Characterization and biological properties of zederone and zedoarondiol from rhizomes of En-lueang (Curcuma cf. Amada)

Abstract

Curcuma cf. amada Roxb., also known as En-Lueang in Thailand, belongs to the Zingiberaceae family and grows from rhizomes. These rhizomes have been used in the Thai and Ayurveda systems of medicine. However, to our knowledge, no biologically active compounds isolated from En-Lueang have been reported. In this study, natural compounds were isolated from En-Lueang and their structures were determined by spectroscopic methods. The two isolated compounds were identified as zederone (1) and zedoarondiol (2) and their cytotoxicities against KG1a cells were investigated. The EtOH extract and EtOAc fraction showed stronger cytotoxic activity than n-hexane fraction against KG1a cells. In contrast, compound 1 showed strong cytotoxicity against KG1a cells, but low cytotoxicity toward normal peripheral blood mononuclear cells (PBMCs). Moreover, all the extracts and 1 had no effect on red blood cell hemolysis. The antioxidant properties of 1 were almost 2-fold higher than that of 2, in accordance with its total phenolic content of 8.8 mg/g, which is 2-fold higher than that of 2 (4.1 mg/g). In summary, two sesquiterpene compounds with leukemic cytotoxicity activity against the KG1a cell line were identified in En-Lueang extracts.