Very-Long-Chain Wax Constituents from Primula veris and P. acaulis: Does the Paradigm of Non-Branched vs. Branched Chain Dominance Universally Hold in all Plant Taxa?

Herein n-, iso- and anteiso-series of very-long-chained (VLC) alkanes (C21 -C35 ), fatty acid benzyl esters (FABEs; C20 -C32 ), and 2-alkanones (C23 -C35 ) were identified in the wax of Primula veris L. and P. acaulis (L.) L. (Primulaceae). For the very first time in a sample of natural origin, the presence of iso- and anteiso-VLC FABEs and 2-alkanones was unequivocally confirmed by synthetic work, derivatization, and NMR. It should be noted that the studied species produced unusually high amounts of branched wax constituents (e. g., >50 % of 2-alkanones were branched isomers). The domination of iso-isomers, probably biosynthesized from leucine-derived starters, is a unique feature in the Plant Kingdom. The plant organ distribution of these VLC compounds in P. acaulis samples (different habitats and phenological phases) pointed to their possible ecological value. This was supported by a eutectic behavior of binary blends of FABEs and alkanes, as well as by high UV-C absorption by FABEs.

Immunomodulatory Constituents of Conocephalum conicum (Snake Liverwort) and the Relationship of Isolepidozenes to Germacranes and Humulanes.

Structural elucidation of three new sesquiterpenoids, namely, (1Z,4E)-lepidoza-1(10),4-dien-14-ol (1), rel-(1(10)Z,4S,5E,7R)-germacra-1(10),6 diene-11,14-diol (2), and rel-(1(10)Z,4S,5E,7R)-humula-1(10),5-diene-7,14-diol (3), isolated from the liverwort Conocephalum conicum, was accomplished by a combination of extensive NMR experiments, 1H NMR simulation, and other means. Additionally, the change of the identity of bicyclogermacren-14-al, previously reported as a C. conicum constituent, to isolepidozen-14-al is proposed. Compounds 2 and 3 appear to be related to 1 via hydration involving a shared intermediate, a substituted cyclopropylmethyl cation, formed by a highly regio- and stereoselective protonation of 1, followed by a stereospecific fission of the three-membered ring. In other words, an isolepidozene derivative might be a branchpoint to humulanes and germacranes; this transformation could be of, up to now, unknown, biosynthetic and/or synthetic relevance. Multivariate statistical analysis of the compositional data of C. conicum extract constituents was used to probe the hypothesized biochemical relations. The immunomodulatory effect of 1-3 and conocephalenol (4) was evaluated in an in vitro model on both nonstimulated and mitogen-stimulated rat splenocytes. The compounds displayed varying degrees of cytotoxicity to nonstimulated splenocytes, whereas 2 and 3 were found to exert immunosuppressive effects on concanavalin A-stimulated splenocytes while not being cytotoxic at the same concentrations.

Essential oils and diethyl ether extracts of Serbian Xeranthemum cylindraceum and X. annum: chemical composition, antimicrobial activity, and chemotaxonomic implications.

Detailed GC and GC-MS analyses of the essential oils and Et2 O extracts of two Xeranthemum species - X. cylindraceum and X. annum - resulted in the identification of 254 components, in total. Terpenoids constituted the major part of both X. cylindraceum and X. annum essential oils and extracts (51.8-65.7%, and 50.7%, resp.). Among the sesquiterpenoids, the extracts of both investigated taxa contained the guaianolide xerantholide, its 11,13-dihydro derivatives, and two additional sesquiterpene lactones: an eudesmanolide, 11,13-dihydroisoalantolactone, and a pseudoguaianolide, confertin. The last two lactones and both isomers of 11,13-dihydroxerantholide have not been previously detected in Xeranthemum species. The isolated extracts of X. cylindraceum and X. annum were tested in a broth microdilution assay against a panel of microorganisms. The tested extracts demonstrated significant antimicrobial inhibitory activity, ranging from 30 to 260 µg/ml, being most active against Bacillus cereus and Staphylococcus aureus, an important human pathogen, with MIC close in value to those of chloramphenicol. Chemotaxonomic significance of the sesquiterpene lactones' distribution in the taxa investigated in this study and those detected earlier in phylogenetically close species (up to the level of the tribe Cardueae) was also discussed.

Essential oil composition of Cachrys cristata--a rare and endangered species in the flora of Serbia.

Cachrys cristata DC. (Apiaceace) is a rare and critically endangered species in the flora of Serbia. Essential oil isolated by hydrodistillation from the aerial parts and fruits of this species was analyzed using combined GC and GC/MS. The oil from the aerial parts was rich in sesquiterpenes (45.7%) and oxygenated sesquiterpenes (32.9%), while the fruit oil consisted of a higher percentage of sesquiterpenes (48.3%) and oxygenated sesquiterpenes (36.7%). The dominant constituents in the oil from aerial parts were phytol (13.1%) and germacrene D (12.9%), while in the fruit oil suberosin (19.7%) and germacrene D (12.3%) were the most abundant.