In this study, we screened sixty medicinal plant species from the Brazilian savanna ("cerrado")

A mixture of flavalignan cinchonains Ia and Ib was isolated from the bark of Trichilia catigua. The structures were established on the basis of spectroscopic data of the natural products and their methylated derivatives including 2D NMR experiments, and compared with data in the literature. These flavalignans exhibited antibacterial activity against Bacillus cereus, Escherichia coli, Pseudomonas aeruginosa and Staphylococcus aureus.

No abstract

Among three strains of Pycnoporus sanguineus, MIP 89007 produced more cinnabarin than MIP 95001 and MIP 95002. The antimicrobial activity of cinnabarin was tested against 11 species of bacteria isolated from food. Bacillus cereus and Leuconostoc plantarum were the most sensitive to cinnabarin, being inhibited by 0.0625 mg/ml. Klebsiella pneumoniae was the least sensitive (>4.0 mg/ml).

In order to obtain new compounds with antibacterial activity, the derivatives 2,4-dihydroxy-6-methylbenzoic acid (orsellinic acid) and 2,4-dihydroxy-6-methylbenzoates (orsellinates) were obtained through alcoholyses of lecanoric acid. All these substances were tested against Gram-positive and Gram-negative bacteria by a microdilution method. Staphylococcus aureus, Xanthomonas campestris var. vesicatoria and Ralstonia solanacearum were most sensitive to n-propyl 2,4-dihydroxy-6-methylbenzoate, n-pentyl 2,4-dihydroxy-6-methylbenzoate and n-hexyl 2,4-dihydroxy-6-methylbenzoate with MIC (Minimal Inhibitory Concentration) values ranging from 62.5 to 7.8 µg⋅mL -1 . These results showed that homologation in carbon chain may lead to compounds with more pronunced activities.