New alkaloids from selected Malaysian alstonia and Lycopodium species and their biological activity / Joanne Yeap Soon Yee

Joanne Yeap , Soon Yee (2020) New alkaloids from selected Malaysian alstonia and Lycopodium species and their biological activity / Joanne Yeap Soon Yee. PhD thesis, Universiti Malaya.

	PDF (The Candidate's Agreement) Restricted to Repository staff only Download (202Kb)
	PDF (Thesis PhD) Download (16Mb)

Abstract

Two Malaysian plants, Alstonia penangiana Sidiyasa (family: Apocynaceae) and Lycopodium platyrhizoma J.H.Wilce (family: Lycopodiaceae), were investigated for their alkaloidal composition. This project represents the first reported phytochemical study on these two plant species. A total of 94 alkaloids (1−94) were isolated and characterized from the leaf and stem-bark extracts of Alstonia penangiana, a plant endemic to Penang Island, Malaysia. Of these, 32 are new alkaloids. The leaf extract of A. penangiana yielded a total of 15 new alkaloids, including a pair of type-A and type-B macroline isomers (1, 2), four macroline oxindoles (20–23), three talpinine-type oxindoles (41–43), two ajmaline alkaloids (57–58), as well as four macroline-akuammiline bisindoles (76–79). The stem-bark extract of A. penangiana gave a total of 19 new alkaloids. These include seven sarpagine alkaloids (32–38), an akuammiline alkaloid 39, a C14 methylene-bridged indolizidine derivative (40), seven macroline-sarpagine bisindoles (80–86), and a macroline-pleiocarpamine bisindole 88. Evaluation of the in vitro growth inhibitory activity of the new alkaloids against a panel of human cancer cell lines, including KB/S, KB/VJ300(−), KB/VJ300(+), PC-3, LNCaP, MCF7, MDA-MB-231, HT-29, and HCT 116 cancer cells showed strong cytotoxicity for the bisindole alkaloids (76–77, IC50 0.3−8.3 μM; 80–86, IC50 0.02−9.7 μM). A total of 19 alkaloids (95−113) were isolated and characterized from the whole plant of Lycopodium platyrhizoma. Of these, three are new alkaloids, including two lycodine alkaloids (95–96) and one fawcettimine alkaloid (110). Lycoplatyrine A (95) is an uncommon lycodine alkaloid having C-2 substituted with a C5N (piperidine) moiety. The alkaloid compositions of the two plants are summarized in Table 2.1 and Table 2.61.

Actions (For repository staff only : Login required)