El-Bacha 2014 Abstract MiP2014
|Cytotoxicity of grape pomace extract (Vitis vinifera L.) from Brazilian wine industry in human hepatocarcinoma HepG2 cells.|
Wine industry produces large quantities of by-products, rich in bioactive compounds from grapes, with potential use for nutraceutical purposes. Grape pomace represents an environmental problem due to its high quantity and its pollutant characteristics. In Brazil, the majority of grape pomace produced is discarded, while part of it is used as fertilizer and as animal ration by small agricultural producers . Since grape pomace is a rich source of polyphenols including phenolic acids, stilbenes, flavonoids and tannins, the use of this by-product for these purposes is very limited, due to their potent anti-microbial and potential anti-nutrient properties (original). Therefore, other applications are required to decrease environmental impact of grape pomace and, concomitantly, add value to this residue. In this study we evaluated the cytotoxicity of a grape pomace extract, obtained from Brazilian wine industry, in human hepatocarcinoma cells (HepG2).
Hydro-alcoholic extracts were obtained from red grape (Pinot noir) pomace, derived from white wine vinification and concentrated by reverse osmosis. Grape pomace extract was characterized with respect to its bioactive compounds and antioxidant capacity. In vitro bioactivity was assessed on HepG2 cells as a function of viability, cellular respiration and lactate production under short, medium and long-term incubation periods.
Grape pomace extract had high contents of polyphenol compounds and antioxidant capacity, compared to previously published data . Total phenolics, flavonoids and anthocyanins where (mean±SE) 34,060±1,490 mg galic acid Eq/100 g, 2,146±191 mg catechin Eq/100 g and 258.69±1.66 mg cyanidin3-glycoside/100 g, respectively. The main anthocyanins found in grape pomace extract were 3-O-glucosides. Pomace extract antioxidant capacity was (mean±SE, mmol Trolox Eq/g) 101.43±0.12 and 16.71±1.78, by TEAC and ORAC assays, respectively. HepG2 viability reduced in a time- and concentration-dependent manner. Short-term incubation had no effect whereas medium- and long-term incubation induced a maximum of 30% and of 70% reduction in viability, respectively. Cell respiration and lactate production were assessed in short-term incubations, in order to evaluate grape pomace polyphenols bioactivity on HepG2 bioenergetics irrespective of effects on cell viability. Treated cells presented a significant 60% increase in ROUTINE respiration. Additionally, the ROUTINE flux control ratio (R/E) was higher in treated (0.52) when compared to control (0.40) cells. Moreover, the fraction of oxygen consumption utilized for ATP synthesis, (R-L)/E, significantly increased from 0.16 in control to 0.27 in treated HepG2 cells. These results indicate that treated cells present a lower respiratory reserve capacity and also suggest an increased requirement for ATP. Interestingly, lactate production decreased in treated cells, indicating a decreased utilization of glucose and, possibly, a compensatory effect due to increased mitochondrial respiration.
• O2k-Network Lab: BR_Rio de Janeiro_Da Poian AT
Labels: MiParea: Respiration, Pharmacology;toxicology Pathology: Cancer Stress:Cell death Organism: Human Tissue;cell: Liver Preparation: Intact cells
Regulation: Aerobic glycolysis, ATP production Coupling state: LEAK, ROUTINE, ET
HRR: Oxygraph-2k Event: C3, Oral MiP2014, Flavonoids
1-Inst Nutrition; 2-Inst Chem Lab Bioquímica Nutritional Alimentos; 3-Inst Medical Bioch; FedUniv Rio de Janeiro, Brazil. – [email protected]
The increase in respiration, related to phosphorylation in treated HepG2 cells, seems to be an early sign of bioenergetic alterations due to polyphenol compounds in grape pomace extract, which are possibly involved in cytotoxicity observed at longer incubations. The mechanisms underlying these effects are to be determined and might be related to decreased glucose utilization by HepG2 cells. Therefore, we reasoned that pomace produced from white wine vinification from Brazilian winemaking presents important pharmacological properties possibly related to potential anticancer effects on HepG2 cells.
Supported by: CAPES, CNPq and FAPERJ (Brazil).
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