Two new lignans from Dipteronia dyeriana Rong Guo a,b , Min Luo c , Chun Lin Long a, * , Ma Lin Li c, * , Zhi Qin Ouyang d , Yi Ping Zhou c , Yue Hu Wang a , Xing Yu Li a,b , Ya Na Shi a,b a Kunming Institute of Botany, Chinese Academy of Sciences, Kunming 650204, China b Yunnan Agricultural University, Kunming 650201, China c Yunnan Laboratory of Pharmacology for Natural Products, Kunming Medical College, Kunming 650031, China d Yunnan Introduction & Propagation Center for Rare & Endangered Plants, Kunming 650032, China Received 7 March 2008 Abstract A new sesquilignan, 7 0 ,8 0 -didehydroherpetotriol (1), and a new lignan glycoside, (+)-isolariciresinol-9 0 -O-a-L-rhamnopyra- nosyl-(1 ! 6)-b-D-glucopyranoside (2), were isolated from the branches of Dipteronia dyeriana. Their structures were elucidated by spectroscopic methods and chemical evidence. Compound 1 possessed inhibitory activity against human leukaemia K562 cells with an IC 50 value of 39 mmol/L. # 2008 Chun Lin Long. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved. Keywords: Aceraceae; Dipteronia dyeriana; Lignans; Didehydroherpetotriol; Leukaemia Aceraceae comprises two genera, Acer and Dipteronia [1]. The plants of genus Acer contains various bioactive substances, such as triterpenoids with antitumor activity [2], stilbene glycosides with hepatoprotective and antioxidative activity [3,4], and diarylheptanoids as inhibitors of nitric oxide production [5]. To the best of our knowledge, there was not any report of chemical constituents and bioactivity on the genus Dipteronia. In our program to search antitumor agents from natural products, we have investigated Dipteronia dyeriana Henry collected from Pingbian County of Yunnan Province. In this paper, we report the structure elucidation of compounds 1 and 2 isolated from the branches of this plant, along with the inhibitory effects of compound 1 against human leukaemia K562 and human hepatoma HepG2 cells. Compound 1 was obtained as pale yellow powder, [a] D 24.8 + 54.0 (c 0.50, MeOH), with UV (MeOH) absorption bands of 300 (4.11), 279 (4.15) and 234 (4.21) nm (l max : log e). Its molecular formula was assigned as C 30 H 30 O 9 on the basis of the HR-ESI-MS m/z [MÀH] À 533.1804 (calcd. 533.1811). In its IR (KBr) spectrum, absorption bands due to hydroxyl groups and aromatic ring were observed at 3406, 1608 and 1517 cm À1 . The 13 C NMR spectrum (Table 1) of 1 exhibited 30 carbon signals, including 13 quaternary carbons, 11 methines, three methylenes and three methoxy carbons. Extensive analysis and comparison of the 1 H and 13 C NMR spectra of 1 with herpetotriol [6] suggested that compound 1 was a sesquilignan. However, instead of two dihydrobenzofuran segments in herpetotriol, there was one dihydrobenzofuran [d 150.4 (C-4 0 ), 134.2 (C-5 0 ), 89.6 (C-7 00 ) and 55.1 (C-8 00 )] and one benzofuran segment [d 143.9 www.elsevier.com/locate/cclet Available online at www.sciencedirect.com Chinese Chemical Letters 19 (2008) 1215–1217 * Corresponding authors. E-mail addresses: long@mail.kib.ac.cn (C.L. Long), limalinb@vip.163.com (M.L. Li). 1001-8417/$ – see front matter # 2008 Chun Lin Long. Publishedby Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved. doi:10.1016/j.cclet.2008.06.051