Bombax is the common name for members of the Bombaceae, a family including many commercially important members, e.g., the baobab, the balsa, the kapok and several species of the genera Bombax and Ceriba whose seed fibres are used as filling materi- als. Bombax malabaricum DC. syn. B. ceiba L. and Salmalia malabaricum DC.) is also known as silk-cotton tree. It is widely cultivated in Pakistan, India, China and Australia. B. malabaricum was introduced into Egypt several decades ago as an ornamental plant and shade tree [1], [2], [3]. All parts of the plant have medic- inal significance, e.g., leaves are reported to have application in skin eruptions and they are used to reduce blood sugar levels; roots and flowers are regarded as having diuretic, laxative and restora- tive properties. The gum is useful in acute dysentery. Phytochem- ical investigations of different parts of this plant resulted in the iso- lation of naphthol and naphthoquinone derivatives, anthocyanins, shamimin a flavonoid C-glycoside), and lupeol [4], [5], [6]. Compound 1 was isolated from the n-BuOH fraction of the 70 % alcoholic extract of the leaves of Bombax malabaricum by column chromatography on polyamide, followed by column chromato- graphy on Sephadex LH-20. Compound 1 was obtained as an amorphous yellow powder. The 13 C-NMR spectrum of com- pound 1 showed an obvious similarity with 1,3,6,7-tetrahydroxy- xanthone; however, one of the singlets in the 1 H-NMR spectrum and a CH signal in the 13 C-NMR spectrum were missing [7]. An additional quaternary carbon atom was observed at d = 107.58, which was attributed to C-2. Remaining signals in the 1 H- and 13 C-NMR spectra were in agreement with a C-glycoside. Indeed, Isolation of Mangiferin from Bombax malabaricum and Structure Revision of Shamimin Abdelaaty A. Shahat 1, 2 , Rasmeia A. Hassan 1 , Naglaa M. Nazif 1 , Sabine Van Miert 2 , Luc Pieters 2 , Faiza M. Hammuda 1 , Arnold J. Vlietinck 2 Affiliation: 1 Department of Pharmaceutical Sciences, National Research Cen- tre, Dokki, Cairo, Egypt ´ 2 Department of Pharmaceutical Sciences, University of Antwerp, Antwerp, Belgium Correspondence: Dr. A. A. Shahat ´ Department of Pharmaceutical Sciences ´ University of Antwerp ´ Universiteitsplein 1 ´ 2610 Antwerp ´ Belgium ´ Fax: +32 3 820 27 09 ´ E-mail: shahat@uia.ua.ac.be Received: April 8, 2003 ´ Accepted: July 26, 2003 Bibliography: Planta Med 2003; 69: 1068±1070 ´  Georg Thieme Verlag Stuttgart ´ New York ´ ISSN 0032-0943 Abstract Repeated column chromatography of the n-BuOH fraction of the 70 % EtOH of the dried leaves of Bombax malabaricum led to the isolation of mangiferin, a xanthone. Mangiferin was identified by UV, 1 H- and 13 C-NMR spectroscopy and electrospray mass spec- trometry. It was found to be identical to shamimin, a compound for which originally a flavonol structure was proposed, and the structure of which has to be revised. Letter 1068