The amino acid composition of the leaves (g/kg) was determined as aspartic acid 5.21 g, threonine 6.14 g, serine 5.96 g, glutamic acid 9.51 g, glycine 4.17 g, alanine 5.50 g, valine 6.57 g, methionine 10.15 g, isoleucine 4.88 g, leucine 7.71 g, leucine 7.71 g, tyrosine 3.44 g, phenylalanine 6.32 g, histidine 3.19 g, lysine 7.18 g, arginine 4.99 g and total amino acids 80.84 g (Orlovskaya et al. 2007b). They also determined the mineral composition of the leaves (mg %), Na (2070), K (690), Ca (690), Mg (207) and P (207), and 16 were microelements Cu (0.345), Zn (0.414), Ag (0.0007), Mo (0.035), Li (0.207), Pb (0.069), Co (0.007), Ni (0.021), Ti (1.380), V (0.021), Cr (0.041), Fe (20.7), B (2.07), Al (13.8), Si (34.5) and Mn (2.07). The leaves and ethanol leaf extract also contained the following flavonoids (% of total phenolic compounds) (Orlovskaya et al. 2007b): luteolin-7-glucoside 35.19 %, 6.03 %; rutin 0.08 %, 6.33 %; dihydroquercetin 0.91 %, 0; vitexin 5.31 %, 0; orientin 0.46 %, 0; hyperoside 0.01 %, 7.47 %; apigenin 0, 0.89 %; hesperidin 2.33 %, 0; robinin 0, 1.27 %, respectively. The leaves and ethanol leaf extract also contained the following (% of total phenolic compounds): coumarin–4 hydroxycoumarin 0.88 %, 0; phenolic acids–gallic acid 0, 23.48 %; cichoric acid 0, 5.86 %; hydroxycinnamic acids–chlorogenic acid 0.10 %, 23.79 %; neochlorogenic acid 6.88 %, 2.38 %; caffeic acid 38.55 %, 6.30 %; ferulic acid 0, 5.54 %; phenolic glycoside–arbutin 9.31 %, 0, respectively.

From artichoke leaves the following compounds were isolated: flavonoids (apigenin, luteolin, luteolin-4′-glucoside, cynaroside, scolimoside, cosmoside, quercetin, rutin, isorhamnetin and luteolin-7-gentiobioside) (El-Negoumy et al. 1987; Hinou et al. 1989) and phenolic acids (cynarin, chlorogenic acid, caffeic acid, neochlorogenic acid, quinic acid, 4-caffeylquinic acid, 1-caffeylquinic acid (Dranik 1966), and isochlorogenic acid), along with the more uncommon scopoletin, hesperitin, hesperidoside, esculetin-6-O-β-glucoside and maritimein (Hinou et al. 1989). Glycosyl flavonoids (cynaroside and scolymoside) were found to be the major constituents, along with cynaropicrin, a sesquiterpene lactone, and the triterpene lupeol and chlorogenic acid in artichoke leaves (Noldin et al. 2003). Cynarin, the main compound described for artichoke, was detected in very low concentration. From the dried leaf powder, the following flavonoids were isolated: luteolin-7-O-α–l-rhamnosyl(1 → 6)-β-d-glucopyranoside, luteolin-7-O-β-d-glucopyranoside (cynaroside), apigenin-7-O-α-l-rhamnosyl(1 → 6)-β-d-glucopyranoside (apigenin-7-rutinoside) and apigenin-7-O-β-d-glucopyranoside (Zhu and Zhang 2004). Eight phenolic compounds were isolated from the n-butanol-soluble fraction of artichoke leaf extract: four caffeoylquinic acid derivatives, chlorogenic acid (1), cynarin (2), 3,5-di-O-caffeoylquinic acid (3) and 4,5-di-O-caffeoylquinic acid (4), and the four flavonoids, luteolin-7-rutinoside (5), cynaroside (6), apigenin-7-rutinoside (7) and apigenin-7-O-β-d-glucopyranoside (8) (Zhu et al. 2004). The main polyphenols detected in different tissues and developmental stages of 6 artichoke varietal types were chlorogenic acid, cynarin, luteolin 7-O-rutinoside and luteolin 7-O-glucoside (Negro et al. 2012). ‘Violet de Provence’ artichoke proved to retain the highest content of total phenols. Single polyphenols accumulated preferentially in specific parts of capitula. In leaves, most polyphenols were detected in the productive stage of the plant. Thirty-nine chlorogenic acids were detected in the leaves of 12 species of the Asteraceae family including Cynara scolymus (Jaiswal et al. 2011). Both chlorogenic acids based on trans– and cis-cinnamic acid substituents were identified. Assignment to the level of individual regioisomers was possible for seven caffeoylquinic acids (1–7), 11 dicaffeoylquinic acids (17–27), six feruloylquinic acids (9–14), two p-coumaroylquinic acids (15–16), two caffeoyl-feruloylquinic acids (28 and 29), four caffeoyl-p-coumaroylquinic acids (30–33), three dicaffeoyl-succinoylquinic acids (34–36), two dicaffeoyl-methoxyoxaloylquinic acids (37 and 38) and one tricaffeoylquinic acid (39). In addition, one caffeoylshikimic acid (40), one caffeoyltartaric acid (41), three dicaffeoyltartaric acids (42–44) and three caffeoyl-feruloyltartaric acids (45–47) were detected.

The carbohydrates of the leaves comprised alcohol-soluble sugars 21.34 % with traces of glucose; cold water-soluble polysaccharides 5.1 % made up of rhamnose: xylose: arabinose: mannose: glucose: galactose in the ratio of 1.0:1.4:tr: 24.6:7.3; hot water-soluble polysaccharides 0.78 % made up of rhamnose: xylose: arabinose: mannose: glucose: galactose in the ratio of 1.62:3.2:2.2:1.0:tr:2.4; pectinic substances 2.4 % made up of rhamnose: xylose: arabinose: mannose: glucose: galactose in the ratio of 4.3:1.0:2.5:0:0:1.4; hemicelluloses 2.63 % made up of rhamnose: xylose: arabinose: mannose: glucose: galactose in the ratio of tr:8.76:4.6:1.4:1.0:4.8 (Orlovskaya et al. 2007a).

In the leaves of cultivated and wild Cynara cardunculus, the flavones were the major compounds, whereas in the floral stem, caffeoylquinic acids were the most abundant (Pandino et al. 2011a). In particular, ‘Sylvestris Creta’ (var. sylvestris, wild cardoon) and ‘Violetto di Sicilia’ (var. scolymus, globe artichoke) showed the highest content of caffeoylquinic acid ∼ 95 % of the total measured polyphenols. The major compounds present in the leaf were luteolin derivatives in globe artichoke and apigenin derivatives in wild and cultivated cardoon.

From the cauline leaves of C. scolymus, cyanarin, a substance with stimulatory action on biliary secretion and cholesterinic metabolism, was isolated (Panizzi and Scarpati 1954). From artichoke leaves the following flavonoids were isolated: luteolin 7-β-glycoside and luteolin 7-β-rutinoside (Dranik et al. 1964); a flavonoid glycoside, cynarotriside, having the structure luteolin 7-[O-β-d-glucopyranosyl-(6 → 1)-O-β-l-rhamnopyranoside]-4′-O-β-d-glucopyranoside (Dranik and Chernobai 1966); luteolin, cynaroside (luteolin-7-glucoside) and scolymoside (luteolin-7-β-rutinoside) (Constantinescu et al. 1967); and apigenin, luteolin, apigenin-7-O-glucoside, cynaroside (luteolin-7-glucoside) and scolymoside (luteolin-7-β-rutinoside) (Hammouda et al. 1993). From the leaves the following phenolic acids and flavonoids were detected: chlorogenic acid, 1,3-di-O-caffeylquinic acid, cryptochlorogenic acid, neochlorogenic acid and 3,5-di-O-caffeylquinic acid; flavonoids: luteolin-4′-O-glucoside, luteolin 7-O-glucoside and luteolin 7-O-rhamnoglucoside (Bombardelli et al. 1977). The following organic acids were detected in artichoke: glyceric, malic, citric, glycolic, lactic and succinic acids (Bogaert et al. 1972). Lattanzio and Morone (1979) found that chlorogenic acid content declined from 4.4 to 1.6 % dry matter (dm). As the plant developed to the stage of differentiation of the capitulum and remained stable, a similar tendency was detected for cynaroside (0.4–0.16 % dm) and scolymoside (0.7–0.15 % dm), while the behaviour of cynarin was just the opposite, increasing gradually as the plant grew (0.01–0.05 % dm).

Hydroxymethyl acrylic acid was isolated from artichoke leaves (Bogaert et al. 1974). Two phenolic glucoside gallates, 2-methoxy-4-(2, 3-dihydroxy-propionyl)-phenyl-1-O-(6′-O-galloyl)-β-d-glucopyranoside and 4-hydroxy-3-methoxy-phenyl-1-O-(6′-O-galloyl)-β-d-glucopyranoside, were isolated from the leaves (Liu et al. 2009b). A sesquiterpenic lactone cynarolide was isolated from artichoke leaves (Drozdz 1968). Two guaiane-type sesquiterpene lactones, cynarinins A and B, together with seven known compounds, cynarascoloside C, cynaropicrin, aguerin B, grosheimin, aguerin A dehydrocynaropicrin and cynaratriol, were isolated from aerial part of Cynara scolymus (Li et al. 2005). Guaianolides, cynaropicrin and grosheimin, isolated from artichoke leaves were found to be associated with the leaf bitterness (Cravotto et al. 2005). Bioconversion of the chemicals generated 15 sesquiterpene lactone derivatives which were subjected to a taste sensory panel. Bitterness was markedly abated by either the loss of exomethylenes or the opening of the lactone ring. The bitterness of sesquiterpene lactones cynaropicrin and grosheimin derivatives was found not to be directly related to molecular polarity (Scotti et al. 2007). Cyanaropicrin, the bitter principle was found only in the green aerial parts in the stem sprouts, leaf stalks and green buds (up to 0.6 %) and in leaf lamina 0.5–4.5 % (in one case to 6.5 %) (Schneider and Thiele 2009). Young leaves contained more bitter principle than old ones. The top of the leaves showed 80 % more bitter substance than the leaf base. No bitter substance was found in the roots, completely developed blossoms and fruits. Three new guaianolides, 11-H-13-ethylsulfonylgrosheimin (grosulfeimin); 8-deoxy-11,13-dihydroxygrosheimin; and 8-deoxy-11-hydroxy-13-chlorogrosheimin and 8-epigrosheimin were isolated from the leaves (Barbetti et al. 1993). Other guaianolides, cynaropicrin, 3-deydrocynaropicrin, grosheimin, cynarolide and cynaratriol, had been isolated from artichoke (Barbetti et al. 1992; Jouany et al. 1975; Bernhard et al. 1979; Bernhard 1982). Besides cynaratriol, its derivatives 3,11,13-triacetylcynaratriol and 3,13-dibenzoyl-cynaratriol were also identified from the leaves (Bernhard 1982). A guaiane-type sesquiterpene lactone, 3β, 8α, 11β, 13-tetrahydroxy-10(14)-guaien-1α, 4β, 5α, 6βH-6α, 12-olide, and a known sesquiterpene lactone, cynarinin A, were isolated from the leaves (Liu et al. 2009a).

Apigenin 7-O-glucoside, cynarin, narirutin, gallic acid and caffeic acid were found as the main flavonoids and phenolic constituents in all parts of artichoke (flowers, leaves, roots, stems, stumps) (Thi and Park 2008). Water extraction gave higher value of total phenolic compounds and flavonoids than that by methanol or methanol:water extractions. Artichoke stem was found to be rich in non-starch polysaccharide (NSP) (∽38 g NSP/kg) and was similar to the receptacle (∽34 g NSP/kg), but bracts were heavily lignified; the stem could prove useful as sources of pectic polysaccharide-rich supplements (Femenia et al. 1998).

In commercially available artichoke leaf extract, the following compounds were identified: 8-deoxy-11-hydroxy-13-chlorogrosheimin, cryptochlorogenic acid, chlorogenic acid, neochlorogenic acid, cynarin, cynaratriol (tentatively), grosheimin, 8-deoxy-11,13-dihydroxygrosheimin, luteolin-7-O-rutinoside, luteolin-7-O-glucoside and cynaropicrin (Fritsche et al. 2002) The concentration of the compounds, namely, chlorogenic acid, cynarin and luteolin-7-O-glucoside, was in the range of 0.35–18.34, n.d.−1.02, 0.04–10.65 mg/g, respectively. Cynar opicrin, the predominant bitter artichoke leaf principle, was present at concentrations between <0.06 and 22.6 mg/g.

Ribulose-1,5-diphosphate carboxylase in artichoke leaves was separated, purified and characterized (Pacoda et al. 1985; Cardinali et al. 1986; Miceli et al. 1986). Cardinali et al. (2012) reported that the cationic peroxidase isoenzyme (CysPrx) isolated from artichoke leaves possessed some interesting properties, suggesting that CysPrx could be a considered as a potential candidate for industrial peroxidase application. In addition, from the CysPrx sequence, two full-length cDNAs, CysPrx1 and CysPrx2, differing for three amino acids, were isolated.

Artichoke seeds were found to have crude protein 21.6 %, crude fibre 17.1 %, crude oil 24.05 % and ash 3.8 % (Foti et al. 1999). Artichoke seed oil was found to be an unsaturated semi-drying oil, with a high saponification value and acidic. It thus would require purification before used as edible oil. The fatty acid composition showed a high content of polyunsaturated acids (oleic acid 26.73 %, linoleic acid 58.89 %, linolenic acid 0.25 %) and to contain cholesterol (0.2 %), campesterol (12.8 %), Δ⁵-stigmasterol (16.2 %), β-sitosterol (45.6 %), Δ⁷-stigmasterol and Δ7-avenasterol ( 18.4-6.6 %). The oil had a yield of 20.5 %, free acidity (oleic acid) 11.3 %, acid value 22.4 mg/g, iodine value 108.4 g/100 g, unsaponifiable matter 0.9 %, mean molecular mass 306.2 and refractive index 1.4682 (25 °C) (Miceli and De Leo 1996).

Artichoke seed oil was found to be rich in oleic and linoleic acids (Hassanein et al. 2011). The fatty acid profile of artichoke oil comprised 14:0 (0.1 %), 16:0 (11.3 %), 16:1 (0.1 %), 18:0 (3.2 %), 18:1 n−9 (30.2 %), 18:1 n−7 (0.70 %), 18:2 (53.5 %), 20:0 (0.40 %), 20:1 (0.20 %) 24:0 (0.30 %). Among the triacylglycerols (TAGs), LLL, LLO LLP LOO and LOP were the major components in artichoke seed oil (L = linoleic, O = oleic, P = palmitic). Artichoke seed oil had a whole sterol content (as silyl derivatives) of 1.2 % of the total lipids and had high content of 5-stigmasterol (22.7 %), β-sitosterol (33.1 %) and 7-stigmasterol (25.7 %) and also possessed campesterol (9.5 %), avenasterol (6.4 %), spinasterol (2.2 %) and isofucosterol (0.4 %). The total content of free sterol (FS) and acylated sterol (AS) as 9-anthroylnitrile derivatives isolated from the oil was 390 mg/100 g oil (0.39 % of total lipid) comprising 280 mg/100 mg of free sterol and 110 mg/100 g acylated sterol. Both FS and AS showed the presence of β-sitosterol, isofucosterol,7-stigmasterol, avenasterol, spinasterol and β-stigmasterol/campesterol (inseparable pair). Artichoke oil also had high content (1,000 ppm) of free sterylglycerols (FSG) (687 ppm) and acylated sterylglycerols (ASG) (313 ppm) as 1-anthroylnitrile derivatives. It was found that β-sitosterol was the major component in both FSG and ASG fractions, followed by campe-/stigma-SG, isofuco-SG, 7-stigma-SG and spina-SG. Artichoke oil was found to have 311 ppm total tocopherols comprising 96.5 % α-tocopherol, 2.5 % γ-tocohpherol and 1.0 % δ-tocopherol.

Seeds and leaves of the artichoke had been reported to contain different constituents such as caffeoylquinic acid derivatives, mono- and di-caffeoylquinic acids, bitter sesquiterpene such as cynaratriol and cynaropicrin and flavonoids glycosides like apigenin, luteolin, cynaroside, scolymoside, quercetin and others (Georgieva et al. 2011). The content of total phenolics, chlorogenic acid and 1.5 dicaffeoyl-quinic-acid (cynarin) in germinating seeds varied considerably between different genetic lines and were higher than that reported in artichoke leaves (Ben-Hod et al. 1992). The authors concluded that compared to the traditional extraction from leaves, germinating seeds offer a richer and more dependable source for cynarin supply.

According to Maccarone et al. (1999), Cynara species grain oil especially cardoon had superior alimentary quality with a high content of oleic and linoleic acids in a balanced ratio, a good amount of α-tocopherol and low amounts of free acids, peroxides, saturated and linolenic acids. Triacylglycerols were the dominant constituents together with very little amounts of phospholipids and glycolipids. Curt et al. (2002) reported a range of 20–31.6 % seed oil content for C. cardunculus. Cynara seed oil profile was characterized in terms of major fatty acids as 10.7 % palmitic, 3.7 % stearic, 25.0 % oleic and 59.7 % linoleic.

At harvest the total biomass and root production, averaged for all Cynara cardunculus genotypes, were 20.4 and 9.8 t DM/ha; they were influenced by genotype (Raccuia and Melilli 2004). On average for all of the genotypes, the roots showed a total sugar content of 367 g DM/kg, with a cv. of 17.1 %; the main compound was inulin (85.0 % of total sugars). The wild cardoon ‘SR1’ showed the highest total sugar content (470 g/kg DM). On average for all of the genotypes, the total sugar and inulin yields were 3.6 and 3.0 t/ha, respectively. Studies showed that globe artichoke (Cynara cardunculus subsp. scolymus) crop for heads utilization, at the end of their harvest, gave a remaining above-ground biomass production, on average of all genotypes, of 10.3 t/ha DM with a range of 5.7 to 15.7 t/ha of DM, partitioned between leaves (53.4 %) and stalks (47.6 %) (Raccuia et al. 2004b). The root yield resulted on average of all genotypes 5.7 t/ha of DM. The total extracted sugars from roots resulted on average of all genotypes, 249 g/kg of DM, where inulin accounted for 89.4 % of total sugars. Root total sugars yield resulted on average of all genotypes 1.41 t/ha.

Artichoke by-products such as leaves, external bracts and stems that are produced by the artichoke-processing industry represent a huge amount of discarded material (about 80–85 % of the total biomass of the plant), which could be used as a source of inulin but also of phenolics especially chlorogenic acid and 1,5-O-dicaffeoylquinic, 3,5-O-dicaffeoylquinic and 3,4-O-dicaffeoylquinic acids and should be considered as a raw material for the production of natural nontoxic food additives and neutraceuticals (Lattanzio et al. 2005, 2009; Ceccarelli et al. 2010).

In Spain, a leading artichoke producer in Europe, the residues proceeding from artichoke industry can form up to 60 % of the harvested plant material. Forty-five phenolic compounds were identified in artichoke waste (Sánchez-Rabaneda et al. 2003): gallic acid; caffeoylquinic acid 1,2, 3; dicaffeoylquinic acid 1, 2,3, 4,5, 6, 7; protocatechuic acid; esculin; chlorogenic acid; p-coumaric acid-O-glucoside isomers 1 and 2; eriodictyol-glucuronide; rutin (quercetin-3-O-rutinoside); dicaffeoylquinic acid derivative; hyperoside (quercetin-3-O-galactoside); luteolin-7-O-rutinoside; cynaroside (luteolin-7-O-glucoside); isoquercitrin (quercetin-3-O-glucoside); luteolin-7-O-glucuronide; luteolin-7-O-galactoside; naringenin-O-hexoside; avicularin (quercetin-3-O-arabinoside); isorhoifolin (apigenin-7-O-rutinoside); quercetin-O-pentoside; quercitrin (quercetin-3-O-rhamnoside); luteolin-7-O-neohesperidoside; apigenin-O-glucoside; prunin (naringenin-7-O-glucoside); naringin (naringenin-7-O-neohesperidoside); scolimoside (luteolin-7-O-rhamnoside); apigenin-7-O-glucuronide; quercetin-O-pentoside; phloridzin (phloretin-2-O-glucoside); feruloylquinic acid-O-glucoside; luteolin; quercetin; naringenin; and apigenin chrysoeriol. Caffeoylquinic and dicaffeoylquinic acids were the main compounds in the waste residue. A high molecular weight inulin was fabricated from artichoke agroindustrial wastes using environmentally benign aqueous extraction procedures (Lopez-Molina et al. 2005). The main constituent monosaccharide in artichoke inulin was fructose, and its degradation by inulinase indicated that it contained the expected beta-2,1-fructan bonds. Its FT-IR spectrum was identical to that of chicory inulin. The data indicated that artichoke inulin will be suitable for use in a wide range of food applications.

In various molecular, cellular and in-vivo test studies, artichoke (Cynara scolymus) leaf extracts showed antioxidative, hepatoprotective, antimicrobial, antiviral, anticancer, urinative, choleretic and anticholestatic effects as well as inhibitory actions on cholesterol biosynthesis and LDL oxidation (Kraft 1997; Lattanzio et al. 2009). The antidyspeptic actions ware mainly based on increased choleresis. Regarding clinical data, lipid-lowering, antiemetic, spasmolytic, choleretic and carminative effects had been described, along with good tolerance and a low incidence of side effects. The results of several clinical investigations showed the efficacy and safety of artichoke extracts (Cynara scolymus) in the treatment of hepato-biliary dysfunction and digestive complaints, such as sensation of fullness, loss of appetite, nausea and abdominal pain (Wegener and Fintelmann 1999). Earlier findings on a lipid-lowering and hepatoprotective effects were confirmed, and flavonoids and caffeoylquinic acids were reported to be mainly responsible for the observed actions. These and other pharmacological properties of artichoke are elaborated below.

In ABTS and DPPH tests, turmeric extract was found to be the most active, followed by artichoke and dandelion (Menghini et al. 2010). A luteolin-rich artichoke extract retarded low-density lipoprotein (LDL) oxidation in a dose-dependent manner as measured by a prolongation of the lag phase to conjugated diene formation, a decrease in the rate of propagation, and a sparing of endogenous LDL α-tocopherol during oxidation (Brown and Rice-Evans 1998). The pure aglycone, luteolin (1 μM), demonstrated an efficacy similar to that of 20 μg/ml artichoke extract in inhibiting lipid peroxidation. Luteolin-7-O-glucoside, one of the glycosylated forms in the diet, also demonstrated a dose-dependent reduction of LDL oxidation that was less effective than that of luteolin. Studies of the copper-chelating properties of luteolin-7-O-glucoside and luteolin suggested a potential role for chelation in the antioxidative effects of artichoke extract. The results demonstrated that the antioxidant activity of the artichoke extract was related in part to its constituent flavonoids which acted as hydrogen donors and metal ion chelators, and the effectiveness was further influenced by their partitioning between aqueous and lipophilic phases.

The crude flower head and leaf extracts and different phenolic fractions tested showed good antioxidant activity in the control of the oxidative damage caused by peroxyl radicals (the β-carotene/linoleate assay) (Lattanzio et al. 2005). All phenolics exhibited good antioxidant activity against peroxyl and hydroxyl radicals when assessed using the β-carotene/linoleate assay and the metmyoglobin assay. The same phenolics showed a lower activity when assessed using the deoxyribose assay. Overall, luteolin, caffeoylquinic acids and hydrolyzable tannins, being the most representative artichoke phenolics, may be considered the phenolic constituents responsible for the antioxidant properties of artichoke extracts. In addition other phenolics present in the extracts such as p-coumaric, ferulic, vanillic, syringic acids and apigenin-7-glucoside may contribute to the total antioxidant capacity of the extracts.

Artichoke leaf extract exerted a concentration-dependent inhibition of oxidative stress when human leukocytes were stimulated with agents that generated reactive oxygen species (ROS): hydrogen peroxide, phorbol-12-myristate-13-acetate (PMA) and N-formyl-methionyl-leucyl-phenylalanine (FMLP) (Perez-Garcia et al. 2000). Cynarin, caffeic acid, chlorogenic acid and luteolin, constituents of artichoke leaf extract, also exhibited a concentration-dependent inhibitory activity in the above models, contributing to the antioxidant activity of the extract in human neutrophils.

The 75 % ethanol artichoke leaf extract exhibited the highest antioxidant activity as evaluated by 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay as well as yielded the largest quantity of polyphenolic compounds (Vamanu et al. 2011). The optimum concentration of 10 mg/ml gave maximum antioxidant activity of 65.15 %. The MIC values obtained using the freeze-dried extract ranged from 5.0 to 15.0 mg/ml. Total phenolic content varied from 2.12 to 30.38 mg/g of the extract. In separate studies, the ethanol extracts prepared from Cynara scolymus seeds and leaves were found to have DPPH radical scavenging activities (Georgieva et al. 2011). At any studied concentration of the seeds extract, the percent of the scavenged DPPH radicals was considerably higher than that calculated for the leaves extract. All investigated individual artichoke compounds from commercially artichoke leaf extract—chlorogenic acid, cynarin, luteolin and luteolin-7-O-glucoside—showed a remarkable antioxidative effect, chlorogenic acid being the strongest antioxidant compound (Fritsche et al. 2002).

Antioxidant phenolics were extracted from artichoke by-products: raw artichoke (RA), blanched (thermally treated) artichoke (BA) and artichoke blanching waters (ABW) by both methanol and water extractions (Llorach et al. 2002). Phenolic contents (expressed as caffeic acid derivatives) (grams per 100 g of dry extract) were 15.4 and 9.9 for RA when extracted with methanol and water, respectively; 24.3 and 10.3 for BA when extracted with methanol and water, respectively; and finally, 11.3 g of phenolics/100 ml of ABW. The artichoke extracts from industrial by-products showed a high free radical scavenging activity (versus both DPPH* and ABTS* + radicals) as well as capacity to inhibit lipid peroxidation (ferric thiocyanate method). The results suggested the possible use of artichoke extracts from industrial by-products as ingredients to functionalize foodstuffs (to decrease lipid peroxidation and to increase health-promoting properties). In another study one gram (dry matter) of artichoke was found to have a DPPH activity and a FRAP value in-vitro equivalent to those of 29.2 and 62.6 mg of vitamin C and to those of 77.9 and 159 mg of vitamin E, respectively (Jiménez-Escrig et al. 2003). Artichoke extracts showed good efficiency in the inhibition in vitro of low-density lipoprotein oxidation. Neither ferric-reducing ability nor 2,2′-azinobis(3-ethylbenzothiazolin-6-sulfonate) radical scavenging activity was modified in the rat plasma of the artichoke group with respect to the control group. Among different antioxidant enzymes measured (superoxide dismutase, glutathione peroxidase, glutathione reductase and catalase) in erythrocytes, only glutathione peroxidase activity was elevated in the artichoke group compared to the control group. 2-Aminoadipic semialdehyde, a protein oxidation biomarker, was decreased in plasma proteins and haemoglobin in the artichoke-fed group versus the control group. The results confirmed the in-vitro protective oxidative activity of artichoke in a rat model.

Studies demonstrated that artichoke polyphenolic extract protected cultured rat hepatocytes from the oxidative stress caused by glucose oxidase, comparable to the well-known antioxidant, N,N′-diphenyl-p-phenylenediamine (DPPD) (Miccadei et al. 2008). Further, the extract as well as chlorogenic acid prevented the loss of total glutathione and the accumulation of malondialdehyde. Artichoke leaf aqueous extracts exhibited a dose-dependent free radical scavenging effect of DPPH and an inhibitory effect of xanthine oxidase (Zan et al. 2013). The extract was found to contain phenolic compounds, flavonoids and saponins such as chlorogenic acid, caffeic acid, isoquercetrin and rutin.

The antioxidant capacity of cooked artichokes, measured by three different assays, enormously increased after cooking, particularly after steaming (up to 15-fold) and boiling (up to 8-fold) (Ferracane et al. 2008). Boiling increased the concentration of dicaffeoylquinic acid isomers much more than steaming or frying which showed similar patterns of dicaffeoylquinic concentrations. However, all cooking practices, particularly frying, decreased flavonoid concentration.

In double-blinded study carried out in 22 members of the Polish rowing team who were randomly assigned to a supplemented group (n = 12), receiving 1 gelatin capsule containing 400 mg of artichoke leaf extract three times a day for 5 weeks, or a placebo group (n = 10), plasma total antioxidant capacity (TAC) was significantly higher in the supplemented group than in the placebo group during restitution (Skarpanska-Stejnborn et al. 2008). Serum total cholesterol levels at the end of the study were significantly lower in the supplemented group than in the placebo group. The authors concluded that consuming artichoke leaf extract, a natural vegetable preparation of high antioxidant potential, resulted in higher plasma TAC than placebo but did not limit oxidative damage to erythrocytes in competitive rowers subjected to strenuous training.

The ethanol extract and fractions (chloroform, ethyl acetate and n-butanol) of the ethanol extract of fresh involucral bracts of cardoon, Cynara cardunculus, exhibited concentration-dependent antioxidant activity in the FRAP (ferric reducing antioxidant power) assay and scavenging of 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical assays (Kukić et al. 2008).

A significant increase in bile flow was observed in anesthetized Wistar rats after acute treatment with artichoke leaf extract as well as after repeated administration (Sánchez-Rabaneda et al. 2003). The choleretic effects of artichoke extract were similar to those of the reference antidyspeptic compound dehydrocholic acid (DHCA).

In a randomized placebo-controlled double-blind cross-over study of 20 subjects, administration of a standardized, artichoke extract Hepar-SL forte was found to have a choleretic effect (Kirchhoff et al. 1994). At 120 and 150 minutes the volume of bile secreted under the active treatment was also significantly higher than under the placebo. In the placebo group, bile secretion fell below the initial level after 3 hours. An effective period of about 120–150 minutes was regarded as satisfactory to influence enzymatic digestion and the motor function of the intestine when the test substance was given postprandially. No side effects or changes in the laboratory parameters in connection with the experiment were observed. Results indicated that artichoke extract could be recommended for the treatment of dyspepsia, especially when the cause may be attributed to dyskinesia of the bile ducts or disorder in the assimilation of fat.

In postmarketing surveillance (phase IV) studies patients with non-specific gastrointestinal complaints receiving treatment with globe artichoke leaf extract (Hepar-SL forte; up to 1.92 g daily for 6 weeks (Fintelmann and Menssen 1996) or 6 months (Fintelmann and Petrowicz 1998) were monitored. In one study involving 533 patients with non-specific gastrointestinal complaints, including dyspepsia, functional biliary tract complaints, constipation and gastric irritation, seven adverse events (weakness, hunger, flatulence) were reported (1.3 % of participants), but no serious adverse events were reported (Fintelmann and Menssen 1996). In the second postmarketing surveillance study involving 203 patients with symptoms of dyspepsia who received globe artichoke leaf extract up to 1.92 g daily for up to 6 months, no adverse events were recorded (Fintelmann and Petrowicz 1998). The physicians’ overall judgement of tolerability was given as ‘good’ or ‘excellent’ in 98.5 % of cases. In another postmarketing surveillance study for artichoke leaf extract in a sub-group of patients with irritable bowel syndrome (IBS) symptoms, analysis of data revealed significant reductions in the severity of symptoms and favourable evaluations of overall effectiveness by both physicians and patients (Walker et al. 2001). Additionally, 96 % of patients rated artichoke extract as better than or at least equal to previous therapies administered for their symptoms, and the tolerability of the extract was very good.

Studies by Marakis et al. (2002) found that artichoke leaf extract showed promise in ameliorating upper gastrointestinal symptoms and improving quality of life in otherwise healthy subjects suffering from dyspepsia. Of the 516 participants, 454 completed the study. There was a significant reduction of all dyspeptic symptoms, with an average reduction of 40 % in global dyspepsia score for both dosage groups of 320 or 640 mg daily. There were no differences in the primary outcome measures between the two groups, but relief of state anxiety, a secondary outcome, was greater with the higher dosage. Health-related quality of life was significantly improved in both groups compared with baseline. The efficacy of artichoke leaf extract treatment of patients with functional dyspepsia (129 artichoke treatment, 115 placebo) was assessed in a 6-week, double-blind, randomized controlled trial (Holtmann et al. 2003). The overall symptom improvement over the 6 weeks of treatment was significantly greater with artichoke extract than with the placebo. Similarly, patients treated with artichoke extract showed significantly greater improvement in the global quality-of-life scores (NDI) compared with the placebo-treated patients.

In a subset analysis of a previous dose-ranging, open, postal study in adults (208) suffering dyspepsia, 2 months intervention of artichoke leaf extract was found to ameliorate symptoms of irritable bowel syndrome (IBS) in otherwise healthy volunteers (Bundy et al. 2004). A significant shift in self-reported usual bowel pattern away from ‘alternating constipation/diarrhoea’ towards ‘normal’ was observed. Nepean Dyspepsia Index (NDI) total symptom score significantly decreased by 41 % after artichoke treatment. Similarly, there was a significant 20 % improvement in the NDI total quality-of-life (QOL) score in the subset after treatment.