Donato Di Venere

Browning phenomena in stored artichoke (Cynara scolymus L.) heads: enzymic or chemical reactions?.

Abstract Data concerning phenolics and polyphenol oxidase in artichoke heads are presented. Biochemical changes at different physiological stages and after mechanical damage or chilling injuries, together with the characteristics of iron/phenolic complexes and the subcellular localization of polyphenol oxidase, are considered. Results lead to a proposed mechanism of browning phenomena in cold-stored, non-mechanically damaged, artichoke heads.

Antioxidative and Apoptotic Properties of Polyphenolic Extracts from Edible Part of Artichoke (Cynara scolymus L.) on Cultured Rat Hepatocytes and on Human Hepatoma Cells

Cultured rat hepatocytes and human hepatoma HepG2 cells were used to evaluate the hepatoprotective properties of polyphenolic extracts from the edible part of artichoke (AE). The hepatocytes were exposed to H2O2generated in situ by glucose oxidase and were treated with either AE, or pure chlorogenic acid (ChA) or with the well known antioxidant, N, N′-diphenyl-p-phenilenediamine (DPPD). Addition of glucose oxidase to the culture medium caused depletion of intracellular glutathione (GSH) content, accumulation of malondialdehyde (MDA) in the cultures, as a lipid peroxidation indicator, and cell death. These results demonstrated that AE protected cells from the oxidative stress caused by glucose oxidase, comparable to DPPD. Furthermore, AE, as well as ChA, prevented the loss of total GSH and the accumulation of MDA. Treatment of HepG2 cells for 24 h with AE reduced cell viability in a dose-dependent manner, however, ChA had no prominent effects on the cell death rate. Similarly, AE rather than ChA induced apoptosis, measured by flow cytometric analysis of annexin and by activation of caspase-3, in HepG2 cells. Our findings indicate that AE had a marked antioxidative potential that protects hepatocytes from an oxidative stress. Furthermore, AE reduced cell viability and had an apoptotic activity on a human liver cancer cell line.

Artichoke polyphenols induce apoptosis and decrease the invasive potential of the human breast cancer cell line MDA‐MB231

The human breast cancer cell line, estrogen receptor negative, MDA‐MB231, was used to evaluate the antitumor effect of polyphenolic extracts from the edible part of artichokes (AEs). Treatment of cancer cells reduced cell viability and inhibited cell growth in a dose‐dependent manner. Importantly, AEs did not have any effect on normal breast epithelial cell line, MCF10A. Chlorogenic acid (ChA), the most representative component of the polyphenolic fraction of artichoke, had no prominent effects on the cell death rate of MDA‐MB231 cells. The addition of AEs to the cells, rather than ChA, triggered apoptosis via a mitochondrial and a death‐receptor pathway, as shown by the activation of caspase‐9 and caspase‐8, respectively. Furthermore, an increase of the Bax:Bcl2 ratio and up‐regulation of cyclin‐dependent kinase inhibitor, p21WAF1, crucial apoptotic players, were documented. According to our data on activation of caspase‐9, a loss of mitochondrial transmembrane potential (Ψm) was shown. Cell motility and invasion capabilities were remarkably inhibited by AEs‐treatment in highly invasive MDA‐MB231 cells. In addition, a significant decrease of proteolytic activity of metalloproteinase‐2 protein (MMP‐2), involved in degrading components of the extracellular matrix, was detected. Our findings indicate that AEs reduced cell viability, inhibited cell growth, triggered apoptotic mechanisms, and showed inhibitory properties against the invasive behavior of MDA‐MB231 cancer cell line. Altogether, these data indicate the potential chemopreventive activity of artichoke polyphenolic extracts. J. Cell. Physiol. 227: 3301–3309, 2012.

Long Term Exposure to Polyphenols of Artichoke (Cynara scolymus L.) Exerts Induction of Senescence Driven Growth Arrest in the MDA-MB231 Human Breast Cancer Cell Line

Polyphenolic extracts from the edible part of artichoke (Cynara scolymus L.) have been shown to be potential chemopreventive and anticancer dietary compounds. High doses of polyphenolic extracts (AEs) induce apoptosis and decrease the invasive potential of the human breast cancer cell line, MDA-MB231. However, the molecular mechanism underlying AEs antiproliferative effects is not completely understood. We demonstrate that chronic and low doses of AEs treatment at sublethal concentrations suppress human breast cancer cell growth via a caspases-independent mechanism. Furthermore, AEs exposure induces a significant increase of senescence-associated β-galactosidase (SA-β-gal) staining and upregulation of tumour suppressor genes, p16INK4a and p21Cip1/Waf1 in MDA-MB231 cells. AEs treatment leads to epigenetic alterations in cancer cells, modulating DNA hypomethylation and lysine acetylation levels in total proteins. Cell growth arrest correlates with increased reactive oxygen species (ROS) production in AEs treated breast cancer cells. Inhibition of ROS generation by N-acetylcysteine (NAC) attenuates the antiproliferative effect. These findings demonstrate that chronic AEs treatment inhibits breast cancer cell growth via the induction of premature senescence through epigenetic and ROS-mediated mechanisms. Our results suggest that artichoke polyphenols could be a promising dietary tool either in cancer chemoprevention or/and in cancer treatment as a nonconventional, adjuvant therapy.

Purification, biochemical characterization and cloning of a new cationic peroxidase isoenzyme from artichoke.

A cationic soluble peroxidase isoenzyme (CysPrx) has been purified and characterized from artichoke (Cynara cardunculus subsp. scolymus (L.) Hegi) leaves by combination of aqueous two phase extraction, ion exchange chromatography, and gel filtration. The purification fold was 149 and the activity recovery 5.5%. CysPrx was stable from 5 to 45 °C with a pH optimum around 5.5; the pI was 8.3 and the MW of 37.7 ± 1.5 kDa. MALDI-TOF MS analysis provided partial peptide sequences and resolved CysPrx isoenzyme into two putative isoforms. The presence of these isoforms was confirmed by the isolation of full-length cDNA encoding CysPrx that generate two slightly different sequences coding for two putative CysPrx: CysPrx1 and CysPrx2. The obtained MS peptides showed a 35% coverage with 100% identity with the two CysPrx deduced protein sequences. A molecular modeling analysis was carried out to predict in silico the protein structure and compare it with other plant Prx structures. Considering that CysPrx is quite stable, the study carried out in this paper will offer new insights for the production of the recombinant protein for utilization of CysPrx as an alternative Prx for food technology, biomedical analysis and bioremediation.

Antimicrobial Potential of Wild Edible Herbaceous Species

Natural products, either as pure compounds or as standardized extracts, provide unlimited opportunities to control microbial growth, owing to their chemical composition and diversity. Many herb and spice extracts possess antimicrobial activity against a range of bacteria, yeast, and moulds. Because of their antimicrobial properties, they could be very useful, either as food preservatives or as natural biopesticides. In particular, extracts from wild edible herbaceous species are rich in phenolic compounds. A wide variety of phenolics derived from herbs and spices possesses potent biological activities contributing to their effect against spoilage microorganisms. Many studies have pointed out the antimicrobial properties of certain classes of phenolic compounds, such as hydroxybenzoic, coumaric, and caffeic acid derivatives, flavonoids and coumarins, catechin, epicatechin, proanthocyanidins, and tannins. Moreover, some authors studied the relationship between molecular structure and antimicrobial activity of some phenolic compounds. The antimicrobial activity of polyphenols is principally due to inhibition of some important cellular functions (nucleic acid synthesis, cytoplasmatic membrane functionality, etc.) and to disruption of membrane integrity with consequent leakage of cellular contents.