Secondary metabolites from Centaurea lippii

Abstract

The genus Centaurea is known to contain a variety of secondary metabolites of various types, especially sesquiterpene lactones and flavonoids, which have been shown to be biologically active [1][2][3].Centaurea lippii L. (Asteraceae), synonyms Volutaria lippii (L.) Cass.; Volutarella lippii (L.) Cass.; Amberboa lippii (L.) DC., is widely distributed in all Mediterranean areas [4]. Previous phytochemical investigation of this species has led to the isolation of sesquiterpene lactones [5]. The present work concerned the phytochemical study of the chloroform and the n-butanolic soluble parts of the aqueous ethanol extract of the leaves and flowers of the Algerian species.Centaurea lippii was collected during the flowering phase in May 1998, in the East of Algeria, and was authenticated by Prof. A. Kaabeche (Biology Department, University of Setif Algeria).Air-dried and powdered leaves and flowers (1267 g) of Centaurea lippii were macerated with EtOH for 24 h three times. After filtration, the filtrates were combined, concentrated at room temperature, and diluted with 800 mL H 2 O. After remove of chlorophyll, the remaining aqueous solution was extracted successively with CHCl 3 , EtOAc, and n-BuOH to obtain the extracts: chloroform (12 g), ethyl acetate (1 g), and n-BuOH (16 g).The chloroform extract was chromatographed on a 70-230 mesh silica gel column eluted with a gradient of chloroformacetone to yield 8 fractions from which the most important compound 1 was isolated and purified by preparative TLC on silica gel using chloroform-acetone-EtOAc (1:1:3) as eluent.The n-BuOH extract was applied to a polyamide SC6 column eluted with a gradient of toluene-MeOH to yield 9 fractions. Three flavonoid glycosides 2-4 contained in several fractions were isolated by preparative TLC using water-MeOHmethyl-ethyl ketone-acetylacetone (13:3:3:1) as solvent. Purification of each compound for spectral analysis was carried out using MeOH over Sephadex LH-20 column [6].The structures were elucidated by IR, UV, 1 H NMR, 13 C NMR, and MS analysis. All these data were in good agreement with the respective literature data [6][7][8][9][10].Compound 1. C 20 H 26 O 7 , mp 143°C. IR spectrum (KBr, Q, cm -1 ): 1759 (J-lactone), 1705 (C=O conjugated ester), 3356 (-OH). 1 H NMR (250 MHz, CDCl 3 + 2 drops of CD 3 OD, G, ppm, J/Hz): 4.78 (1H, m, H-1), 2.20 (1H, m, H-2), 2.25 (1H, m, H-2c), 2.55 (1H, m, H-3), 2.00 (1H, m, H-3c), 4.81 (1H, d, J 5-6 = 9.7, H-5), 5.25 (1H, t, J 6-5 = J 6-7 = 9.7, H-6), 3.12 (1H, m, H-7), 5.15 (1H, m, H-8), 2.50 (1H, m, H-9), 2.55 (1H, m, H-9c), 5.67 (1H, d, J 13-7 = 2.7, H-13), 6.14 (1H, d, J 13c-7 = 3.3, H-13c), 1.47 (1H, s, H-14), 3.99 (1H, d, J 15-15c = 13.9, H-15), 4.23 (1H, d, J 15c-15

Antioxidant and antiproliferative activities of the n-butanol extract of Centaurea maroccana Ball aerial parts

“…In addition, several Centaurea species are considered to be valuable sources of bioactive secondary metabolites, particularly, flavonoids and sesquiterpene lactones [15] -which are significant chemotaxonomic indicators [16].…”

Natural sesquiterpenoids

“…No new cis,cis-germacranolides were obtained this year. Known germacrane lactones have been identified as components of Brachanthemum gobicum, 229 Centaurea arenaria, 230 Centaurea lippii 231 Carpesium rosulatum, 232 Lactuca aculeata, 233 Smallanthus sonchifolius 234 and Vernonia scorpioides. 235 The conformational properties of 6-epi-desacetyllaurenobiolide have been investigated.…”

LC-ESI-MS/MS Phenolic Profile of Volutaria lippii (L.) Cass. Extracts and Evaluation of Their In Vitro Antioxidant, Antiacetylcholinesterase, Antidiabetic, and Antibacterial Activities

“…Pharmacological and phytochemical studies on several Volutaria species have reported that these plants are rich in sesquiterpene lactones and flavonoids which possess various biological activities [7, 8]. Previous study reported the isolation of one sesquiterpene lactone identified as cnicin and three flavonoids, identified as nicotiflorin, isovitexin and isoquercitrin, from the n-butanol extract of V. lippii [9]. Other works released on V. lippii were conducted to the isolation of two sesquiterpene lactones identified as amberboin and grosshemin [10, 11].…”