Nurgün Küçükboyacı

Assessment of enzyme inhibitory and antioxidant activities of lignans from Taxus baccata L.

Phytochemical investigations of Taxus baccata L. by successive chromatographic methods resulted in the isolation of the lignans lariciresinol (1), taxiresinol (2), 3´-demethylisolariciresinol- 9´-hydroxyisopropylether (3), isolariciresinol (4), and 3-demethylisolariciresinol (5) as well as taxoids. Compounds 1 - 5 were evaluated for their acetylcholinesterase (AChE), butyrylcholinesterase (BChE), and lipoxygenase (LOX) inhibitory activities, which play a role in the pathogenesis of Alzheimer’s disease (AD), by in vitro spectrophotometric methods, while they were also screened for their antioxidant capacity in 2,2-diphenyl-1- picrylhydrazyl (DPPH) radical scavenging, ferrous ion-chelating effect, and ferric-reducing antioxidant power (FRAP) at 125, 250, 500, and 1000 μg ml-1. All compounds exhibited a moderate inhibition against both BChE and LOX, whereas they were inactive towards AChE. The compounds displayed a great scavenging activity against DPPH especially at 500 and 1000 μg ml-1. Besides, they were found to exert noteworthy reducing antioxidant power on ferric ions. In particular, the FRAP of compounds 2 (3.552 ± 0.02), 4 (3.021 ± 0.71), and 5 (3.533 ± 0.01) were as high as that of the reference chlorogenic acid (3.618 ± 0.01) at 1000 μg ml-1. None of the compounds exhibited chelating ability against ferrous ions.

Isolation of active constituents from cherry laurel (Laurocerasus officinalis Roem.) leaves through bioassay-guided procedures

ETHNOPHARMACOLOGICAL RELEVANCE The fresh leaves of Laurocerasus officinalis Roem. (Rosaceae) are externally used against pain and feverish symptoms in Turkish folk medicine. AIM OF THE STUDY Effects of the extracts, fractions and isolated compounds from the leaves of L. officinalis were investigated using in vivo models of inflammation and pain in mice. METHODS The crude ethanolic extract from the leaves of plant was sequentially fractionated into five subextracts; explicitly, n-hexane, chloroform, ethyl acetate (EtOAc), n-butanol, and remaining water extracts. Further studies were carried out on the most active EtOAc subextract was further subjected to fractionation through column chromatography. For the anti-inflammatory activity, carrageenan-induced hind paw edema and acetic acid-induced increase in capillary permeability models, and for the antinociceptive activity p-benzoquinone-induced writhing test in mice were employed. RESULTS Ethanolic extract of the leaves was shown to possess significant inhibitory activity in the assay methods without inducing any gastric damage. Through bioassay-guided fractionation and isolation procedures three phenolic compounds, 2-O-β-D-glucopyranosyl-2-hydroxyphenyl-acetic acid (1), kaempferol-3-O-β-D-xylopyranosyl-(1→2)-O-β-D-glucopyranoside (2) and (+)-catechin (3) were isolated from the active fraction and their structures were elucidated by spectral techniques (1D and 2D NMR, ESIMS). CONCLUSION The experimental data verified that Laurocerasus officinalis leaves displayed remarkable anti-inflammatory and antinociceptive activity.

Volatile compounds from the aerial part and fruits of Grammosciadium pterocarpum Boiss. growing in Turkey

Volatile constituents obtained from crushed fruits and aerial parts of Grammosciadium pterocarpum Boiss. (Apiaceae) by microdistillation were analyzed by gas chromatography (GC) and GC–mass spectrometry (GC–MS) systems, simultaneously. Fifteen components comprising 99.5% of the volatile oil of the fruit and twenty components comprising 97.4% of the volatile oil of the aerial parts were identified. The main constituents of the fruit volatiles were found to be linalool (68.4%) and β-pinene (22.0%), whereas caryophyllene oxide (55.1%) and β-caryophyllene (15.3%) were found to be major constituents in the volatiles of the aerial parts.

Chemical composition and antimicrobial activity of the essential oil of Conyza canadensis (L.) Cronquist from Turkey

Abstract The essential oils obtained from the aerial parts and the roots of Conyza canadensis (L.) Cronquist (Asteraceae) at the flowering stage, collected from Turkey were simultaneously analysed by GC-FID and GC-MS. Forty-six components comprising 82.8% of the essential oil from the aerial parts and seven components comprising 96.7% of the roots oil were identified. Major constituents of the essential oil of the aerial parts were found to be limonene (28.1%), spathulenol (16.3%) and β-pinene (9.7%), whereas cis-lachnophyllum ester (86.5%), (2Z,8Z)-matricaria ester (3.9%) and β-pinene (2.3%) were identified to be main constituents in the volatiles of the root parts. In addition, antimicrobial activity of the essential oils was screened against Gram-positive and Gram-negative bacteria as well as one strain of fungus by broth microdilution method. Both of the essential oils exhibited antifungal activity against Candida albicans ATCC 10231 with 0.078 μg/ml MIC values. The highest antibacterial activity was observed by aerial parts oil against Escherichia coli RSKK 234 (MIC: 0.039 μg/ml). This is the first report on the chemical composition and antimicrobial activity of the essential oils obtained from C. canadensis growing in Turkey.

New HPLC-chemometric approaches to the analysis of isoflavones in Trifolium lucanicum Gasp.

New HPLC-chemometric approaches were proposed for the simultaneous chromatographic quantification of daidzein, genistein, formononetin, and biochanin A in the samples consisting of the aerial parts of Trifolium lucanicum Gasp. (Leguminosae). Partial least squares and principal component regression algorithms were applied to the multiple chromatographic data set obtained by measuring at 240, 248, 256, and 264 nm to construct HPLC-partial least squares and HPLC-principal component regression calibrations. Chromatographic separation was carried out by using a mobile phase containing methanol, acetate buffer (pH=4.75) and acetonitrile (21:58:21, v/v/v) on the reversed phase column, Supelcosil™ LC-18 (15 cm×4.6 mm id). In addition, conventional HPLC based on the detection at a single wavelength was used for the determination of each compound in the extracts of T. lucanicum. The validity and applicability of the proposed HPLC-chemometric and conventional HPLC methods were performed by analyzing various synthetic plant samples. A good agreement was observed in the application of the proposed HPLC-chemometric tools to the synthetic and extracted samples of T. lucanicum.

Phytotoxicity, Toxicity on Brine Shrimp and Insecticidal Effect of Chrysophthalmum gueneri Aytac & Anderb. Growing in Turkey

Objectives: The aim of this study was to investigate the probable toxicity on brine shrimp, phytotoxicity, and insecticidal activity of Chrysophthalmum gueneri Aytac & Anderb. Materials and Methods: The MeOH (80%) extract obtained from the whole plant of C. gueneri was fractionated through subsequent solvent extractions in increasing polarity with n-hexane, chloroform, and n-butanol. The MeOH (80%) extract and all fractions of C. gueneri were evaluated for their biologic activities using in vitro screening bioassays such as brine shrimp lethality test and phytotoxicity against Lemna minor, as well as insecticidal activity against Rhyzopertha dominica and Tribolium castaneum. Results: The findings showed that the n-hexane and chloroform fractions of the plant had significant phytotoxic activities with 100% growth inhibition (GI) at 1000 μg/mL against L. minor. Moreover, the MeOH (80%) extract (53% GI) and n-butanol fraction (46.6% GI) of the plant had moderate phytotoxic activities at 1000 μg/mL. Otherwise, no samples had toxicity on the brine shrimps. In addition, the remaining water fraction had low insecticidal activity with 20% mortality against T. castaneum. Conclusion: Our results show that the n-hexane and chloroform fractions of C. gueneri had potential phytotoxic effects.

Cytotoxic, Phytotoxic and Insecticidal Activities of Chrysophthalmum montanum (DC.) Boiss.

Objectives: To investigate the in vitro cytotoxic, phytotoxic, and insecticidal activity of Chrysophthalmum montanum (DC.) Boiss. Materials and Methods: The crude methanol (80%) extract of the aerial parts of C. montanum was fractionated to obtain n-hexane, chloroform, n-butanol, and remaining water fractions. The crude extract and subsequent solvent fractions of the plant were evaluated for their biological activities using screening bioassays such as cytotoxicity on brine shrimp lethality, phytotoxicity against Lemna minor L., and insecticidal activity against Rhyzopertha dominica and Tribolium castaneum. Results: The cytotoxicity assay revealed that the crude extract, n-hexane, and chloroform fractions of the plant had positive lethality with LD50 values of 71.51, 126.62, and 75.95 µg/mL, respectively. The extract and its fractions, except for the remaining water fraction, showed phytotoxic activity, which was expressed as percentage growth regulation in a concentration-dependent manner. n-hexane and chloroform fractions in particular had 100% growth inhibition (GI) at 1000 μg/mL, followed by the n-butanol fraction (62.6% GI) and crude extract (40.0% GI) of the plant at the same concentration. Otherwise, all samples had no insecticidal activity against R. dominica and T. castaneum. Conclusion: This study demonstrates that C. montanum contains bioactive compounds related to potential biological activities such as cytotoxic and phytotoxic.

Analysis of the essential oils of subgenus Caropodium from Turkey; Grammosciadium schischkinii (V.M.Vinogr. & Tamamsch.) V.M.Vinogr., G. haussknechtii Boiss., G. pterocarpum Boiss. and G. platycarpum Boiss. & Hausskn. ex Boiss.

Abstract The composition of the hydrodistilled essential oils obtained from aerial parts of Grammosciadium schischkinii (V.M.Vinogr. & Tamamsch.) V.M.Vinogr., G. haussknechtii Boiss., G. pterocarpum Boiss. and G. platycarpum Boiss. & Hausskn. ex Boiss. (Apiaceae) which belong to subgenus Caropodium, growing in Turkey, were simultaneously analyzed by GC and GC-MS. The analysis revealed fifty-seven constituents, accounting 84.3–99.5% of the oils. The essential oil composition of G. schischkinii and G. haussknechtii which are endemic taxa to Turkey, have herein demonstrated for the first time. Moreover, we firstly defined the chemical characterization of the essential oil obtained from G. platycarpum gathered from Turkey. Oil samples showed different chemical compositions with regard to species and locations. Linalool (88.5 and 94.2%) was the main component of the oil samples from G. platycarpum, while hexadecanoic acid (20.6%) was the major in the oil sample of G. haussknechtii. Caryophyllene oxide (45.9 and 20.7%) was defined as the principal constituent in the oil samples of G. schischkinii and G. pterocarpum, respectively. In addition, phytol (19.1%) was determined as the main component in the oil of G. haussknechtii and this compound was first determined in the highest amount among the essential oils of the genus Grammosciadium.