Urospermal a glucoside from urospermum picroides

Phytochemistry
1984.0

Abstract

The roots of Urospermum picroides afforded urospermal A 15-O-β-D-glucoside. The aerial parts of Urospermum picroides (L.) Scop. ex F.W. Schmidt contain the melampolide urospermal A and the p-hydroxyphenyl acetate of the corresponding glucoside [1]. We have now studied the polar fractions from the roots. Thin-layer chromatography afforded two compounds, the glucosides 1 and 2. Acetylation gave the acetates 3 and 4, the latter being identical with the acetylation product of the glucoside 2 isolated from the aerial parts [1]. The ¹H NMR spectrum of 3 (Table 1) was close to that of 4. However, the signals of the p-hydroxyphenyl acetate were replaced by an additional acetate methyl signal. As observed previously [1] the hydrogen-bonded 8α-hydroxyl group was not acetylated. The ¹H NMR spectrum of the natural compound 1 could be measured only in deutero-pyridine (Table 1). All signals were assigned by spin decoupling in the usual way, starting with the H-7 signal although all signals were broadened and some were partly overlapped. The ¹H NMR spectrum of 3 in deutero-chloroform was very clear and again all the signals were assigned by spin decoupling. The presence of a β-glucoside moiety followed from the couplings. While electron impact mass spectrometry gave no molecular ions, the chemical ionization mass spectra of 1 and 3 gave clear [M + 1]⁺ ions. Two new triterpenes from the root of Periandra dulcis were found to be 3,25-dioxoolean-12(13)-en-30-oic acid and 3,25-dioxoolean-18(19)-en-30-oic acid.

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