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In this study, an NMR spectral analysis of the mixture of diastereomeric acetals, synthesized from 2,3-dihydrofurane and a racemic mixture of citronellol, was performed. 1H-NMR full spin analysis was achieved by manually adjusting δH and J values (previously calculated using the Spartan software) to fit the experimentally available values, followed by further optimization using MestreNova software. 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 diastereotopic protons of tetrahydrofuranyl moiety and diastereomer discrimination. The NMR spectral data of individual diastereomers – chemical shifts, coupling constants, HMBC and NOESY interactions were systematized in appropriate tables and schemes. To the best of our knowledge, this is for the first time that the complete assignment of tetrahydrofuranyl moiety was performed, and the data obtained herein may be of great importance for the utilization of this protecting group in the future.

This study explores the chemical composition of essential oils from two Serbian Bupleurum species (Apiaceae), Bupleurum praealtum L. and Bupleurum affine L., traditionally recognized in Chinese medicine for their therapeutic potential but less studied for their essential oils. Through GC-MS analysis, we identified 230 constituents, revealing distinct profiles between the species. Perillyl 2-methylbutanoate was identified in B. affine oil for the first time, confirmed using synthetic approaches and characterized by advanced spectroscopic techniques, including two-dimensional NMR and spin-simulation of 1H NMR spectra. Additionally, new natural compounds, including tentatively identified 4-decyl acetate and 4-undecyl acetate, were discovered. The study also reports five stereoisomeric esters of tetradeca-5,7,9,11-tetraen-1-ol. These findings significantly contribute to the understanding of the phytochemical diversity within the genus Bupleurum and underscore potential differences in ecological adaptations or biosynthetic pathways among species. [ABSTRACT FROM AUTHOR]

Marrubiin is a diterpene with a long history of a wide range of biological activities. In this study, the anti-inflammatory effects of marrubiin were investigated using several in vitro and in vivo assays. Marrubiin inhibited carrageenan-induced peritoneal inflammation by preventing inflammatory cell infiltration and peritoneal mast cell degranulation. The anti-inflammatory activity was further demonstrated by monitoring a set of biochemical parameters, showing that the peritoneal fluid of animals treated with marrubiin had lower levels of proteins and lower myeloperoxidase activity compared with the fluid of animals that were not treated. Marrubiin exerted the most pronounced cytotoxic activity towards peripheral mononuclear cells, being the main contributors to peritoneal inflammation. Additionally, a moderate lipoxygenase inhibition activity of marrubiin was observed. [ABSTRACT FROM AUTHOR]