Plant extracts to control Alternaria alternata in Murcott tangor fruits.

BACKGROUND: Alternaria alternata causes the Alternaria brown spot disease (ABS) in many tangerines and their hybrids worldwide. Plant extracts offer an alternative method for controlling this disease, which control is based on chemical fungicides. AIMS: To identify plant species with antifungal properties against A. alternata, the causal agent of the ABS. METHODS: Plant extracts prepared from leaves, barks, flowers, and stalks collected from 105 plant species in the State of Minas Gerais, Brazil, were tested for activity against the fungus A. alternata in vitro and in vivo. RESULTS: The most promising extract was obtained from Anadenanthera colubrina, which reduced the disease on Murcott tangor fruits to levels obtained with commercial fungicides. Artemisia annua, Cariniana estrelensis, Ficus carica, and Ruta graveolens presented moderate in vitro antifungal activity, but no effects were observed on the disease when the extracts were applied to fruits inoculated with the fungus. Besides, A. colubrina was the most active extract against A. alternata in the in vitro assay. CONCLUSIONS: The results obtained in the in vitro and in vivo assays suggested that the fungal growth test, which uses 96-well polypropylene plates, seems to be appropriate for selecting potential plant species for testing new methods to control ABS.

Evaluation of native and exotic Brazilian plants for anticancer activity.

Native and exotic Brazilian plants collected in the State of Minas Gerais were evaluated for their anticancer potential. Methanol extracts from leaves of 51 plant species were tested for cytotoxicity against four tumor cell lines: B16 (murine skin), HL-60 (human leukemia), MCF-7 (human breast), and HCT-8 (human colon). Plant extracts that exhibited IC(50) values less than 30 microg/ml against any tumor cell line were tested on sea urchin egg development and mouse erythrocytes. In addition, all extracts were evaluated for their general toxicity using the brine shrimp lethality assay. The most active extracts against the tumor cells were those obtained from Lantana fucata, Copaifera langsdorffii, and Momordica charantia. These three extracts inhibited sea urchin development from the first cleavage, but those from C. langsdorffii and M. charantia were very active against mouse erythrocytes. Only the L. fucata extract presented no hemolytic activity. Consequently, although the extracts of L. fucata, M. charantia, and C. langsdorffii could be useful in the development of new anticancer products, the first of these extracts is the most promising since it did not present unspecific toxicity, as suggested by negative results obtained with brine shrimp lethality and mouse erythrocytes assays.