dc.description.abstract | Background: Cancer is a disease in which uncontrolled cell growth occurs which grows abnormally and destroys its initial form and function. One of the causes of this occurrence is a gene mutation. This mutation can occur due to various factors, namely UV rays, physical factors, chemical factors, and even natural factors. Cancer is a major health problem in the world. Breast cancer is a malignancy in breast tissue that can originate from the ductal epithelium or lobules. This cancer is one of the most common cancers in Indonesia and is the second leading cause of death. Duku leaves, which are included in the Meliaceae family, are a type of medicinal plant that contains bioactive compounds which have various pharmacological activities, one of which is as a basic anticancer ingredient. Objective: This study aims to test the activity of the active fraction of duku leaves in inhibiting the MCF-7 cell cycle and promoting apoptosis of MCF-7 cells. Methods: The stages of this research included sample collection, preparation of duku leaf simplisia, phytochemical screening, preparation of ethanol extract of duku leaves, preparation of active fractions of duku leaves, testing of cytotoxic activity, and testing of apoptosis induction and cell cycle inhibition. Results: Based on the test results, it was found that duku leaves contain secondary metabolites such as flavonoids, saponins, tannins, glycosides, alkaloids, and steroids/triterpenoids. Additionally, based on the conducted tests, the active fraction of duku leaves exhibited cytotoxic activity with an IC50 value of 68.163±1.104 μg/mL. The active fraction of duku leaves also showed activity in inducing apoptosis, indicated by an increase in the percentage of cells undergoing early apoptosis by 12.9%. In the cell cycle inhibition test, the active fraction of duku leaves demonstrated activity in inhibiting the cell cycle at the Sub G1 phase with a increase in the number of cells by 0.3% | en_US |