New seco-apotirucallane triterpenoids, pachyphylinin A (1) and B (2), were isolated from the stem bark of Aglaia pachyphylla alongside nine triterpenoid compounds (3-11). The structures were elucidated and identified through various spectroscopic analyses, including 1D and 2D NMR, HRTOF-MS, FTIR, as well as ECD, complemented by computational calculation using TD-DFT. In the process, pachyphylinin A (1) and B (2) were tested for cytotoxic activity against the breast cancer cell line (MCF-7). The results showed cytotoxic activities against MCF-7 with IC50 values in the range of 98.8-500 µM.