Terpenoids from Melampodium perfoliatum.

The phytochemical study of the aerial parts of Melampodium perfoliatum afforded six melampolides (1, 3, 5-8), a eudesmanolide (9), two diterpene lactones (10, 11), and two ent-kaurane derivatives (12, 13), together with the known melampodin (2) and polymatin A (4). The structures of the compounds were elucidated by physical data analysis and chemical reactions. Compounds 2, 4, 5, and 10 exhibited dose-dependent anti-inflammatory activity on the 12-O-tetradecanoylphorbol-13-acetate-induced ear edema model, with ID50 values of 1.14, 0.56, 1.15, and 1.49 µmol/ear, respectively, compared to the reference compound indomethacin (0.24 µmol/ear).

Use of herbarium data to evaluate weediness in five congeners.

It is often desirable to quantify a plant's relative weediness or synanthropy, that is, the degree to which a species associates with human-caused disturbance, in order to study and understand the biology, ecology and evolution of weeds and invasive plants. Herbarium specimens are among the most accessible and verifiable sources of data on distribution and habitat. However, the habitat distribution of species may not be reflected accurately by herbarium specimen data, due to well-known biases in plant collection. Here, we assess how well herbarium specimens reflect species' weediness, when compared with direct field surveys. We used five species of Melampodium (Asteraceae) and classified their degree of weediness with a modification of Nuorteva's synanthropy index, based on herbarium specimens. We then modelled the distribution of our focal species in Mexico using MaxEnt and identified a polygon of ∼3000 km(2) in the state of Nayarit, Mexico, where there was a high probability of finding all five species. Systematic field searches in the target area documented all visible populations of four species along major and minor roads. Then we, again, classified their degree of weediness with the synanthropy index, based now on field data, and compared. We found that herbarium data were an accurate predictor of a species' weediness relative to its congeners despite the well-documented skew of herbarium data towards natural areas, which our data reflected as well. So, herbarium data can be used to classify species' weediness relative to each other, but not in absolute terms, if the specimens were correctly identified and none of the species were subject to particular collection bias. This study is the first attempt to compare herbarium and field data on this subject and may be relevant for other types of investigations based on herbarium data. Our work also highlights the usefulness of distribution models based on herbarium specimens.

Sesquiterpenoids from Pittocaulon filare.

The phytochemical study of Pittocaulon filare afforded three oplopanes (1-3), a eudesmane (6), and three oplopane glucosides (7-9), one of them reported as its acetyl derivative (7a), together with several known compounds. The structures of the compounds were elucidated by spectroscopic analysis and chemical reactions. The anti-inflammatory activity of compounds 1-5 was determined using the 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced ear edema model, and the effect of compounds 1-4 on the recruitment of neutrophils was evaluated using the myeloperoxidase test. Compounds 1 and 2 were the more active anti-inflammatory agents, with lower ID50 values (0.17 and 0.18 µmol/ear, respectively) than indomethacin (0.24 µmol/ear), but they had a lesser effect on the inhibition of neutrophil infiltration than both indomethacin and compound 3, indicating that the tested compounds do not have the same ability to inhibit edema and to prevent cell infiltration.

The evolutionary history of the white-rayed species of Melampodium (Asteraceae) involved multiple cycles of hybridization and polyploidization.

PREMISE OF THE STUDY: Polyploidy plays an important role in race differentiation and eventually speciation. Underlying mechanisms include chromosomal and genomic changes facilitating reproductive isolation and/or stabilization of hybrids. A prerequisite for studying these processes is a sound knowledge on the origin of polyploids. A well-suited group for studying polyploid evolution consists of the three species of Melampodium ser. Leucantha (Asteraceae): M. argophyllum, M. cinereum, and M. leucanthum. METHODS: The origin of polyploids was inferred using network and tree-based phylogenetic analyses of several plastid and nuclear DNA sequences and of fingerprint data (AFLP). Genome evolution was assessed via genome size measurements, karyotype analysis, and in situ hybridization of ribosomal DNA. KEY RESULTS: Tetraploid cytotypes of the phylogenetically distinct M. cinereum and M. leucanthum had, compared to the diploid cytotypes, doubled genome sizes and no evidence of gross chromosomal rearrangements. Hexaploid M. argophyllum constituted a separate lineage with limited intermixing with the other species, except in analyses from nuclear ITS. Its genome size was lower than expected if M. cinereum and/or M. leucanthum were involved in its origin, and no chromosomal rearrangements were evident. CONCLUSIONS: Polyploids in M. cinereum and M. leucanthum are of recent autopolyploid origin in line with the lack of significant genomic changes. Hexaploid M. argophyllum also appears to be of autopolyploid origin against the previous hypothesis of an allopolyploid origin involving the other two species, but some gene flow with the other species in early phases of differentiation cannot be excluded.