The Structural Determination of a New Steroidal Metabolite from the Brown Alga Sargassum asperifolium

Abstract

An investigation of the natural products chemistry of the brown alga Sargassum asperifolium from the red sea yielded a new steroidal metabolite, 24-vinyl cholest -4-ene -24-ol -3 one, saringosterone (3), a known steroidal metabolite, 24-vinyl cholest -5-ene -3b, 24-diol, saringosterol (4), and known diterpene with a hydroazulene skeleton, dictyone (1). The identification of the isolated metabolites was established mainly by spectral methods and chemical transformation of the dictyone (1) to its acetate (2).

Towards a better understanding of medicinal uses of the brown seaweed Sargassum in Traditional Chinese Medicine: A phytochemical and pharmacological review

“…Phytosterols such as saringosterol and fucosterol have been identified in some species (Wang et al, 1997;Ayyad et al, 2003). Fucosterol, a characteristic component of brown seaweeds, was found to be the major phytosterols (485%) in S. despiense, S. latifolium and S. carpophyllum (Karawya et al, 1987;Wang et al, 1997).…”

Sterols from the brown alga Cystoseira foeniculacea: Degradation of fucosterol into saringosterol epimers

“…The duplicate signals (C-17, C-20, C-22 to C-24, C-27 to C-29) in the 13 C NMR spectrum of 2/3 were in accordance with the occurrence of the two C-24 epimers. Further analysis of 2D NMR data, in particular HMBC and 1 H-1 H COSY spectra allowed corrections of some attributions for the 13 C NMR data of these compounds (Table 1) in comparison with those reported in the literature (Ayyad et al, 2003;Huh et al, 2012). Moreover, after its storage during 24 h at room temperature in an unsealed vial, a further NMR analysis of fucosterol (1) was performed and additional signals were then observed on its 1 H and 13 C NMR spectra.…”

“…The chromatographic profile of this sterol fraction showed two main peaks which were separated and obtained in sufficient amounts, by repetitive chromatographic runs, for further NMR study. The complete analysis of the NMR data of the two sub-fractions along with a comparison with literature data allowed their structure to be elucidated as fucosterol (1) (Hwang et al, 2012) and an epimeric mixture of saringosterols (2 and 3) (Ayyad et al, 2003;Catalan et al, 1983;Huh et al, 2012). The duplicate signals (C-17, C-20, C-22 to C-24, C-27 to C-29) in the 13 C NMR spectrum of 2/3 were in accordance with the occurrence of the two C-24 epimers.…”

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“…The identification of the isolated metabolite was established mainly by spectral methods and the chemical transformation its acetate. 26 18,19-epoxyxenic-19-methoxy-18-hydroxy-4-acetoxy-6,9,13-triene (66) and 18,19-epoxyxenic-18,19-dimethoxy-4-hydroxy-6,9,13-triene (67) were obtained by column chromatography of the hexane fraction of the methanol extract of Padina pavonia (L.) Gaill. collected from the Red Sea at Hurghada.…”

“…79 Later, the investigation of the natural products chemistry of the brown alga Sargassum asperifolium from the red sea yielded two steroidal metabolite, 24-vinyl cholest-4-ene-24-ol-3-one, saringosterone (235), and 24-vinyl cholest-5-ene-3β,24-diol, saringosterol (236). 26 The steroidal compound, stigmasta-5,(E)-24(28)-dien-3-β-ol, fucosterol (237) was isolated from the petroleum ether fraction of the alcoholic extract of the brown alga, Dictyota dichotoma (Hudson) Lamouroux, which was collected from the Red Sea coasts at Hurgada. 25 Fucosterol was also obtained from the brown alga Sargassum sp.…”