Pergamon Tetrahedron Letters 41 (2000) 1579–1581 TETRAHEDRON LETTERS Pterocarposide, an isoaurone C-glucoside from Pterocarpus marsupium S. S. Handa, ∗ Rajinder Singh, Rakesh Maurya, N. K. Satti, K. A. Suri and O. P. Suri ICMR Centre for Advanced Research on Formulation, Standardization and Quality Control of Traditional Remedies/Natural Products, Regional Research Laboratory, Jammu 180 001, India Received 1 September 1999; revised 13 December 1999; accepted 16 December 1999 Abstract An isoaurone C-glucoside, the first compound of this type, has been isolated from an aqueous extract of the heartwood of Pterocarpus marsupium. The structure has been arrived at using spectroscopic data. © 2000 Elsevier Science Ltd. All rights reserved. Keywords: isoaurone C-glucoside; Pterocarpus marsupium heartwood; aqueous extract. Pterocarpus marsupium Roxb., also known as Indian kino or Bija sar, has been extensively used in the treatment of diarrhea, toothache, fever, urinary tract and skin infections. 1,2 The successful use of aqueous extracts from this heartwood for the treatment of diabetic patients, in the Indian System of Medicine, stimulated us to investigate the extract, reported to be rich in polyphenolic compounds, 3–5 for its chemical constituents. In this paper, we wish to report the isolation and structure elucidation of a novel chemical entity, an isoaurone C-glucoside, named as pterocarposide (1). This constitutes the first report about the natural occurrence of isoaurone glycosides. The powdered heartwood (5 kg) of Pterocarpus marsupium was exhaustively extracted with hot water (4×16 l). The concentrated extract (500 g) was suspended in H 2 O (2.0 l) and successively partitioned with EtOAc and n-BuOH. Part (65 g) of the n-BuOH extract (170 g) on repeated flash chromatography over silica gel using CHCl 3 :MeOH (9:1) as solvent, afforded pterocarposide (1) (160 mg) as a yellow crystalline solid, 6 m.p. 243–245°C, [α] D 29 +16.6 (c 0.35, CH 3 OH). Pterocarposide (1) was assigned the molecular formula, C 21 H 20 O 9 (FAB-MS, m/z 416 [M] + and 417 [M+H] + ). This conclusion was supported by the 13 C NMR, CPD and DEPT spectra. The presence of hydroxyl groups, a lactone carbonyl, and the phenyl nucleus was indicated by the IR absorptions at 3300, 1740, 1600 and 1448 cm −1 . The UV spectrum of the compound showed absorption maxima at λ max MeOH 202, 250, 271 and 388 nm which underwent bathochromic shifts to 219, 249, 343 and 454 nm in the presence of 0.1N NaOH while no shifts were recorded with NaOAc and AlCl 3 . The 1 H and 13 C NMR spectra 7 indicated the presence of an ∗ Corresponding author. Tel: (0191) 546368; fax: (0191) 548607; e-mail: rrlj@nde.vsnl.net.in (S. S. Handa) 0040-4039/00/$ - see front matter © 2000 Elsevier Science Ltd. All rights reserved. PII: S0040-4039(99)02334-5 tetl 16262