Sezgin Celik

Bioactivity of two Turkish endemic Centaurea species, and their major constituents

The antioxidant activity, general toxicity and cytotoxicity of the methanol extracts of Centaurea urvillei subs. armata and C. mucronifera have been assessed, respectively, by the DPPH assay, the brine shrimp lethality and the MTT cytotoxicity assays. The reversed-phase HPLC analysis of the methanol extracts afforded two bioactive dibenzylbutyrolactone-type lignans, matairesinoside (1) and arctiin (2). The structures of these lignans were elucidated by comprehensive spectroscopic analyses as well as by the direct comparison of experimental data with respective literature data.

Volatile constituents of aerial parts of three endemic Centaurea species from Turkey: Centaurea amanicola Hub.-Mor., Centaurea consanguinea DC. and Centaurea ptosimopappa Hayek and their antibacterial activities

The volatile constituents of the aerial parts of Centaurea amanicola Hub.-Mor., Centaurea consanguinea DC. and Centaurea ptosimopappa Hayek were extracted by hydrodistillation and analysed by GC and GC–MS. Altogether 94 components were identified. Sesquiterpenoids, fatty acids and carbonylic compounds were the most abundant components in the oils. Hexadecanoic acid and (Z,Z )-9,12-octadecadienoic acid were the main fatty acids in all the examined samples, that showed different patterns of composition. The study on the biological activity of the oils showed an action mainly against the Gram-positive pathogens.

Antimicrobial Activity of Centaurea Species

Abstract The antimicrobial activity of the ethyl acetate, acetone, chloroform, and ethanol extracts from the Centaurca. species C. ptosomipappoides. Wagenitz, C. odyssei. Wagenitz, C. ptosomipappa. Hayek, C. amonicola. Hub. Mon, and C. kurdica. Reichardt (Compositae) were investigated by agar-well diffusion assay, and all of the extracts exhibited an antimicrobial effect against most of the bacteria and all of the yeasts tested. Although the plants and extracts differed in their activities against the microorganisms tested, the extracts displayed no antifungal activity against the fungi tested. Ethyl acetate extracts showed most significant inhibitory activity, and the yeasts were more suscebtible to the extracts than the bacteria in general. Therefore, minimal inhibitory concentration (MIC) of only ethyl acetate extracts of the samples was determined for some bacteria and the yeasts. In conclusion, C. kurdica. was the most active antimicrobial plant. Ethyl acetate extract of C. odyssei. and C. kurdica. should be further evaluated against human pathogenic yeast isolates, as its antimicrobial activity is stronger than the standard antibiotic ketokonazole.

Anthemis wiedemanniana essential oil prevents LPS-induced production of NO in RAW 264.7 macrophages and exerts antiproliferative and antibacterial activities in vitro.

Anthemis wiedemanniana is known in folk medicine for the treatment of microbial infections, cancer and also urinary and pulmonary problems. In this study, the chemical composition of the essential oil from A. wiedemanniana was evaluated and its antibacterial activity was tested against 10 bacterial strains. The oil was also tested for its potentiality to inhibit nitric oxide production in RAW 264.7 macrophages and for its cytotoxicity against four human cancer cell lines. A. wiedemanniana oil, rich of oxygenated monoterpenes (25.4%), showed a good antibacterial activity against Gram-positive bacteria and a good activity against the two Gram-negative bacteria, Escherichia coli and Proteus vulgaris. Besides that, it exhibited a high inhibitory effect on the LPS-induced nitrite production and a strong cytotoxic activity, especially against amelanotic melanoma (C32) and large lung cell carcinoma (COR-L23) cell lines.

Centaurea species in Turkey (A): Centaurea odyssei Wagenitz (Asteraceae) in Kazdagi (Mt. Ida) National Park

Kazdagi (Mt. Ida: 1774 m) is in northwestern Turkey. The rock type is mainly schist, and the soil is brown forest soil without lime. For these reasons, Kazdagi is one of the most important floristic areas in Turkey. With regard to genetic resources, this area is of major importance for in situ conservation of plant genetic diversity. Centaurea odyssei Wagenitz is a threatened very local endemic species, growing only in three small areas on Kazdagi. These populations are under heavy grazing stress. Morphological, anatomical and palynological studies are described and autecological and conservation aspects of the species are discussed.

Assessment of free-radical scavenging activity of Gypsophila pilulifera: assay-guided isolation of verbascoside as the main active component

Gypsophila pilulifera, Boiss & Heldr, Caryophyllaceae, is a perennial medicinal herb that grows in the southwestern region of Turkey. Except for only one report on the isolation of cytotoxic saponins from the underground parts of G. pilulifera, there are no published thorough phytochemical or bioactivity studies on this species. In the present study, the free-radical scavenging activity of extracts and fractions of the stems of G. pilulifera was evaluated, using a slightly modified and more precise version of the 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay, reported here for the first time. The DPPH assay-guided HPLC-PDA-purification of the active solid-phase extraction fraction (50% methanol in water) of the methanolic extract exhibited verbascoside as the main free-radical scavenger present in this species. The structure of this active compound was resolved by spectroscopy, and the free-radical scavenging potential of verbascoside was determined.

Extracts of Centaurea bornmuelleri and Centaurea huber-morathii inhibit the growth of colon cancer cells in vitro

SUMMARY Plants from the genus Centaurea (C.) (Family: Asteraceae alt. Compositae), widely distributed inAsia, Europe and North America, have traditionally been used in the treatment of variousailments. As a part of our on-going studies on the plants from the genus C. for theirphytochemistry and biological activities, extracts of the seeds of Turkish endemic C. species, C.bornmuelleri and C. huber-morathii, were tested for their cytotoxicity towards the CaCo2 coloncancer cell line as well as for the toxicity towards the brine shrimps, using the MTT and the brineshrimp lethality assays, respectively. Among the extracts, the MeOH extract of these plantsshowed significant toxicity towards the brine shrimps (LD 50 = 55.2 × 10 -2 and 42.4 10 -2 mg/ml,respectively). The MeOH extract of both C. species also inhibited the growth of CaCo2 coloncancer cells in the MTT assay (IC 50 = 29.9 and 33.0 g/ml, respectively). As the most prominentactivities in both assays were observed with the MeOH extracts, it can be assumed that thecompound(s) responsible for these activities are polar in nature. Key words: Asteraceae; Compositae; Centaurea bornmuelleri; Centaurea huber-morathii; MTT assay;Brine shrimp lethality assay; Colon cancer; CaCo2

Bioactivity of Centaurea Persica Boiss (Asteraceae)

The free-radical-scavenging property, antibacterial activity and brine shrimp toxicity of petroleum ether (PE), dichloromethane (DCM) and methanol (MeOH) extracts of Centaurea persica, a Turkish medicinal plant, were assessed using the 2,2-diphenyl-1-picryl-hydrazyl (DPPH) assay, the resazurin microtiter plate based assay, and the brine shrimp lethality assay, respectively. Additionally, the disc diffusion assay was also used to assess antibacterial activity. Only the MeOH extract of C. persica exhibited a significant free-radical-scavenging property in the DPPH assay, with an RC50 value of 0.025 mg/mL. However, in the TLC-based qualitative assay, petroleum ether and DCM extracts showed an extremely low level of free-radical-scavenging property. Among the solid-phase extraction fractions of the MeOH extract, the fractions eluted with 60% and 80% MeOH in water exhibited the highest level of free-radicalscavenging activity (RC50 = 0.010 and 0.015 mg/mL, respectively). While DCM extract showed reasonable antibacterial activity against five out of the nine test strains both in the disc diffusion assay and in the resazurin assay, the MeOH extract was highly active against both Escherichia coli and ampicillin-resistant E. coli strains. Among the solid-phase extraction fractions of the MeOH extract, fractions eluted with 80% MeOH in water and 100% MeOH displayed significant antibacterial potencies against both E. coli species. None of the extracts showed any significant toxicity towards brine shrimps (LD50 = >1.00 mg/mL).

Centaurea species in Turkey (B): Comparative studies of two closely related species, C. kurdica Reichardt and C. sclerolepis Boiss

Morphological, anatomical, palynological, achene structure, and ecological features of two endemic Centaurea L. species, C. kurdica Reichardt and C. sclerolepis Boiss., were studied in detail. Pollen studies showed that the pollen grains of the species could be described as prolate-spheroidal in C. kurdica, and prolate in C. sclerolepis. The SEM study of achene surfaces showed that the cell wall in C. kurdica is thicker than that of C. sclerolepis, especially on the margins. It was determined that the soil in which C. sclerolepis grows is richer in organic matter and Ca++ and Mg++ ions than that below C. kurdica. It was also found that the root anatomy shows significant variations between the species and can be used to differentiate them.