Thesis (M.Sc.)--Chulalongkorn University, 2013

Ten compounds were obtained from the leaf and root extracts of Citrus hystrix. Structural elucidation of all isolated compounds were performed by NMR data and compared with the published data. Hesperidin (1) and neohesperidin (2) were afforded from the BuOH extract whereas alkyl alcohol (3) and oxypeucedanin hydrate (4) were also obtained from the dichloromethane extract of C. hystrix leaves. The root extract of this plant gave limonin (5), xanthyletin (6), crenulatin (7), 5-hydroxynoracronycine (8), citracridone-I (9) and umbelliferone (10). All isolated compounds were tested for their anti-acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) activities. The results found that most of them showed low to moderate inhibition in dose-dependent manners. The IC50 value towards AChE of neohesperidin (2) was 160.1 μM, and that of oxypeucedanin hydrate (4) towards BChE was 260.8 μM. Xanthyletin (6) showed the highest inhibition towards AChE and BChE with IC50 value of 116.2 and 37.4 μM, respectively, with a mixed inhibitory mode towards BChE. The BChE inhibitory activity and mode of inhibition of xanthyletin were reported for the first time.