Further Aporphine Alkaloids from Phoebe lanceolata

Transcription

1 Molbank 008, M58 Short Note PEN ACCESS molbank ISSN Further Aporphine Alkaloids from Phoebe lanceolata Deepak K. Semwal *, Usha Rawat and G. J. P. Singh Department of Chemistry,.N.B. Garhwal University Srinagar, Uttarakhand 4674, India Department of Chemistry, Punjab University, Chandigarh, Punjab, India *Author to whom correspondence should be addressed; Tel. (+9) Received: 30 September 008 / Accepted: 6 November 008 / Published: 3 November 008 Abstract: Stem bark of Phoebe lanceolata was extracted with ethanol and fractionated with ethyl acetate yielded soluble and insoluble fractions. Ethyl acetate insoluble fraction was subjected to column chromatography afforded two oxalyl-fused didehydroaporphine alkaloids, N-6/C-7 oxalyl-fused,9-dihydroxy-,0-dimethoxy 6a,7-didehydroaporphine and N-6/C-7 oxalyl-fused,,9,0-tetramethoxy 6a,7-didehydroaporphine along with well known β-sitosterol and β-sitosterol glucoside. The structures of isolated compounds were elucidated by chemical and spectral analysis. Keywords: Phoebe lanceolata, Lauraceae, aporphine alkaloid, laurodionine. Introduction Phoebe lanceolata belonging to family Lauraceae is an evergreen tree and well reputed in traditional medicine in India []. Ethanolic extract of the stem bark showed antidiabetic, antibacterial and antifungal activity (preliminary work done by us at different laboratory). We recently reported an aporphine alkaloid, nordelporphine [] from this source and now outlined the isolation and characterization of two oxalyl-fused didehydroaporphine alkaloids.

2 Molbank 008 M58 (Page ). Results and discussion Compound was isolated as black crystals, m.p C (uncorr.) deduced the molecular formula C 0 5 N 6 from the molecular ion at m/z in the LC-EIMS (positive mode). This compound was elucidated as N-6/C-7 oxalyl-fused,9-dihydroxy-,0-dimethoxy 6a,7- didehydroaporphine by direct comparison (UV, IR and NMR) to published data for laurodionine [3] isolated from P. formosana. Compound was isolated as black-brown crystals, m.p C deduced the molecular formula C 9 6 N from the molecular ion at m/z in the EIMS. The IR absorptions at υ KBr 734 max cm- was characteristic for carbonyl function. NMR spectrum revealed the presence of four methoxy (δ 3.9, 3.63, 3.76 and 3.85) and three aromatic protons (δ 7.8, 7. and 6.73). Figure. Chemical structures of compound and. R 3 3a C a b 6 N 6a a 7a C R R R C 3 C 3 Figure. Important MBC and NESY correlations of compound. 3 C 3 3a C a b 6 N 6a a 7a C C 3 MBC NESY

3 Molbank 008 M58 (Page 3) 3 C NMR spectrum expressed the evidence for two carbonyl groups (δ and 73.33). DEPT (35 0 ) showed the presence of four C 3, two C, three C and thirteen quaternary carbons. MBC and NESY correlations are shown in Fig.. These data were somewhat similar to that of except the presence of two methoxy groups instead hydroxy groups. n methylation [4], compound afforded black brown product identical to indicated that the locations of methoxy groups in were similar to those of hydroxy groups in. The MBC correlation of C 3 - (δ 3.9) to C- (δ 44.54), C 3 - (δ 3.63) to C- (δ 59.8), C 3-9 (δ 3.76) to C-9 (δ 5.3) and C 3-0 (δ 3.85) to C-0 (δ 48.77) whereas the NESY correlation of C 3 - to C 3 - and - (δ 7.8); C 3 - to C 3 - and -3 (δ 7.); C 3-9 to C 3-0 and -8 (δ 6.73) and C 3-0 to C 3-9 and - were further confirmed the position of all methoxy groups. EIMS (positive mode) revealed a molecular ion at m/z 393, another ion at m/z 377 (loss of C 4 ) and the most abundant ion [C 6 5 N 4 ] + at m/z 75 was due to loss of C 5 0. n the basis of these findings and the proposed structure described by Castedo et al., [5], the compound was characterized as N-6/C-7 oxalyl-fused,,9,0-tetramethoxy 6a,7-didehydroaporphine. 3. Experimental 3.. General Melting points were determined on Perfit melting point apparatus; UV spectra on Perkin-Elmer, Lambda- 5 spectrophotometer in Me; IR spectra on Perkin-Elmer, Spectrum RX I FT-IR spectrophotometer (KBr discs); NMR spectra on JEL NMR spectrophotometer (300 Mz for and 5 Mz for 3 C in DMS, TMS as internal standard); LC-EIMS on Finnigan MAT spectrophotometer. Preparative TLC (0.5 mm thick layer) was carried out on silica gel (Merck 0-40 μ) spots were detected using UV at 54 and 365 nm and Dragendorff s reagent. 3.. Plant material Stem bark (6 kg) of P. lanceolata was collected from Kartikswami temple, Dist. Chamoli (Uttarakhand) and identified by Prof. R.D. Gaur, Department of Botany,.N.B. Garhwal University Srinagar. A voucher specimen (GU-7598) of the plant was deposited in the Departmental erbarium Extraction and isolation Coarsely powdered stem bark ( kg) was extracted twice with 95% ethanol (5L) at 50 0 C (5 hours) on a heating mantle. After removal of the solvent under reduced pressure, the residue (30 g) was fractionated with EtAc (repeated 3-4 times) yielded soluble and insoluble portions. The insoluble portion (0 g) was pre-adsorbed onto silica gel (50 g) and subjected to column chromatography over silica gel (500 g, Merck, 60-0 mesh). The elution was perform first with CCl 3 and then with CCl 3 containing increasing amount of Me. The fractions obtained were collected every 50 ml. The elution with CCl 3 Me (47:3 9:) afforded twelve fractions of 50 ml. These fractions were

4 Molbank 008 M58 (Page 4) combined on the basis TLC analysis and subjected to preparative TLC in CCl 3 Me (8:) afforded compounds (3 mg) and (0 mg), purified by recrystallised with CCl 3 Me (:) N-6/C-7 oxalyl-fused,,9,0-tetramethoxy 6a,7-didehydroaporphine () Black-brown crystals (CCl 3 /Me); m.p C; [α] 0 D : (c 0.3, Me); M.F. C 9 N 6, UV λ Me max : 06, 68, 434 nm; IR υ KBr : 956, 734, 66, 554, 47 max cm-., 3 C, MBC and NESY NMR data: see Table-; LCMS: 393 [M] +, 377 [C 5 N 6 ] +, 75 [C 6 5 N 4 ] +, 48 [C 8 6 N ] + ; Elemental analysis: (found C- 67.4%, %, N and %; calculated for C 9 N 6 C- 67.7%, %, N and %). Table. 3 C and NMR data of in DMS d 6 Position δ C ppm δ ppm (J z) DEPT NESY MBC C a C b C C s C , a C t (3.8) C , t (3.8) C , a C C 7a C s C , 5.83, C C s C 3.85, , 6.0, 5.3 a C C C C s C , C s C 3 3.9, C s C , C s C , Methylation of compound Dimethyl sulfate (.5 mg) and dry potassium carbonate (.5 mg) were added to compound (5 mg) in 5 ml of acetone. The mixture was stirred vigorously and refluxed for 30 minutes in round bottom

5 Molbank 008 M58 (Page 5) flask on water bath. The concentrated filtrate afforded methylated product, M.P C as a black brown compound. Acknowledgements The work was supported by UGC New Delhi, India; Grant No. 33-8/007(SR). Authors are grateful to Prof. M. S. M. Rawat for providing lab facilities and NIPER Chandigarh for scanning LCMS of isolated compounds. References. Gaur, R.D. Flora of Garhwal North West imalaya. Trans Media: Srinagar Garhwal. 999, p Semwal, D.K.; Rawat, U. Nordelporphine alkaloid from bark of Phoebe lanceolata. rient. J. Chem. 007, 3, Chen, C.C.; uang, Y.L.; Lee, S.S.; u, J.C. A new oxalyl- fused aporphine alkaloid from Phoebe formosana. J. Nat. Prod. 997, 60, Luo, Y.; Liu, Y.; Luo, D.; Li, B.; Zhang, G. Cytotoxic alkaloids from Boehmeria siamensis. Planta Med. 003, 69, Castedo, L.; Sal, C.; Sad, J.M.; Suau, R. Synthesis of oxoaporphines. An unusual photocyclization-photoreduction of,3-diaryl-δ -pyrroline-4,5-diones. J. rg. Chem. 98, 47, by the authors; licensee Molecular Diversity Preservation International, Basel, Switzerland. This article is an open-access article distributed under the terms and conditions of the Creative Commons Attribution license (