J. Math. Fund. Sci.,Vol. 53, No. 1, 2021, 97-108 97 Received February 18 th , 2020, Revised April 8 th , 2021, Accepted for publication April 11 th , 2021. Copyright © 2021 Published by ITB Institute for Research and Community Services, ISSN: 2337-5760, DOI: 10.5614/j.fund.math.sci.2021.53.1.7 Chemical Constituents of Indonesian Micromelum minutum Leaves and Their Cytotoxicity Against MCF-7 and 4T1 Breast Cancer Cells Ratna Asmah Susidarti 1,2* , Edy Meiyanto 1,2 , Muthi’ Ikawati 1,2 , Normaidah 2,3 & Nurramadhani A. Sida 2,4 1 Department of Pharmaceutical Chemistry, Faculty of Pharmacy, Universitas Gadjah Mada, Sekip Utara, Yogyakarta, 55281, Indonesia 2 Cancer Chemoprevention Research Center, Faculty of Pharmacy, Universitas Gadjah Mada, Sekip Utara, Yogyakarta, 55281, Indonesia 3 Professional Pharmacist Study Program, Faculty of Mathematics and Natural Science, Universitas Lambung Mangkurat, Banjarbaru 70714, Indonesia 4 Faculty of Pharmacy, Universitas Halu Oleo, Kendari, 93232, Indonesia *E-mail: ratna_asmah@ugm.ac.id Abstract. Micromelum minutum is used widely in traditional folk medicine. Although this species has been investigated extensively and several bioactive compounds have been isolated, little work has been done on Indonesian M. minutum. This research aimed to study the chemical constituents and biological activities of M. minutum cultivated in Bantimurung Bulusaraung National Park, South Sulawesi, Indonesia. The isolated compounds were assessed for their cytotoxicity towards MCF-7 and 4T1 cell lines by MTT method. The dried ground leaves of M. minutum were sequentially macerated with n-hexane, ethyl acetate, and methanol. The n-hexane and ethyl acetate extracts contained a flavonoid 5,7-dihydroxy-3,4',8-trimethoxyflavone (1) which inhibited MCF-7 and 4T1 cell viability by 50% at concentrations of 369±8 and 227±5 μM, respectively. Further separation of the ethyl acetate extract by column chromatography yielded acetyldihydromicromelin A (2) and a mixture of dihydromicromelin A (3) and dihydromicromelin B (4), which were not active toward MCF-7 and 4T1 cells. Keywords: 5,7-dihydroxy-3,4',8-trimethoxyflavone; breast cancer cell line; cytotoxic activity; dihydromicromelin derivatives; Micromelum minutum. 1 Introduction Micromelum minutum is a shrub or small tree under the Rutaceae family and widely used in several traditional medicines. The leaves are used to cure fever and headache, scabies, leprous spots, ringworm and are also considered to be emmenagogue, while the boiled roots are applied to treat ague [1].