Phytochemical analysis and metal-chelation activity of achillea tenuifolia lam

ABSTRACT

Achillea tenuifolia Lam. [Asteraceae] afforded a dichloromethane fraction from which three known compounds beta-sitosterol [compound1], 5-hydroxy, 4',6,7- trimethoxy flavone [salvigenin compound 2], and methyl-gallate [compound 3] were isolated for the first time. The structure of isolated compounds was elucidated by different spectroscopic methods. Applying the molar-ratio method, the complexation of salvigenin with Fe [III], Cu[II] and Zn[II], the most abundant type of metal ions in the body, were then evaluated. It was determined that stoichiometric ratio of salvigenin with these cations were as Fe[Salvigenin][2] [H2O][2] and Cu[Salvigenin][2][H2O][2] in methanolic solution without pH control, while zinc ions didn't form significant complexes. The results were confirmed more, by computational molecular modeling of the structure of proposed ligand-complexes by semi-imperical PM3 calculations, which determined negative heat of formation for the complexes Fe[III] and Cu[II] ions as -689.7 and -573.5, respectively and proposed chelating affinity of salvigenin in the following order Fe[III] > Cu[II] >> Zn[II]