Steroidal saponins from Asparagus africanus☆
Introduction
Asparagus africanus (Liliacae) (local names `Seriti' or `K'estancha') is a widely spread thorny shrub about 1 to 3 m long distributed along the great rift valley of Ethiopia. It is used in the indigenous system of medicine for various health ailments Watt, & Breyer-Brandwijk, 1962, Abate, 1989, Abebe, & Ayehu, 1993. Recent phytochemical investigation of the root of this plant has led to the isolation of antiprotozoal compounds muzanzagenin and (+)-nysol (Oketch-Rabah et al., 1997). This paper describes the isolation, structural elucidation and complete and chemical shifts assignments of two new spirostanosides and a new oligofurostanoside from the methanol extract of the roots of this plant.
Section snippets
Results and discussion
Solvent partition and chromatography of the saponin mixture obtained from the methanol extract of the roots of A. africanus produced three major saponins 1, 2 and 3. Compounds 1 and 2 showed spiroacetal absorption in their IR spectra whereas compound 3 showed no spiroacetal absorption but gave an intense red colour with Ehrlich reagent (Stahl, 1965, Kiyosawa et al., 1968; Tschesche, Tjoa, Wulff, & Noronha, 1968). Structural determinations of the three saponins were mainly based on 1D (, ,
General
Melting points were determined in open capillaries in an electrothermal melting apparatus. FAB-MS was recorded with a ZAB-E (VG analytical (Micromass)); matrix: thioglycerol and `magic bullet'.
Proton correlated NMR spectra were recorded with a VARIAN UNITY INOVA 600 NMR spectrometer at 313 K, spectra with a VARIAN UNITY INOVA 400 NMR spectrometer at 313 K. Concentration 60 mmol/l. Tubes: 5 mm diameter (Kontes). Triple resonance probe head with shielded z-gradient (600 MHz); dual probe with
Acknowledgements
The authors wish to express their gratitude to Dr. M. Schmid (Institute of Pharmaceutical Chemistry, University of Graz) for measurement of capillary electrophoresis and to Dr. F. Bucar (Institute of Pharmacognosy, University of Graz) for measurement of GC–MS spectra of sugars. We thank Professor Dr. A. Hiermann (Institute of Pharmacognosy, University of Graz) for his technical assistance and cooperation. AD gratefully acknowledges ÖAD, Austria, for the scholarship award and EHNRI, Addis Ababa,
References (14)
- et al.
Phytochemistry
(1985) - et al.
Phytochemistry
(1991) - et al.
Tetrahedron
(1968) - et al.
Phytochemistry
(1996) - Abate, G. Etse Debdabe (Ethiopian traditional medicine). Addis Abeba University press, Addis Abeba 1989,...
- et al.
- et al.
Magnetic Resonance Chemistry
(1995)
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Part of the Ph.D. thesis of AD.