Quatro linhagens virulentas do fungo Bipolaris euphorbiae (previamente identificado como Helminthosporium sp.), isoladas de Euphorbia heterophylla de quatro estados do Brasil, foram estudadas quanto a produção de fitotoxina, que promove murcha e desfolha da referida erva daninha brasileira, popularmente denominada leiteiro e comumente encontrada nas culturas de soja. O isolado Bipolaris euphorbiae linhagem I (EUPH petropar do estado de Mato Grosso), produziu fitotoxina in-vitro quando cultivada sob condição estática, durante 7 dias, a 28 °C em meio mínimo suplementado com glucose 1,5 %, como fonte única de carbono. A fitotoxina foi também produzida quando o isolado foi cultivado em frutose, galactose, manose, xilose e sacarose. A adição de fonte de nitrogênio (extrato de levedura, peptona e extrato de malte) ao meio de cultivo não influenciou a produção da mesma. A fitotoxina produzida pela linhagem I apresentou maior atividade em pH 6,0 , permaneceu estável na faixa de pH entre 3 e 9 e demonstrou elevada termoestabilidade, mantendo-se ativa após ter sido aquecida durante uma hora a 90 °C.

Four virulent strain isolates of the fungus, Bipolaris euphorbiae (previously identified as a Helminthosporium sp.), isolated from host plants in four states within Brazil were screened for the production of phytotoxins that promoted wilting and defoliation of the Brazilian weed, Euphorbia heterophylla, commonly found growing among soyabean crops. Only one isolate, B. euphorbiae Strain I (EUPH petropar from Mato Grosso state), produced phytotoxin in-vitro when grown in stationary culture for 7 d at 28 ° C on minimum salts medium supplemented with 1.5 % glucose as the sole carbon source. Phytotoxin was also produced when the fungal strain was grown on fructose, galactose, mannose, xylose and sucrose. The addition of nitrogen source (yeast extract, peptone or malt extract) to the culture medium did not influence phytotoxin production. The phytotoxin produced by Strain I was most active at pH 6.0, stable between pH 3-9, and was highly thermostable, remaining fully active when heated at 90 ° C for 1 h.

Phytochemical investigation of the flowers of Wedelia paludosa afforded two diterpenes, ent-kaur-16-en-19-oic acid and ent-kaur-9(11),16-dien-19-oic acid, three acylated triterpenes, 3beta-O-hexa-decanoylolean-12-en-28-oic acid, 3beta-O-pentadecanoylolean-12-en-28-oic acid and 3beta-O-tetradecanoylolean-12-en-28-oic acid, and three steroids, stigmasterol, 3beta-O-beta-D-glycopyranosyl sitosterol and 3beta-O-beta-D-glycopyrano-sylstigmasterol. The substances were identified by their spectral data.

The flowers of Stiffitia chrysantha Mikam(Asteraceae) contain eriodictiol, quercetin, luteolin and b-D-glycopyranosil-sitosterol. These compounds and its derivatives were identified by their 1H and 13C NMR, infra-red and mass spectra data. The heteronuclear 2D NMR were used to confirm the assignments of the proton and carbon chemical shifts, it was used to eliminate definitively the ambiguous correlation reported in the literature for C-5 and C-9 of quercetin and C-23 and C-25 of b-D-glycopyranosil-sitosterol.