Rocha, Giseli S.
Matsumoto, Reginaldo S.
Lombardi, Ana Teresa
Lima, Maria Ines S.
Total Authors: 4
 Univ Fed Sao Carlos, Dept Hidrobiol, SP-310, Km 235, BR-13565905 Sao Carlos, SP - Brazil
 WasserCluster, Biolog Stn Lunz, Dr Carl Kupelwieser Promenade 5, A-3293 Lunz Am See - Austria
 Univ Fed Sao Carlos, Dept Bot, SP-310, Km 235, Caixa Postal 676, BR-13565905 Sao Carlos, SP - Brazil
Total Affiliations: 3
Anais da Academia Brasileira de Ciências;
n. 3, 3,
Web of Science Citations:
Annona glabra L. is a semi-deciduous tree that contains several active substances, including secondary metabolites, with antifungal activity. Phytopathogenic strains of the genus Pythium cause billion dollar losses all over the world on natural and crop species. Searching for eco-friendly algaecides and fungicides, we analyzed the effects of acetone extracts of A. glabra leaves on the algae Rhaphidocelis subcapitata (Korshikov) and on the oomycete Pythium aphanidermatum (Edson). We evaluated ten extract concentrations for each organism -0 to 400 mg L-1 for algae and 0-1000 mu g disc(1) for oomycete. The results showed no effect on algae up to 75 mg L-1, but a significant inhibitory effect at 125 mg L-1 and above, which reduced the growth rate and the final biomass of the algae. Extract concentrations above 200 mg L-1 were completely inhibitory. The half maximal inhibitory concentration for 72 and 96 h of exposure to our crude extracts are comparable to those obtained with commercial fungicides and herbicides used in aquatic ecosystems. The P. aphanidermatum inhibition concentrations have effects comparable to fungicides as Cycloheximide and Bifonazole. Some substances isolated from the extracts are described as antifungals, which could explain part of anti-oomycete activity. Our results highlight the importance of searching bioactive compounds from plants. (AU)