biologia plantarum

Biologia plantarum 45:85-89, 2002 | DOI: 10.1023/A:1015196423320

Effects of Cadmium, Lead, Mercury and Zinc on °-Aminolevulinic Acid Dehydratase Activity from Radish Leaves

V.M. Morsch¹, M.R.C. Schetinger¹, A.F. Martins¹, J.B.T. Rocha¹

¹ Departamento de Química, Universidade Federal de Santa Maria, Santa Maria, Rio Grande do Sul, Brazil

The purpose of the present study was to investigate the in vitro and the in vivo effects of cadmium, zinc, mercury and lead on δ-aminolevulinic acid dehydratase (ALA-D) activity from radish leaves. The in vivo effect of these metals on growth, DNA and protein content was also evaluated. The results demonstrated that among the elements studied Cd²⁺ presented the highest toxicity for radish. 50% inhibition of ALA-D activity (IC₅₀) in vitro was at 0.39, 2.39, 2.29, and 1.38 mM Cd²⁺, Zn²⁺, Hg²⁺ and Pb²⁺, respectively. After in vivo exposure Cd²⁺, Zn²⁺, Hg²⁺ and Pb²⁺ inhibited ALA-D by about 40, 26, 34 and 15%, respectively. Growth was inhibited by about 40, 10, 25, and 5% by Cd²⁺, Zn²⁺, Hg²⁺, and Pb²⁺, respectively. DNA content was reduced about 35, 30, 20, and 10% for Cd²⁺, Zn²⁺, Hg²⁺, and Pb²⁺, respectively. The metal concentration in radish leaves exposed to Cd²⁺, Zn²⁺, Hg²⁺, and Pb²⁺ was 18, 13, 6, and 7 μmol g^-1, respectively. The marked ability of radish to accumulate Cd²⁺ and Zn²⁺ raises the possibility of using this vegetable as a biomonitor of environmental contamination by these metals.

Keywords: cell growth; DNA content; heavy metals; proteins; toxicity

Subjects: δ-aminolevulinic acid dehydratase, heavy metals; cadmium, δ-aminolevulinic acid dehydratase; cell growth, δ-aminolevulinic acid dehydratase; DNA content, δ-aminolevulinic acid dehydratase; heavy metals; lead, δ-aminolevulinic acid dehydratase; mercury, δ-aminolevulinic acid dehydratase; proteins, heavy metals; radish, δ-aminolevulinic acid dehydratase; Raphanus sativus; zinc, δ-aminolevulinic acid dehydratase

Published: March 1, 2002  Show citation