Elsevier

Phytochemistry

Volume 70, Issue 5, March 2009, Pages 675-683
Phytochemistry

Pregnane glycosides from Hoodia gordonii

https://doi.org/10.1016/j.phytochem.2009.02.006Get rights and content

Abstract

Hoodia gordonii is a ‘weight loss’ herb, which has gained popularity in the western countries as an appetite suppressant dietary supplement. Phytochemical study of its aerial parts led to isolation of seven pregnane glycosides (hoodigosides W–Z, hoodistanalosides A–B). Their structures were elucidated by chemical degradation studies and spectroscopic methods, including 1D and 2D NMR and CD spectroscopic methods.

Graphical abstract

Pregnane glycosides (1, 2, 59) were isolated from the aerial parts of Hoodia gordonii. These constituents consisted of five pregnane derivatives namely hoodigogenin A, isoramanone, calogenin, and two unprecedented skeletons, hoodistanal and dehydrohoodistanal as the aglycones.

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Introduction

Hoodia gordonii (Asclepiadaceae) is a succulent plant, indigenous to the summer rainfall regions of the Kalahari Desert in South Africa, Namibia, and Botswana. There are 13 reported species of the Hoodia genus, which have been a part of African food for centuries (Anonymous, 2007, Muller and Albers, 2002). Various uses of Hoodia have also been reported in African folklore such as for treatment of abdominal cramps, hemorrhoids, tuberculosis, diabetes, and as an aphrodisiac (Folden, 2008, Rubin et al., 2002). However, it has recently been known as an appetite suppressant (Anonymous, 2007, MacLean and Luo, 2004, Van Heerden et al., 1998, Van Heerden et al., 2007).

In our previous phytochemical studies on H. gordonii, we have reported the isolation and characterization of 11 new oxypregnane glycosides (hoodigosides A–K) (Pawar et al., 2007b), and 10 new calogenin glycosides (hoodigosides L–U) (Pawar et al., 2007a). These compounds were used as markers for developing HPLC, and LC–MS based methods for identification, and quality control of H. gordonii plant materials, and dietary supplements (Avula et al., 2006, Avula et al., 2007). Here we report the isolation, and characterization of seven new pregnane glycosides (1, 2, 5–9), along with three known compounds (3, 4, 10) (Schemes 2 and 3). These constituents were identified as the glycosides of hoodigogenin A, isoramanone, calogenin, and two novel chemotypes of aglycones, namely hoodistanal, and dehydrohoodistanal (Scheme 1). The structures of the isolates were identified by extensive spectroscopic and chemical studies.

Section snippets

Results and discussion

The CHCl3 extract of the aerial parts of H. gordonii was fractionated by multistep column chromatography to yield steroidal glycosides 1–10.

Based on the 13C NMR spectrum and HRESIMS m/z 1045.5711 for a sodiated molecular ion, the molecular formula for compound 1 was determined as C54H86O18. The presence of four sugar moieties was evident as its 1H NMR spectrum showed signals for four anomeric protons at δH 4.72 (d, J = 7.2 Hz), 4.94 (d, J = 11.2 Hz), 5.12 (d, J = 9.6 Hz), and 5.26 (d, J = 9.2 Hz), and

Concluding remarks

Previous phytochemical studies have shown that H. gordonii contains an abundance of pregnane glycosides, which comprise of hoodigogenin A, and calogenin as the aglycones (Dall’Acqua and Innocenti, 2007, Pawar et al., 2007a, Pawar et al., 2007b). Hoodigogenin A is an unique pregnane derivative from Hoodia, due to the tigloyl ester substitution at C-12. Although calogenin bisdesmosides have been reported from other plants in Asclepiadaceae family (Al-Yahya et al., 2000, Deepak et al., 1996,

General experimental procedures

NMR spectra were recorded on a Varian AS400 NMR spectroscope at 400 MHz (1H) and 100 MHz (13C). Proton and carbon chemical shift values are relative to internal standard TMS and were acquired in C5D5N and CDCl3. High-resolution mass spectra (positive) were acquired using electro-spray ionization (ESI) source, on an Agilent Series 1100 SL spectrometer. Optical rotations were measured on the Autopol IV polarimeter and specific rotations are expressed as deg.10.g−1.cm2. The ECD spectrum of compound 8

Acknowledgements

Part of the research was funded by “Botanical Dietary Supplements: Science-Base for Authentication” of the US Food and Drug Administration Grant No. FD-U-002071-07. The authors would like to thank Missouri Botanical Garden, USA for authentic plant material and Dr. V. Joshi for plant identification. The authors also thank Dr. B. Avula for assistance in acquiring the mass data. Y.J.S. is thankful to NCNPR for graduate research assistantship.

References (30)

  • M.A.-A. Al-Yahya et al.

    Pregnane glycosides from Caralluma russeliana

    J. Nat. Prod.

    (2000)
  • Anonymous

    Bogus raw material tarnishes Hoodia’s equity, but committed report strong sales

    Nutr. Bus. J.

    (2007)
  • B. Avula et al.

    Determination of the appetite suppressant P57 in Hoodia gordonii plant extracts and dietary supplements by liquid chromatography/electrospray ionization mass spectrometry (LC–MSD–TOF) and LC–UV methods

    J. AOAC Int.

    (2006)
  • B. Avula et al.

    Chemical fingerprinting of Hoodia species and related genera: chemical analysis of oxypregnane glycosides using high-performance liquid chromatography with UV detection in Hoodia gordonii

    J. AOAC Int.

    (2007)
  • D. Deepak et al.

    Pregnane glycosides from Hemidesmus indicus

    Phytochemistry

    (1996)
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