Antimicrobial activities of eucalyptus leaf extracts and flavonoids from Eucalyptus maculata.

AIMS: We investigated the antimicrobial activities of eucalyptus leaf extracts to find effective antibacterial agents. METHODS AND RESULTS: The antimicrobial activities of leaf extracts from 26 species of eucalyptus were measured. Extracts of Eucalyptus globulus, E. maculata and E. viminalis significantly inhibited the growth of six Gram-positive bacteria (Staphylococcus aureus, MRSA, Bacillus cereus, Enterococcus faecalis, Alicyclobacillus acidoterrestris, Propionibacterium acnes), and of a fungus (Trichophyton mentagrophytes), but they did not show strong antibacterial activity against Gram-negative bacteria (Escherichia coli, Pseudomonas putida). 2',6'-dihydroxy-3'-methyl-4'-methoxy-dihydrochalcone, eucalyptin and 8-desmethyl-eucalyptin, isolated from E. maculata extracts, exhibited potent antimicrobial activities against seven micro-organisms with minimum inhibitory concentrations (MIC) ranging from 1.0 to 31 mg l(-1). CONCLUSIONS: The eucalyptus extracts and three compounds from E. maculata were found to be effective against micro-organisms that cause food poisoning, acne and athlete's foot. SIGNIFICANCE AND IMPACT OF THE STUDY: This study shows potential uses of extracts from E. globulus, E. maculata and E. viminalis, and antimicrobial compounds isolated from E. maculata.

Cloning, sequence analysis, and expression of ligninolytic phenoloxidase genes of the white-rot basidiomycete Coriolus hirsutus.

Two cDNAs and two genomic DNAs coding for the allelic forms of the ligninolytic phenoloxidase were isolated from the white-rot fungus Coriolus hirsutus. The cloned genes were identified in genetic libraries by hybridization screening using four deoxyoligonucleotide probes which corresponded to the partial amino acid sequence of the purified enzyme. Each cDNA encoded the full-length of the phenoloxidase, a protein consisting of 499 amino acid residues, and its putative signal peptide of 21 amino acid residues. The nucleotide sequences of the two alleles differed by 18 single base changes within the open reading frames resulting in one amino acid substitution. Ten small introns interrupted both genomic DNAs as indicated by direct comparison with the corresponding cDNAs. Putative eukaryotic regulatory sequences, "CAAT" and "TATA," were observed in the 5'-flanking region of both genomic DNAs. Each of the phenoloxidase cDNAs was successfully expressed in an active form in Saccharomyces cerevisiae using the useful yeast expression vector YEp51.