A new benzophenone from Mesua congestiflora, an inhibitor against human B lymphocyte cancer cell line Gwendoline C.L. Ee a, *, Soek S. Teh a , Huey C. Kwong a , Siau H. Mah a , Yang M. Lim b , Mawardi Rahmani a a Department of Chemistry, Faculty of Science, Universiti Putra Malaysia, 43400 UPM Serdang, Selangor, Malaysia b Faculty of Medicine and Health Science, Universiti Tunku Abdul Rahman, 43000 Kajang, Selangor, Malaysia 1. Introduction Cancer is a deadly disease which is continuously threatening our global health. Standard treatments such as chemotherapy and radiation therapy are usually administered to patients. However, these treatments bring about many short and long term side effects. Natural compounds from plants contain a wide range of therapeutic agents. Mesua, belonging to the flowering plant family Clusiaceae, was selected for this work in our search for new potential anti- cancer natural products. This genus consists of about 48 species in tropical southern Asia. Chemical constituents from this genus which include an abundance of xanthone derivatives (Bandaranayak et al., 1975; Ee et al., 2005a; Govindachari et al., 1967; Teh et al., 2011; Walia and Mukerjee, 1984), coumarin derivatives (Awang et al., 2010; Bandaranayak et al., 1975; Ee et al., 2011; Morel et al., 1999; Verotta et al., 2004) and triterpene derivatives (Ee et al., 2005a) have been reported. The biological activities of this genus such as acetylcholinesterase inhibitory activity (Awang et al., 2010), antibacterial (Mazumder et al., 2004; Verotta et al., 2004) and anti-cancer (Ee et al., 2005b) have also been studied. However, there are no reports on Mesua congestiflora (Fig. 1). 2. Results and discussion Congestiflorone, with molecular formula C 28 H 32 O 4 , was obtained as yellowish crystals from the hexane extract of M. congestiflora. The melting point is 128.7–129.5 8C. The HRESIMS spectrum revealed a molecular ion peak at 431.1820 [MÀH] À (calculated 431.2223). The IR spectra also exhibited absorptions of conjugated carbonyl (C 55 O) at 1740 cm À1 , ether group (C–O) at 1298 cm À1 and aromatic group (C 55 C) at 1615 and 1458 cm À1 . The characteristic signals for UV spectrum were 216 nm and 312 nm. The 1 H NMR spectrum provided signals of an intense hydroxyl groups (d 12.50, s, H-1) and a sharp singlet proton (d 6.09, s, H-2). The downfield OH was due to chelation with the adjacent C 55 O. The HMBC and DEPT spectrum revealed the OH to have connectivities with d 98.7, 105.6 and 164.7 (see Fig. 2). The latter downfield signal was assigned as C-1. Hence, the quaternary carbon with signal d 105.6 was positioned at C-6. The sharp singlet proton, d 6.09 has 1 J connectivity with d 98.7 (C-2) as seen in HMQC and correlated to the quaternary carbons at d 105.6 (C-6), 107.6 (C-4), 163.5 (C-3) and 164.7 (C-1) in the HMBC. The 1 H NMR spectrum showed a series of proton signals indicating the appearance of mono-substituted phenyl group (ring B). This was demonstrated by the existence of two sets of triplets at d 7.35 (2H, J = 6.5 Hz, overlapped) and d 7.43 (1H, J = 6.5 Hz) and one set of doublet d 7.56 (2H, J = 6.9 Hz, overlapped). In the 13 C NMR spectrum, the signals at d 127.4 (C-10 and C-12, overlapped), 128.0 (C-9 and C-13, overlapped) and 130.6 (C-11) belong to the phenyl group. Meanwhile, d 7.35 (H-10 and H-12) was correlated to d 142.0 (C-8) while d 7.43 (H-11) was correlated to d 128.0 (C-9 and C-13). The signal at d 7.56 (H-9 and H-13) was correlated to d 130.6 (C-11) and 199.2 (C-7) via 3 J correlations (see Fig. 2). All these observations situate the phenyl group at C-7 of the main benzophenone skeleton. Phytochemistry Letters 5 (2012) 545–548 A R T I C L E I N F O Article history: Received 1 March 2012 Received in revised form 21 May 2012 Accepted 22 May 2012 Available online 6 June 2012 Keywords: Benzophenone Congestiflorone Mesua congestiflora A B S T R A C T An investigation on the secondary metabolites from the roots of Mesua congestiflora was carried out. A new benzophenone–congestiflorone (1) and one xanthone, a-mangostin (2) were obtained. Structures of these compounds were determined using spectroscopic methods which included 1D and 2D NMR, GC– MS, IR and UV techniques. The cytotoxic activities of this new metabolite against cancer cell lines such as SNU-1, LS-174T, HeLa, SK-MEL-28, NCI-H23, IMR-32, Hep-G2 and K562 were evaluated using the MTT assays. Congestiflorone (1) gave good cytotoxic activity against Raji lymphoma cell line. ß 2012 Phytochemical Society of Europe. Published by Elsevier B.V. All rights reserved. * Corresponding author. Tel.: +60 3 8946 6785; fax: +60 3 8943 5380. E-mail address: gwen@science.upm.edu.my (Gwendoline C.L. Ee). Contents lists available at SciVerse ScienceDirect Phytochemistry Letters jo u rn al h om ep ag e: ww w.els evier.c o m/lo c ate/p hyt ol 1874-3900/$ – see front matter ß 2012 Phytochemical Society of Europe. Published by Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.phytol.2012.05.010