Chemical investigations and antiproliferative activities of the alkaloids from Tabernaemontana polyneura / Tang Sin Yee

Tang , Sin Yee (2024) Chemical investigations and antiproliferative activities of the alkaloids from Tabernaemontana polyneura / Tang Sin Yee. PhD thesis, Universiti Malaya.

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Abstract

The alkaloidal content of a Malaysian plant, Tabernaemontana polyneura (family: Apocynaceae), was investigated. A total of 72 alkaloids (1−72) were isolated and characterized from the bark and leaf extracts of T. polyneura, collected from Fraser’s Hill, in the state of Pahang, Peninsular Malaysia. The bark extract yielded 16 new alkaloids, including ten iboga (1−10), one chippiine (30), three vobasine (33−35), one cleavamine (54), and one vobasinyl-iboga bisindole alkaloids (66), while the leaf extract only yielded known alkaloids. Among the new alkaloids, polyneurine A (1) is characterized by a -lactone unit embedded within the iboga skeleton, while polyneurines I (30) and J (9) are the first examples of chippiine and seco-coronaridine alkaloids that incorporate an additional pyrrolidine ring. The biosynthetic pathways toward alkaloids 1, 3−5, 9, and 30 were also proposed. Polyneurine P and four known bisindole alkaloids (66−70) displayed pronounced growth inhibitory activity (IC50 0.34−9.02 μM) against HT-29, HCT 116, MDA-MB-231, A549, and MCF7 cancer cells.

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