Glechomenes A-G, diterpenoids with anti-inflammatory activities from the aerial part of Glechoma longituba

Ten diterpenoids including six unreported abietane-type diterpenoids Glecholmenes A-F (1–6) and an undescribed labdane-type diterpenoid Glecholmene G (9), together with three known diterpenoids (7,8,10), were firstly isolated from the aerial part of G. longituba. Their structures were established mainly by nuclear magnetic resonance (NMR) and high-resolution electrospray ionization mass spectrometry (HR-ESI-MS) methods. Electronic circular dichroism (ECD) calculations and X-ray crystallographic analyses were used for the determination of their absolute configurations. The anti-inflammatory activity of all compounds was evaluated using the classical LPS-induced NO release model in RAW264.7 cells. Compound 2 displayed significant anti-inflammatory activities with IC50 values of 29.08 ± 1.40 μM (Aminoguanidine hydrochloride as the positive control, IC50 = 21.84 ± 0.48 μM). [Display omitted] •Seven previously undescribed diterpenoids were discovered from G. longituba.•All the compounds were isolated from this plant for the first time.•Labdane-type diterpenoids were found in G. longituba for the first time.•The absolute configurations were determined by X-ray single crystal diffraction and ECD calculations.•Compound 2 exhibited significant anti-inflammatory activity.