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Medicinal plants are abundant in the Brazilian flora including the Cerrado region.Extracts of sixteen plant species of the Brazilian Cerrado were investigated in vitro for antiviral activity against bovine herpesviruses type 1 (BoHV-1), infectious bursal disease virus (IBDV) and avian reovirus. Eight plants presented potent antiviral activity. Erythroxylum deciduum, Lacistema hasslerianum and Xylopia aromatica againstBoHV-1; Gochnatia polymorpha and Lithraea molleoides against avian reovirus; and Banisteriopsis variabilis, Byrsonima intermedia and Campomanesia xanthocarpa against both viruses. No extract was active against IBDV.

The aqueous extract from Polymnia sonchifolia leaves (AE) was tested for inhibitory activity on aflatoxin B1(AFB1) production and growth of Aspergillus flavus. The cytotoxicity of AE on Vero cells was also performed. Suspensions of A. flavus spores were inoculated into 50 mL of YES medium together with different concentrations of the AE. The aflatoxin B1 was extracted, analyzed by thin layer chromatography and quantified by photodensitometry. All the concentrations of AE induced inhibition of AFB1 production. The aqueous extract showed in vitro cytotoxicity to Vero cells only at concentrations above 500 µg/mL. Key words: aflatoxin B1, Aspergillus flavus, Polymnia sonchifolia, cytotoxicityThis work reports the inhibitory activity of aqueous leaf extract from P. sonchifolia against Aspergillus flavus growth and aflatoxin B1 production, and citotoxicity to Vero cells. MATERIALS AND METHODS Preparation of plant extractLeaves of P. sonchifolia were collected in Capão Bonito city, São Paulo state, Brazil and dried at 40ºC. Dried leaves were pulverized in mill (Condux) to obtain a fine powder. The powdered leaves (100 g) were extracted with water at room temperature for 5 hours. After filtration and removal of water, the extract was lyophylized (Flaxidry mp). This aqueous extract (AE) was stored at 4ºC until use. Culture conditionsAspergillus flavus IMI 190 (Internatinal Mycology InstituteLondon) was grown on potato dextrose agar (Difco Laboratories, Detroit, Mich) plates for 10 days at 25ºC. The spore suspension used as inoculum was prepared washing the culture with sterile 0.01% solution of Tween 80 (Merck, Germany). The number of spores in suspension was determined through counting in a Neubauer Chamber.

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Authentication of cell lines is of paramount importance to validate the results from their use in biomedical research. Although isoenzyme polymorphism is the standard method, molecular methods based on mitochondrial DNA (mtDNA) have been developed to replace it. The aim of this study was the improvement of our isoenzyme electrophoretic analysis and the validation of one molecular technique targeted at mtDNA for the authentication of our animal cell lines. The combined method of cellular lysing through osmotic shock, followed by freezing-thawing in N 2 to obtain isoenzyme extracts, and with 42 × 10 6 cells maintained the best efficiency. The superior electrophoretic conditions were PAGE run at 200 V. All cell lines had isoenzymatic mobility corresponding to their species to lactate dehydrogenase, malatedehydrogenase, and glucose-6-phosphate dehydrogenase isoenzymes, and could be distinguished from each other. Two molecular techniques based on mtDNA were tested, one on the cytochrome b gene and other on cytochrome c oxidase I subunit gene. Due to difficulties in distinguishing all cell lines using only one these techniques, we merged the primers of two methods in such a way that there was a sufficient differentiation of all DNA fragments. The sequencing of these PCR products was also performed to validate these data.