Diterpenoids with potential anti-inflammatory activity from the aerial parts of Nepeta glutinosa.

A phytochemical study on the aerial parts of Nepeta glutinosa Benth. from Tajikistan led to the isolation of twelve previously undescribed diterpenoids, designated nepglutinones A-L, along with three known analogues. Their structures were elucidated by comprehensive spectroscopic analysis. The absolute configurations of nepglutinones A and D were unequivocally established by single-crystal X-ray diffraction analysis, while those of the remaining undescribed compounds were determined by comparison of experimental and calculated electronic circular dichroism (ECD) spectra. All isolates were evaluated for their effects on cell viability and inhibition of nitric oxide (NO) production in lipopolysaccharide-stimulated RAW 264.7 macrophages. Nepglutinone F reduced cell viability to 53.3% at 100 μM. In the anti-inflammatory assay, nepglutinones B and G, the known compound 14α,18-dihydroxy-7,15-isopimaradiene, and the ethyl acetate fraction showed weak inhibition of NO production, with IC50 values of 61.5 ± 1.59, 69.9 ± 1.49, 65.3 ± 1.76 μM, and 44.95 ± 0.48 μg/mL, respectively (andrographolide IC50 = 5.49 ± 0.14 μM).