Bioactivity evaluations of ingredients extracted from the flowers of Citrus aurantium L. var. amara Engl.

Citrus aurantium L. var. amara Engl, a member of genus Citrus (Rutaceae), widespread in China, is used as folk medicine for the treatment of helping digest, phlegm, enteritidis, stomachic and other deceases. In the present research, silica gel column, Sephadex LH-20, mass spectrometer (MS) and nuclear magnetic resonance (NMR) were used to separate and identify the chemical compounds from the flowers of C. aurantium var. amara, and several bioactivity assays were used to evaluate their antioxidant, anti-inflammatory, anti-virus and antitumour activities. Two major compounds, 5-hydroxy-6,7,3',4'-tetramethoxyflavone (HTF) and limonexic acid (LA), were isolated and identified from C. aurantium var. amara for the first time. The results of the bioactivity assays showed that HTF and LA displayed significant antioxidant activities and showed significant inhibition effects on the B16 cell lines at a concentration range from 6.25 to 50 μg/ml, and on the SMCC-7721 cell lines from 12.5 to 200 μg/ml. The antitumour effect, anti-inflammatory activity and the inhibiting expression of HBsAg and HBeAg of 2.2.15 cells displayed the tendency in a concentration-dependent manner. These two compounds from C. aurantium var. amara could potentially be used as a promising natural agent in the pharmaceutical industries.