Phytochemical compounds and anti-corrosion activity of Veronica rosea.

The aim of this work is the phytochemical study of the butanolic extract of the aerial parts of Veronica rosea. Four compounds 1-4 have been isolated using different chromatographic methods. The structures of these compounds were determined by NMR spectral analysis and mass spectroscopy. The adsorption and anticorrosion effects of this extract were investigated towards the corrosion of copper in 1 M HNO3 aqueous by the weight loss technique and potentiodynamic polarization. The results showed that the butanolic extract is a good inhibitor and the inhibition efficiency increases with increasing of concentration of the inhibitor. The adsorption of this extract on the copper specimen surface was spontaneous and obeyed the Langmuir's adsorption isotherm. Large value of adsorption equilibrium Constant (Kads = 35 L g-1) was obtained. The polarization experiments confirmed the data obtained by gravimetric weight-loss. Tafel plot of polarization curves indicates that the extract acts as a mixed type inhibitor.