Two new sesquiterpenes from Sonchus oleraceus and inhibitory mechanism on murine haemangioendothelioma (EOMA) cell lines.

Sonchus oleraceus is a kind of medicinal and edible plant which is widely distributed. In this study, two new sesquiterpenes 1 and 2 along with three known compounds 3-5 were isolated from Sonchus oleraceus by the methods of column chromatography. The structures of the two novel compounds were constructed on the basis of HR-MS and NMR spectra. Cytotoxicities of 1 and 2 were assayed on EOMA cell lines and 1 exhibited no inhibitory effect while 2 elicited moderate inhibitory effect on EOMA cells with IC50 value of 26.5 µM. Western Blot assay indicated that 2 could suppress EOMA cell proliferation by inducing apoptosis through Bax/caspase-3 pathway.

Novel browning alleviation technology for fresh-cut products: Preservation effect of the combination of Sonchus oleraceus L. extract and ultrasound in fresh-cut potatoes.

Enzymatic browning is considered a critical factor that adversely decreases the quality of fresh-cut products. Although many individual physical or chemical methods have been explored to control browning, there are few approaches combining these technologies. In the present study, Sonchus oleraceus L. extract (SOLE) and ultrasound treatment efficiently controlled the activities of polyphenol oxidase, peroxidase, phenylalanine ammonia-lyase, lipoxygenase, soluble quinones, and intermediate and advanced products, and a lower malondialdehyde content and higher antioxidant capacity were observed in fresh-cut potato slices. More than 50 phenolics and flavonoids were identified in SOLE by liquid chromatography-tandem mass spectrometry. In conclusion, the combined SOLE and ultrasound treatment could serve as a promising method for attenuating enzymatic browning.

Cytotoxic Sesquiterpenes from Sonchus oleraceus.

BACKGROUND: Sonchus oleraceus is a large and widespread plant in the world. It is edible to humans as a leaf vegetable and is also used as a folklore medicinal herb in the treatment of infections and inflammatory disease, but limited research on its chemical constituents has been done. OBJECTIVE: To isolate and identify the bioactive ingredients from S. oleraceus. METHODS: 20kg of S. oleraceus was extracted twice with 75% alcohol. The concentrated extract was suspended in H2O and partitioned with petroleum ether, dichloromethane, ethyl acetate and n-butanol, respectively. The ethyl acetate phase was subjected to repeated normal chromatography on a silica gel column chromatography and eluted with a gradient of CH2Cl2-MeOH to give 12 crude fractions. Fraction 6 was subjected to ODS silica gel column chromatography, Sephadex LH-20 and HPLC to yield 1 and 2. Cell viability of 1 and 2 on A549, H292 and Caco2 cell lines were assayed by MTT method. Apoptosis analysis and apoptosis related proteins were detected subsequently. RESULTS: Two new sesquiterpenes were isolated from S. oleraceus and identified by NMR spectra and HR-ESIMS. 1 selectively suppressed the viability of A549 and H292 cells with IC50 values of 14.2, and 19.5µM respectively, while possessing no cytotoxicity against Caco2 cells (IC50 > 100µM). 2 did not exhibit cytotoxicity against A549, H292 and Caco2 cells (IC50 > 100µM). 1 significantly decreased the density of live cells and could cause cell apoptosis at 10 and 20µM in a dose-dependent manner. After treatment of 1 for 24h, the level of cleaved caspase-3 was increased accompanied by the reduction in procaspase-3 expression, and the downregulation of Bcl-2 was associated with the enhancement of Bax expression. 1 could lead to the up-regulation of cytochrome c and activation of caspase-9. CONCLUSION: 1 and 2 are new sesquiterpenes from S. oleraceus. 1 could induce apoptosis in A549 and H292 cells through Bax/caspase-9 pathway.

Sonchus oleraceus Linn extract enhanced glucose homeostasis through the AMPK/Akt/ GSK-3ß signaling pathway in diabetic liver and HepG2 cell culture.

The extracts of S. oleraceus Linn (SOL) and its main phenolic compounds have shown anti-diabetic effects, but their underlying mechanisms for glucose homeostasis remain unclear. The aim of this study is to evaluate the anti-diabetic mechanism of SOL by using the streptozocin (STZ) induced diabetic rat model. When diabetic rats were fed with SOL at a dose of 400 mg/kg/day for 6 weeks, the concentrations of triglycerides (TG), total cholesterol (TC), and low-density lipoprotein cholesterol (LDL-C) were reduced by 43%, 22%, and 16%, respectively. Meanwhile, it was also found that daily feeding of SOL to diabetic rats led to a decrease in plasma glucose level by approximately 23%. Positive effects were observed on glucose homeostasis due to the down-regulation of AMPK/Akt/GSK-3ß pathway, as indicated by the suppressions of adenosine 5'-monophosphate (AMP)-activated protein kinase (AMPK), protein kinase (Akt) phosphorylation, glycogen synthase kinase 3 beta (GSK-3ß), and the hepatic insulin resistance. In HepG2 cells, AMPK, Akt and GSK-3ß showed a consistent transcript regulation. SOL at dose of 400 mg/kg/day feeding for 6 weeks showed a positive effect comparable to metformin.

Anti-inflammatory effect of self-emulsifying delivery system containing Sonchus oleraceus Linn extract on streptozotocin-induced diabetic rats.

Edible Sonchus oleraceus Linn is a medicinal plant with many bioactivities such as anti-diabetic activity and anti-inflammatory activity. However, the main bioactive components such as polyphenols in S. oleraceus Linn are poorly absorbed in gastrointestinal tract and rapidly metabolized. Thereby, a self-emulsifying delivery system containing S. oleraceus Linn extracts (SSEDDS) was introduced to evade these problems. Herein, the anti-inflammatory effect of SSEDDS on streptozotocin-induced diabetic rats was investigated. The plasma glucose level was increased and plasma insulin level was decreased in diabetic rats. The levels of NF-κB, TNF-α, and IL-6 in the liver were significantly improved in diabetic rats (p < 0.05). Conversely, daily fed diabetic rats with 100, 200 and 400 mg/kg/day of SSEDS and 1 mg/kg/day metformin for 4 weeks, significantly (p < 0.05) restored all the above mentioned parameters to near normal levels. The immuno-histochemical studies confirmed the anti-inflammatory effects of SSEDDS.

Inhibitory effect of the extract from Sonchus olearleu on the formation of carcinogenic heterocyclic aromatic amines during the pork cooking.

The aim of this study was to assess the inhibitory effects of Sonchus olearleu extract on the generation of heterocyclic amines in roasted pork patties cooked by pan-frying. All samples were cooked for two different durations (45 min and 105 min) under 200 °C and 230 °C. 2-amino-3-methylimidazo[4,5-f]quinoline (IQ), 2-ami- no-3,8-dimethylimidazo[4,5-f]quinoxaline (MeIQx), 2-amino-3,4,8-trimethylimidazo[4,5-f]quinox-aline (4,8-DiMeIQx), harman, and norharman were detected and quantified. In patties cooked at 230 °C for 105 min, S. olearleu extract (0.5%) significantly inhibited the formation of IQ, harman, and norharman by 39%, 67%, and 63%, respectively. In contrast to IQ, the levels of harman and norharman were significantly reduced by the extracts tested. However, no such effects were observed for MeIQx and 4, 8-DiMeIQx. Notably, the inhibitory effect on heterocyclic amines is significantly correlated with the antioxidant potential and total phenolic content of S. olearleu extract.

Chlorogenic acid and caffeic acid from Sonchus oleraceus Linn synergistically attenuate insulin resistance and modulate glucose uptake in HepG2 cells.

The crude extract of Sonchus oleraceus Linn (CE) and its main phenolic acids (PA), chlorogenic acid and caffeic acid have anti-diabetic activity, but the mechanisms for their effects on glucose intake remain largely unknown. Aim of this study was to examine the synergistic effect of chlorogenic and caffeic acid from S. oleraceus Linn attenuate insulin resistance and modulate glucose uptake in HepG2 cells. Major phenolic acids in SOL were isolated and identified by HPLC. Insulin-resistance HepG2 cell model was used to elucidate the effect of CE on glucose metabolism. Pre-treatment of HepG2 cells with CE or PA enhanced levels of glucose production and avoided the decrease total levels of IRS-1 triggered by high insulin concentration. CE or PA pre-treatment also could prevent the inactivation of the PI3K/AKT pathway, as well as the diminution of GLUT4 levels induced by high glucose. These findings suggested that CE and its main phenolic acids improved insulin sensitivity of HepG2 cells treated with insulin, preventing or delaying a potential hepatic dysfunction through the attenuation of the insulin signaling blockade and the modulation of glucose consumption.

Sonchus oleraceus Linn protects against LPS-induced sepsis and inhibits inflammatory responses in RAW264.7 cells.

ETHNOPHARMACOLOGICAL RELEVANCE: Sonchus oleraceus Linn (SOL) belongs to family of Asteraceae, is a traditional medicinal plant, which has been used to treat tumor, inflammatory diseases, infection and so on in Chinese folk culture. AIM OF THE STUDY: This work investigated the influence of aqueous ethanol extract of whole plant of SOL and contribution of its main components on inflammation METHODS AND RESULTS: Oral administration of SOL (10 mg/kg) to mice reduced the expression of inflammatory cytokines including IL-6, IL-1ß, and TNF-α, in the LPS-induced sepsis mouse model. Major phenolics in SOL were isolated and determined by HPLC. Results indicate that SOL at the concentration range from 25 to 100 µg/mL and its main components, chlorogenic acid, caffeic acid (25-100 µM) significantly reduced the pro-inflammatory cytokine IL-1ß, IL-6, TNF-α, attenuated iNOS and COX-2 expression in LPS-stimulated Macrophages. In addition, western blot analysis showed SOL suppressed inducible nitric oxide synthase (iNOS) protein expression and the phosphorylation of extracellular signal-regulated kinase (ERK), p38, c-Jun N-terminal kinase (JNK). CONCLUSION: The underlying mechanism of anti-inflammation might be in according with the inhibition of MAPKs activation as well as down regulation of iNOS and cyclooxygenase-2 (COX-2).

Potential effect of Olea europea leaves, Sonchus oleraceus leaves and Mangifera indica peel extracts on aromatase activity in human placental microsomes and CYP19A1 expression in MCF-7 cell line: Comparative study.

Aromatase inhibitors (AIs) provide novel approaches to the adjuvant therapy for postmenopausal women with estrogen-receptor-positive (ER+) breast cancers. In this study, different plant extracts from Olea europaea leaves (OLE), Sonchus oleraceus L. (SOE) and Mangifera indica peels (MPE) were prepared to identify phytoconstituents and measure antioxidant capacities. The effects of these three extracts on aromatase activity in human placental microsomes were evaluated. Additionally, the effects of these extracts on tissue-specific promoter expression of CYP19A1 gene in cell culture model (MCF-7) were assessed using qRT-PCR. Results showed a concentration-dependent decrease in aromatase activity after treatment with OLE and MPE, whereas, SOE showed a biphasic effect. The differential effects of OLE, SOE and MPE on aromatase expression showed that OLE seems to be the most potent suppressor followed by SOE and then MPE. These findings indicate that OLE has effective inhibitory action on aromatase at both the enzymatic and expression levels, in addition to its cytotoxic effect against MCF-7 cells. Also, MPE may be has the potential to be used as a tissue-specific aromatase inhibitor (selective aromatase inhibitor) and it may be promising to develop a new therapeutic agent against ER+ breast cancer.

Anti-tumor effect of hot aqueous extracts from Sonchus oleraceus (L.) L. and Juniperus sabina L - Two traditional medicinal plants in China.

ETHNOPHARMACOLOGICAL RELEVANCE: Sonchus oleraceus (L.) L (SO) and Juniperus sabina L (JS) are traditional medicinal plants in China. And the aqueous extracts of them have been used to treat tumor, inflammatory diseases, infection and so on in Chinese folk culture. However, the underlying mechanisms of their anti-tumor activities have not been illustrated yet. OBJECTIVE: This study aims to evaluate the inhibitory effects of aqueous extracts from SO and JS on tumor cells. MATERIALS AND METHODS: The prepared aqueous extracts of SO and JS were used to treat HepG-2 and K562 tumor cells, while the human peripheral blood mononuclear cells (PBMCs) were set as normal control. The viabilities, cell cycle and apoptosis of tumor cells after extracts treatment were assessed, in addition the expression of apoptosis-related genes (FasL, caspase 3, 6, 7, 8, 9, and 10) were analyzed. Meanwhile, the adherence and migration of HepG-2 were tested, and the expression levels of MMPs and ICAM-1 were analyzed. On top of that, the pSTAT in the two cells were also analyzed and suggested the related signaling pathway that the extracts acted on with in these tumor cells. RESULTS: Results showed that aqueous extracts of SO and JS have inhibitory effects on HepG-2 and K562 cells by decreasing cell viability and inducing apoptosis via up-regulation of the expression of the apoptosis-related genes FasL, caspase 3 and caspase 9. The extracts had different IC50 on tumor cells and PBMCs, which could block the tumor cell cycle at the G(0)/G(1) stage and significantly inhibit the adherence of HepG-2 cells. The extracts inhibited migration of these cells by inhibiting the expression of ICAM-1, MMP-2 and MMP-9. Further study indicated that the inhibition of pSTAT1 and 3 might be responsible for the inhibitory effects of the extracts on tumor cells. DISCUSSION AND CONCLUSION: The results of this study indicated that SO and JS extracts had the anti-tumor effects, which may be developed as novel anti-tumor drugs and used in cancer therapy.

Effects of boiling and in vitro gastrointestinal digestion on the antioxidant activity of Sonchus oleraceus leaves.

Leaves of Sonchus oleraceus L. are especially rich in phenolic compounds and have potent extractable antioxidants. However, it is not known how their antioxidant activity changes after cooking and gastrointestinal digestion. We recorded the profile of phenolics and their associated antioxidant activity in both raw and boiled S. oleraceus leaf extracts after in vitro gastric and intestinal digestion, and quantified their antioxidant potentials using Caco-2 and HepG2 cells. Boiling significantly diminished the oxygen radical absorbance capacity (ORAC) and concentrations of ascorbate and chicoric acid in the soluble fractions. In contrast, 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging and concentrations of caftaric and chlorogenic acids were unaffected. Phenolics in the soluble fraction were absorbed into cultured human cells and exerted antioxidant activity. Only chlorogenic acid content remained stable during gastrointestinal digestion. S. oleraceus appears to be an excellent dietary source of phenolic antioxidants.

Antioxidant and antidiabetic profiles of two African medicinal plants: Picralima nitida (Apocynaceae) and Sonchus oleraceus (Asteraceae).

BACKGROUND: Diabetes mellitus (DM) is a metabolic disease characterized by chronic hyperglycaemia generally associated with oxidative stress. The present study aims at evaluating the antioxidant and antidiabetic potential of methanol and hydroethanol extracts of the stem bark and leaves of Pricralima nitida and the Sonchus oleraceus whole plant respectively. METHODS: The in vitro antioxidant activity was assessed using 1,1-Diphenyl-2-picrilhydrazyl (DPPH) for free radical-scavenging properties of the extracts, and the Folin-Ciocalteu method in determining their phenol contents. The antidiabetic activity was tested in mice following streptozotocin diabetes induction, and selected oxidative stress markers (Malondialdehyde, Hydrogen peroxides and Catalase) were measured in order to evaluate the level of oxidative stress in treated animals. RESULTS: The in vitro antioxidant activity using DPPH showed IC50 ranging from 0.19 ± 0.08 to 1.00 ± 0.06 mg/mL. The highest activity was obtained with the hydroethanol extracts of S. oleraceus (0.19 mg/mL and P. nitida (0.24 mg/mL). Polyphenol contents ranged from 182.25 ± 16.76 to 684.62 ± 46.66 µg Eq Cat/g. The methanol extract of P. nitida showed the highest activity, followed by the hydroethanol extract of S. oleraceus (616.89 ± 19.20 µEq Cat/g). The hydroethanol extract of whole plants (150 mg/Kg) and methanol leave extract of P. nitida (300 mg/Kg) exhibited significant antidiabetic activities with 39.40% and 38.48% glycaemia reduction, respectively. The measurement of stress markers in plasma, liver and kidney after administration of both extracts showed significant reduction in MDA and hydrogen peroxide levels, coupled with a substantial increase in catalase activity. CONCLUSIONS: These findings suggest that S. oleraceus whole plant and P. nitida leaves possess both antidiabetic and antioxidant properties, and therefore could be used as starting point for the development of herbal medicines and/or source of new drug molecules against diabetes.

Protective effects of Sonchus asper (L.) against KBrO3-induced oxidative stress in rat testis.

Sonchus asper is used traditionally in the treatment of kidney inflammation, hormonal imbalance and impotency. Sonchus asper methanolic extract (SAME) was investigated for its possible preventive effect against potassium bromate (KBrO3) induced oxidative damages in male rats using biochemical, molecular and histopathological markers in this study. 5 groups, each group of 6 rats were taken kept under standard conditions. Group 1 remained untreated while Group II was given 20 mg/kg KBrO3 orally (in aqueous saline) and Group III, and IV were treated with 100; 200 mg/kg b.w., of SAME after 48 h of KBrO3 treatment. KBrO3 administration in rats significantly altered (P<0.01) the serum level of reproductive hormones, activities of antioxidant enzymes and glutathione contents (GSH), which was significantly reversed P<0.001) by co-treatment of 100 mg/kg and 200 mg/kg b.w., SAME. Administration of SAME in rats also significantly P<0.001) reversed the lipid peroxidation induced by KBrO3 in rats, which could be due to the presence of some plant bioactive constituents.

Protective effect of Sonchus asper extracts against experimentally induced lung injuries in rats: a novel study.

In this study, protective effects of methanol extract (SAME) were evaluated against carbon tetrachloride induced oxidative stress in lungs. Male Sprague-Dawley rats were orally fed with various doses (100, 200 mg/kg body weight) of SAME and (50 mg/kg body weight) of rutin after 48 h of CCl(4) treatment (3 ml/kg body weight, 30% in olive oil) biweekly for 4 weeks. The results showed that administration of extracts and rutin significantly restored lung contents of reduced glutathione and activities of catalase, peroxidase, superoxide dismutase, glutathione peroxidase, glutathione-S-transferase, glutathione reductase, quinine reductase were reduced while lipid peroxide, hydrogen peroxide, nitrite, DNA fragmentation% and activity of γ-glutamyl transferase, increased by CCl(4), were reversed towards the control levels by the supplement of Sonchus asper extracts and rutin. Lung histopathology showed that S. asper extracts and rutin reduced the incidence of lung lesions induced by CCl(4) in rats. These results suggest that S. asper fractions and rutin could protect lung against the CCl(4)-induced oxidative damage in rats.

Antioxidant activity of puha (Sonchus oleraceus L.) as assessed by the cellular antioxidant activity (CAA) assay.

There is considerable interest in antioxidant dietary components that can be protective against degenerative diseases in humans. Puha (Sonchus oleraceus L.) is a rich source of polyphenols, and exhibits strong antioxidant activity as measured by the 2,2-diphenylpicrylhydrazyl (DPPH) assay. However, the potential of puha to protect against degenerative diseases requires that low molecular weight antioxidants (LMWA) are absorbed by, and active in, human cells. The cellular antioxidant activity (CAA) assay was used to investigate the antioxidant activity of puha leaf extracts. Preparation methods of freezing and freeze-drying reduced the total polyphenolic content compared with fresh puha, but did not affect the LMWA potential as determined by the DPPH assay. The IC(50) values were 0.012 ± 0.003 mg/mL and 0.010 ± 0.005 mg/mL for freeze-dried and fresh puha leaves, respectively. Using the CAA assay, it was shown that LMWAs from foliar extracts of puha were effectively absorbed into HepG2 cells, and exerted antioxidant activity at levels comparable to those of extracts from blueberry fruits, the much-touted antioxidant superfood. Methylene blue staining of HepG2 cells indicated that puha extracts were not cytotoxic at concentrations below 100 mg DW/mL. The data indicate the potential of puha as a nutraceutical supplement for human health.

Antioxidant and antibacterial activity of six edible wild plants (Sonchus spp.) in China.

The total phenolic and flavonoid, antioxidant and antibacterial activities of six Sonchus wild vegetables (Sonchus oleraceus L., Sonchus arvensis L., Sonchus asper (L.) Hill., Sonchus uliginosus M.B., Sonchus brachyotus DC. and Sonchus lingianus Shih) in China were investigated. The results revealed that S. arvensis extract and S. oleraceus extract contained the highest amount of phenolic and flavonoid, respectively. Among the methanol extracts of six Sonchus species, S. arvensis extract exhibited the highest radical (DPPH and ABTS+ scavenging power and lipid peroxidation inhibitory power. It also exhibited the highest reducing power at 500 µg mL⁻¹ by A (700) = 0.80. The results of antibacterial test indicated that the S. oleraceus extract showed higher activity than the other five Sonchus wild vegetables extracts, both in Gram-negative bacteria (Escherichia coli, Salmonella enterica and Vibrio parahaemolyticus) and in a Gram-positive bacterium (Staphylococcus aureus). These results indicate that Sonchus wild food plants might be applicable in natural medicine and healthy food.

Anti-inflammatory and antipyretic effects of Sonchus oleraceus in rats.

ETHNOPHARMACOLOGICAL RELEVANCE: Sonchus oleraceus L. has been used to relieve headaches, general pain, hepatitis, infections, inflammation and rheumatism in Brazilian folk medicine. Nevertheless, scientific information regarding this species is scarce; there are no reports related to its possible anti-inflammatory effects. AIM OF THE STUDY: This study was aimed at evaluating the scientific basis for the traditional use of Sonchus oleraceus using in vivo inflammatory models. MATERIALS AND METHODS: Carrageenan-induced paw edema, peritonitis and febrile response induced by lipopolysaccharide tests, as well as fibrovascular tissue growth induced by s.c. cotton pellet implantation were used to investigate the anti-inflammatory activity of Sonchus oleraceus hydroethanolic extract (SoHE) in rats. RESULTS: The SoHE at test doses of 100-300 mg/kg p.o. clearly demonstrated anti-inflammatory effects by reduced paw edema induced by carragenan, inhibited leukocyte recruitment into the peritoneal cavity and reduced LPS-induced febrile response, and in the model of chronic inflammation using the cotton pellet-induced fibrovascular tissue growth in rats, the SoHE significantly inhibited the formation of granulomatous tissue. The extract administered at 300 mg/kg p.o. had a stronger anti-inflammatory effect than indomethacin (10mg/kg) or dexamethasone (1mg/kg). CONCLUSION: The hydroethanolic extract of Sonchus oleraceus markedly demonstrated anti-inflammatory action in rats, which supports previous claims of its traditional use.

Fatty acid derived compounds--the dominant volatile class of the essential oil poor Sonchus arvensis subsp. uliginosus (Bieb.) Nyman.

Chemical composition of the essential oil hydrodistilled from aerial parts of Sonchus arvensis subsp. uliginosus is reported for the first time. GC and GC-MS analyses of the oil enabled the identification of 114 components that represented 97.4% of the total oil. Main identified constituents were heneicosane (28.4%), (Z)-3-hexen-1-ol (19.0%), (E)-2-hexen-1-ol (11.6%), 1-eicosanol (7.5%) and tricosane (5.3%). Fatty acid derived compounds ("green leaf' volatiles, alkanes, n-alkenes, n-aldehydes and n-alcohols) were by far predominant (89.4%). A much lower percentage of shikimate metabolites (5.0%), carotenoid-derived compounds (1.7%) and terpenoids (0.9%) has also been detected in the oil. Compositions of the essential oils of S. arvensis subsp. uliginosus and other 18 randomly chosen species, characterized by a wide range of essential oil yields, belonging to different plant genera, were compared using multivariate statistical analysis. The results strongly suggest that the main volatiles of essential oil poor species (yields less then 0.1%) are fatty acid- and carotenoid derived compounds, while essential oil rich taxa (essential oil yields much higher then 0.1%) are generally characterized by the specific production of mono- and sesquiterpenoids, and/or phenylpropanoids.

Nutritional quality of some wild leafy vegetables in South Africa.

Wild vegetables play an important role in the diet of inhabitants of different parts of the world. Among the wild vegetables of South Africa are Chenopodium album, Sonchus asper, Solanumnigrum and Urtica urens. The leaves of these plants were analysed for their nutritive value, anti-nutritive components and polyphenolic contents. The protein contents of their leaves ranged between 13.25% and 26.44%, while the fibre and mineral (ash) contents were 16.08-23.08% and 13.0-27.75%, respectively. U. urens contained the highest concentrations of calcium, potassium, phosphorus and zinc. A high level of iron was observed in S. asper. These values were found to be comparable with or higher than those of commonly used vegetables such as spinach, lettuce and cabbage. The total phenolic contents ranged between 4.58 and 10.53 mg/g. In terms of anti-nutritional principles, all the vegetables had comparatively lower concentrations of phytate, alkaloids and saponins. Considering the amount of available mineral elements in the vegetables, these plants could be valuable and important contributors to the diets of the people in South Africa.

Antioxidant properties of Mediterranean food plant extracts: geographical differences.

Locally grown, wild food plants seasonally contribute a considerable portion of the daily diet in certain Mediterranean areas and it has been suggested that the beneficial effects of the Mediterranean diet on human health partly originate from the antioxidant effect of flavonoid-rich food plants. The nutrient content of most wild plants is higher than that of cultivated ones and may vary depending on the prevailing environmental conditions. Accordingly, three local Mediterranean plant foods (i.e. Cichorium intybus, Sonchus oleraceus, Papaver rhoeas) were collected in Greece (Crete), southern Italy, and southern Spain in order to assess possible differences in their in vitro antioxidant potential. The biological assays revealed diverse intra-plant specific antioxidant effects for the tested extracts ranging from no activity to almost complete protection. Furthermore, substantial differences in the polyphenol content were found for the nutritionally used part of the same plant originating from different locations. However, no clear correlations between the polyphenol content and the extracts' antioxidant activities were found. Taken together, the data suggest that certain local Mediterranean plant foods possess promising antioxidant activity and that the observed biological effects are possibly influenced by the geographically-dependent environmental conditions prevailing during plant growth.