Planta Med 2008; 74 - PB42
DOI: 10.1055/s-0028-1084387

Secondary metabolites from the pericarps of Juglans regia L. (Juglandaceae)

E Kavroulaki 1, A Karioti 2, AR Bilia 2, H Skaltsa 1
  • 1Department of Pharmacognosy & Chemistry of Natural Products, School of Pharmacy, Panepistimiopolis-Zografou, 15771 Athens, Greece
  • 2Department of Pharmaceutical Sciences, University of Florence, Ugo Schiff 6, Polo Scientifico, Sesto Fiorentino, 50019, Florence, Italy

Naphthoquinones in walnut pericarps play an important role in the protection of walnuts against fungal attacks [1, 2]. However, little is known about the phenolic content of walnut pericarps. In search of new antifungal agents of plant origin, the pericarps of Juglans regia L. were investigated for their chemical content. Nut pericarps were extracted with solvents of increasing polarity at room temperature. Chromatographic investigations were carried out on both unpolar and polar fractions of J. regia using VLC, CC over both silica gel and Sephadex-LH-20 and RP-HPLC. The polar extracts of nut pericarps were found to be a rich source of phenolic acids, namely, caffeic, ferulic, dimethoxycaffeic, chlorogenic, vanillic, gallic and ellagic acids. Chromatographic separations of the unpolar extract (CH2Cl2) afforded the naphthoquinones, regiolone (1), sclerone (2), 4-hydroxy-1-tetralone (3) and 4-methoxyjuglone (4), the diarylheptanoid juglanin B (5) and the dihydrophaseic acid (6). All structures were deduced by means of 1& 2 D NMR techniques (COSY, HSQC, HMBC, HSQC-TOCSY, ROESY) and mass spectrometric analyses.

1

2

3

4

5

6

References: 1. Mahoney, N. et al. (2000), J. Agric. Food Chem. 48:4418–4421.

2. Mahoney, N. et al. (2004), J. Agric. Food Chem. 52:1882–1889.