Flavonoids from Friesodielsia discolor Uma Prawat *, Duangraudee Phupornprasert, Akkarapol Butsuri, Abdul-Wahab Salae, Sompong Boonsri, Pittaya Tuntiwachwuttikul Laboratory of Natural Products Chemistry, Faculty of Science and Technology, Phuket Rajabhat University, Muang, Phuket 83000, Thailand 1. Introduction Friesodielsia is a genus of Annonaceae with about 60 species found in Africa and Asia (Le Thomas, 1969), with five species occurred in Thailand (Chalermglin, 2001). Until 1948, species belonging to this genus were placed under Oxymitra (Perry, 1980). Only a few species of the genus have been chemically investigated. Hexahydroxanthenic derivatives and a flavanone have been isolated from F. kingii (syn. O. kingii) (Richomme et al., 1990), alkaloids, flavonoids, phenylpropanoids and terpenoids were found in the leaves and twigs of F. velutina (syn. O. velutina) (Achenbach and Hemrich, 1991), benzyl benzoates, bisabolene sesquiterpenes and flavonoides were found in the stem bark of F. enghiana (Fleischer et al., 1997), and a diformylchalcone, a dimethylchalcone, a formylflavanone, a dimethylflavanone, an alkaloid (À)-crotepoxide and benzyl benzoate were isolated from the stem and root bark of F. obovata and were tested for antiplasmodial activity (Joseph et al., 2007). In the course of our continuing search for bioactive constituents from Thai medicinal plants, preliminary screening of the ethyl acetate extract of the leaves of Friesodielsia discolor displayed cytotoxicity against human tumor cell lines, KB (epidermoid carcinoma in the mouth) and MCF-7 (human breast adenocarcinoma) with IC 50 values of 11.87 and 6.13 mg/ml, respectively, and also showed antimycobacteria activity against Mycobacterium tuberculosis with an MIC value of 200 mg/ml. Chemical and biological studies on this species have not been reported previously. This paper reports the isolation, structure elucidation and biological activities of four new flavonoids, 3 0 -formyl-2 0 ,4 0 -dihydroxy-6 0 -methoxychalcone (1), 8- formyl-7-hydroxy-5-methoxyflavanone (2), 8-formyl-5,7-dihy- droxyflavanone (3) and 5,3 0 -dihydroxy-7-methoxyflavone (6), and two known compounds, lawinal (4) and tectochrysin (5) (Fig. 1), found in this plant. 2. Results and discussion The fresh leaves of F. discolor were extracted with EtOAc and the extract was partitioned between CH 2 Cl 2 and water. Chro- matographic separation of the CH 2 Cl 2 fraction on silica gel led to the isolation of compounds 1–6 (Fig. 1) Compound 1 was obtained as yellow needles and had the molecular formula C 17 H 14 O 5 (m/z 299.0916, [M+H] + , calcd for C 17 H 15 O 5 + 299.0919) by HR-TOF-MS. The UV spectrum showed absorption bands at l max 292 and 341 nm and the IR spectrum indicated hydroxyl (n max 3136 cm À1 ), aldehyde (n max 2849, 2766 cm À1 ) and carbonyl (n max 1626 cm À1 ) functional groups. The 1 H NMR spectrum of 1 (Table 1) showed a three-proton multiplet at d H 7.59–7.64 (3H) and a two-proton doublet of doublet at d H 7.61 (J = 7.4, 2.1 Hz) (2H), assigned to a monosubstituted phenyl ring (ring B) (Ye et al., 2004). A pair of AB system doublets at d H 7.80 and 7.86 (J = 15.6 Hz) indicated the presence of an a,b- unsaturated ketone moiety. The above data, suggested a chalcone Phytochemistry Letters 5 (2012) 809–813 A R T I C L E I N F O Article history: Received 1 May 2012 Received in revised form 1 September 2012 Accepted 24 September 2012 Available online 4 October 2012 Keywords: Friesodielsia discolor Annonaceae Flavonoids Antimycobacterial Antiplasmodial Cytotoxicity A B S T R A C T Phytochemical investigation of the fresh leaves of Friesodielsia discolor (Craib) D. Das led to the isolation of four new flavonoids, 3 0 -formyl-2 0 ,4 0 -dihydroxy-6 0 -methoxychalcone (1), 8-formyl-7-hydroxy-5- methoxyflavanone (2), 8-formyl-5,7-dihydroxyflavanone (3) and 5,3 0 -dihydroxy-7-methoxyflavone (6), together with two known compounds, lawinal (4) and tectochrysin (5). The structures of the compounds were elucidated by spectroscopic analysis, mainly 1D and 2D NMR techniques ( 1 H, 13 C, COSY, HMQC and HMBC), as well as comparison with literature data. The isolates were tested for antiplasmodial, antimycobacterial and cytotoxic activities. Compounds 1, 2, 5 and 6 exhibited cytotoxicity against human tumor cell lines, KB and MCF-7 with the IC 50 values in the range of 3.45–14.82 mg/ml. Compounds 1, 2, and 5 also showed significant antiplasmodial activity with respective IC 50 values of 2.75, 2.78 and 2.08 mg/ml. ß 2012 Phytochemical Society of Europe. Published by Elsevier B.V. All rights reserved. * Corresponding author. Tel.: +66 76 523252; fax: +66 76 211778. E-mail address: umaprawat@pkru.ac.th (U. Prawat). 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.2012.09.007