Three New and Other Limonoids from the Hexane Extract of Melia azedarach Fruits and Their Cytotoxic Activities

AbstractA defatted fraction obtained from the hexane extract of the fruits of Melia azedarach L. (chinaberry tree; Meliaceae) exhibited cytotoxic activities against leukemia (HL60), lung (A549), stomach (AZ521), and breast (SK‐BR‐3) cancer cell lines with IC50 values in the range of 2.9–21.9 μg/ml. Three new limonoids, 3‐deacetyl‐4′‐demethylsalannin (5), 3‐deacetyl‐28‐oxosalannin (14), and 1‐detigloylohchinolal (17), along with 16 known limonoids, 1–4, 6–13, 15, 16, 18, and 19, and one known triterpenoid, 20, were isolated from the fraction. The structures of new compounds were elucidated on the basis of extensive spectroscopic analyses and comparison with literature. These compounds were evaluated for their cytotoxic activities against the four cancer cell lines mentioned above. 3‐Deacetyl‐4′‐demethyl‐28‐oxosalannin (16), which exhibited potent cytotoxicity against AZ521 (IC50 3.2 μM) cells, induced typical apoptotic cell death in AZ521 cells upon evaluation of the apoptosis‐inducing activity by flow cytometry. This work provided, furthermore, valuable information on the structural features of limonoids of the fruits and/or seeds of Melia azedarach and related Meliaceae plants, M. toosendan and Azadirachta indica.