Secondary Metabolites and Mineral Elements of Manotes expansa and Aframomum alboviolaceum Leaves Collected in the Democratic Republic of Congo

Abstract

Background and Aims: Manotes expansa Sol. ex Planch. and Aframomum alboviolaceum (Ridl.) Schum.  are two plants belonging respectively to the family Connaraceae R.Br. and Zingiberaceae Martino widely used in traditional medicine for the treatment of eye diseases, fever, headaches, gastritis as well as asthma. The aim of the present study is the valorization of these two plants collected in the Democratic Republic of Congo by a quantitative and qualitative analysis of secondary metabolites and mineral elements in their leaves.
 Materials and Methods: The determination of secondary metabolites in the leaves of Manotes expansa and Aframomum alboviolaceum was carried out by UV-Visible spectrophotometry and X-ray fluorescence spectrophotometry for the identification and quantitative analysis of mineral elements.
 Results: The results showed that the leaves of these two plants are rich in phenolic compounds, i.e. 442.2 mgEqAG/g for the leaves of A. alboviolaceum, 370.64 mgEqAG/g for the red leaves and 282.64 mgEqAG/g green leaves of M. expansa. Although being part of the same plant, the red and green leaves of M. expansa presented a totally different phytochemical profile. The contents of condensed tannins, anthocyanins and flavonoids are respectively 0.3%, 0.68% and 3.29% for the leaves of A. alboviolaceum; 0.58%, 0.36% and 6.89% for the red leaves, and 0.65%, 0.26% and 7.55% for the green leaves of M. expansa.  The mineral content in the leaves of both plants remains dominated by the high concentration of potassium (K), calcium (Ca), Magnesium (Mg), Manganese (Mn) and Iron (Fe).
 Conclusion: The high content of phenolic compounds and essential trace elements makes the leaves of M. expansa and A. alboviolaceum potential candidates to alleviate several health problems in Africa in general and particularly in the Democratic Republic of Congo.