Abietane Diterpenes from Sagittaria montevidensis ssp montevidensis Charm . & Schltdl

The family Alismataceae comprises 12 genera and about 75 species of herbaceous aquatic plants and some of these species are used in traditional Chinese medicine. There are only two genera that are naturally found in Brazil: Echinodorus and Sagittaria. Sagittaria species are known to produce biologically active compounds such as clerodane, pimarane, labdane and rosane-type diterpenoids. As part of our continuous work on plants from Alismataceae, we now describe the isolation and characterization of two new diterpenes abietanes derivatives, 3β-hydroxy-9α, 13αepidioxyabiet-8(14)-ene (1) and 3-oxo-9α, 13αepidioxyabiet-8(14)-ene (2), which were obtained from the crude methanolic extracts of the fresh petioles of Sagittaria montevidensis ssp montevidensis. The structures of the new metabolites were determined on basis of spectrometric analysis including HREIMS, IR, H and C 1 and 2D NMR and also by comparison of their NMR data with those of related metabolites. Results and Discussion


Introduction
The family Alismataceae comprises 12 genera and about 75 species of herbaceous aquatic plants and some of these species are used in traditional Chinese medicine.There are only two genera that are naturally found in Brazil: Echinodorus and Sagittaria.2][3][4][5][6] As part of our continuous work on plants from Alismataceae, [7][8][9] we now describe the isolation and characterization of two new diterpenes abietanes derivatives, 3β-hydroxy-9α, 13αepidioxyabiet-8(14)-ene (1) and 3-oxo-9α, 13αepidioxyabiet-8(14)-ene (2), which were obtained from the crude methanolic extracts of the fresh petioles of Sagittaria montevidensis ssp montevidensis.The structures of the new metabolites were determined on basis of spectrometric analysis including HREIMS, IR, 1 H and 13 C 1 and 2D NMR and also by comparison of their NMR data with those of related metabolites.

Results and Discussion
Fresh petioles of Sagittaria montevidensis ssp montevidensis were extracted with MeOH.After removal of solvent, this extract was partitioned between H 2 O and EtOAc.The EtOAc fraction was chromatographed on silica Gel 60 to yield the compounds 1 and 2.
The structure of 1 was completely assigned by a combination of one and two-dimensional NMR methods.The carbon resonances at δ C 78.4 (CH), 80.9 (C) and 79.3 (C) in the 13 C NMR and DEPT spectra suggested the presence of the oxymethine and endoperoxide groups.Furthermore, the presence of the two sp 2  The 1 H NMR spectrum of 1 confirmed the presence of an oxymethine hydrogen (δ H 3.10, dd, J 10.8; 4.5 Hz); one olefinic hydrogen (δ H 6.12, d, J 2.7) and an isopropyl group (δ H 0.93, d, J 6.9 Hz).In addition, three intense singlet are also observed at δ H 0.91, 0.94, 1.06 corresponding to methyl groups.

General experimental procedures
Optical rotations were measured on an ORD 306 spectropolarimeter J-720 in CHCl 3 at 25 °C.IR spectra were measured on a FTIR (KBr) Bomen MB Series spectrometer. 1 H, 13 C 1 and 2D NMR spectra were taken on a Varian Mercury plus BB spectrometer, operating at 300.059 MHz for 1 H and 75.458MHz for 13 C in (CD 3 ) 2 CO solution using TMS as internal standard.HRMS were carried out using a Micromass VG AutoSpec.spectrometer operating at 70 eV.

Plant material
The plant material was collected in Curitiba-Paraná, Brazil and authenticated by Dr. Maria do Carmo Amaral (Instituto de Biologia, Universidade Estadual de Campinas).Voucher specimens (# UEC 115194) were deposited in the Herbarium of the Instituto de Biologia, Universidade Estadual de Campinas.