Phytockmistry,Vol. 33, No. 2, pp. 515- 517, 1993 003 l-9422/93 $6.00 + 0.00 Printedin GreatBritain. 0 1993PergamonPressLtd A PRENYLATED PTEROCARPAN FROM MUiVDULEA STRIATA FRBDBRIC MANJARY, ALAIN PETITJEAN, JEAN-YVES CONAN, MARIE THBRBSE MARTIN,* FRANC• IS FRAPPIER,* PHILIPPE RASOANAIVO~and SUZANNE RATsrMAMANGA-URvErtGt FacultCdes Sciences de la Reunion, 15 avenue Rene Cassin, 97487 Saint Denis Cedex, France, DOM; *Museum National d’Histoire Naturelle, Laboratoire de Chimie, 63 rue Buffon, 75321 Paris Cedex 05, France; TInstitut Malgache de Recherches Appliquks, B 3833, lOl-Antananarivo, Madagascar (Received8 .Jub 1992) zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLK Key Word Index-Munduleu striata; Fabaceae; pterocarpan; striatine. new prenylated pterocarpan, striatine was isolated from aerial parts of zyxwvutsrqponmlkjihgfedcbaZYXWVUT Munduleu striata. Its chemical structure was established by 1D and 2D NMR spectral analysis. Abstract-A INTRODUCTION Mundulea strinta Baker is a shrub which is found growing wild throughout Madagascar [l]. In some regions, the local population uses crushed leaves or stem bark of this plant as fish poison [2]. Toxic effects have been also reported [S]. In continuation of our work directed towards the discovery of new insect-control agents, we have investigated the aerial parts of Mundulea striata. The present paper describes the isolation and structure elucidation of a new pterocarpan, striatine. Prior to our work, no previous phytochemical and biological studies on this species have been reported. RESULTSAND DISCUSSION 1 Preliminary bioassay directed fractionation showed that the active compound was localized in the chloroform-soluble fraction of the ethanolic extract. TLC analysis of this fraction revealed the presence of one major component detectable in UV together with four others which were assumed to be triterpenes on the basis of the purple colouration obtained with sulphuric acid spray reagent and positive Liebermann-Burchard test [4]. Silica gel column chromatography of this fraction using hexane and increasing amounts of chloroform led to the isolation of striatine (1). The molecular formula of striatine was determined as C2sH2s04 from its chemical ionization mass spectrum and i3C NMR spectral data. The UV spectrum suggested an unconjugated aromatic system [S]. The bathochromic shift observed with alkali indicated the presence of one or more phenolic groups. This was further supported by the strong colouration with ethanolic ferric chloride.. Structure 1 was established on the basis of the data obtained from the 2D NMR spectra in addition to conventional 1D NMR methods. Interpretation of the ‘H NMR spectrum was assisted by an ‘H-‘H COSY experiment. Assign- ments of the protonated carbon signals were done after an ‘H-13C heteronuclear shift correlated NMR experiment (Table 1). Thus, the aliphatic protons of the chromane part of 1, typical of basic pterocarpan skeleton, were unequivocally assigned: a doublet at 6 5.47 was assigned to H-l la; H&a appeared at 63.47 as ddd and H-6c1 and H-6/I each as dd respectively at 63.58 and 4.21. The proton signal of the prenyl groups attached to C-10 were identified by examination of their coupling pattern: methylene and olefinic methine protons formed an ABX system with AB system appearing at 63.32 (H-l’a) and 3.45 (H-1’8; the X part (H2’) resonating at 65.29, further coupled with the two methyl groups resonating respectively at 6 1.74 and 1.81 via long range interaction. The proton signals of the prenyl residue attached to C-2 were unambiguously assigned: a singlet at 61.47 was ascribed to the genrdimethyl groups; multiplication of the olefinic protons 515 Short Reports 516 Table 1. “C 1 128.9 CH la 112.2 c 2 126.6 C 3 t56.2 C 4 105.5 CH 4a 155.5 C 6 66.5 CH, 6a 6b 40.1 CH 118.8 c 7 112.3 CH 8 108.2 CH 9 155.8 C 10 110.4 C 1Oa 158.4 C lla 78.4 CH 1’ 23.2 CH, 2’ 121.5 CH C 3 134.8 4’ 25.8 CH, 5 17.8 1” 39.3 CH, C 2” 27.1 CH, 3” 27.1 4” 147.9 CH, CH 5” 113.6 CH, Table 2. ‘H-13C ‘H 1 tSc forming an ABX system was evident from examination of their coupling pattern: H-S’r, H-5”fi and H-4” as zyxwvutsrqponm dd, respectively, at 65.30, 5.36 and 6.20. In the aromatic region of the spectrum, two singlets at 66.44 and 7.40 1.40 s were assigned to the puru oriented protons H-4 and H-l, whereas two doublets at 66.36 and 6.93 were ascribed to the ortho oriented protons H-S and H-7. Chemical shifts of the quaternary carbons of zyxwvutsrqponmlk 1 were 6.44 s definitively assigned by the use of ‘HJ3C long range connectivities techniques namely HMBC [6], which also H, 3.58 zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA dd 11.4, - 10.6 confirmed the structure of striatine. Long range connecH, 4.21 dd 4.7, - 10.6 3.47 ddd 11.4, 6.5,4.7 tivities (Table 2) observed for H-l, H-4, H-Sa, H-lla allowed us to assign accurately the quaternary carbons 6.93 d 8.0 C-2, C-3, C-4a and C-la. This series of long range 6.36 d 8.0 connectivities is in perfect agreement with the chromane fragment of 1 and suggested that the l,l-dimethyl fragment is connected to C-2. This was evidenced by the observation of a long range connectivity from the methyl 5.47 d 6.5 singlet Me-2” to C-f”, C-2, C-3” and C-4“. Turning to the H, 3.32 dd 7.4, - 15.6 second fragment of 1, long range connectivities observed H, 3.45 dd 6.5, - 15.6 for H-6a, H-7 and H-8 were consistent with the benzo5.29 m 7.4, 6.5, -1.1, -1.1 furan fragment of structure 1 and allowed us to assign unequivocally the quaternary carbons C-6b, C-9, C-10 1.74 d -1.1 and C-1Oa. Moreover, it was deduced that the 3,31.81 d -1.1 dimethyl ally1 residue is attached to C-10. This was confirmed by the observation of an extensive long range 1.47 s connectivity from the methylene protons CH2-1’ to C-9, 1.47 C-10, C-lOa, C-2’ and C-3’. Therefore, striatine is (6aRiid 6.20 11.7, 10.6 cis)-6a,lla-dihydro-l0-(3-methyl-2-butenyl)-2-(l,l~imeH, 5.30 dd 10.6, -0.8 thyl-2-propenyl)-6H-benzofuro[3,2-c] El] benzopyranH, 5.36 dd 17.7, -0.8 3,9-dial (1). and ‘H NM R spectral data for striatine 3 long range correlations (+) observed in the ‘H-J3C 4 6 6a 7 8 la + f + + + + + 2” 3” 4” + + -t f f + + + 5”a 5”fi f + + + 6b + + + 9 + 10 1Oa -I+ + + + i- + + + 2 3’ + + 4 -t 5 + 1” 5’ + + + f 6 6a lla 4’ + 4 4a 2’ + + + 2 1’ aB 1 3 lla OH multiple bond correlation spectrum of striatine (1) f + + “t + 2” 3” + 4” + + + + Short zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGF Reports zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLK 517 EXPERIMENTAL Extraction and isolation. Plant material was collected in Antananarivo (Sabotsy-Namehana) in September 1991. A voucher specimen is deposited at the IMRA. Airdried and powdered aerial parts (500 g) were exhaustively macerated in ethanol (3 x 24 hr). The combined ethanol solns were evapd to near dryness under red. pres. and then partitioned between CHCl, and H,O. The exhausted H,O phase was further extracted with BuOH. The CHCl, extract (1.6 g) was submitted to silica gel CC using hexane and increasing amounts of CHCl, as eluent. Elution with hexaneCHC1, (4: 1) yielded pure striatine (34 mg), amorphous solid, [a];’ - 141” (CHCl,, c 0.82); UV a”‘“x” (log E) 227 (4.10), 289 (3.85); CIMS: 393 [M requires +1]+. HR-MS: Found 392.2001, C,,H,,O, 392.1987. REFERENCES zyxwvutsrqponmlkjihgfedcbaZY 1. Baker, H. (1883) Bn Bull. Sot. Lin. Paris I, 389. 2. Boiteau, P. (1936) Bull. Econ. Madag., 4eme trimestre, 111. 3. Rasoanaivo, P., Petitjean, A. and Conan, J. Y. (1992) Fitoterupia (in press). 4. Ciulei, I. (1982) M ethodologyfor Analysis of Vegetable Drugs, Document published on behalf of UNIDO by the Bucharest office of the joint UNIDO, Romania Centre. 5. Scott, A. I. (1964) Interpretation of the UV Spectra of Natural Products, p. 92. Pergamon Press, Oxford. 6. Martin, G. E. and Crouch, R. C. (1991) J. Nat. Prod. 54, 1.