A new dimeric resveratrol from the roots of Shorea roxburghii Winitra Patcharamun a , Jirapast Sichaem a , Pongpan Siripong b , Suttira Khumkratok c , Jonkolnee Jong-aramruang d , Santi Tip-pyang a, ⁎ a Natural Products Research Unit, Department of Chemistry, Faculty of Science, Chulalongkorn University, Bangkok 10330, Thailand b Natural Products Research Section, Research Division, National Cancer Institute, Bangkok 10400, Thailand c Walai Rukhavej Botanical Research Institute, Mahasarakham University, Mahasarakham 44000, Thailand d Department of Chemistry, Faculty of Science, Burapha University, Chonburi 20231, Thailand article info abstract Article history: Received 15 October 2010 Accepted in revised form 31 December 2010 Available online 14 January 2011 A new resveratrol dimer, roxburghiol A (1) together with eleven known compounds were isolated from the roots of Shorea roxburghii. Their structures were identified on the basis of spectroscopic evidence and physicochemical properties. All isolated compounds were evaluated for their cytotoxicity (KB and HeLa cells). Compounds 8 and 9 showed potent cytotoxicity against both KB and HeLa cell lines with IC 50 values of 6.5, 8.5 and 8.7, 10.1 μg/mL, respectively. © 2011 Elsevier B.V. All rights reserved. Keywords: Dipterocarpaceae Shorea roxburghii Roxburghiol A Cytotoxicity 1. Introduction The genus Shorea belongs to the Dipterocarpaceae family and comprises 22 species [1] in Thailand. Shorea roxburghii locally known as “Pha-yom” is a deciduous and medium to large-sized tree widely distributed in many parts of Thailand. Its bark has been used to treat dysentery, diarrhoea and cholera by the local people of India [2]. There are no reports on phytochemical investigation of this plant. Previous phytochem- ical study on the Shorea species revealed the presence of various stilbenoids [3]. These stilbenoids, some of which show interesting biological activities such as cytotoxic [4], antioxi- dant [5], antiplatelet aggregation [6] and cyclooxygenase inhibitory activities [7]. Our phytochemical investigation of this plant has resulted in the isolation of a new resveratrol dimer, roxburghiol A (1) along with eleven known compounds (2–12)(Fig. 1). This paper also describes the isolation and structure elucidation of a new resveratrol dimer (1), and all isolated compounds were tested for their cytotoxicity (KB and HeLa cells). 2. Experimental 2.1. General NMR spectra were recorded with a Varian model Mercury + 400 spectrometer operated at 400 MHz for 1 H NMR and 100 MHz for 13 C NMR and a Bruker 400 AVANCE spectrometer at 400 MHz for 1 H NMR and 100 MHz for 13 C NMR. Adsorbents such as Sephadex LH-20 and silica gel (60 Merck cat. No. 7730, 7734 and 7749) were used for quick column chromatography, preparative TLC, open column chromatography and centrifugal thin layer chromatograph (Chromatotron), respectively. ESIMS and HRESIMS data were obtained from a mass spectrometer model VG TRIO 2000 and Micromass LCT and Bruker MICROTOF models, respectively. Circular dichroism (CD) spectra were recorded on a JASCOJ-715 spectropolarimeter. UV–visible adsorption spectra were recorded on UV-2552PC UV–Vis spectrometer (Shimadzu, Kyoto, Japan). Optical rotations were measured on a Jasco P-1010 polarimeter. Melting points were determined with Fisher–Johns Melting Point Apparatus. Fitoterapia 82 (2011) 489–492 ⁎ Corresponding author. Natural Products Research Unit, Department of Chemistry, Faculty of Science, Chulalongkorn University, Bangkok 10330, Thailand. Tel.: +66 2 218 7625; fax: +66 2 218 7598. E-mail address: Santi.Ti@chula.ac.th (S. Tip-pyang). 0367-326X/$ – see front matter © 2011 Elsevier B.V. All rights reserved. doi:10.1016/j.fitote.2011.01.003 Contents lists available at ScienceDirect Fitoterapia journal homepage: www.elsevier.com/locate/fitote