Variation in essential, trace and toxic elemental contents in Murraya koenigii – A spice and medicinal herb from different Indian states

Curry leaves (Murraya koenigii), collected from 19 different Indian states, were analyzed for six minor (Ca, Cl, K, Mg, Na and P) and 20 trace (As, Ba, Br, Ce, Co, Cr, Cs, Cu, Fe, Hg, La, Mn, Rb, Sb, Sc, Se, Sr, Th, V and Zn) elements by instrumental neutron activation analysis (INAA). In addition, Ni, Cd and Pb were determined by atomic absorption spectrophotometry (AAS). Most elements vary over a wide range, depending on geo-environmental factors and local soil characteristics. Fe, Mn, Na, K, Rb, Se and P vary by a factor of 3–5 whereas Br, Cs, Sc, Th and Zn vary by an order of magnitude. Leaves collected from the southern zone were enriched in K, Mg, Mn, Cl and P but depleted in Se. However, leaves from the northern zone were particularly enriched in Ca whereas those from the western zone were enriched in Zn. Concentrations of most elements from the eastern zone were on par with the mean values. Cr, Fe, Cu, V and Zn are known to play an important role in the maintenance of normoglycemia by activating β-cells of pancreas. Percent contributions of diabetically important elements from curry leaves were 1–2% of daily dietary intake (DDI) but are likely to be in bioavailable form thus making them effective for treatment of diabetes. Rb and Cs are linearly correlated (r = 0.93) as their salts enhance the absorption of insulin in the lower respiratory tract by breakdown of glucose. Inorganic elements may remain complexed with organic ligands.