Chemical constituents and cytotoxic activities from the root of Cryptocarya concinna

Cryptocarya concinna Hance (Lauraceae) is a medium-sized evergreen tree and distributed in altitude 500 – 1,500 m broad-leaved forests in Taiwan and southern China. In our cytotoxic screening, the methanolic extract from the root of C. concinna exhibited cytotoxic activities against human cervical cancer SiHa cells, human ovarian cancer SKOV-3 cells, and human osteosarcoma U2OS cells. Here we investigated the chemical constituents from the root of this plant and studied their cytotoxic activities. Furthermore, the results of cytotoxic activity were determined by Alamar Blue assay.

The methanolic extract of the root of C. concinna was partitioned into the ethyl acetate-soluble and water-soluble layers. The ethyl acetate-soluble layer showed potent cytotoxic activities against various cancer cell lines, including SiHa, SKOV-3, and U2OS. The bioassay-guided fractionation of the active ethyl acetate-soluble layer led to the isolation of 22 compounds, including three new chalcones, concichalcones A-C (1-3), together with 19 known compounds, including 16 flavonoids, two chalcones, and a steroid. The structures of these new compounds were elucidated by 1D and 2D NMR, UV, IR, ESIMS, and HRESIMS analyses. Most importantly, three pairs of flavonoid stereoisomers, cryptoflavanones A & B (8, 9), cryptoflavanones C & D (14, 15), and cryptoflavanones E & F (20, 21) were separated for the first time. Among these isolates, cryptocaryone (4), infectocaryone (5), and a mixture of cryptocaryanones A & B (11, 12) exhibited potent cytotoxic activities against U2OS cancer cell line, with IC₅₀ values of 2.81 ± 0.07, 3.90 ± 0.50, and 3.90 ± 0.50µM, respectively.