Araştırma Çıktıları

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    A comparative investigation on phenolic composition, antioxidant and antimicrobial potentials of Salvia heldreichiana Boiss. ex Bentham extracts
    (ELSEVIER, 2019-01-01) Bardakci, H.; Celep, E.; Gozet, T.; Kurt-Celep, I.; Deniz, I.; Sen-Utsukarci, B.; Akaydin, G.
    The purpose of the present work is to screen phenolic composition and evaluate the antioxidant and antimicrobial activities of the main extract and subextracts of Salvia heldreichiana, an endemic plant from Turkey. The aerial parts have been powdered and extracted with MeOH initially and then partitioned with chloroform (CHCl3), ethyl acetate (EtOAc) for the generation of subextracts along with the remaining water (R-H2O). Total phenolic, phenolic acid, flavonoid and proanthocyanidin contents present in the MeOH, CHCl3, EtOAc and R-H2O extracts were measured. Presence of 22 phenolic metabolites were confirmed by utilizing LC-MS/MS in MRM scan mode and then Rosmarinic acid (RA) contents of each extract were quantified by HPTLC-densitometry, since the biological effects of many medicinal plants, including Salvia sp. is attributed to RA content. Antioxidant capacities of the aforementioned extracts were estimated using several procedures including free radical scavenging and metal-associated activity and then disc diffusion method was employed to designate their antibacterial and antifungal activities. The results obtained from the current study has revealed a positive correlation between the phenolic composition and the antioxidant profile as well as the antimicrobial activities of the extracts. Among the tested extracts, EtOAc subextract showed the highest antioxidant and antimicrobial activities consistent with the highest phenolic and RA content. (C) 2019 SAAB. Published by Elsevier B.V. All rights reserved.
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    Phytochemical characterization and antioxidant activities of the fruit extracts of several Crataegus taxa
    (ELSEVIER, 2019-01-01) Bardakci, H.; Celep, E.; Gozet, T.; Kan, Y.; Kirmizibekmez, H.
    This study was designed to comparatively evaluate the phytochemical composition and antioxidant potentials of fruit extracts from five Crataegus taxa (C. monogyna, C. orientalis, C. pontica, C. rhipidophylla and C. turcicus) growing wild in the flora of Turkey. Antioxidant activities of the samples were investigated using DPPH radical scavenging, FRAP, CUPRAC and total antioxidant capacity tests. Total phenol, phenolic acid, flavonoid, and proanthocyanidin contents were measured spectrophotometrically. Additionally, the presence of some phenolic compounds in the extracts was investigated by LC-MS/MS. Furthermore, the extracts used for the antioxidant activity studies were standardized for chlorogenic acid and hyperoside by HPTLC densitometry. Among the tested extracts, C. turcicus contained the highest phenolic (398.48 +/- 0.98 GAE/g extract) and total flavonoid contents (23.87 +/- 2.74 QE/g extract) content while C. monogyna contained by far the highest total proanthocyanidin (175.65 +/- 10.59 EGCG-E/g extract), hyperoside (0.42\%) and chlorogenic acid (0.90\%) contents. Crataegus monogyna exhibited the highest antioxidant activity in FRAP, CUPRAC, and TOAC tests. Good correlation was found between the phenolic content and antioxidant parameters. This is the first report related with comparison of these five species in respect to phenolic profile and antioxidant activity. (C) 2019 SAAB. Published by Elsevier B.V. All rights reserved.
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    Evaluation of the influence of in vitro human digestion simulation on the chemical composition and bioactivities of Ziziphus jujuba Mill.
    (AKADEMIAI KIADO ZRT, 2022-01-01) Barak, T. H.; Bardakci, H.; Kurt-Celep, I.; Ozdemir, K.; Celep, E.
    Fruit of Ziziphus jujuba Mill. are used as functional foods for centuries due to their rich content and bioactivities. Although in vitro antioxidant and hypoglycaemic activity of jujube fruit were investigated previously, the bioavailability phenomenon has been disregarded so far. For this study, 80\% ethanol extract of Ziziphus jujuba fruit (ZJE) was investigated for its in vitro hypoglycaemic and antioxidant potentials, before and after the interaction with simulated human digestion. DPPH scavenging activity, FRAP, CUPRAC, and TOAC assays were used for this purpose. Moreover, inhibition potentials of a-amylase and a-glucosidase enzymes and advanced glycation end products (AGE) were examined for the hypoglycaemic effect. Results indicated that ZJE showed significant antioxidant and dose dependent enzyme and AGE inhibition activity. Nonetheless, subsequent to simulated human digestion in vitro bioactivities of ZJE were significantly lowered for bioavailable fraction (IN). Protocatechuic acid (PA) (major phenolic compound of the fruit) contents of the extract and fractions were measured via HPTLC for more accurate understanding of the effects of human digestion and bioavailability profile.
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    In Vitro Anti-Aging Potential Evaluation of Maclura pomifera (Rafin.) Schneider 80\% Methanol Extract with Quantitative HPTLC Analysis
    (GALENOS PUBL HOUSE, 2022-01-01) Barak, Timur Hakan; Celep, Inci Kurt; Senturk, Tugba Buse; Bardakci, Hilal; Celep, Engin
    Objectives: Maclura pomifera (Rafin.) Schneider is a widespread species all around the world, which is also frequently cultured for ornamental purposes. Previous studies revealed that M. pomifera fruits are rich in prenylated isoflavonoids, exhibit noteworthy biological activities, and have probable benefits, particularly, when applied topically. Considering that phenolic compounds are important sources in the development of anti -aging cosmetic products, this study investigated the anti-aging potential of M. pomifera 80\% methanolic extract (MPM) by evaluating antioxidant and extracellular matrix degrading enzymes inhibiting activity. Materials and Methods: For this study, the inhibitory potential of 80\% MPM against different enzymes associated with the aging process was evaluated. Given the unequivocal role of oxidative stress in aging, in vitro antioxidant tests were employed as well. Moreover, osajin was determined as the major bioactive isoflavonoid of the sample by high performance thin layer chromatography analysis. Results: Results of the mechanistically different antioxidant assays exhibited notable antioxidant potential of the extract. Inhibition potential of MPM against hyaluronidase, collagenase, and elastase enzymes, which are directly linked to acceleration of the aging process, was investigated and results revealed that MPM inhibited the aforementioned enzymes explicitly. MPM had notable phenolic and flavonoid content
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    Effect of brewing material and various additives on polyphenolic composition and antioxidant bioactivity of commercial Tilia platyphyllos Scop. infusions
    (MARMARA UNIV, 2020-01-01) Bardakci, Hilal; Barak, Timur Hakan; Ozdemir, Kevser; Celep, Engin
    Herbal infusions have become very popular due to their pleasant flavor as well as their positive influence on health. The compositions of such infusions are affected by the extraction technique, duration, additives as well as container materials. This study implements comparison of antioxidant activities and phenolic contents of the infusions commercially purchased Tilia platyphyllos Scop. samples, one of the most preferred herbal infusions worldwide, prepared by using teapots with different materials. Antioxidant potencies of the samples were examined using tests with different mechanisms such as free radical scavenging test (DPPH), metal-related activity tests (CUPRAC, FRAP). On account of assessing the phenolic profile, total phenol, phenolic acid and flavonoid contents were estimated spectrophotometrically. In addition, the presence of protocatechuic acid in the extracts was investigated by HPTLC densitometry (between 0.762-1.037 w/w\%). Besides, antioxidant activities (DPPH, CUPRAC and TOAC) of the extracts were re-calculated after addition of natural/synthetic sweeteners, brown and white sugar, lemon, flower and pine honeys to the infusions. Results showed that the highest total antioxidant capacity was seen on Tiliae infusions prepared in ceramic teapot (672.80 +/- 1.40 mg AAE/g DE). Moreover, stevioside addition enhanced DPPH radical scavenging of Tiliae extracts (2781.76 +/- 44.38 EC50 in mu g/mL). This is the first report related with comparison of these brewing materials and additives in respect to their phenolic content and antioxidant activity of herbal teas.