Nemophilosides A-I, nine meroterpenoid glucosides isolated from Nemophila menziesii

Nine previously undescribed meroterpenoid glucosides, named nemophilosides A-I, were isolated from the whole plant extract of Nemophila menziesii. Their molecular structures were determined from their NMR and MS spectra, and the absolute configurations were confirmed using ECD spectroscopy by comparing the experimental data with calculated data. The meroterpenoids consist of monoterpenoids and hydroquinone moieties; however, meroterpenoids obtained as glycosides are relatively rare, which distinguishes this class of compounds. Their skeletons are similar to those of cannabinoids and shikonins, suggesting homologous biosynthetic pathways. Compared with the well-known meroterpenoids, the monoterpenoid moieties of the compounds isolated in this study were characterized by oxidation. Although these compounds showed little or no inhibitory activity against fatty acid amide hydrolase and acetylcholinesterase, compound 6 regulated NO production in RAW264.7 cells.