0. Muiioz, C. Schneider, E. Breitmaier 52 1

Notiz / Note

A New Pyrrolidine Alkaloid from Schizanthus integrvolius Phil. Orlando Muiioz", Christiane Schneiderq and Eberhard Breitmaier"

Departamento de Quimica, Facultad de Ciencias Quimicas, Universidad de Chile", Casilla 653, Santiago, Chile

Institut fur Organische Chemie und Biochemie der Universitat Bonnb, Gerhard-Domagk-Strale 1, D-53121 Bonn

Received November 11, 1993

Key Words: Alkaloids I Galactopyranosides, 6-deoxy- I Schizantus integrifolius I Carbohydrates

A new pyrrolidine alkaloid has been isolated from the leaves of Schizantus integrifolius Phil. Its structure was elucidated by one- and two-dimensional NMR methods as l-methyl-2-

(1-methyl-2-pyrrolidiny1)ethyl 6-deoxy-3-0-[ (Z)-2-methyl-2- butenoyll-a-galactopyranoside (1).

A new pyrrolidine alkaloid of the hygroline type was isolated from the ethanol extract obtained from the leaves of Schizanfhus integrifolius Phil. (Solanaceae) by column chromatography. High- resolution mass spectrometry affords a molecular mass of 371.2316, corresponding to the molecular formula C19H33N06 and including four double bond equivalents. The I3C-NMR spectrum presents a CH signal with hC = 102.2 which is characteristic of an anomeric pyranose ring carbon atom. The sugar moiety turns out to be 6-deoxy-a-galactopyranosyl (a-fucopyranosyl) by means of an HH COSY contour plot and the HH coupling constants (4 Hz for the anomeric proton, 3 Hz between 3-H and 4-H, a quartet with 7 Hz of doublets with 3 Hz due to coupling between 5-H and 6-H3, and an equatorial 4-H), consuming one double bond equivalent. The 'H-NMR spectrum further displays an alkene pro- ton with 8" = 5.86 which splits into a quartet (7 Hz) of quartets (2 Hz). An HMBC contour plot and NOE difference spectroscopy identify this partial structure as (Z)-2-methyl-2-butenoyl (angeloyl) with two additional double bond equivalents. A l-methyl-2-(1- methyl-2-pyrrolidiny1)ethyl residue arises from the connectivities of the HH COSY experiment and the remaining double bond equival- ent. Its linkage to the anomeric carbon C-1 of the galactopyranosyl ring is indicated by an NOE enhancement of the proton signal with 8H = 3.76 upon irradiation of the anomeric proton with 8" = 5.00. A deshielding of 3-H in the 6-deoxygalactopyranosyl ring locates the esterification with (Z)-2-methyl-2-butenoic (angelic) acid at C- 3.

The high-resolved mass spectrum supported this structure 1: A prominent fragment with m/z = 84 (C5HION) resulting from a split- ting to the nitrogen confirms the pyrrolidine ring. The fragment with m/z = 83 (C5H70) follows from an a splitting with respect to the oxygen of the acid. Additional fragmentations are indicated in formula 2.

According to these results, the new pyrrolidine alkaloid has the structure l-methyl-2-(l-methyl-2-pyrrolidinyl)ethyl 6-deoxy-3-0- [(Z)-2-methyl-2-butenoyl]-a-galactopyranoside (1); the absolute configurations of the fucose (D or L) and of the hygroline moiety could not be determined from the sample available (6 mg).

1.19AB1.82 1

27.8 1.46AB1.60 1.43ABl. 87

HB multiplicitica and coupling conmtanta [Hz]

6-deoxy-a-galactopyranosyl part

3-13 d 9 d 3 d 3 - d 3 - d 3 - q ?

- d ? -

(2)-2-methyl-2-butanoyl part

This work was supported by the Deutsche Forschungsgemein- schuft.

Liebigs Ann. Chem. 1994,521 -522 0 VCH Verlagsgesellschaft mbH, D-69451 Weinheim, 1994 0170-2C41/94/0505-0521 $10.00+.25/0

522 0. Muiioz, C. Schneider, E. Breitmaier

2

specimen is deposited in the Facultad de Ciencias Herbarium Uni- versidad de Chile, Santiago, Chile. The air dried and finely pow- dered leaves were extracted with light petroleum ether and then percolated with ethanol at room temp. The ethanol extract was partitioned as described Further purification was performed by column chromatography on aluminium oxide (ac- tivity 90, basic) with methanol (2 vol. %) in ethyl acetate as eluant (Rf = 0.5, dichloromethane with 0.5 vol. %methanol). An amorph- ous substance with [a]$!' = +14.2 (c = 1.03, ethanol) was obtained. - C19H33N06: mlz found 371.2316 (MS), calcd. 371.2308. - NMR data (6 mg sample, CDC13, 500 MHz for 'H, 125 MHz for I3C, assignments based on HH COSY, CH COSY, HMBC, NOE differ- ence spectroscopy) see formula 1, 'H chemical shifts (6,) and coup- ling constants ( J H H , Hz) in italics. - MS fragmentations see for- mula 2.

[ I ] A. San Martin, C. Labbe, 0. Muiioz, M. Castillo, M. Reina, G. de la Fuente, A. Gonzales, Phytochemistry 1987,26, 819-822.

L2] 0. Muiioz, R. Hartmann, E. Breitmaier, J Nut. Prod. 1991, 54, 1094- 1096.

[248/93]

Experimental Schizunthus integrijbfius Phil. was collected in October 1991 in

the mountain region of the Serena province of Chile. A voucher

Liebigs Ann. Chem. 1994, 521 -522