmol TEs/g adm) and FRAP (40.96 μmol TEs/g adm)] assays. The aqueous extract also exhibited considerable inhibitory activity of tyrosinase (10.48 μmol kojic acid equivalents/g adm) and α-glucosidase [1320.53 μmol acarbose equivalents (ACEs)/g adm]. It has been determined that the methanolic extract showed significant AChE (31.57 μmol galanthamine equivalents (GALAEs)/g adm) and α-amylase (6.75 μmol ACEs/g adm) inhibitory activity. The ethyl acetate, which contains low polarity compounds, showed the highest BChE inhibitory activity (6.87 μmol GALAEs/g adm). In general, it is found that there is a positive correlation between the phytochemical contents of the extracts and their biological activities. The results indicate that O. gigantea extracts could be considered as a novel source of bioactive agents with functional connections. © 2018 Elsevier B.V.Item Can the stalks of Papaver somniferum L. be an alternative source of bioactive components?(Elsevier B.V., 2018) Kirkan B.; Ozer M.S.; Sarikurkcu C.; Copuroglu M.; Cengiz M.; Tepe B.Alternative raw materials for designing novel products are gaining interest in the scientific area. The aim of this study is to investigate the antioxidant and enzyme inhibitory activities of the extracts obtained from Papaver somniferum L. stalks as well as the determination of chemical composition. Antioxidant capacity was tested by using different chemical methods including radical scavenging, reductive effect, phosphomolybdenum and metal chelating assays. Enzyme inhibitory effect was investigated against cholinesterase, tyrosinase, α-amylase and α-glucosidase. To detect chemical composition, phenolic profile was determined by high performance liquid chromatography (HPLC) as well as total contents of the phytochemicals. The aqueous extract was found to contain high amount of phenolics and flavonoids [9.87 μmol gallic acid equivalents (GAEs)/g dry plant (dp) and 0.09 μmol rutin equivalents (REs)/g dp, respectively]. The methanol and aqueous extracts were also found to contain considerable amounts of (−)-epicatechin and syringic acid. Antioxidant activity tests were resulted in the superiority of the methanol extract. The extracts did not show inhibitory activity on cholinesterases and tyrosinase. Inhibitory activity of the aqueous extract on α-amylase and α-glucosidase were found to be 9.85 and 78.64 μmol acarbose equivalents (ACEs)/g dp, respectively. As a result, P. somniferum stalks, one of the major by-products of poppy cultivation, can be used as the alternative source of antioxidant and enzyme inhibitory compounds in food and medical industries. © 2018 Elsevier B.V.Item Phenolic profile, antioxidant and enzyme inhibitory potential of Onosma tauricum var. tauricum(Elsevier B.V., 2018) Kirkan B.; Sarikurkcu C.; Ozer M.S.; Cengiz M.; Atılgan N.; Ceylan O.; Tepe B.This study focused on phytochemical characterization and biological evaluation, both antioxidant and enzymatic inhibition, of ethyl acetate (OTT-EtOAc), methanol (OTT-MeOH), and water (OTT-W) extracts from Onosma tauricum var. tauricum aerial parts. The OTT-W extract was found to be the richest one in terms of its phenolic and flavonoid contents. Amounts of the phenolic and flavonoid compounds were determined as 40.88 μmol GAEs/g and 7.40 μmol REs/g dry plant (dp), respectively. The OTT-MeOH and OTT-W extracts were also found to contain significant amounts of chlorogenic acid, rosmarinic acid, p-hydroxybenzoic acid, caffeic acid, rutin, p-coumaric acid, trans-cinnamic acid, luteolin, and apigenin. The OTT-W extract showed remarkable antioxidant activity in phosphomolybdenum, ferrous ion chelating, reducing power, and radical scavenging assays. The OTT-MeOH extract exhibited inhibitory activity on acetylcholinesterase (AChE) (54.62 μmol GALAEs/g dp), while the extracts remained almost inactive on butyrylcholinesterase (BChE). The OTT-W extract also exhibited inhibitory activity on tyrosinase (90.66 μmol KAEs/g dp) and α-glucosidase (2258.87 μmol ACEs/g dp). The results suggest that especially the OTT-MeOH and OTT-W extracts can be used as a source of alternative natural products in the treatment of diseases caused by the enzymes evaluated here. © 2018 Elsevier B.V.