A new degraded limonoid, named isodictamdiol A (1), two known degraded limonoids (2, 3) and a new nature product of quinoline alkaloid (4) along with five known quinoline alkaloids (5-9) were isolated from the root bark of Dictamnus angustifolius G. Don ex Sweet. Certain useful NMR data were generalized to determine the structures of compounds 1 and 4. The structural elucidation of Compound 4 was first reported herein. Compounds 1-9 showed significant inhibitory effects on platelet aggregation induced by ADP at 250 μM, while Compound 4 showed potent anti-platelet aggregation activity. © 2013 Elsevier B.V.