Triterpenoid saponins from a cytotoxic root extract of Sideroxylon foetidissimum subsp. gaumeri.
Evaluation of the cytotoxicity of an ethanolic root extract of Sideroxylonfoetidissimum subsp. gaumeri (Sapotaceae) revealed activity against the murine macrophage-like cell line RAW 264.7. Systematic bioassay-guided fractionation of this extract gave an active saponin-containing fraction from which four saponins were isolated. Use of 1D ((1)H, (13)C, DEPT135) and 2D (COSY, TOCSY, HSQC, and HMBC) NMR, mass spectrometry and sugar analysis gave their structures as 3-O-(beta-D-glucopyranosyl-(1-->6)-beta-D-glucopyranosyl)-28-O-(alpha-L-rhamnopyranosyl-(1-->3)[beta-D-xylopyranosyl-(1-->4)]-beta-D-xylopyranosyl-(1-->4)-alpha-L-rhamnopyranosyl-(1-->2)-alpha-L-arabinopyranosyl)-16alpha-hydroxyprotobassic acid, 3-O-beta-D-glucopyranosyl-28-O-(alpha-L-rhamnopyranosyl-(1-->3)[beta-D-xylopyranosyl-(1-->4)]-beta-D-xylopyranosyl-(1-->4)-alpha-L-rhamnopyranosyl-(1-->2)-alpha-L-arabinopyranosyl)-16alpha-hydroxyprotobassic acid, 3-O-(beta-D-glucopyranosyl-(1-->6)-beta-D-glucopyranosyl)-28-O-(alpha-L-rhamnopyranosyl-(1-->3)-beta-D-xylopyranosyl-(1-->4)[beta-D-apiofuranosyl-(1-->3)]-alpha-L-rhamnopyranosyl-(1-->2)-alpha-L-arabinopyranosyl)-16alpha-hydroxyprotobassic acid, and the known compound, 3-O-beta-D-glucopyranosyl-28-O-(alpha-L-rhamnopyranosyl-(1-->3)[beta-D-xylopyranosyl-(1-->4)]-beta-D-xylopyranosyl-(1-->4)-alpha-L-rhamnopyranosyl-(1-->2)-alpha-L-arabinopyranosyl)-protobassic acid. Two further saponins were obtained from the same fraction, but as a 5:4 mixture comprising 3-O-(beta-D-glucopyranosyl)-28-O-(alpha-L-rhamnopyranosyl-(1-->3)-beta-D-xylopyranosyl-(1-->4)[beta-D-apiofuranosyl-(1-->3)]-alpha-L-rhamnopyranosyl-(1-->2)-alpha-L-arabinopyranosyl)-16alpha-hydroxyprotobassic acid and 3-O-(beta-D-apiofuranosyl-(1-->3)-beta-D-glucopyranosyl)-28-O-(alpha-L-rhamnopyranosyl-(1-->3)[beta-D-xylopyranosyl-(1-->4)]-beta-D-xylopyranosyl-(1-->4)-alpha-L-rhamnopyranosyl-(1-->2)-alpha-L-arabinopyranosyl)-16alpha-hydroxyprotobassic acid, respectively. This showed greater cytotoxicity (IC(50)=11.9+/-1.5 microg/ml) towards RAW 264.7 cells than the original extract (IC(50)=39.5+/-4.1 microg/ml), and the saponin-containing fraction derived from it (IC(50)=33.7+/-6.2 microg/ml).
Sánchez-Medina
Alberto
A
School of Health and Bioscience, University of East London, London, UK.
Stevenson
Philip C
PC
Habtemariam
Solomon
S
Peña-Rodríguez
Luis M
LM
Corcoran
Olivia
O
Mallet
Anthony I
AI
Veitch
Nigel C
NC
D000818:Animals; D000972:Antineoplastic Agents, Phytogenic / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology; D002240:Carbohydrate Sequence; D002460:Cell Line; D009682:Magnetic Resonance Spectroscopy; D051379:Mice; D008969:Molecular Sequence Data; D010936:Plant Extracts / Q000737:chemistry*; D018517:Plant Roots / Q000737:chemistry*; D012503:Saponins / Q000737:chemistry / Q000302:isolation & purification* / Q000494:pharmacology; D029632:Sapotaceae / Q000737:chemistry*; D021241:Spectrometry, Mass, Electrospray Ionization; D014315:Triterpenes / Q000737:chemistry / Q000302:isolation & purification* / Q000494:pharmacology
D000972:Antineoplastic Agents, Phytogenic; D010936:Plant Extracts; D012503:Saponins; D014315:Triterpenes