Lignans from the Twigs of Litsea cubeba and Their Bioactivities

Litsea cubeba, an important medicinal plant, is widely used as a traditional Chinese medicine and spice. Using cytotoxicity-guided fractionation, nine new lignans 1–9 and ten known analogues 10–19 were obtained from the EtOH extract of the twigs of L. cubeba. Their structures were assigned by extensive 1D- and 2D-NMR experiments, and the absolute configurations were resolved by specific rotation and a combination of experimental and theoretically calculated electronic circular dichroism (ECD) spectra. In the cytotoxicity assay, 7′,9-epoxylignans with feruloyl or cinnamoyl groups (compounds 7–9, 13 and 14) were selectively cytotoxic against NCI-H1650 cell line, while the dibenzylbutyrolactone lignans 17–19 exerted cytotoxicities against HCT-116 and A2780 cell lines. The results highlighted the structure-activity relationship importance of a feruloyl or a cinnamoyl moiety at C-9′ or/and C-7 ketone in 7′,9-epoxylignans. Furthermore, compound 11 was moderate active toward protein tyrosine phosphatase 1B (PTP1B) with an IC₅₀ value of 13.5 μM, and compounds 4–6, 11 and 12 displayed inhibitory activity against LPS-induced NO production in RAW264.7 macrophages, with IC₅₀ values of 46.8, 50.1, 58.6, 47.5, and 66.5 μM, respectively.

Four new monacolin analogs from Monascus purpureus-fermented rice

Four new monacolin analogs, monacolin T (1), monacolin U (2) 6a-O-methyl-4,6-dihydromonacolin L (3), and 6a-O-ethyl-4,6-dihydromonacolin L (4) were isolated from the ethanolic extract of Monascus purpureus-fermented rice. Their structures were determined by a combination of 1D, 2D NMR experiments (¹H-¹HCOSY, HSQC, HMBC, and ROESY), and mass spectrometry. In vitro cytotoxic assay, all compounds were inactive at the concentration of 10 µM.