A New Acylated Flavonol Triglycoside from Carrichtera annua Khaled A. Abdel-Shafeek, † Moustafa M. El-Messiry, † Abdelaaty A. Shahat, †,‡ Sandra Apers, ‡ Luc Pieters, ‡ and Medhat M. Seif-El Nasr* ,† Pharmacognosy and Phytochemistry of Medicinal Plants Department, National Research Centre, 12311 Dokki, Cairo, Egypt, and Department of Pharmaceutical Sciences, University of Antwerp, Universiteitsplein 1, B-2610 Antwerp, Belgium Received November 17, 1999 A new acylated flavonol triglycoside, quercetin 3-O-[(6-feruloyl--glucopyranosyl)-(1f2)--arabinopyra- noside]-7-O--glucopyranoside (1), as well as the known flavonoid quercetin, were isolated from the whole plants of Carrichtera annua. The structure of 1 was established by UV, MS, and 1D and 2D NMR spectroscopy, including DEPT, DQF-COSY, TOCSY, HSQC, HSQC-TOCSY, and HMBC experiments. Carrichtera annua (L.) DC. is small hispid herb belong- ing to the Cruciferae (or Brassicaceae), representative of herbs and shrubs in mainly temperate regions. It occurs in different areas in Egypt, such as the Nile delta, the Mediterranean coastal area, and Sinai. 1 Although plants of the Cruciferae are used in traditional medicine for the treatment of many diseases, such as cancer, rheumatism, diabetes, and bacterial and fungal infections, no phy- tochemical investigations on C. annua have been reported yet. 2-4 As part of a phytochemical study on Egyptian medicinal plants, we report here the isolation and structure elucidation of a new acylated flavonol triglycoside (1). Compound 1 was obtained from the n-BuOH-soluble part of the methanolic extract of C. annua. Its 1 H and 13 C NMR spectra showed the presence of a quercetin moiety, three sugar residues, a caffeic acid moiety, and a methoxyl group. The chemical shifts of C-2 and C-3 (δ 156.7 and 134.5, respectively) indicated C-3 substitution of the quercetin moiety. 5 A 13 C NMR signal at δ 160.9 was assigned to C-5, based on its long-range 13 C- 1 H correlation observed in a HMBC experiment with the 1 H NMR signal at δ 6.40 (H- 6), whereas the 13 C NMR signal at δ 162.8 showed correlations to both H-6 and H-8 (δ 6.60); hence the latter 13 C NMR signal was assigned to C-7. The assignment of H-8 was confimed by its long-range correlation to the 13 C NMR signal at δ 155.8 (C-9). C-7 showed a three-bond correlation with an anomeric proton at δ 5.05. Hence, compound 1 was a 3,7-disubstituted quercetin derivative. Indeed, the UV spectrum and its changes after addition of shift reagents indicated the presence of free hydroxyl groups at C-5, C-3′, and C-4′; the absorption maximum at 332 nm (in MeOH) confirmed that the C-3 hydroxyl was substituted. 6 TLC after acid hydrolysis with appropriate reference compounds indicated the presence of quercetin as aglycon, and glucose and arabinose. The 2D NMR spectra allowed the assignment of all 1 H and 13 C NMR signals of the 7-glycosyl residue, which could be identified as a glucopyranoside. 5 The -configuration of the anomeric carbon was evident from the coupling constant of H-1′′′′′ (J ) 7.5 Hz) observed in the 1 H NMR spectrum. 7 A methoxyl singlet, observed at δ 3.72 in the 1 H NMR spectrum of 1, was correlated with a quaternary carbon at δ 147.8 in the HMBC spectrum. Based on the long-range 13 C- 1 H correlations observed for the caffeic acid moiety, the latter signal could be assigned to C-3′′′′ of this acyl residue, which, therefore, was identified as a feruloyl group. The trans-configuration of the C-7′′′′-C-8′′′′ double bond was evident from the large coupling constant (J ) 15.8 Hz) between H-7′′′′ and H-8′′′′. The carbonyl group of the feruloyl moiety, occurring at δ 166.4, showed a long-range 13 C- 1 H correlation with a 1 H NMR signal at δ 4.17, assigned to one of the H-6′′′ hydrogens of a hexose unit, representing the second glucose residue. All 1 H and 13 C NMR signals of this glucosyl moiety could be assigned based on the 2D NMR spectral data. A TOCSY experiment showed a correlation between one of the H-6′′′ signals at δ 4.17 and the anomeric proton at δ 4.44, demonstrating that they belonged to the same spin system. Characteristic correlations observed in the HMBC, DQF-COSY, and TOCSY experiments are shown in Figure 1. The -config- uration of the anomeric carbon was evident from the coupling constant of H-1′′′ (J ) 7.8 Hz) observed in the 1 H NMR spectrum. In this way the 6-O-trans-feruloyl-- glucopyranosyl residue could be characterized unambigu- ously. The anomeric proton of this residue, observed at δ 4.44, showed a long-range correlation with a 13 C NMR signal at δ 79.9, corresponding to a proton at δ 4.10 in the HSQC spectrum. The latter signal showed a 1 H- 1 H correlation, observed in the DQF-COSY experiment, with the third * To whom correspondence should be addressed. Tel.: +20 2 337 16 15. Fax: +20 2 337 09 31. † National Research Centre. ‡ University of Antwerp. Figure 1. Structure of 1 and characteristic correlations observed in HMBC (CfH), DQF-COSY, and TOCSY NMR experiments. 845 J. Nat. Prod. 2000, 63, 845-847 10.1021/np990579i CCC: $19.00 © 2000 American Chemical Society and American Society of Pharmacognosy Published on Web 05/06/2000