Wai Foong Ku

Date of Award

1-1-2011

Thesis Type

masters

Document Type

Thesis

Divisions

science

Department

Dept of Chemistry

Institution

University of Malaya

Abstract

The alkaloidal content of Malaysian plant, Alstonia angustiloba Miq., was investigated and the results are summarized as below (Table). A total of 20 alkaloids were isolated and characterized, of which, three were new alkaloids, viz., angustilobine C (1), andransinine (2), and angustiphylline (3). Angustilobine C (1) and andransinine (2) are alkaloids of the angustilobine- and andranginine type, respectively, while angustiphylline (3) is a new bisindole alkaloid constituted from the union of uleine and secovallesamine moieties. Alkaloids 1 and 2 were obtained from the leaf extract while the bisindole 3 was isolated from the bark extract. In addition to the new alkaloids, seventeen known alkaloids were also obtained which were: 19,20-E-vallesamine (4), 17-O-acetylvallesamine (5), yunnannensine (6), angustilobine A (7), angustilobine B (8), nor-6,7-secoangustilobine B (9), nor-6,7-seco-19,20-epoxyangustilobine B (10), undulifoline (11), condylocarpine (12), 20S-tubotaiwine (13), N(4)-demethylechitamine (14), 17-O-acetyl-N(4)-demethylechitamine (15), alstolucine B (16), vincamine (17), 16R,19E-isositsirikine (18), venoterpine (19), and cantleyine (20). Angustilobine C (1) showed moderate cytotoxicity towards both drug-sensitive and vincristine-resistant KB cells (IC50 7.76 and 7.33 g/mL, respectively), while andransinine (2) reversed multidrug resistance in vincristine-resistant KB cells (KB/VJ300 cells, IC50 1.61 g/mL in the presence of 0.1 g/mL of vincristine).

Note

Dissertation submitted in fulfilment of the requirement for the degree of Master of Science

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