Lignans and aporphine alkaloids in bark of Liriodendron tulipifera

Lirionol, a novel tetracyclic lignan, has been isolated from the bark of Liriodendron tulipifera and its structure determined by spectroscopic analysis. In addition, syringic acid methyl ester, (+)-pinoresinol, (+)-syringaresinol, N-(2-hydroxy-2-phenylethyl)benzamide and O-methyl-N-norlirinine have also been isolated. The structures of lirinine and related compounds isolated from the leaves of this tree-species by Yunusov et al. are also discussed.     

Optical resolution of (±)-dehydrodiisoeugenol: Structure revision of acuminatin

The lignan, acuminatin, whose structure was previously reported as 3, was found to be identical with the methyl ether of (+)-dehydrodi-isoeugenol, and therefore its structure must now be revised to (+)-2.     

Reciprocal crosses between Magnolia stellata and Magnolia kobus do not show significant reproductive barriers in seed formation

Congeneric invasive species reduce genetic endemism of native species through hybridization and sometimes cause extinction through genetic or demographic swamping. In the range of Magnolia stellata, a native rare subtree species, Magnolia kobus, an invasive planted/escaped tree species, can also be found. In order to examine possible natural hybridization between the two species, a reciprocal cross-pollination experiment was conducted, and fruit set, seed set, female reproductive success in seed formation (FRS; fruit set × seed set) and seed weight were estimated. With M. stellata as the maternal tree, there were no significant differences in all measurements between intra- and interspecific crosses. With M. kobus as the maternal tree, there were also no significant differences in all measurements except fruit set. These results suggest that there are no reproductive barriers between the two species and planted/escaped M. kobus near the natural habitat of M. stellata presents a threat through hybridization.     

Evolution of sesquiterpene lactones in angiosperms

The paper attempts to discover an outline of the evolutionary trends of sesquiterpene lactones in angiosperms. The working method involves the quantification of skeletal specialization and oxidation state of the compounds and the assignment of evolutionary advancement indices, based on such data, to taxa. In the angiosperms as a whole, sesquiterpene lactone evolution proceeds by diversification of structural types and by amplification of the oxidation state of the molecules. The opposite trend appears to operate at lower hierarchical level, in the Asteraceae. In this family, which contains most of the known compounds of the class, sesquiterpene lactone evolution follows two parallel pathways in the tribes belonging to two groups of the subfamily Asteroideae.     

Phylogenetic relationships in Magnoliaceae subfam. Magnolioideae: a morphological cladistic analysis

Relationships within Magnolioideae have been the subject of persistent debate; the main point at issue mostly being the disposition of tribes, genera and sections. A morphological cladistic analysis of the subfamily using Liriodendron as the out-group showed that Magnolioideae consisted of a large basal polytomy, but with five resolved and variously supported clades. Manglietia constituted a clade with sect. Rytidospermum of Magnolia subg. Magnolia. Kmeria and Woonyoungia formed a pair. Pachylarnax, Parakmeria and Manglietiastrum were grouped together, and sect. Splendentes and Dugandiodendron also formed a pair. The largest and best supported clade consisted of Magnolia subg. Magnolia sects. Oyama and Maingola, Magnolia subg. Yulania, Michelia, Aromadendron, Alcimandra, Elmerrillia, Paramichelia and Tsoongiodendron, with sect. Oyama of Magnolia subg. Magnolia is sister to the remainder. Although Magnolia sect. Maingola, Aromadendron, Alcimandra and Elmerrillia constituted a poorly resolved subclade, Aromadendron formed a monophyletic clade with Alcimandra. Within the Michelia/Magnolia subgen. Yulania subclade, Paramichelia was sister to Tsoongiodendron. These results are supported by similar placement of taxa within various molecular analyses of the family, but the low level of resolution indicates that more morphological data are needed to improve phylogenetic signal. Our results support the molecular analyses in suggesting that Magnolia is best considered to be a large and diverse genus, but that the relationships between the taxa within it require more detailed clarification, with more extensive sampling and a combined molecular and morphological approach being needed.     

(−)-Maglifloenone,a novel spirocyclohexadienone neolignan and other constituents from Magnolia liliflora

A new neolignan designated (?)-maglifloenone and the known one futoenone, both of which contain the rarely occurring spirocyclohexadienone skeleton, have been isolated together with the tetrahydrofuranolignan (+)-veraguensin, an optically inactive tertiary base taspine and β-sitosterol from the leaves and twigs of Magnolia liliflora. The structure and stereochemistry of (?)-maglifloenone have been deduced from the spectral data and the mass fragmentation of (?)-maglifloenone and futoenone have been rationalized. This is the first report of two neolignans of spirocyclohexadienone skeleton and of taspine from the Magnoliaceae family and the second report of the natural occurrence of futoenone.     

Neolignans from Magnolia denudata

New neolignans, denudatin A and B (hydrobenzofuranoids) and denudatone [spiro(5,5)undecanoid], together with three known neolignans including burchelli