Structural Characterization of Yohimbine-type Alkaloids from Pausinystalia yohimbe by UPLC-QTOF

YH Wang; B Avula; M Wang; IA Khan

doi:10.1055/s-0032-1307641

Planta Medica, Inhaltsverzeichnis

Structural Characterization of Yohimbine-type Alkaloids from Pausinystalia yohimbe by UPLC-QTOF

YH Wang ¹, B Avula ¹, M Wang ¹, IA Khan ¹^,²

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

Abstract

Pausinystalia yohimbe (Yohimbe), formerly known as Corynanthe yohimbe, is an evergreen tree native to Africa. Chemical constituents from Yohimbe bark include tannins and indole alkaloids. Yohimbe bark contains about 6% total alkaloid in which yohimbine represents 10–15% [1]. The tryptamine alkaloid yohimbine is a prescription medicine that has been used to treat erectile dysfunction and explored as a remedy for type-II diabetes in animal and human models carrying polymorphisms of the α2A-adrenergic receptor gene [2]. P. yohimbe is widely distributed over-the-counter as an herbal aphrodisiac.

With the aim of discovering a fast method in quality control of Yohimbe products, an UPLC-QTof method was developed for separation and structural characterization of yohimbine-type alkaloids from P. yohimbe. The separation was achieved by using C-18 column material with a gradient system composed of 50 mM ammonium formate and acetonitrile. According to tandem mass spectra of yohimbine, the cleavage occurred between C2-C3 and C5-C6, and gave the product ions at m/z 144 and 212 Da. The ions at m/z 212 further yielded ions at m/z 194, 180, 162 and 134 corresponding to fragments [212-H₂O]⁺, [212-MeOH]⁺, [212-MeOH-H₂O]⁺, [212-H₂O-HOAc]⁺, respectively. The fragmentation pathway of yohimbine is proposed in Figure 1. This method is useful for monitoring yohimbine-type alkaloids from Yohimbe and its related products.

Fig.1: Proposed fragmentation pathway 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, and the Global Research Network for Medicinal Plants (GRNMP), King Saud University. References: [1] Beta JM, White KD, et al., (1995)J AOAC Int 78: 1189–1194. [2] Rosengren AH, Johubka R, et al. (2010) Science 327: 217–220.