Flavonoids of the Exudate of Centaurea calcitrapa

Abstract

The large genus Centaurea (Asteraceae) comprises about 500 species mostly distributed around the Mediterranean area and in Western Asia [1]. About 50 species grow in Algeria, among which Centaurea calcitrapa, known as Bou Neggar, is largely distributed [2]. C. calcitrapa is used in traditional medicine as antidiabetic and diuretic [3,4]. Several previous chemical studies have been reported on the genus [5][6][7][8][9].Continuing our research on the chemical constituents of Algerian Centaurea species [10-16], we report here the isolation of six flavonoids and a sesquiterpene lactone, cnicin, from the chloroform exudate of the aerial parts of Centaurea calcitrapa L.Fresh aerial parts (1.8 kg) were extracted with a mixture of toluene-ethyl acetate (6:4) twice during 15 min. The obtained solutions were combined and concentrated. During the concentration, a precipitate was formed. This precipitate was filtered and washed with petroleum ether to give a pure white compound 1 (2.65 g) as a major component, identified as cnicin [12]. The residual solution was concentrated to give 11.52 g of extract, which was chromatographed on a silicagel column eluted with a gradient of chloroform-acetone to yield eight fractions, which were purified on preparative TLC Silica gel 60 GF plates eluted with a mixture of CHCl 3 -MeOH-H 2 O (80:9:1) to give compounds 2-7. Purification of each compound for spectral analysis was carried out using MeOH over a Sephadex LH-20 column.The structures of these compounds were established using UV spectroscopy, 1 H and 13 C NMR, and MS analyses. All the data were in good agreement with the respective literature data.Compound 1. C 20 H 26 O 7 , mp 143qC. IR spectrum (KBr, Q, cm -1 ): 1756 (J-lactone), 1707 (C=O conjugated ester), 3385 (OH). Mass spectrum (FAB + , 70 eV), m/z: 379 [M + H] + , 247 [(1c,2c-OH -Et) acrylic acid], 229 [247 -H 2 O]. 1 H NMR (250 MHz, CDCl 3 + 2 drops CD 3 OD, G, ppm, J/Hz): 6.3 (1H, s, H-18c), 6.25 (1H, d, J 13c, 7 = 3.3, H-13c), 6.1 (1H, s, H-18), 5.75 (1H, d, J 13, 7 = 2.7, H-13), 5.2 (1H, t, J 6,5 = J 6,7 = 8.2, H-6), 5.15 (1H, m, H-8), 5.05 (1H, m, H-1), 4.

Cytotoxic and apoptotic effects of endemic Centaurea fenzlii Reichardt on the MCF-7 breast cancer cell line

“…Compound 5 had a molecular ion peak at m/z 329 [M-H] -and yielded several ions at m/z 314, 299, and 271. Fragmentation behavior of these compounds was determined with jaceosidin, cirsiliol, or 6-methoxykaempferol 3-methyl ether, which were previously isolated from Centaurea and showed moderate antitumor activity against MCF-7 cells (Forgo et al, 2012;Kitouni et al, 2015).…”

New perspectives of purple starthistle (Centaurea calcitrapa) leaf extracts: phytochemical analysis, cytotoxicity and antimicrobial activity

“…Therefore, C. calcitrapa can be considered as a species with high phenolic diversity. Flavonoids such as apigenin, luteolin, kaempferol, kaempferol 3- O -glucoside, eupatorin and jaceosidin have been previously detected in the C. calcitrapa (Al-Easa and Rizk 1992 ; Formisano et al 2012 ; Kitouni et al 2015 ). In the study of Öksüz et al ( 1984 ), apigenin and jaceosidin have been isolated from all of the investigated Centaurea species ( C. virgata , C. kilea Boiss., C. inermiss Velen.…”

“…The MeOH extract has shown a strong antibacterial activity towards certain pathogens including species of Bacillus , Pseudomonas , Staphylococcus , Streptococcus , Salmonella , Enterobacter , Enterococcus, Acinetobacter, and Escherichia genera (Toribio et al 2004 ; Soumia et al 2014 ; Moghannem et al 2016 ). Several phytochemical studies revealed sterols, sesquiterpene lactones and their closely related group of triterpenoids, bisabolenes, lignans and flavonoids as constituents of C. calcitrapa extracts (Karawya et al 1975 ; Dawidar et al 1989 ; Al-Easa and Rizk 1992 ; Marco et al 1992 ; Formisano et al 2012 ; Bruno et al 2013 ; Kitouni et al 2015 ).

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A Review on Antidiabetic Activity of Centaurea spp.: A New Approach for Developing Herbal Remedies

“…e presence of flavonoids in C. bornmuelleri is significant and might be responsible for the desired activity [67]. e phytochemical analysis of C. calcitrapa proved the presence of sterols, sesquiterpene lactones, and their closely related group of triterpenoids, bisabolenes, lignans, and flavonoids as the main secondary metabolites [124][125][126][127][128][129][130]. C. hypoleuca contains higher amounts of catechin and chlorogenic acid than the other phenolic compounds, which are known to be responsible for various biological activities such as antioxidant, neuroprotective, antidiabetic, hepatoprotective, and antiarthritic properties [72,[147][148][149].…”