Tagetes lucida Cav. essential oil and the mixture of its main compounds are antibacterial and modulate antibiotic resistance in multi-resistant pathogenic bacteria.

We evaluated an essential oil (EO) of Tagetes lucida Cav. and the mixture of its main compounds against multi-drug resistant bacteria. We found that EO and the partially reconstituted blend of its main components have antibacterial activity and inhibit antibiotic resistance (ampicillin, chloramphenicol, nalidixic acid, vancomycin and imipenem) in strains of Staphylococcus aureus ATCC 29213 and Pseudomonas aeruginosa HIM-MR01. The T. lucida EO alone or added to the antibiotics showed antimicrobial activity against S. aureus and P. aeruginosa. The EO main bioactive compounds were methyl eugenol (relative abundance in EO: 46·15%), estragole (32·93%), linalool (2·48%) and geraniol (0·33%). The mixture (PREO) of those compounds at those proportions inhibited the growth of P. aeruginosa in 45% at 683·62 µg ml-1 and that of S. aureus in 51·7% at 39·04 µg ml-1 . The PREO had higher antibacterial and modulatory activities than the original EO. In conclusion, we overcame the unpredictability of EO activity (due to their natural variability) by determining which EO components inhibited bacteria and then producing a PREO to generate a reproducible mixture with predictable antibacterial and modulation of resistance activities. Thus, the PREO, and its components, show potential as alternatives to manage multidrug-resistant pathogens.

Genetic variation in Mexican Jatropha curcas L. estimated with seed oil fatty acids.

The genetic diversity of Mesoamerican populations of the biofuel plant Jatropha curcas, using the fatty acids of the seeds as chemical markers was studied. The oil content of the whole seed in 135 accessions from 38 sites varied between 8.020% and 54.28%. The prevalent fatty acids were oleic acid (18:1) and linoleic acid (18:2), and the proportion of unsaturated fatty acids varied between 74.5% and 83.7%. A study with cloned plants grown in common garden showed that both the content of oil as well as the proportion of fatty acids are highly inheritable, therefore these chemical markers are valid for estimating the genetic diversity of the species. An analysis of principal components showed that the fatty acids that contribute more to the variance are stearic, oleic, linoleic, methylpalmitic, gadoleic and ricinoleic. The populations were classified in ten groups when the data were analyzed for fatty acids by analysis of clusters, showing the elevated genetic variation in natural populations of this native species of Mesoamerica. A discriminant analysis separated the populations in accordance with their geographic origin, which was verified with a Mantel test. Using the Monmonier's algorithm two genetic barriers between the populations were identified. The results are discussed in light of their microevolutionary significance.

Antiinflammatory constituents from Heterotheca inuloides.

Three new compounds, cadalen-15-oic acid (1), 3,7-dihydroxy-3(4H)-isocadalen-4-one (2), and dicadalenol (3), were isolated from the aerial parts of Heterotheca inuloides (Mexican arnica), together with the known compounds 7-hydroxycadalene (4), 7-hydroxy-4alphaH-3,4-dihydrocadalene (5), 1alpha-hydroxy-1(4H)-isocadalen-4-one (6), 1alpha-hydroxy-4alphaH-1,2,3,4-tetrahydrocadalen-15-oic acid (7), 7-(3,3-dimethylallyloxy)coumarin, caryolan-1,9beta-diol, and quercetin. The structures of the new compounds were elucidated by spectroscopic methods. The antiinflammatory activities of the extracts and the isolated compounds were evaluated by determining the inhibition of TPA-induced mouse ear edema. The natural products 3, caryolan-1,9beta-diol, and quercetin were the most active substances tested and displayed dose-dependent activities.

Effect of some leaf essential oil phenotypes from coastal redwood on growth of its predominant endophytic fungus,Pleuroplaconema sp.

Experiments were performed to assess the effect of four foliar essential oil phenotypes from a coastal redwood (Sequoia sempervirens) population on isolates ofPleuroplaconema sp., its ubiquitous endophytic fungus. Isolates were exposed to essential oils extracted from their trees of origin and from other trees. The hypotheses tested were: (1) redwood leaf essential oils extracted from distinct trees would have a differential effect onPleuroplaconema sp. growth, and (2) growth of isolates from a particular tree would be differentially affected when exposed to essential oil phenotypes different from that of their tree of origin. The essential oil phenotypes were differentially inhibitory, but the pattern of inhibition did not support the second hypothesis.Pleuroplaconema sp. showed low average tolerance to all of the essential oils; two phenotypes reduced growth 70-80% and the other two 50-60% at the dose tested. The overall growth response of individual isolates to all treatments suggests that more than one fungus genotype per tree was represented in the experiment. The variability in tolerance of individual isolates to the essential oils was low for three phenotypes. The low tolerance ofPleuroplaconema sp. to redwood essential oils, in spite of its predominance and specialization in this conifer, is discussed considering: (1) the possible pathogenic ancestry of this fungus, and (2) that essential oil phenotypes may be important in controlling the activity ofPleuroplaconema sp. after it colonizes the leaf.