Bioactive alkaloids from Brunsvigia radulosa☆
Introduction
The genus Brunsvigia, subtribe Amaryllidinae, tribe Amaryllideae (Amaryllidaceae), is widely distributed over both summer- and winter- rainfall regions of the southern and southwestern regions of South Africa. Several Amaryllideae species have been used in the traditional medicine of the indigenous peoples of the country (Hutchings, Scott, Lewis & Cunningham, 1996). In a continuation of our phytochemical studies on genera from the subtribes Amaryllidinae and Crininae (Viladomat, Bastida, Codina, Nair & Campbell, 1997), we have investigated the taxon Brunsvigia radulosa Herb. The choice of this species was prompted by a report of the inhibitory activity of an extract of the plant against P 388 lymphocytic leukaemia in mice (Charlson, 1980), and by our own observation of moderate activity against two strains of Plasmodium falciparum. In the present study we describe the isolation and characterisation of the novel alkaloid 1-O-acetylnorpluviine (1), together with the known structures, 1-epideacetylbowdensine, crinamine, crinine, hamayne, lycorine, anhydrolycorin-6-one (2) and sternbergine. In addition, in order to provide a further structure for our studies on the antiplasmodial and cytotoxic activity of Amaryllidaceae alkaloids, crinamine was converted to the C-3/C-11 epoxide, apohaemanthamine (3).
Section snippets
Results and discussion
The alkaloids were isolated from an ethanol extract of the fresh bulbs of Brunsvigia radulosa. 1-O-acetylnorpluviine (1) gave a M+ ion at 315.1465 in the high resolution EI mass spectrum, which corresponded with a molecular formula, C18H21NO4. The mass spectrum and the -NMR spectrum showed structural features similar to those of the known pyrrolo[de]phenanthridine alkaloid, 1-O-acetylcaranine (Pettit, Gaddamidi, Goswami & Cragg, 1984). The four singlets at 6.74, 6.64, 3.83, and 1.90 in the
General
Mps are uncorr. IR spectra were recorded in KBr discs. EIMS were obtained at 70 eV. NMR spectra were measured using Varian VXR 400 and VXR 500 instruments, in the solvents specified and with TMS as int. standard. Chemical shifts are reported in units (ppm) and coupling constants (J) in Hz. Silica gel 60 F254 (Merck) was used for analytical (0.25 mm) TLC and flash cc was carried out on Silica gel N for thin layer chromatography (Macherey Nagel). Spots on chromatograms were detected under UV
Acknowledgements
Financial support from the Medical Research Council and the University of Cape Town is gratefully acknowledged. We also thank Dr J. du Preez from the Department of Nature Conservation, Bloemfontein, for the collection and authentication of the plant material.
References (13)
Antineoplastic constituents of some southern african plants
J. Ethnopharmacol
(1980)- et al.
Alkaloids from Brunsvigia josephinae
Phytochemistry
(1994) - et al.
Composition and antimalarial activity in vitro of Tetradenia riparia
Planta Med
(1997) - et al.
Cytotoxic and antimalarial alkaloids from Brunsvigia littoralis
Planta Med
(1998) - et al.
Alkaloids of the amaryllidaceae. Part XIII: The structure of haemanthamine and crinamine
J. Amer. Chem. Soc
(1960) - et al.
Carbon-13 nuclear magnetic resonance spectra of Amaryllidaceae alkaloids. Part I: Alkaloids with the crinane skeleton
Mag. Res. Chem
(1985)
Cited by (76)
Isolation of the antibacterial alkaloid distichamine from Crossyne Salisb. (Amaryllidaceae: Amaryllideae: Strumariinae)
2021, South African Journal of BotanyRecent Applications of Selected Name Reactions in the Total Synthesis of Alkaloids
2021, Recent Applications of Selected Name Reactions in the Total Synthesis of Alkaloids
- ☆
Part 7 in the series “Alkaloids from South African Amaryllidaceae”. For part 6 see Nair et al., 1998. [Nair, J.J., Campbell, W.E., Gammon, D.W., Albrecht, C.F., Viladomat, F., Codina, C. & Bastida, J. (1998). Phytochemistry, 49, 2539].