Available online at www.sciencedirect.com Biochemical Systematics and Ecology 36 (2008) 461e466 www.elsevier.com/locate/biochemsyseco A new guaianolide and other constituents from Achillea ligustica Azzedine Boudjerda a, Hanene Zater a, Samir Benayache b, Jean-Claude Chalchat c, Javier Gonzalez-Platas d, Francisco Leo´n e,f, Ignacio Brouard e, Jaime Bermejo e, Fadila Benayache a,* a Laboratoire de Phytochimie et Analyses Physico-Chimiques et Biologiques, Equipe Associe´e a` l’A. N. D. R. S., Universite´ Mentouri, Route de A€ın El Bey, 25 000 Constantine, Algeria b Laboratoire de Valorisation des Ressources Naturelles et Synthe`se de Substances Bioactives, Equipe Associe´e a` l’A. N. D. R. S., Universite´ Mentouri, Route de A€ın El Bey, 25 000 Constantine, Algeria c Laboratoire de Chimie des Huiles Essentielles, Universite´ Blaise Pascal de Clermont, Aubie`re, France d Dpto. Fı´sica Fundamental II, Servicio de Difraccio´n de Rayos X. e I.U.B.O ‘‘Antonio Gonzalez’’, Universidad de La Laguna, Avda. Astrofı´sico Francisco Sanchez 3, 38206 La Laguna, Tenerife, Spain e Instituto de Productos Naturales y Agrobiologı´a, CSIC, Instituto Universitario de Bio-organica ‘‘Antonio Gonzalez’’, Avda. Astrofı´sico Francisco Sanchez 3, 38206 La Laguna, Tenerife, Spain f Instituto Canario de Investigacio´n del Cancer (ICIC), Avda. Astrofı´sico Francisco Sanchez 2, 38206 La Laguna, Tenerife, Spain Received 5 August 2007; accepted 16 November 2007 Keywords: Chlorinated guaianolide; Achillea ligustica; Asteraceae; Anthemideae 1. Subject and source The aerial parts of Achillea species are widely used in folk medicine (Orkiszewska et al., 1985; Simonpoli, 1993). The species of this genus, contain essential oils (Palic´ et al., 2003; Sadyrbekov et al., 2006), flavonoids (Valant- Vetschera, 1985; Krenn et al., 2003) and sesquiterpene lactones (Balboul et al., 1997; Todorova et al., 2007). As part of our ongoing research on the Asteraceae family (Bentame`ne et al., 2005; Dendougui et al., 2006; Zaiter et al., 2007), we report on the chemistry of Achillea ligustica All. collected in June 2004 in Jijel in the eastern Algeria. A voucher specimen (CAL01/06/04) has been deposited in the Herbarium, Biology Department, Mentouri University of Constantine. 2. Previous work Previous studies on A. ligustica All. collected from different areas of Europe, reported on essential oils (Maffei et al., 1993; Tzakou et al., 1995a; Tuberoso et al., 2005; Filippi et al., 2006), flavonoids (Tzakou et al., 1995b), * Corresponding author. Tel./fax: þ213 31 81 88 83. E-mail address: [email protected] (F. Benayache). 0305-1978/$ - see front matter Ó 2007 Elsevier Ltd. All rights reserved. doi:10.1016/j.bse.2007.11.006 462 A. Boudjerda et al. / Biochemical Systematics and Ecology 36 (2008) 461e466 sesquiterpene lactones (Bruno and Herz, 1988; Ahmed et al., 2003), piperidine amide (Greger et al., 1984), lignans (Stojanovic´ et al., 2005) and biological activities of methanolic extract of this species (Conforti et al., 2005). 3. Present study Air-dried flowering aerial parts (224 g) of A. ligustica (Asteraceae, Anthemideae) were extracted in a Soxhlet apparatus with ethanol (48 h). After removal of solvent up to 40 C in vaccuo, the obtained extract (72 g) was frac- tionated by CC on silica gel 230e400 mesh (hexaneeEtOAc step gradients and then with increasing percentages of MeOH) to yield 21 fractions obtained by combining the eluates on the basis of TLC analysis. Fraction 1 (660 mg) eluted with hexaneeEtOAc (90:10) was submitted to silica gel column chromatography (230e400 mesh) using benzene as eluent. Posterior purification on Sephadex LH-20 column eluted by the hexaneeCH2Cl2eMeOH (2:2:1) system led to the isolation of (E)-ethyl-3,7-dimethyl-3,6-octadienoate (9 mg) (Patel et al., 1979). Fraction 5 (350 mg) eluted with hexaneeEtOAc (70:30) was chromatographed on a silica gel column using hexaneeEtOAc with increasing polarity to obtain three subfractions. These subfractions eluted with hexaneeEtOAc (80:20), (70:30) and (2:1), respectively, gave after purification by preparative TLC developed with CH2Cl2-Me2CO (40:1), borneol (6 mg) (Tsankova and Ognyanov, 1985), 2-oxoisodauc-5-en-12-al (8 mg) (Hansson and Wickberg, 1992) and 1-tricontanol (7 mg) (Ferheen et al., 2005). Fraction 6 (400 mg) eluted with hexaneeEtOAc (65:35), was chromatographed on a silica gel column using CH2Cl2eMe2CO (20:1) followed by preparative TLC developed with hexaneeEtOAc (4:1), to obtain b-sitosterol (5.5 mg) (Ness et al., 1992) and filifolide A (4 mg) (Torrance and Steelink, 1974). Fraction 10 (790 mg) eluted with EtOAceMeOH (95:5) was submitted to a silica gel column using CH2Cl2eMeOH (20:1) followed by preparative TLC developed with hexaneeEt2O (2:3), to obtain Santin (7 mg) (Long et al., 2003) and the new sesquiterpene lactone 1 (10.1 mg). All the structures were identified by spectral anal- ysis, mainly HR-EI-MS and 2D NMR (COSY, ROESY, HSQC, HMBC) as well as by comparing their spectroscopic data with those reported in the literature. In our best knowledge, compound 1 is new and named algerianolide. We report on the isolation and structural identification of 1. 2' 14 1' OH O H HO Cl 10 9 O 2 1 8 H 3 5 7 O 11 H H 13 O 15 O 1 Algerianolide (1) was obtained as colourless crystals. The HR-EI-MS showed the molecular formula C17H21O7Cl by exhibiting ions at m/z 372.0988 (calc. 372.0976) and m/z 374.0932 (calc. 374.0946). This spectrum also exhibited þ þ signals at m/z 337.1299 [M À Cl] (calc. 337.1287), 319.1173 [M À Cl À H2O] (calc. 319.1182), 301.1062 þ [M À Cl À 2H2O] (cal. 301.1076), 296.0616 (cal. 296.0629) and 294.0669 (cal. 294.0659) [M À CH3CO2H À þ H2O] , which suggested that this compound contained two hydroxyl and an acetate groups and confirmed the presence of the chlorine atom. The 1H NMR spectrum showed two sets of typical signals for exomethylene protons at dH 6.21 (d, J ¼ 3.5 Hz, H-13a) and dH 5.41 (d, J ¼ 3.2 Hz, H-13b), these two allylic coupled protons were typical for an exomethylene group conjugated with the lactonic carbonyl of a sesquiterpene lactone. In the 1He1H COSY spec- trum, the correlations of H-13a and H-13b led to the assignment of H-7 at dH 3.54, which led to H-6 at dH 4.21 as a doublet of doublets (J ¼ 11.0, 9.9 Hz). This proton correlated with the carbon at dC 81.3 in the HSQC spectrum, in- 1 1 dicating a C-6 lactonized sesquiterpene lactone. The correlations of H-6 in the He H COSY spectrum, led to H-5 at dH 3.13 as a doublet (J ¼ 11.0 Hz). The multiplity of H-5 indicated that C-4 was tetrasubstitued. Re-examination of the 1 H NMR spectrum confirmed the presence of the acetate group by exhibiting a 3H singlet at dH 2.16 (dC 21.3 from HSQC) and showed the presence of two other methyl groups. One of the methyl groups (dC 18.0, dH 1.74) which cor- related with H-5 in the HMBC experiment spectrum (Fig. 1) must be C-15; while the other one (dC 23.5, dH 1.51) must A. Boudjerda et al. / Biochemical Systematics and Ecology 36 (2008) 461e466 463 14 O Me 1' Cl HO O HO H H 2 10 9 H Me 1 8 2' H 3 4 5 7 H 6 H O 11 H H 13 Me O 15 H 12 O HMBC HC Fig. 1. Representative HMBC correlations for compound 1. be C-14. In the same spectrum (HMBC), the protons of C-15 correlated with C-5, with the quaternary carbon at dC 67.4 which may be attributed to C-4 and with the carbon of the CH at dC 63.7 (dH 3.62) assigned to C-3. Re-examination of 1 1 the He H COSY spectrum, particularly, the correlations of H-7, led to the attribution of the multiplet at dH 2.21 and the broad doublet (J ¼ 15.6 Hz) at dH 1.96 to H-8b and H-8a, respectively (dC 31.9). In the same spectrum, these two protons showed correlations with the proton corresponding to the doublet of doublets (J ¼ 7.3, 1.7 Hz) at dH 5.09 sug- gesting its attribution to H-9. The value of the chemical shift of H-9 indicated that the acetate group was attached to C-9 (dC 74.6). This was further supported from the presence of the correlation observed in the HMBC spectrum between 0 H-9 and the carbon of the carbonyl at dC 169.9 attributed to the acetate group (C-1 ) because of its correlation with the 0 protons of the methyl group at dH 2.16 (CH3-2 ). In addition, this spectrum showed correlations between H-13a, H-13b 0 and the carbon at dC 169.9. This observation indicated that C-12 and C-1 had the same chemical shift and confirmed the presence of 17 carbon atoms in the structure. This spectrum also showed correlations of both H-8a and the protons of CH3-14 with a hydroxylated quaternary carbon at dC 77.5 which may be attributed to C-10. Hydroxylation of C-10 was supported by the observed correlation between it and the proton of the hydroxyl group at dH 2.33. This assumption was confirmed by the correlation between the hydroxyl proton and C-9. The same spectrum (HMBC) showed correlations of H-3 and the protons of CH3-14 with the quaternary carbon atom at dC 84.5, which may be attributed to C-1.