Chemical constituents of Simarouba versicolor

From the roots, stems and fruits of Simarouba versicolor (Simaroubaceae) were isolated quassinoids ( 3, 5-7), triterpenoids ( 8-14), a mixture of steroids ( 15-17), the flavonoid kaempferol ( 18) and the squalene derivative 11,14-diacetoxy-7,10; 15,18-diepoxy-6,19-dihidroxy-6,7,10,11,14,15,18,19-octahydrosqualene ( 19). Spectral data were used for structural characterization.


INTRODUCTION
Some species of the small family Simaroubaceae (28 genera containing 25 species of tropical and semitropical shrubs and trees) have furnished wood for construction and others have been used in folk medicine.In the last few years, the therapeutic purposes have increased because of its antimalarial, antiinflammatory, antileukemic, antifeedant, and antiviral activities (Engler and Prantl 1872).In Brazil, the Simaroubaceae family is represented by the genera Quassia and Picrolemma, in the Amazonian Region, Castela and Picrasma, in the south of the country, and Simaba, Simarouba and Picrolemma which are present throughout Brazil (Hall et al. 1983).
Correspondence to: Raimundo Braz-Filho E-mail: braz@uenf.br*Member of Academia Brasileira de Ciências Species of the genus Simarouba have been reported previously as bioproducers of anticancer, antiviral, antimalaric, antiinflammatory (Polonsky 1973), insecticide and amoebacide agents (Polonsky 1985).This latter species has been used in the traditional medicine and is very known in China and Mexico.
The present paper deals with the isolation of the known quassinoids (3, 5-7), triterpenoids (8-14), a mixture of steroids (15-17), the flavonoid kaempferol (18) and a squalene derivative (19) from specimens of Simarouba versicolor collected in Cascavel (stems and fruits) and Pacatuba (roots) in the State of Ceará, in the northeastern of Brazil.This region has a very distinct climate, which is different from the place where the specimen was collected for the previous investigation.The structures of the compounds reported in this paper were established on the basis of spectral data, including 2D NMR experiments of 19.
11-Acetylamarolide (3) was isolated from a specimen of S. versicolor collected in Paraná, state located in the South of Brazil (Ghosh et al. 1977).
The presence of steroids 15-17 in a mixture was mainly deduced by 13 C NMR spectral data, which involved comparison with values reported in the literature (Blunt andStother 1977, Chaurasia andWichtl 1987).The peaks at m/z 414 ([M] + . of 15), 412 ([M] + . of 17) and 400 ([M] + . of 16) observed in the mass spectrum was also used for the identification of these compounds.
The number of linked hydrogens for each carbon signal of 19 (mp 149.8-153.2o C) was deduced by comparative analysis of HBBD (30 singlet signals corresponding to 34 carbon atoms) and DEPT-13 C NMR [signals corresponding to 8 quaternary carbons (including two carbonyl of acetyl groups at δ C 170.92 and 170.78, which were also suggested by IR spectrum), 5 representing 6 methine carbons (two sp 2 and four oxygenated), 10 methylene carbons and 9 representing 10 methyl carbons (two of acetyl groups at δ C 21.13 and 21.07, in accordance with the singlet signals observed in the 1 H NMR at δ H 2.03 and 2.04)] spectra (Table I).These data in combination with results obtained by 1 H NMR (1D and 2D 1 H-1 H-COSY) and by heteronuclear 2D 1 H-13 C-COSY-n J CH (n=1, direct correlation via one bond -HETCOR -13 C detected, conventional method; n=2 and 3, long-range spin-spin interaction -COLOC -13 C detected, conventional method) spectra and comparison with values reported in literature for eurylene (19) (Itokawa et al. 1991, Morita et al. 1993) were used to complete 1 H and 13 C chemical shift assignments unambiguously.The differences observed in the comparison of the 13 C chemical shifts (Table I) may be attributed to mistakes previously reported using CDCl 3 as solvent (Itokawa et al. 1991), which was also used in our experiments, or to a solvent effect when the comparative analysis involves data obtained in CDCl 3 and pyridine-d 5 (Morita et al. 1993), as summarized in Table I.The 13 C NMR spectral data obtained in pyridine-d 5 (Morita et al. 1993) were used to eliminate the mistakes observed in the previous attribution when was used CDCl 3 (Itokawa et al. 1991).However, the mistakes corre-sponding to CH 3 -25/CH 3 -30 (δ C 17.58 and not 25.7 or 25.8), shielded as consequence of the γ -effect attributed to CH 2 -4/CH 2 -21, and CH 3 -1/CH 3 -24 (δ C 25.24 and not 17.6 or 17.7), free of this γ -effect, were maintained (Table I).On the basis of this γeffect, the ambiguous assignments may now be eliminated, as shown in Table I.The results obtained by 1 H-1 H-NOE difference spectra (Table I) were also used to confirm these data and to obtain stereochemical information on some stereogenic carbon atoms of 19.The absolute configuration of eurylene ( 19), mp 146-148 o C, [α] D +4.32 • , was established by Xray analysis and Mosher's method (Itokawa et al. 1991, Morita et al. 1993).

General Experimental Procedure
Melting points (mp) were measured on a Mettler (FP-52) micro-melting point apparatus and are uncorrected; IR spectra were recorded on a Perkin-Elmer 720 spectrophotometer;

Extraction and Isolation
Dry and powdered roots (480g) were extracted, at room temperature, with hexane and following with acetone.The residue obtained from the acetone extract, after evaporation of the solvent under vacuum, was chromatographed on a silica gel column to give the compounds 5 to 13, 19 and a mixture of the steroids 15, 16 and 17 (Alves- de-Lima et al. 1982, Alves-de-Lima et al. 1983, Alves-de-Lima et al. 1984, Siqueira et al. 1985).

Fig. 3 -
Fig. 3 -Comparison of the chemical shifts of C-20 to C-25 of 11 with the corresponding values of sapelin A (Z=α-OH,H; R=H) reported in the literature(Jolad et al. 1981.The coupling constant (J = 9.0 Hz) observed for signals of 11 and 11a reveal an axial-axial interaction between H-24 and H-23.

Fig. 5 -
Fig. 5 -Comparison of the 13 C chemical shifts of atoms CH-21 and CH-23 of 13 and 14 and deduction of the relative configurations.

TABLE I 1D and 2D 1 H and 13 C NMR spectral data for compound 19, in CDCl 3 and TMS as internal standard, compared with values (in parenthesis, in CDCl 3 and pyridine-d 5 respectively) described in the literature (Itokawa et al. 1991, Morita et al. 1993) for eurylene (19). Chemical shifts in δ (δ H and δ C , ppm) and coupling constants (J , in parenthesis) in Hz.*
1 H and 13 C NMR spectra (1D and 2D) were run on Bruker AC-200 ( 1 H: 200 MHz; 13 C: 50 MHz) and Varian XL 100