Quantitative determination of stachydrine via HPTLC in cardioactive Leonurus and Leonotis drugs

Abstract

Tea preparations from aerial parts of the Central and Eastern European Lamiaceae Leonurus cardiaca L. are traditionally used as a remedy against tachyarrhythmia, heart failure, and other cardiac disorders [1–3]. Nevertheless, a scientific basis for these therapeutic effects had not been established [4] until just recently an antiarrhythmic refined extract was prepared from this drug via bioassay guided fractionation [1], making the development of improved methods of extract characterisation necessary. In Chin.Ph. [5] the „alkaloids“ of the tea preparation of the closely related and similarly used East Asian Leonurus japonicus Houtt. [6] are regarded as the active constituents and quantified photometrically after Reinecke's complexation, calculated as stachydrine. Unfortunately, both the quantification method by complexation and the accompanied TLC method of the Chin.Ph. are deemed to be „not reproducible“ by current experimental literature, such as Heuberger et al. 2008 [7]. Therefore, a state of the art HPTLC method was developed, using a CAMAG automatic HPTLC system with scanner and winCATS analysis software for reproducible stachydrine quantification. Silica gel 60 F254 HPTLC plates were scanned at 517nm after development with MeOH:CH2Cl2:NH325% (8:2:3) and derivatisation with Vágújfalvi solution. The related cardioactive [8–10] South African Leonotis leonurus (L.)R.Br. was co-investigated. These measurements revealed stachydrine contents (w/w) of 0.2 to 1.1% for the L. japonicus drug, 0.3% for the material from L. leonurus, 0.5 to 1.5% for the L. cardiaca samples, and 6.6% for the antiarrhythmic refined extract of L. cardiaca.