Over 1,400 species of Formosan plants have been screened for cytotoxicity and Cryptocarya concinna Hance (Lauraceae) was found to be one of the most bioactive species. C. concinna is a medium-sized evergreen tree and distributed in altitude 500-1,500 m broad-leaved forests in Taiwan and southern China. Previously, we reported three new chalcones concichalcones A-C (1-3), two new flavanoid cryptoflavanones E-F (7-8), and 19 known compounds from the active ethyl acetate soluble layer of the root of C. concinna.
Continuing investigation of the active layer, additional three new chalcones, concichalcone D (4), concichalcon E (5) and concitocaryone (6), together with five known compounds, including two flavonoids, two amide alkaloids, and one lignan have been isolated. The structures of these new compounds were elucidated by NMR, UV, IR, ESIMS, and HRESIMS analyses. Different human cell lines, including cervical cancer SiHa cells, osteosarcoma U2OS cells, and normal keratinocyte HaCaT cells, were used to examine the cytotoxic profiles of these compounds. A new compound concichalcone D (4) has a significant cytotoxic activity on U2OS and SiHa cells, with IC50 values less than 15 μM. The known compounds cryptocaryone, infectocaryone, cryptocaryanones A, and cryptocaryanone B exhibited potent cytotoxic activities in all the cell lines examined, with the IC50 values less than 10 μM. Two compounds, cryptocaryanones A and concichalcone D (4), exhibited a mild selectivity between cancer and normal cells, as their IC50 values were significantly higher in the normal keratinocyte HaCaT cells. Interestingly, a mixture of cryptoflavanones A & B showed a differential cytotoxic activity in SiHa cells (IC50 value less than 20 μM) over the U2OS and HaCaT cells (IC50 value higher than 20 μM).