Low molecular weight procyanidins from grape seeds enhance the impact of 5-Fluorouracil chemotherapy on Caco-2 human colon cancer cells

PLoS One. 2014 Jun 6;9(6):e98921. doi: 10.1371/journal.pone.0098921. eCollection 2014.


Objective: Grape seed procyanidins (PC) are flavan-3-ol oligomers and polymers known for their biological activity in the gut. Grape seed extract (GSE) have been reported to reduce intestinal injury in a rat model of mucositis. We sought to investigate effects of purified PC fractions differing in mean degree of polymerization (mDP) combined with 5-Fluorouracil (5-FU) chemotherapy on the viability of colon cancer cells (Caco-2).

Design: SixPC fractions (F1-F6) were isolated from Cabernet Sauvignon seeds at two ripeness stages: pre-veraison unripe (immature) and ripe (mature), utilizing step gradient, low-pressure chromatography on a Sephadex LH-20 resin. Fractions were tested on Caco-2 cells, alone and in combination with 5-FU. Eluted fractions were characterized by phloroglucinolysis and gel permeation chromatography. Cell viability was determined by the 3-(4,5-Dimethylthiazol-2yl)-2,5-diphenyl-tetrazolium bromide) (MTT) assay.

Results: All isolated fractions significantly reduced Caco-2 cell viability compared to the control (P<0.05), but F2 and F3 (mDP 2-6) were the most active fractions (immature F2 = 32% mDP 2.4, F3 = 35% mDP 5.8 and mature F2 = 13% mDP 3.6 and F3 = 17% mDP 5.9; percentage of viable cells remaining) on Caco-2 cells. When combined with 5-FU, immature fractions F1-F3 enhanced the cell toxicity effects of 5-FU by 27-73% (P<0.05). Mature seed PC fractions (F1-F4) significantly enhanced the toxicity of 5-FU by 60-83% against Caco-2 cells (P<0.05). Moreover, some fractions alone were more potent at decreasing viability in Caco-2 cells (P<0.05; immature fractions = 65-68% and mature fractions = 83-87%) compared to 5-FU alone (37%).

Conclusions: PCs of mDP 2-6 (immature F1-F3 and mature F1 and F4)not only enhanced the impact of 5-FU in killing Caco-2 cells, but also surpassed standard 5-FU chemotherapy as an anti-cancer agent.The bioactivity of PC is therefore attributed primarily to lower molecular weight PCs.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Antineoplastic Agents / pharmacology*
  • Antioxidants / chemistry
  • Antioxidants / pharmacology
  • Biflavonoids / chemistry*
  • Biflavonoids / pharmacology*
  • Caco-2 Cells
  • Catechin / chemistry*
  • Catechin / pharmacology*
  • Cell Survival / drug effects
  • Colonic Neoplasms / pathology*
  • Drug Synergism
  • Fluorouracil / pharmacology*
  • Grape Seed Extract / chemistry*
  • Humans
  • Molecular Weight
  • Proanthocyanidins / chemistry*
  • Proanthocyanidins / pharmacology*


  • Antineoplastic Agents
  • Antioxidants
  • Biflavonoids
  • Grape Seed Extract
  • Proanthocyanidins
  • procyanidin
  • Catechin
  • Fluorouracil

Grant support

Professor Gordon Howarth is supported by a South Australian Health and Medical Research Institute Cancer Council Senior Research Fellowship. The current study was performed under the collaboration between Wine Science and Business Group, The University of Adelaide and Australian Wine Research Institute (AWRI). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.