Analysis of Essential oil, Quantification of Six Glycosides, and Nitric Oxide Synthase Inhibition Activity in Caryopteris incana

Caryopteris incana (Verbenaceae) has been used to treat cough, arthritis, and eczema in Oriental medicine. The two fractions ($CHCl_3-$ and BuOH fractions) and the essential oil of the plant material were subjected to the inducible nitric oxide synthase (iNOS) assay. The $IC_{50}$ of the $CHCl_3$ fraction and the essential oil on LPS-induced macrophage RAW 264.7 cells were $16.4{\mu}g/mL$ and $23.08{\mu}g/mL$, respectively. On gas chromatography (GC)-mass spectroscopy (MS) analysis, twenty-five components representing 85.5% amount of total essential oil were identified. On the chromatogram, three main substances, trans-pinocarveol, cis-citral, and pinocarvone, occupied 18.8%, 13.5% and 18.37% of total peak area. Furthermore, by HPLC-UV analysis, six compounds including one iridoid (8-O-acetylharpagide)- and five phenylethanoid glycosides (caryopteroside, acteoside, phlinoside A, 6-O-caffeoylphlinoside, and leucosceptoside A) isolated from the BuOH fraction were quantified. The content of six compounds were shown as the following order: caryopteroside (162.35 mg/g) > 8-O-acetylharpagide (93.28 mg/g) > 6-O-caffeoylphlinoside (28.15 mg/g) > phlinoside (22.60 mg/g) > leucosceptoside A (16.87 mg) > acteoside (7.05 mg/g).