Sesquiterpenes from the leaves of Laurus nobilis L.
Ten sesquiterpenes, together with 12 known compounds were isolated from leaves of Laurus nobilis L. Based on spectroscopic analyses, the 10 compounds were determined to be eudesmane lactones and their corresponding methyl esters. Most of these compounds exhibited moderate-to-significant cytotoxicity towards K562 leukemia cells. One compound had a higher cytotoxicity than doxorubicin, while other compounds had moderate to no activity.
Microbial transformation of sesquiterpene lactones by the fungi cunninghamella echinulata and rhizopus oryzae
Incubations of the fungi Cunninghamella echinulata and Rhizopus oryzae with the sesquiterpene lactones (+)-costunolide (1), (+)-cnicin (2), (+)-salonitenolide (3), (-)-dehydrocostuslactone (4), (-)-lychnopholide (5), and (-)-eremantholide C (6) were perfomed. Incubation of 1 with C. echinulata afforded Delta11(13)-dihydrogenation and Delta1(10)-epoxidation products (7-10). C. echinulata also hydrolyzed the side chain of 2, and transformed 4 into (+)-11alpha,13-dihydrodehydrocostuslactone (12), a new natural product. R. oryzae converted 4 into both Delta11(13)-dihydrogenation and Delta10(14)-epoxidation products (16 and 17). Both fungi transformed 5 into (-)-16-(1-methyl-1-propenyl)eremantholanolide (13), providing experimental evidence for the biosynthesis of the eremantholide hemiketal unit. Compounds 3 and 6 were not metabolized by either fungus under the test conditions.
Coexistence of Virulence and Antibiotic Resistance Genes in Pasteurella multocida Isolated from Diseased Rabbits
Pasteurella multocida (P. multocida)is considered a predominant pathogenic bacterial agent causing respiratory manifestations (snuffles) in rabbits with considerable economic losses and unfavorable prognosis in Egypt. A few recent P. multocida strains exhibit resistance to the most commonly used antibiotics in the veterinary field. Therefore, the present study was carried out to investigate the prevalence of both virulence and antibiotic resistance genes among P. multocida isolated from diseased rabbits in Sharkia Governorate, Egypt. Only 10 out of 100 tested rabbits` nasal swabs were finally confirmed positive for P. multocida of serogroup A by polymerase chain reaction (PCR). Antibiotic susceptibility testing of the recovered isolates revealed that they were all multidrug resistant (MDR) with a predominance of resistance to amoxicillin, ampicillin, amoxicillin/clavulanic acid, neomycin and tetracycline (100% each), followed by kanamycin and streptomycin (90% each). All the recovered isolates were further subjected to PCR screening of some common virulence and antibiotic resistance genes of interest . With the exception of toxA gene, the other virulence associated genes (ptfA, Omp87 and nanB) were found among all the examined isolates. Totally, all MDR P. multocida isolates contained at least one antibiotic resistance gene with aphA1 being the most prevalent (100%), followed by ermX gene (40%). Antibiotic resistance genotyping demonstrated the presence of multiple antibiotic resistance genes among majority of the isolates (40%) with only one isolate harboring 4 genes encoding identical resistance phenotypes. Evidentially, all MDR P. multocida isolates possessed at least 3 virulence genes accompanied by the attendance of antibiotic resistance genes. These findings evidenced that rabbits are potential sources of pathogenic P. multocida strains harboring virulence and antibiotic resistance genes. Therefore, it is evident that there is an urgent need for the judicious use of antibiotics in rabbits` treatment systems to successfully mitigate the propagation of drug resistance across P. multocida species.