In this investigation, chromatographic separations of the diethyl ether extracts of two European annual Bupleurum taxa, B. praealtum and B. veronense, yielded nine new natural products, namely, a series of esters of stereoisomeric tetradeca-5,7,9,11tetraen-1-ols (1−4 and 8), a tetra-unsaturated γ-tetradecalactone (5), a dibenzylbutyrolactone lignan (7-oxoarcitin, 6), a falcarinolrelated 17-membered macrolide (7) possessing a conjugated diyne-system, and an acylphloroglucinol derivative (9). All these new compounds were fully characterized by NMR, IR, UV, MS, and optical rotation measurement, including 1 H NMR full spin spectral simulation, whereas the absolute configurations of 1, 5, and 9 were determined via chemical correlations and NMR analysis of Mosher esters. The in vitro potential immunomodulatory activities of 1, 4, 5, and (+)-arcitin were assessed by determining their effects on the functional properties of isolated rat splenocytes and peritoneal macrophages. The results obtained support the known immunomodulatory ethnomedicinal usage of Bupleurum species.

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, 1 H 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.

A very mild, stoichiometric PPh3–CCl4 method for the preparation of diverse acetals of aromatic and aliphatic aldehydes was developed.

Herein, an NMR spectral analysis was performed of a mixture of diastereomeric acetals synthesized from 2-fluorobenzaldehyde and a racemic mixture of 4-methylpentan-2-ol. The simulated 1H- and 13C-NMR spectra of individual diastereomers, as well as their superimposed and summed spectra, were compared with the obtained experimental spectra. Spin simulation of proton signals was particularly useful for the assignment of the aromatic part of the molecules and of the diastereotopic protons of the methylene groups. The isomer NMR spectral data - chemical shifts, coupling constants, HMBC and NOESY interactions were systematized in appropriate tables and schemes.