ANALYSIS OF TRACE ELEMENTS AND ORGANIC CONSTITUENTS IN ARJUNA (TERMINALIA ARJUNA) BARK

Abstract

Arjuna (Terminalia Arjuna) bark powder is a widely used heart tonic as described in ancient Sanskrit texts. Five samples including two commercial brands, collected from different places have been analyzed for elemental contents by neutron activation analysis (NAA), atomic absorption spectrophotometry (AAS) and inductively coupled plasma-mass spectrometry (ICP-MS) for 27, 14 and 22 elements respectively. In all 23 elements have been determined by three different techniques and a maximum of 32 elements have been determined in Arjuna bark. All the elements show wide variation depending on their origin. A comparison for some elemental concentrations by different techniques suggests good agreement even though AAS and ICP-MS require sample dissolution. The bark powder is particularly enriched in K (5.87±2.11mg/g), Ca (34.1±10.5 mg/g), Mg (5.41±1.93 mg/g), Fe (2.99±1.77mg/g), Mn (75.5±24.8 pg/g) and Zn (11.9±8.9 p.g/g). Further, Mo, Rb, Cs, Sr and V were also found in few p.g/g amounts. Also Ca/P (105 ± 50) ratio is much higher compared to K/P (16.4 ± 4.6). NAA has the advantage of being non-destructive compared to MS and ICP-MS where sample dissolution is required. Thin layer chromatography (TLC) and column chromatography were used to separate three new organic compounds; 1-phenylazo 2-naphthalenol, 2-isopropyl naphtho [2, 3, [3], furan 4, 9-dione and tartaric acid with Rf = 0.79, 0.63 and 0.72 respectively from the methanolic extract of Arjuna bark. The compounds were identified by elemental analysis, infrared and NMR spectra and further confirmed by GC-MS where fragmentation pattern have been proposed. It is proposed that metal ions remain complexed with the naturally occurring organic ligands making them bioavailable. Thermogravimetric studies suggest three stage decomposition followed by —16% non-volatile matter left at 900 °C