Montbresides A–D: Antibacterial p-coumaroyl esters of a new sucrose-based tetrasaccharide from Crocosmia × crocosmiiflora (montbretia) flowers

Shagufta Perveen, Ian Sadler, Raha Orfali, Dalal M Al-Taweel, Lorna Murray, Stephen Fry

Research output: Contribution to journalArticlepeer-review

Abstract

Crocosmia × crocosmiiflora (montbretia) flowers yielded four esters (montbresides A–D) of anew sucrose-based tetrasaccharide, 3-O-b-D-glucopyranosyl-4´-O-a-D-rhamnopyranosyl-sucrose[b-D-Glc-(1®3)-a-D-Glc-(1«2)-b-D-Fru-(4¬1)-a-D-Rha]. All four possess O-p-coumaroylresidues on C-3 of fructose and C-4 of a-glucose, plus O-acetyl residues on C-2 and C-3 ofrhamnose and C-6 of fructose. Montbresides A and B are additionally O-acetylated on C-1 of fructose. The p-coumaroyls are trans- in montbresides A and C and cis- in B and D. Elemental compositions were determined from MS data, and structures from 1D and 2D NMR spectra. Monosaccharide residues were identified from selective 1D TOCSY spectra and TLC, andacylation sites from 2D HMBC spectra. Enantiomers were distinguished by enzymic digestion. Montbretia flower extracts were cytotoxic against six human cancerous cell-lines, but purified montbresides lacked cytotoxicity. Each montbreside displayed antibacterial activity against Staphylococcus aureus (minimal inhibitory concentration ~6 μg/ml). Montbretia is a potential source of new cytotoxins and antibacterial agents.
Original languageEnglish
Article number 104377
JournalFitoterapia
Volume139
Early online date19 Oct 2019
DOIs
Publication statusE-pub ahead of print - 19 Oct 2019

Keywords

  • Crocosmia × crocosmiiflora
  • Phenolic glycoside
  • Sucrose-based tetrasaccharide
  • Montbresides A–D
  • Cytotoxicity
  • Antibacterial activity

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