title: Biologically active vallesamine, strychnan, and rhazinilam alkaloids from Alstonia: Pneumatophorine, a nor-secovallesamine with unusual incorporation of a 3-ethylpyridine moiety.
abstract: Four alkaloids comprising two vallesamine, one strychnan, and one pyranopyridine alkaloid, in addition to 32 other known alkaloids were isolated from two Malayan Alstonia species, Alstonia pneumatophora and Alstonia rostrata. The structures of these alkaloids were determined using NMR and MS analyses, and in one instance, confirmed by X-ray diffraction analysis. The nor-6,7-secovallesamine alkaloid, pneumatophorine, is notable for an unusual incorporation of a 3-ethylpyridine moiety in a monoterpenoid indole. The rhazinilam-type alkaloids (rhazinicine, nor-rhazinicine, rhazinal, and rhazinilam) showed strong cytotoxicity toward human KB, HCT-116, MDA-MB-231, and MRC-5 cells, while pneumatophorine, the uleine alkaloid undulifoline, and the strychnan alkaloids, N4-demethylalstogustine and echitamidine, induced concentration dependent relaxation in phenylephrine-precontracted rat aortic rings.
authors.affiliation: Department of Chemistry, University of Malaya, 50603 Kuala Lumpur, Malaysia.
authors.forename: Jun-Lee
authors.initials: JL
authors.lastname: Lim
authors.affiliation: Institute of Biological Sciences, University of Malaya, 50603 Kuala Lumpur, Malaysia.
authors.forename: Kae-Shin
authors.initials: KS
authors.lastname: Sim
authors.affiliation: Institute of Biological Sciences, University of Malaya, 50603 Kuala Lumpur, Malaysia.
authors.forename: Kien-Thai
authors.initials: KT
authors.lastname: Yong
authors.affiliation: Department of Biomedical Sciences, University of Nottingham Malaysia Campus, Jalan Broga, 43500 Semenyih, Selangor, Malaysia.
authors.forename: Bi-Juin
authors.initials: BJ
authors.lastname: Loong
authors.affiliation: Department of Biomedical Sciences, University of Nottingham Malaysia Campus, Jalan Broga, 43500 Semenyih, Selangor, Malaysia.
authors.forename: Kang-Nee
authors.initials: KN
authors.lastname: Ting
authors.affiliation: Department of Chemistry, University of Malaya, 50603 Kuala Lumpur, Malaysia.
authors.forename: Siew-Huah
authors.initials: SH
authors.lastname: Lim
authors.affiliation: Department of Chemistry, University of Malaya, 50603 Kuala Lumpur, Malaysia.
authors.forename: Yun-Yee
authors.initials: YY
authors.lastname: Low
authors.affiliation: Department of Chemistry, University of Malaya, 50603 Kuala Lumpur, Malaysia. Electronic address: tskam@um.edu.my.
authors.forename: Toh-Seok
authors.initials: TS
authors.lastname: Kam
mesh_terms: D000447:Aldehydes / Q000737:chemistry / Q000494:pharmacology; D000470:Alkaloids / Q000737:chemistry* / Q000494:pharmacology*; D031051:Alstonia / Q000737:chemistry*; D000818:Animals; D000972:Antineoplastic Agents, Phytogenic / Q000737:chemistry / Q000494:pharmacology; D001011:Aorta / Q000187:drug effects; D002227:Carbazoles / Q000737:chemistry / Q000494:pharmacology; D045744:Cell Line, Tumor / Q000187:drug effects; D018360:Crystallography, X-Ray; D004353:Drug Evaluation, Preclinical / Q000379:methods; D006576:Heterocyclic Compounds, 4 or More Rings / Q000737:chemistry / Q000494:pharmacology; D006801:Humans; D026121:Indole Alkaloids / Q000737:chemistry* / Q000494:pharmacology; D007212:Indolizines / Q000737:chemistry / Q000494:pharmacology; D007769:Lactams / Q000737:chemistry / Q000494:pharmacology; D015394:Molecular Structure; D010656:Phenylephrine / Q000494:pharmacology; D011714:Pyrans / Q000737:chemistry / Q000494:pharmacology; D011725:Pyridines / Q000737:chemistry / Q000494:pharmacology; D051381:Rats; D046948:Secologanin Tryptamine Alkaloids / Q000737:chemistry / Q000494:pharmacology; D014665:Vasodilator Agents / Q000737:chemistry / Q000494:pharmacology
chemical_list: D000447:Aldehydes; D000470:Alkaloids; D000972:Antineoplastic Agents, Phytogenic; D002227:Carbazoles; D006576:Heterocyclic Compounds, 4 or More Rings; D026121:Indole Alkaloids; D007212:Indolizines; D007769:Lactams; C000608325:N4-demethylalstogustine; D011714:Pyrans; D011725:Pyridines; D046948:Secologanin Tryptamine Alkaloids; D014665:Vasodilator Agents; C000608324:pneumatophorine; C480458:rhazinal; C529483:rhazinicine; C000608326:rostracine; D010656:Phenylephrine; C009170:rhazinilam; C085228:echitamidine; C039675:3-ethylpyridine
keywords: Alstonia pneumatophora; Alstonia rostrata; Apocynaceae; Cytotoxicity; Indole alkaloids; NMR; Vasorelaxation