Simple indole bases of Desmodium gangeticum (Leguminosae)

Abstract

Previously, we reported1-3 the occurrence of seven indole-3-alkylamine bases in the above-ground portions of Desmodium pulchellum Benth, ex Baker. We also appraised the significance of the co-presence of these and related bases, in several plant species, in the light of tryptophan metabolism in plants. To extend the knowledge of content and distribution of simple indole bases in the genus Desmodium, we have now investigated the alkaloidal constituents of Desmodium gangeticum DC. The present communication is an account of the isolation and characterization of four known indole-3-alkylamine bases, viz. 5-methoxy-N,N-dimethyltr~tamine,~ N,N-dimethyltry~tamine,~ and their N-oxide^,^ and two P-carboline alkaloids, viz. Nb-methyltetrahydroharman4 and 6-methoxy-2-methyl-harbolinium cation, from the above-ground portions of D. gangeticum. Incidentally, this is the first report of isolation of the last-named alkaloid from a plant source.The quaternary nature of the P-carboline alkaloid was revealed from its isolation as reineckate salt from alkaline solution, its high pK, value ( E 10.8), and its u.v. absorption spectra in neutral ethanol and ethanolic alkali ( A , , ,240, 250,272-275sh, 290, and 342 mp; a bathochromic shift of the major bands by about 10 mp was observed in 0 . 0 5~ ethanolic alkali). The u.v. absorption spectra of the alkaloid indicated its similarity with Nb-methyl-P-carbolinium ati ion.^ Chemical proof for its structure was gained from its reduction with sodium and ethanol to 1 , 2 , 3 , 4 -t e t r a h y d r 0 -6 -m e t h o x y -2 -r n e t h y l -~e .~ Although tetrahydroharman and N,-methyltetrahydroharman bases are known4 to occur in the Leguminosae, a quaternary P-carbolinium alkaloid of the type mentioned here appears to have been isolated only from the L~ganiaceae.~ D. gangeticum DC. which grows abundantly in India has been known as a drug in the Ayurvedic system of medicine.' Its roots are used as astringent, in diarrhoea, in chronic fever, biliousness, snake-bite, and poisoning. Assays in this laboratory indicate that air-dried samples of this plant normally contain 0.01-0.03% total alkaloid, but that fresh material contains more than three times the amount present in dry and preserved samples. I n addition, fresh

Methanol extract of Desmodium gangeticum roots preserves mitochondrial respiratory enzymes, protecting rat heart against oxidative stress induced by reperfusion injury

“…Previous phytochemical screening of DG had suggested the presence of 5-methoxy-N,N-dimethyltryptamine, N,N-dimethyltryptamine and their N-oxides, N-methyl-tetrahydroharman and 6-methoxy-b-carbolinium cation from aerial parts, and ter-b-phenylethylamines and candicine in the roots (Banerjee & Ghosal 1969). Some pterocarpanoids such as gangetin, gangetinin and desmodin , the isoflavanoid phytoalexin desmocarpin and the flavone glycosides 4′,5,7-trihydroxy-8-prenyl-flavone, 4′O-a-L-rhamnopyranosyl-(1→6)-b-D-glucopyranoside have been isolated from the stems of DG.…”

Plantes de Nouvelle-Calédonie. LXXXIII. Alcaloïdes des Tiges Feuillées de Melicope leptococca

“…Aprés chromatographies successives sur colonnes d'alumine, puis de sílice, dix alcaloides ont été isolés et neuf identifiés á des composés connus par leurs caractéristiques physiques et spectrales et par comparaison avec des échantillons authentiques. II s'agit de trois furo [2,3b]quinoléines acronydine (1) (5), kokusaginine (2) (6-8) et acronycidine (3) (9); de trois acridones: mélicopicine (4) (9)(10)(11), melicopidine (5) (9)(10)(11) et acronycine (6) (10)(11)(12), et de trois dérivés indoliques:méthyl-2 methoxy-6 tét-rahydro^-carboline (7) (13,14), méthoxy-5 N,N-díméthyltryptamine (8) (15,16) et son Nb-oxyde (9) (16,17).…”

New Cytotoxic N-Methylated β-Carboline Alkaloids from the Marine Ascidian Eudistoma gilboverde

“…β-Carboline alkaloids with a quaternary methylated nitrogen are known from a number of different terrestrial plant genera; − however, they have rarely been isolated from marine organisms. To the best of our knowledge, the only N -methyl β-carbolinium derivatives described from marine sources were recently reported from the soft coral Lignopsis spongiosum and the ascidian Pseudodistoma sp .…”

“…The structure of compound 3 was therefore identified as the 14-methyl analogue of eudistomidin C. The absolute stereochemistry at C-10 in 3 was tentatively assigned as S, based on analogy with compound 6, since the optical rotations of 3 (R D +12.9°) and 6 (R D +15.6°) 6 had the same sign and were close in magnitude. β-Carboline alkaloids with a quaternary methylated nitrogen are known from a number of different terrestrial plant genera; [17][18][19][20][21][22] however, they have rarely been isolated from marine organisms. To the best of our knowledge, the only N-methyl β-carbolinium derivatives described from marine sources were recently reported from the soft coral Lignopsis spongiosum 23 and the ascidian Pseudodistoma sp.…”