MyMedR

Leucoridines A-D, cytotoxic Strychnos-Strychnos bisindole alkaloids from Leuconotis

Gan CY, Etoh T, Hayashi M, Komiyama K, Kam TS

J Nat Prod, 2010 Jun 25;73(6):1107-11.

PMID: 20515042 DOI: 10.1021/np1001187

Four new bisindole alkaloids of the Strychnos-Strychnos type, leucoridines A-D (1-4), were isolated from the stem-bark extract of Leuconotis griffithii. Alkaloids 1-4 showed moderate cytotoxicity against drug-sensitive and vincristine-resistant human KB cells.

Strychnan and secoangustilobine A type alkaloids from Alstonia spatulata. Revision of the C-20 configuration of scholaricine

Tan SJ, Low YY, Choo YM, Abdullah Z, Etoh T, Hayashi M, et al.

J Nat Prod, 2010 Nov 29;73(11):1891-7.

PMID: 21043460 DOI: 10.1021/np100552b

A total of 25 alkaloids were isolated from the leaf and stem-bark extracts of Alstonia spatulata, of which five are new alkaloids of the strychnan type (alstolucines A-E, 1-5) and the other, a new alkaloid of the secoangustilobine A type (alstolobine A, 6). The structures of these alkaloids were established using NMR and MS analysis and, in the case of alstolucine B (2), also confirmed by X-ray diffraction analysis. A reinvestigation of the stereochemical assignment of scholaricine (13) by NMR and X-ray analyses indicated that the configuration at C-20 required revision. Alkaloids 1, 2, 6, 7, 9, 10, and 13 reversed multidrug resistance in vincristine-resistant KB cells.

Leuconicines A-G and (-)-eburnamaline, biologically active strychnan and eburnan alkaloids from Leuconotis

Gan CY, Low YY, Etoh T, Hayashi M, Komiyama K, Kam TS

J Nat Prod, 2009 Dec;72(12):2098-103.

PMID: 20035556 DOI: 10.1021/np900576b

Seven new indole alkaloids of the Strychnos type, leuconicines A-G (1-7), and a new eburnan alkaloid, (-)-eburnamaline (8), were isolated from the stem-bark extract of two Malayan Leuconotis species. The structures of these alkaloids were established using NMR and MS analysis and in the case of 8 also by partial synthesis. Alkaloids 1-5 reversed multidrug resistance in vincristine-resistant KB cells.

Leucophyllidine, a cytotoxic bisindole alkaloid constituted from the union of an eburnan and a new vinylquinoline alkaloid

Gan CY, Robinson WT, Etoh T, Hayashi M, Komiyama K, Kam TS

Org. Lett., 2009 Sep 3;11(17):3962-5.

PMID: 19708704 DOI: 10.1021/ol9016172

A cytotoxic bisindole alkaloid possessing an unprecedented structure constituted from the union of an eburnan half and a novel vinylquinoline alkaloid has been isolated from Leuconotis griffithii. The structure was established by analysis of the spectroscopic data and confirmed by X-ray diffraction analysis. A possible biogenetic pathway to the novel quinolinic coupling partner is presented from an Aspidosperma precursor.

Grandilodines A-C, biologically active indole alkaloids from Kopsia grandifolia

Yap WS, Gan CY, Low YY, Choo YM, Etoh T, Hayashi M, et al.

J Nat Prod, 2011 May 27;74(5):1309-12.

PMID: 21428274 DOI: 10.1021/np200008g

Three new indole alkaloids (1-3), named grandilodines A-C, and five known ones were obtained from the Malayan Kopsia grandifolia. The structures were established using NMR and MS analyses and, in the case of 1 and 2, were confirmed by X-ray diffraction analyses. Alkaloids 1, 3, and lapidilectine B (8) were found to reverse multidrug resistance in vincristine-resistant KB cells.

Displaying all 5 publications