Artocarpus species (Moraceae) are evergreen trees with a milky juice and large edible fruits. There are about 50 species in tropical Asia, Polynesia, and the Pacific islands [1,2]. Artocarpus species have been used in folk medicine for their anti-inflammatory, antioxidant, antibacterial, and antiplatelet activities [3][4][5][6]. Plants of the genus Artocarpus are rich in prenylflavonoids [3,[7][8][9][10][11][12][13][14][15][16].To further understand the chemotaxonomy of the genus Artocarpus and to continue searching for novel bioactive metabolites from Moraceae plants, A. heterophyllus was chosen for a phytochemical investigation.Carefull examination of this plant has resulted in the isolation of nine constituents, 1-9. Compounds 3-9 were isolated from this species for the first time. The structures of these compounds were established by means of spectral experiments.Cyclomorusin (1) [3] and cycloartocarpin A (2) [17] were obtained as colorless needles, whereas brosimone I (3) [18] was isolated as a yellow powder with mp 150-152qC. The IR and NMR data of these compounds were consistent with corresponding authentic samples. It is noteworthy that brosimone I (3) was isolated for the first time from this plant.Stearic acid (4) [19], palmitic acid (5) [19], and linoleic acid (6) [19] were isolated as colorless needles. They were identified by comparison of their physical and spectral data with reported values [19]. Squalene (7) was obtained as a colorless oil. The IR and 1 H NMR data corresponded with literature values [20]. Two steroids, E-sitosterol (8) [21] and stigmasterol (9) [21]), gave a positive Liebermann-Burchard test. The molecular formula of compounds 8 and 9 was determined to be C 29 H 50 O (414) and C 29 H 48 O (412), respectively, from EI-MS and 13 C NMR spectra. These two compounds were further identified by comparison of the IR and 1 H NMR spectra with the corresponding literature data. Brosimone I (3). Yellowish powder; mp 150-152qC; [ ] 25 D D +100q (c 0.12, acetone). UV (MeOH, O max , nm) (log H): 260 (4.91), 290 (4.21), 370 (4.25). IR (KBr, Q max , cm -1 ): 3400 (OH), 1652 (C=O). 1 H NMR (500 MHz, acetone-d 6 , G, ppm, J/Hz): 1.08 (6H, t, J = 6.8, CH 3 -19, 20), 1.68, 1.93 (each 3H, d, J = 1.5, CH 3 -14, 15), 2.43 (1H, m, H-18), 5.45 (1H, m, H-12), 6.20 (1H, d, J = 9.0, H-11), 6.40 (1H, d, J = 2.0, H-3c), 6.58 (1H, s, H-8), 6.51-6.60 (2H, m, H-5c, 16), 6.74 (1H, dd, J = 16.0, 7.0, H-17), 7.65 (1H, d, J = 8.0, H-6c), 13.70 (1H, s, OH-5, D 2 O exchangeable). EI-MS m/z (rel. int): 420 [M] + (52), 403 (11), 377 (13), 321 (100).