Ramazan Erenler

Diterpenes from the berries of Juniperus excelsa.

From the hexane extract of berries of Juniperus excelsa, one new and four known diterpenes were isolated besides a known sesquiterpene. The structures of the known diterpenes were identified as isopimaric, isocommunic, (-)ent-trans communic and sandracopimaric acids, along with the sesquiterpene 4a-hydroxycedrol and the new compound which was elucidated as 3 alpha-acetoxylabda-8(17),13(16),14-trien-19-oic acid (juniperexcelsic acid). Cytotoxic activity of the hexane extract was investigated against a panel of cell line and found highly active against LNCaP, KB-V (+VLB) and KB-V (-VLB) cell lines. Furthermore, the hexane and methanol extracts, and the new compound were found to be moderately active against Mycobacterium tuberculosis.

Studies on the antioxidant potential of flavones of Allium vineale isolated from its water-soluble fraction

The aim of this work was to examine the chemical constituents and antioxidant potential of water-soluble fractions from the commonly consumed vegetable, Allium vineale. The water-soluble fraction, containing phenolic compounds, was extracted with ethyl acetate to obtain flavonoids which were separated and purified by repeated column chromatography over Sephadex LH-20, RP C18 and silica gel. The isolated compounds were identified according to their physicochemical properties and spectral data (UV, HPLC-TOF/MS, (1)H NMR, (13)C NMR and 2D NMR). Three flavonoids were isolated and identified as chrysoeriol-7-O-[2″-O-E-feruloyl]-β-d-glucoside (1), chrysoeriol (2), and isorhamnetin-3-β-d-glucoside (3). Antioxidant studies of the aqueous extract and three isolated compounds, 1, 2, 3, were undertaken and they were found to have significant antioxidant activity. Antioxidant activities were evaluated for total antioxidant activity by the ferric thiocyanate method, ferric ion (Fe(3+)) reducing antioxidant power assay (FRAP), ferrous ion (Fe(2+)) metal chelating activity, and DPPH free radical-scavenging activity. The water-soluble ethyl acetate and methanol extraction methods were also compared using HPLC-TOF/MS.

Determination of Antioxidant Activity of Marshmallow Flower (Althaea officinalis L.)

Abstract The antioxidant properties of marshmallow (Althaea officinalis L., Fam. Malvaceae) ethanolic extract was evaluated using different antioxidant tests, including reducing power, free radical scavenging, superoxide anion radical scavenging, and metal chelating activities. The extract of marshmallow (A. officinalis L.) exhibited strong total antioxidant activity. The concentration of 50, 100, and 250 µg/mL of ethanol extract of marshmallow (A. officinalis L.) showed 85.5%, 91.2%, and 96.4% inhibition on peroxidation of linoleic acid emulsion, respectively. On the other hand, 100 µg/mL of standard antioxidant such as butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT), and α‐tocopherol exhibited 94.5%, 99.1%, and 80% inhibition on peroxidation of linoleic acid emulsion, respectively. The extract of marshmallow (A. officinalis L.) had effective reducing power, free radical scavenging, superoxide anion radical scavenging, and metal chelating activities at same concentration (50, 100, and 250 µg/mL). Those various antioxidant activities were compared with standard antioxidants such as BHA, BHT, and α‐tocopherol.

Simple and convenient preparation of novel 6,8-disubstituted quinoline derivatives and their promising anticancer activities

A short and easy route is described for 6,8-disubstituted derivatives of quinoline and 1,2,3,4-tetrahydroquinoline from 6,8-dibromoquinolines 2 and 7 by various substitution reactions. While copper-promoted substitution of 6,8dibromide 2 produced monomethoxides 3 and 4, a prolonged reaction time mainly afforded dimethoxide 6 instead of 5, whose aromatization with DDQ and substitution reaction of dibromide 7 with NaOMe in the presence of CuI also gave rise to dimethoxide 6. Several 6,8-disubstituted quinolines were obtained by treatment of 6,8-dibromoquinoline (7) with n -BuLi followed by trapping with an electrophile [Si(Me)3Cl, S2 (Me)2, and DMF]. Furthermore, 7 was also converted to mono and dicyano derivatives. The anticancer activities of compounds 2, 7, 6, 12, 13, 15, and 16 against HeLa, HT29, and C6 tumor cell lines were tested, and 6,8-dibromo-1,2,3,4-tetrahydroquinoline (2) and 6,8-dimethoxyquinoline (6) showed significant anticancer activities against the tumor cell lines.

Synthesis of hydroxy, epoxy, nitrato and methoxy derivatives of tetralins and naphthalenes

Stereoselective syntheses are described for cis,trans,cis-2,3,5-tribromo-1,4-dihydroxytetralin, trans,trans,cis-2,3,5-tribromo-1,4-dihydroxytetralin, trans,trans,trans-1,4-dihydroxy-2,3-dibromotetralin, trans,trans,trans-1-hydroxy-2,3,4-tribromotetralin, cis,cis,cis-1,2-epoxy-3,5-dibromo-4-hydroxytetralin, anti-1,2:3,4-diepoxytetralin, 1-hydroxy-4-bromonaphthalene, trans,trans,trans-1,4-dinitrato-2,3-dibromotetralin, 1-nitrato-2,3,4-tribromotetralin, 2,3-dibromonaphthalene and 1-methoxy-4-nitrato-2,3-dibromonaphthalene. These isomeric arene oxides and disubstituted naphthalenes provide excellent precursors for a number of 1,4- and 2,3-disubstituted naphthalene derivatives that are difficult to prepare using other routes. The structures of the naphthalene and tetralin derivatives were assigned by NMR and other techniques.

Isolation and identification of a new neo-clerodane diterpenoid from Teucrium chamaedrys L.

Teucrium chamaedrys L. is an aromatic and medicinal plant used as traditional medicine. Aerial parts of the plant material were dried and extracted with hexane–dichloromethane (extract 1), ethyl acetate–dichloromethane (extract 2) and methanol–dichloromethane (extract 3) in a ratio of 1:1 at rt successively. The solvents were evaporated to give crude extracts. Extract 1 was suspended in water at 60°C then partitioned successively with hexane and ethyl acetate to give hexane and ethyl acetate portions. After the column chromatography (silica gel) of ethyl acetate extract, one new and four known compounds were isolated. The new compound was named as 1(12S,18R)-15,16-epoxy-2β,6β-dihydroxy-neo-cleroda-13(16),14-dien-20,l2-olide-l8,l9-hemiacetal (teuchamaedryn D) (4). The known compounds were teucrin A (1), dihydroteugin (2), teucroxide (3), syspirensin A (5). The chromatographic methods were also applied for extract 3 to isolate verbascoside (6) and teucrioside (7). The structure of isolated compounds was elucidated by spectroscopic methods including LC-TOF/MS, 1D NMR and 2D NMR.

Bioassay-guided isolation, identification of compounds from Origanum rotundifolium and investigation of their antiproliferative and antioxidant activities

Abstract Context: Origanum (Lamiaceae) has been used in food and pharmaceutical industries. Objective: Isolation and identification of bioactive compounds from Origanum rotundifolium Boiss. and investigation of their antiproliferative and antioxidant activities. Materials and methods: The aerial part of O. rotundifolium was dried and powdered (1.0 kg ±2.0 g) then extracted with hexane, ethyl acetate, methanol and water. Solvent (3 × 1 L) was used for each extraction for a week at room temperature. The aqueous extract was partitioned with ethyl acetate (3 × 1 L) to yield the water/EtOAc extract subjected to chromatography to isolate the active compounds. The structures of isolated compounds were elucidated by 1 D, 2 D NMR and LC-TOF/MS. Results: Apigenin (1), ferulic acid (2), vitexin (3), caprolactam (4), rosmarinic acid (5), and globoidnan A (6) were isolated and identified. Globoidnan A (6), vitexin (3), and rosmarinic acid (5) revealed the excellent DPPH• scavenging effect with IC50 values of 22.4, 31.4, 47.2 μM, respectively. Vitexin (3) (IC50 3.6), globoidnan A (6) (IC50 4.6), apigenin (1) (IC50 8.9) and ferulic acid (2) exhibited more ABTS•+ activity than standard Trolox (IC50 13.8 μg/mL). Vitexin (3) revealed the most antiproliferative activity against HeLa, HT29, C6 and Vero cells lines with IC50 values of 35.6, 32.5, 41.6, 46.7 (μM), respectively. Discussion and conclusion: Globoidnan A (6) has the most antioxidant effects on all assays. This has to do with the chemical structure of the compound bearing the acidic protons. Vitexin (3) could be a promising anticancer agent.

Bioactivity–guided isolation of flavonoids from Cynanchum acutum L. subsp. sibiricum (willd.) Rech. f. and investigation of their antiproliferative activity

Abstract Cynanchum acutum L. subsp. sibiricum (Willd.) Rech. f. was extracted with hexane, acetone, methanol and water individually. A sample was heated in water then extracted with ethyl acetate. Among the extracts, the ethyl acetate extract exhibited the most antiproliferative activity, so isolation of bioactive compounds was carried out from this extract. A new compound, kaempferol-3-O-β-xylopyranosyl-(1-2)-β-rhamnopyranoside (1) along with five known compounds, quercetin-3-O-β-xyloside (2), kaempferol-3-O-β-glucoside (3), quercetin-3-O-β-glucoside (4), kaempferol-3-O-β-rhamnopyranoside (5), and kaempferol-3-O-β-d-neohesperidoside (6) were isolated from ethyl acetate extract. The structures were elucidated by spectroscopic techniques, basically 1D NMR, 2D NMR and LC-TOF/MS. Antiproliferative effects of isolated compounds were determined by xCELLigence using the HeLa (human uterus carcinoma) cell lines. Compound 2 and compound 5 revealed the good antiproliferative activity against HeLa cell lines.

Synthesis of hexabromo, hydroxy, epoxy, methoxy and nitroxy derivatives of tetralins and naphthalenes

Stereoselective synthesises are described for naphthalene and tetralin derivatives. Hexabromo 2 and 3, monomethoxy 7, dimethoxy 6, dihydroxy 4 and dinitroxy 10 derivatives of tetralin have been obtained. Base-promoted elimination reactions of 6 and 4 provided monomethoxy 8 and 9 and diepoxy 5 naphthalenes respectively. The structures of these products were determined by 1H and 13C NMR spectra, mass spectra and micro analysis.

Bioassay-guided isolation and identification of antioxidant flavonoids from Cyclotrichium origanifolium (Labill.) manden and scheng

Background: Medicinal and aromatic plants play a significant role in drug discovery and development process. Flavonoids, revealing a wide spectrum of biological activities, extensively found in plants are important secondary metabolites. Materials and Methods: Aerial parts of Cyclotrichium origanifolium were collected, dried, and boiled in water then extracted with hexane, ethyl acetate, and n-butanol. Total phenolic content, DPPH· scavenging activity, reducing power (FRAP) activity, and ABTS·+ scavenging activity assays were applied for all extracts. The ethyl acetate extract revealing the most antioxidant activity as well as including the highest phenolic contents was subjected to chromatographic techniques (column chromatography, sephadex LH-20, semipreparative HPLC) to isolate the active compounds. The structure of isolated compounds were elucidated by spectroscopic methods (1D NMR, 2D NMR, and LC-TOF/MS). Results: Isosakuranetin (1), eriodictyol (2), luteolin (3), naringenin (4), and apigenin (5) were isolated and identified. All isolated flavonoids displayed the excellent antioxidant activity. Conclusion: The isolated flavonoids and also plant extract have potency to be a natural antioxidant. Abbreviations used: DPPH•: 1,1-diphenyl-2-picryl-hydrazyl free radical, ABTS•+: 2,2•-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid), UV:Ultraviolet, DNA: Deoxyribonucleic acid, BHT: Butylated hydroxytoluene, BHA: Butylated hydroxyanisole, HPLC: High performance liquid chromatography