Identification of Yohimbe Bark (Pausinystalia johimbe) using Microscopy and UPLC-MS Techniques

V Raman; B Avula; A Galal; YH Wang; IA Khan

doi:10.1055/s-0032-1307529

Planta Medica, Table of Contents

Identification of Yohimbe Bark (Pausinystalia johimbe) using Microscopy and UPLC-MS Techniques

V Raman ¹, B Avula ¹, A Galal ¹, YH Wang ¹, IA Khan ¹^,²

¹National Center for Natural Products Research, Research Institute of Pharmaceutical Sciences, and
²Department of Pharmacognosy, School of Pharmacy, University of Mississippi, MS 38677, USA

Abstract

The raw material of yohimbe is the stem-bark of an evergreen tree Pausinystalia johimbe (K. Schum.) Pierre ex Beille of the flowering plant family Rubiaceae. Yohimbe is a popular herbal supplement used for the treatment of sexual disorders in men. In 2010, yohimbe was one of the twenty top-selling herbal dietary supplements in the USA [1].

The objectives of the present study were to provide a detailed anatomy of yohimbe bark, as well as to determine the yohimbine content from authentic yohimbe bark samples. Authentic samples collected from Cameroon, W. Africa were studied by light and scanning electron microscopy and photomicrographs were prepared. Micromorphology and arrangement of fibers, radially arranged cork cells with thick walls, presence of numerous idioblasts containing sand crystals of calcium oxalate are diagnostic features [2, 3]. A few variations in the structure of fibers were observed and are reported. UPLC-UV-MS analysis was conducted and the yohimbine content was found to be in the range of 0.1–0.91% for various samples.

Fig.1: Micromorphology and anatomy of yohimbe bark (Scanning electron microscopy). a- outer bark in surface view; b- TS of cork showing radially arranged cells with thick walls; c- TS of secondary phloem showing bast fibers in a beaded arrangement; d- a fiber isolated from powdered bark (Bars: a-d=50µm).

Fig.2: Typical UPLC-MS chromatograms of yohimbine

Acknowledgements: This research is supported in part by Science Based Authentication of Dietary Supplements funded by the Food and Drug Administration grant No. 1U01FD004246–01; the United States Department of Agriculture, Agricultural Research Service, Specific Cooperative Agreement No. 58–6408–2-0009; the Global Research Network for Medicinal Plants (GRNMP), King Saud University. References: [1] Blumenthal M, et al., (2011) Herbalgram 90: 64–67 [2] Small J, Adams F, (1922) Pharma J 108: 266, 282–265, 311–264. [3] Upton R, et al. (eds) (2011) American Herbal Pharmacopoeia: Botanical pharmacognosy-microscopic characterization of botanical medicines. CRC Press, New York.