Complexation of Metals with Organic Compounds in Brazilian Medicinal Plants

NASCIMIENTO JÄHNKE, SAMARA; SOUND, IRIS; SOLDATI, ANALIA L.; VICENTE VILAS, VÍCTOR; BAUMANN, WOLFRAM

Madrid, España

Jornada; IV Scientific Meeting of the Spanish Society of Chromatography and Related Techniques USP-CEU; 2004

Spanish Society of Chromatography and Related Techniques

Much is known about the occurrence of metals in plants but little about their species, binding forms and oxidation state, as well [1]. This holds particularly for medicinal plants and even more specific for Brazilian medicinal plants. Three species very common in Brazil have been selected and were brought from there: Jambu (Spilanthes oleracea) -Asteraceae; Beldroega (Portulaca oleracea) - Portulacaceae; Alfavaca (Ocimum gratissimum) - Labiatae. The present speciation study focuses on the complexation of manganese in these plants under normal and under manganese stress conditions. Methods involved are various types of chromatography, such as high performance liquid chromatography (HPLC) online coupled to mass-spectrometry (MS). Since a common preparation for such plants in popular medicine is tea, standardized aqueous extracts have been prepared. By size exclusion chromatography on a PROTONSIL 60-10-DIOL column (Bischoff, Germany) coupled on line to an inductive coupled plasma mass spectrometry instrument (ICP-MS) (ELEMENT 2 thermo electron) and tuned to manganese the range of molecular weight has been defined in which manganese is present. Accordingly, manganese is predominantly bound to small compounds but in some cases like Jambu also to higher molecular weight compounds. Further characterisation of the low molecular weight fraction is now done by reversed phase HPLC and ion-chromatography.   [1] G. Weber, P. Konieczynski, Speciation of Mg, Mn and Zn in extracts of medicinal plants; Anal Bioanal Chem, 375, 1067 - 1073, 2003.