Isoflavonoids and Triterpenoids Isolated from Pterodon polygalaeflorus

Os isoflavonóides 6,7-dimetoxi-3’,4’-metilenodioxi-, 4’-hidroxi-3’,6,7-trimetoxi-, 3,4,6,7tetrametoxi-, 7-hidroxi-6-metoxi-3,4-metilenodioxi-, 2’,6,7-trimetoxi-3’,4’-metilenodioxi-, 2’,3’,4’,7,7-pentametoxie 2’,4’,5,6,7-pentametoxiisoflavona, os triterpenóides lupeol e betulina e o ácido 4-metoxibenzóico foram isolados dos extratos acetônicos do alburno e do cerne de Pterodon polygalaeflorus. As estruturas destes produtos naturais foram caracterizadas por métodos espectrométricos, principalmente experiências de RMN 1D e 2D de hidrogênio e carbono-13, que foram também utilizados para a atribuição inequívoca dos deslocamentos químicos dos átomos de hidrogênio e carbono-13 dos isoflavonóides.


Introduction
In a paper published recently the isolation of diterpenes from fruits of a specimen of Pterodon ploygalaeflorus Benth, Leguminosae family, was reported 1 .As part of our continuing chemical investigation of this plant we have investigated the sapwood and the heartwood.The isoflavones 1-7, p-methoxybenzoic acid (8), lupeol (9), and betulin (10), have been isolated from this plant material.The structures of these natural products were established by spectral data, mainly 1 H-and 13 C-NMR including ho-monuclear and heteronuclear 2D experiments (2, 3a, 5 and 7) and NOE difference spectra (1, 2, 3a, 5 and 7), which were also used for complete assignment of the hydrogen and carbon-13 atom chemical shifts of the isoflavonoid 2, the acetyl derivatives 3a, 5 and 7.
The homonuclear 1 H-x 1 H-COSY, heteronuclear 1 H-x 13 C-COSY-n JCH (n = 1, spin-spin couplings between 13 C and 1 H-atoms via one bond; n = 2 and 3, COLOC = correlation via long-range couplings) 2D shift-correlated NMR spectra 8 of 2, 3a, 5 and 7 (Tables 1-3) and NOE difference spectra 8 of 1, 2, 3a, 5 and 7 (Table 4) together with the application of the shift parameters and the observed multiplicities of the signals of the carbon atoms deduced by comparative analysis of the PND-and DEPT-13 C-NMR spectra 9 , were also used for the complete assignment of the hydrogen and carbon-13 atom chemical shifts  1-4).
Thus, a series of 2D NMR experiments led to the assignment of all 1 H-and 13 C resonances for 2 and 3a (e. g.).In the 1 H-x 13 C-COSY-1 JCH spectra of 2 and 3a the connectivities between the protonated carbon atoms and   Homonuclear NOE difference ( 1 Hx{ 1 H}-NOE) spectra (Table 4) of compounds 1, 2, 3a, 5 and 7 contributed to the assignments (Tables 1 and 2).The EIMS and IR spectra were also used (vide experimental).

General experimental procedures
Mps were determined on a Mettler PF-5 melting point analyser.IR spectra were recorded in KBr using a Perkin-Elmer 720 infrared spectrometer.UV spectra were recorded in MeOH on a Varian-UV/ VIS 634-5 spectrometer.
1 H-and 13 C-NMR spectra were obtained on a Bruker AC-200 spectrometer with standard pulse sequences operating at 200 MHz and 50.3 MHz, respectively, except the 1 H-NMR of 4a and 6 which were recorded on a Varian EM-360 (60 MHz) and Varian XL-100 spectrometers, respectively.The chemical shift values are reported in δ (ppm) and the coupling constants (J) are in Hz; carbon multiplicities were determined by DEPT experiments; 1 Hx 1 H--COSY, 1 H-x 13 C -COSY -1 JCH, 1 H-x 13 C -COSY n JCH (n = 2 and 3, COLOC), NOE difference spectra NMR experiments were carried out using Bruker commercial microprograms.Low-resolution EIMS (70 eV) data were obtained on a GC/MS Finningan 3300F/ 9500 apparatus.Chromatography was performed using Merck Kieselgel 0.05-0.20 mesh and TLC with Merck Kieselgel 60 F254.TLC plates were examined under UV illumination and after exposure to iodine vapour.

Plant material
A specimen of Pterodon polygalaeflorus was collected in Monte Alegre -Bom Jesus, Piauí State, Brazil and identified by Professor Afrânio Gomes Fernandes (Universidade Federal do Ceará, Fortaleza, Ceará, Brazil).A voucher specimen is deposited at the Herbarium Prisco Bezerra of the Departamento de Biologia -Universidade Federal do Ceará.

Methylation of 3
A solution of 3 (100 mg) in anhydrous acetone (40 mL) was treated with Me2SO4 (0.5 mL) in the presence of calcinated K2CO3, under reflux during 24 h.After filtration, the acetone was evaporated and the residue washed with 50% NH4OH.The remaining residue was crystallized from MeOH to give 2.

3a, 5 and
7, and consequently of the other isoflavonoids isolated from Pterodon polygalaeflorus by comparison with data now unambiguously assigned (Tables