Artichoke phenolics

Artichoke phenolics are good hepatoprotective agents against hepatotoxic substances [41]. 

The phenolic and related components present in stems and leaves of sunflower, Helianthus annuus L., and Jerusalem artichoke, Helianthus tuberosus L., were extracted sequentially and their activity as phytotoxic agents evaluated. Total acids and neutral compounds were isolated by extraction with methanol, acetone, and water. The free acids and neutral compounds were partitioned into the organic phase, whereas the acids, present as esters and aglycones, were liberated by subsequent alkaline hydrolysis of the aqueous phase. 

The major components have been identified tentatively as phenolic and fatty acids. At this time, seven phenolics have been identified in only four of the fractions. These are shown in Table III. A measure of the magnitude of the confidence level (cc) with a spectrum of standards is given. The first three entries are from the sunflower the last, from the Jerusalem artichoke. In all fractions isolated, both from the sunflower and the Jerusalem artichoke, a homologous series of fatty acids ranging from Cjo to Ci8 have been identified also by GC-MS. Even-chain, Cj6 to Cjs saturated and Cxs mono- and di-unsaturated, predominated. This is not surprising, since fatty acids are major constituents of plant... 

This method is also used to measure ex vivo low-density lipoprotein (LDL) oxidation. LDL is isolated fresh from blood samples, oxidation is initiated by Cu(II) or AAPH, and peroxidation of the lipid components is followed at 234 nm for conjugated dienes (Prior and others 2005). In this specific case the procedure can be used to assess the interaction of certain antioxidant compounds, such as vitamin E, carotenoids, and retinyl stearate, exerting a protective effect on LDL (Esterbauer and others 1989). Hence, Viana and others (1996) studied the in vitro antioxidative effects of an extract rich in flavonoids. Similarly, Pearson and others (1999) assessed the ability of compounds in apple juices and extracts from fresh apple to protect LDL. Wang and Goodman (1999) examined the antioxidant properties of 26 common dietary phenolic agents in an ex vivo LDL oxidation model. Salleh and others (2002) screened 12 edible plant extracts rich in polyphenols for their potential to inhibit oxidation of LDL in vitro. Gongalves and others (2004) observed that phenolic extracts from cherry inhibited LDL oxidation in vitro in a dose-dependent manner. Yildirin and others (2007) demonstrated that grapes inhibited oxidation of human LDL at a level comparable to wine. Coinu and others (2007) studied the antioxidant properties of extracts obtained from artichoke leaves and outer bracts measured on human oxidized LDL. Milde and others (2007) showed that many phenolics, as well as carotenoids, enhance resistance to LDL oxidation. 

Rechner, A.R., Pannala, A.S., and Rice-Evans, C.A., Caffeic acid derivatives in artichoke extract are metabolised to phenolic acids in vivo. Free Radical Res., 35, 195, 2001. 

Wang M, Simon JE, Aviles IF, Hirshberg J, Olmedilla B, Sandmann G, Southon S, Stahl W. 2003b. Analysis of antioxidative phenolic compounds in artichoke (Cynara scolymus L.). J Agric Food Chem 51 601-608. 

Bastin, M., Effect of wounding on the synthesis of phenols, phenoloxidase, and peroxidase in the tuber tissue of Jerusalem artichoke, Can. J. Biochem., 46, 1339-1343, 1968. 

Subsequent tests with velvetleaf, Kodkia, Jerusalem artichoke, and cocklebur showed that their allelopathic action altered water balance (55,94,95). Growth reductions in sorghum and soybean seedlings in nutrient solution amended with extracts from these weeds correlated with high diffusive resistances and low leaf water potentials. Stomatal closure occurred in plants treated with the more concentrated extracts. Depressions in water potential were due to a reduction in both turgor pressure and osmotic potential. A lower relative water content was also found in velvetleaf-treated plants. These impacts on water balance were not from osmotic factors. Allelochemicals from these weeds have not been thoroughly ascertained, but the present evidence shows that some contain phenolic inhibitors. Lodhi (96) reported that Kodkia contains ferulic acid, chlorogenic acid, caffeic acid, myricetin, and quercetin. As noted earlier, an effect on plant-water relationships is one mechanism associated with the action of ferulic acid. 

Cynara scolymus (artichoke) contains a variety of flavo-noids, phenols, and sesquiterpenoids, including cynarapi-crin, cynaratriol, cynarolide, and isoamberboin. It has been used to lower serum cholesterol, with httle evidence of efficacy (16). 

F. Sanchez-Rabaneda, O. Jauregui, R.M. Lamuela-Raventbs, J. Bastida, F. Viladomat, C. Codina, Identification of phenolic compounds in artichoke waste by LC-MS-MS, J. Chromatogr. A, 1008 (2003) 57. 

Review of Ascorbic Acid Mechanisms of Action. Ascorbic acid and AP have antioxidant activity in fats, oils, vitamin A, and carotenoids. In these systems AP is a better antioxidant than are the phenolic antioxidants BHT and BHA, both from these data and others (29,35). Ascorbic acid protects against oxidation of flavor compounds in wine, beer, fruits, artichokes, and cauliflower (29) presumably by oxygen scavenging. The well-known formation of nitric oxide from nitrites by ascorbic acid is used not only for inhibition of nitrosamine fortnation, but also to promote... 

Artichoke heads Cynara scolymus) are a good source of antioxidant phenolic compounds since they contain large amounts of caffeic acid derivatives and flavonoids. The flavonoids include apigenin and luteolin glycosides. In bracts and receptacles, apigenin 5-glucoside and 7-... 

Caffeic acid derivatives are the main phenolics found in artichoke, and a wide range of caffeoyl quinic derivatives are biosynthesised (Table 2). 

It has also been reported that exposure of artichoke heads to low, non-freezing temperature storage leads to increased levels of caffeoylquinic derivatives, particularly chlorogenic acid, caused by the cold-induced stimulation of PAL activity [39]. Both PAL activity and the phenolic content of artichoke heads show a peak during the early stage of cold storage, followed by a gradual return to very low levels [39]. 

The cold storage of fruit and vegetables can alter phenolic metabolite composition. When the changes in caffeic acid derivatives in artichoke... 

The principal food products providing phenolic antioxidants to the diet of European countries are onions, apples, citms fruits, tea, grapes and red wine. However, many other fruits and vegetables rich in phenolic antioxidants could be also included in this list. For example, berry fruits, cherry tomatoes, some red lettuce cultivars, artichokes, green asparagus, spinach, olives, broccoli and eggplant, are very rieh in antioxidant phenolics. 

Cynarin (1.5 dicaffeoyl-D-quinic acid), the major active principle of globe artichoke, Cynara scolymus (Asteraceae), is formed from the bonding of two phenolic acids, caffeic and quinic acids. Cynarin is a proven hepatoprotective and hypocholesterolaemia agent. 

Leaves of mycorrhizal artichoke grown in microcosm showed enhanced phenolic complement, depending on the inoculum composition. TPC and ARP were significantly higher (50 % and 33 %, respectively) in plants inoculated with the Glomus mixture, compared with control plants (Fig. 85.1). In the field, inoculated plants showed higher phenolics content in the edible parts (flower heads), compared with controls, with the highest values detected in plants inoculated with the... 

Curadi M, Fficciarelli P, Lorenzi R, Graifenberg A, Ceccarelli N (2005) Antioxidant activity and phenolic compounds in the edible parts of early and late Italian artichoke (Cynara scolymus) varieties. Ital J Food Sci 17 33-43... 

Ceccarelli N, Curadi M, Martelloni L, Sbrana C, Picciarelli P, Giovannetti M (2010) Mycorrhizal colonization impacts on phenolic content and antioxidant properties of artichoke leaves and flower heads two years after field transplant. Plant Soil 335 311-323... 

---