Isolation and characterization of cytotoxic and anti-inflammatory constituents from Scoparia dulcis L

Abstract

Scoparia dulcis L. is one of the edible widely distributed Scropholariaceae species in Asia, Africa and America. It is used in the treatment of respiratory and inflammatory diseases, diabetes, hypertension, cancer, hepatitis and tuberculosis. A phytochemical investigation on S. dulcis led to the isolation of two new acyclic diterpenes Acetic acid 6-hydroxy-2-(6-hydroxy-4-methyl-hex-4-enylidene)-4,8-dimethyl-undeca-4,8-dienyl ester (1) and Acetic acid 8-hydroxy-2-(6-hydroxy-4-methyl-hex-4-enylidene)-6,10-dimethyl-undeca-5,9-dienyl ester (2) in addition to eight known compounds (3–10), namely scopadulciol (3), 4-epi-scopadulcic acid B (4), dulcidiol (5), scopadulcic acid B (6), hymenoxin (7), glutinol (8), eupatilin (9) and 5-demethylnobiletin (10). The structures elucidation was performed using spectroscopic means, including 1D and 2D nuclear magnetic resonance and high-resolution electrospray ionization mass spectrum spectrometric analysis. Furthermore, the isolated compounds were investigated for their anti-inflammatory activity through the determination of inhibition of nuclear factor-kappa B activity in human chondrosarcoma (SW1353) cells, the inhibition of inducible nitric oxide synthase mouse macrophages (RAW264.7) and the decrease in cellular oxidative stress in HepG2 cells. Moreover, the cytotoxic activity was investigated against four cancer and two kidney cell lines. Among the isolates, 3, 5 and 10 showed anti-inflammatory activity in terms of inhibiting nuclear factor-kappa B and inducible nitric oxide synthase. Compounds 3–5 were the most cytotoxic towards cancer cell lines (IC50: 3.8 µM to 42.3 µM) followed by 10 (IC50: 30.9- ' 64.4 µM). Cytotoxicity of compounds 3–5 was comparable to the activity of doxorubicin.