Subscribe to RSS
Several Citrus fruit peels are described in different pharmacopoeia monographs, i.e. European Pharmacopoeia [1], Swiss Pharmacopoeia [2] and Chinese Pharmacopoeia [3]. Tinctures or syrups are monographed as well. Up to now there is no TLC identification test for sweet orange (Citrus sinensis Osbeck) and lemon (Citrus limon (L.) Burm. fil.) in the pharmacopoeias. Therefore, the aim of the study was to establish a suitable HPTLC test to identify the citrus peel drugs as well as preparations in order to revise the pharmacopoeia monograph. Moreover, for aged tangerine peel (Citrus reticulata Blanco), a drug traditionally used in Chinese medicine and called Chenpi, a test to discern it from bitter-orange epicarp and mesocarp was established.
The spraying of an aluminium chloride solution (UV 366nm) was found to be a suitable HPTLC detection mode to visualize some typical citrus flavanones, e.g. hesperidin or naringin. The resulting fingerprint allows distinguishing orange, lemon and bitter-orange. In order to discern between aged tangerine and bitter-orange, a subsequent derivatization by natural products/polyethylene glycol 400 (NP/PEG) solutions and evaluation in visible light was found to be effective. Whereas bitter-orange shows a prominent red zone of neoeriocitrin, in tangerine this compound is nonexistent. The results show that an identification of different Citrus species by HPTLC fingerprint is possible. However, since orange and tangerine have similar flavanone contents [4], the identification solely by HPTLC remains insufficient and has to be complemented by macroscopic and microscopic examination.
Acknowledgments: We thank Dixa AG and Hänseler AG, Switzerland, for the supply of herbal drug material and herbal preparations, as well as SWISSMEDIC, Swiss Agency for Therapeutic Products, Pharmacopoeia division, for the financial support.
References: [1] European Directorate for the Quality of Medicines (2009) European Pharmacopoeia 6th Edition (6.5). Online-Edition.
[2] Swissmedic (2006) Pharmacopoeia Helvetica 10th Edition. BBL, Vertrieb Publikationen. Berne.
[3] The State Pharmacopoeia Commission of China (2005) Pharmacopoeia of the People's Republic of China, Vol. 1. Chemical Industry Press. Beijing.
[4] Peterson, J.J. et al. (2006)J. Food Compos. Anal. 19:S66-S73.