This work was carried out to evaluate catalase relative activity of ragweed (Parthenium hysterophorus) aqueous extract, as well as to compare it with catalase activity of other weed species. It consisted of three phases, involving method standardization, comparison of the catalase relative activity in Asteraceae family plants and that of ragweed catalase activity with the following 11 weed species: Euphorbia heterophylla, Alternanthera tenella, Cenchrus echinatus, Panicum maximum, Amaranthus viridis, Ipomoea hederifolia, Galinsoga parviflora, Bidens pilosa, Sonchus oleraceus, Cyperus rotundus and Commelina benghalensis. Reaction of ragweed aqueous extract with hydrogen peroxide had increasing linear response regarding plant extract concentration. In all phases, catalase relative activity of ragweed extract was superior to catalase activity of the other weed species. Data obtained in these phases allowed to conclude that higher relative activity observed for ragweed catalase significantly contributes to the tolerance of this species to paraquat. This higher activity might be due to higher enzymatic concentration in ragweed cells or to higher intrinsic enzymatic activity (enzyme-substrate affnity).Therefore, further studies are necessary to support this conclusion.
Asteraceae; enzyme; paraquat; hydrogen peroxide; tolerance
