Ultrasonic-assisted extraction of Curcuma aromatica: isolation and evaluation of bioactive components with anti-inflammatory activity

Abstract

Curcuma aromatica (Zingiberaceae) has long been used as a promising herb in Thai traditional medicine. Previous chemical constituents of this plant revealed different types of natural compounds, such as terpenoids and curcuminoids. This work evaluated the efficiency of biologically crude extracts from two extraction procedures: ultrasonic-assisted extraction and reflux methods. All extracts investigated the bioactive compounds analyzed by Gas chromatography–mass spectrometry and preliminary cell-based nitric oxide inhibitory screening, and the results implied that 75% ethanol rhizome extract assisted by ultrasonic irradiation exhibited sufficient constituents and biological activity. To explore the major bioactive compounds from this plant, a phytochemical investigation of Curcuma aromatica rhizome extract assisted by ultrasonic technique led to the isolation of six known compounds: (3S)-1,7-diphenylheptan-3-ol (1), germacrone (2), zederone (3), (−)-curcumene (4), curcumin (5), and bisdemethoxycurcumin (6). Their structures were determined on the basis of the spectroscopic data. In addition, (3S)-1,7-diphenylheptan-3-ol (1) was isolated for the first time from a natural source, and the complete spectroscopic data were given. All isolated compounds were submitted to test the anti-inflammatory activity using nitric oxide production in murine macrophage RAW 264.7 cell lines. Except for compounds 5 and 6, all isolated compounds showed moderate nitric oxide inhibition with IC50 ranging from 7.36 ± 0.33 to 70.13 ± 11.14 μg/mL.