Bioeffects of chromium(III) on the growth of Spirulina platensis and its biotransformation

BACKGROUND: In this study the bioeffects of chromium(III) (Cr(III)) on the growth of Spirulina platensis and its biotransformation were investigated. Spirulina platensis was batch cultured in Zarrouk medium containing different concentrations of CrCl₃ · 6H₂O. Total and organic Cr contents in S. platensis were determined by inductively coupled plasma mass spectrometry (ICP‐MS), and Cr speciation was assayed by high‐performance liquid chromatography/ICP‐MS. RESULTS: Results based on the dry weight, growth curve, chlorophyll yield and morphology change of S. platensis indicated that the growth of S. platensis was facilitated by Cr(III) below 4.51 mol L^?1 and inhibited by a higher concentration of Cr(III). It was found that Cr(III) could be accumulated efficiently in S. platensis, with a highest Cr yield of 173.17 g kg^?1 and a highest organic Cr proportion of 50.19 g kg^?1 (96.04% of the total concentration of Cr). No evidence of oxidation of Cr(III) to Cr(VI) in S. platensis cells was found. CONCLUSION: The results of this study suggest that S. platensis could potentially be used as a safe food carrier to accumulate Cr(III) through some metabolic process. Copyright © 2009 Society of Chemical Industry     

Two-stage culture method for optimized polysaccharide production in Spirulina platensis

BACKGROUND: The polysaccharides of Spirulina platensis possess many biological functions. Reproducing the conditions under which S. platensis produces polysaccharides is critical to furthering our understanding of the function of these polysaccharides for commercial mass production. The changes in microalgal polysaccharide production were studied under greenhouse and laboratory conditions using varying light intensities, temperatures, and NaCl concentrations. RESULTS: The polysaccharide yield was positively correlated with culturing under 192 µmol photons m^?2 s^?1 light intensity at 38 °C or in 0.75 mol L^?1 NaCl. However, NaCl reduced the total biomass productivity of S. platensis. To mitigate the negative effects of environmental stress on maximal polysaccharide production, we proposed a two‐stage culture method. The first stage, designed to increase biomass production, involved culturing under 96 µmol photons m^?2 s^?1 light intensity at 28 °C. Following this, on achieving maximum biomass production, the second stage, designed to stimulate polysaccharide production, involved culturing under 192 µmol photons m^?2 s^?1 light intensity at 38 °C for 3 days or in a 0.75 mol L^?1 NaCl medium for 2 days. High‐performance liquid chromatographic analysis revealed that S. platensis polysaccharides were composed of various monosaccharides, including glucose, galactose, rhamnose, mannose, fructose, and mannitol. CONCLUSION: The two‐stage culture can be successfully applied to achieve the goal of polysaccharide mass production. The first stage focuses on rapidly increasing microalgal biomass. The second stage of culture conditions requires modification to maximize polysaccharide yield. Copyright © 2011 Society of Chemical Industry     

Physiological changes, phenolic content and antioxidant activity of Salvia officinalis L. grown under saline conditions

BACKGROUND: Hydroponic culture was used to investigate the effect of NaCl concentrations on the growth, nutrient uptake, phenolic content and antioxidant activity of Salvia officinalis L. leaves. The antioxidant capacity of the methanolic extract of S. officinalis was evaluated by using 2,2‐diphenyl‐1‐picrylhydrazyl (DPPH) radical scavenging test and β‐carotene‐linoleic acid bleaching assay. Physiological and biochemical parameters of S. officinalis were assessed after 4 weeks of salt treatment with 0, 25, 50, 75 and 100 mmol L^?1 NaCl. RESULTS: Plant growth exhibited a reduction of 61% at 100 mmol L^?1 NaCl. Assessment of Na⁺, K⁺ and Ca²⁺ and water contents of shoots and roots showed that S. officinalis is able to regulate Na⁺ concentration by active compartmentation in vacuoles. Salvia officinalis phenolics were increased in response to salinity at the threshold of 75 mmol L^?1 NaCl. This herb was also found to be able to achieve important DPPH^? quenching activity and to inhibit the β‐carotene‐linoleic acid bleaching notably enhanced by salt treatment. It is interesting to highlight the correlation between the phenolic and antioxidant activity, suggesting the involvement of these compounds in this activity. CONCLUSION: Salvia officinalis treated with 75 mmol L^?1 NaCl constitutes a potential source for production of secondary metabolites useful in several applications. Copyright © 2011 Society of Chemical Industry     

Optimisation of Spirulina platensis convective drying: evaluation of phycocyanin loss and lipid oxidation

The aim of the study was the optimisation of Spirulina platensis drying on convective hot air through the response surface methodology. The responses were thiobarbituric acid (TBA) and phycocyanin loss percentage values in final product. Experiments were carried out in perforated tray drier with parallel air flow, and the wet samples thickness and drying air temperatures were in range of 3–7 mm and 50–70 °C, respectively. The statistical analysis showed significant effect (P < 0.05) for air temperature and samples thickness. In the best drying condition, 55 °C and 3.7 mm, presented the phycocyanin loss percentage and the TBA values of approximately 37% and 1.5 mg_MDA kg^?1, respectively. In this drying condition, the fatty acids composition of the microalgae Spirulina did not show significance difference (P > 0.05) in relation to fresh biomass. The lipid profile of dried product presented high percentage of polyunsaturated fatty acids (34.4%), especially the gamma‐linolenic acid (20.6%).     

Improvement of the probiotic growth-stimulating capacity of microalgae extracts by pulsed electric fields treatment

This study aimed to investigate the nutritional character (carbohydrates, proteins, pigments, and phycocyanin), total antioxidant capacity (TAC) and the capability of simulating the growth of Lactobacillus rhamnosus of different extracts from C. vulgaris and A. platensis by means of the application of conventional aqueous extraction procedure and pulsed electric field (PEF) extraction technology. It was confirmed a significantly improved nutritional profile of Chlorella and Spirulina extracts obtained by PEF technology pre-treatment (3 kV/cm, 100 kJ/kg), with specifically higher values in total carbohydrate, Chlorophyll a, Chlorophyll b, and carotenoids content, and TAC. Additionally, Spirulina PEF extract showed a probiotic's growth-stimulating capability of 1 log10 cycle when fermented by Lactobacillus rhamnosus, with a metabolomic profile specifically rich in bioactive short chain fatty acids (SCFAs) and organic acids (3-phenyl lactic acid). The present study points out the applicability of PEF extraction technology under optimized conditions to improve the nutritional and functional character of microalgae and cyanobacterial-derived ingredients.     

Fruit Phenolic Composition of Different Elderberry Species and Hybrids

The aim of this study was to investigate a detailed composition and content of phenolic compounds in fruits of 4 elderberry species (Sambucus nigra, S. cerulea, S. ebulus, and S racemosa) and 8 interspecific hybrids. Hydroxycinnamic acids (HCAs) represented the major share of phenolics in analyzed elderberries; caffeoylquinic and p‐coumaroylquinic acids were most abundant. Flavanols (catechin, epicatechin, and different procyanidins) were the second major phenolic group detected in range from 2% to 30% of total analyzed phenolics. From the group of flavonols, 13 different quercetin glycosides, 7 kaempferol glycosides, and 8 isorhamnetin glycosides have been quantified. Rutin was the major flavonol in all studied genotypes. S. ebulus was characterized by the highest level of total HCAs, catechin, epicatechin, and most flavonols. Some elderberry hybrids, for example JA × RAC, CER × NI, and JA × (JA × NI), are perspective for further studies because they have high content of phenolic compounds. The results of research could contribute to breed cultivars, which may prove interesting for food‐processing industries.     

A comparative study on the fungal communities of wheat Qu for Qingshuang‐type Chinese rice wine

A traditional culture‐dependent method and ribosomal intergenic spacer analysis (RISA) were employed to investigate the fungal communities in two representative samples of wheat Qu (S1, S2). A total of seven species were isolated on media of potato dextrose agar, Czapek and wheat Qu extraction. Owing to the difference in the culture media, a high variability of predominant species was observed. RISA profiles of total DNA exhibited distinguishable bands corresponding to nine fungal species. Similar RISA profiles of two starter cultures were obtained. Sequencing of the internal transcribed spacer fragments from fungal isolates and RISA fingerprint profiles revealed the presence of nine species of fungi in wheat Qu S1: Lichtheimia ramosa, Absidia corymbifera, Aspergillus sydowii, Aspergillus oryzae, Rhizomucor pusillus, Eurotium amstelodami, Issatchenkia orientalis, Emericella nidulans and Cladosporium cladosporioides. In comparison with S1, S2 had a richer fungal diversity. The fungal species derived from S1 were all present in S2 coupled with another two species, namely, Aspergillus niger and Clavispora lusitaniae. Among all species isolated, Aspergillus sydowii was the dominant species in Qingshuang‐type Chinese rice wine wheat Qu. Copyright © 2012 The Institute of Brewing & Distilling     

Fractionation of lipids and purification of γ-linolenic acid (GLA) from Spirulinaplatensis

The microalgae, Spirulinaplatensis, is an excellent source of γ-linolenic acid (GLA), an essential polyunsaturated fatty acid and a potent nutraceutical. The fatty acid composition of S.platensis ARM 740 was determined after transmethylation by gas chromatography (GC). Lipid fractionation was achieved on silica gel column chromatography and preparative TLC. Neutral lipids, glycolipids and phospholipids accounted for 77.0%, 15.6% and 7.4%, respectively, of the total lipid fraction. S.platensis ARM 740 was found to contain 94% of the total GLA in the glycolipid fraction. Attempts were made to purify GLA methyl ester by using urea to form inclusion complexes with the saturated and the less unsaturated FAMEs (fatty acid methyl esters), which enhanced the purity of GLA methyl ester to 84%. A further approach to isolate GLA methyl ester with higher purity involved the use of argentated silica gel chromatography. An initial PUFA concentration step frequently adopted by most researchers to increase GLA purity was not necessary in the isolation of GLA from S.platensis. A GLA methyl ester with a purity of >96% and a recovery of 66% was obtained. Purity of the isolated GLA methyl ester was confirmed by GC and IR analysis with respect to authentic standard.     

Microbial diversity and stability during primary cultivation and subcultivation processes of Tibetan kefir

In this study, we have investigated the microbial diversity and stability in the Tibetan kefir during the primary cultivation and subcultivation processes via a combination of culture‐independent and culture‐dependent methods. According to the culture‐independent methods, the profiles of PCR‐DGGE (polymerase chain reaction–denaturing gradient gel electrophoresis) indicated that nine microbial species were predominant at different cultivation stages; seventy four isolates of seven predominant species were obtained and identified via the culture‐dependent methods. PCR‐DGGE further confirmed that Lactobacillus kefiranofaciens, Lactobacillus kefiri, Lactobacillus paracasei, Streptococcus thermophilus, Kazachstania unispora and Saccharomyces cerevisiae were the most dominant species in the Tibetan kefir during the process of primary cultivation, among which Lb. kefiri, Lb. paracasei and K. unispora showed relative strong stability during both the processes of primary cultivation and subcultivation. These findings suggested that some isolates of the three species possessed the potentiality of being used in the development of direct vat set (DVS) starters for the production of Tibetan kefir and the related products.     

Determination of lactic microflora of kefir grains and kefir beverage by using culture-dependent and culture-independent methods

Abstract: In this study, we investigated the bacterial compositions of kefir grains and kefir beverages collected from different regions of Turkey by using culture‐independent and culture‐dependent methods. In the culture‐independent detection, 10 different species of bacteria were detected in total by using the polymerase chain reaction‐denaturing gradient gel electrophoresis (PCR‐DGGE) analysis of the 16S rRNA gene V3 region. Among these species, Lactobacillus kefiranofaciens was the most dominant one in the kefir grains, while Lactococcus lactis was found to be significantly prevalent in the kefir beverages. In the culture‐dependent detection, the primary differentiation and grouping of the isolates from kefir beverages and kefir grains were performed using repetitive sequence‐based PCR (rep‐PCR) fingerprinting, and the results were validated by 16S rDNA full‐length sequencing. According to the results of culture‐dependent methods, the most frequently isolated species were L. lactis, Leuconostoc mesenteroides, and Lactobacillus kefiri, respectively. Only 3 species, which are L. lactis, Lactobacillus acidophilus, and Streptococcus thermophilus, were detected with both culture‐dependent and culture‐independent methods. This study showed that the combination of both methods is necessary for a detailed and reliable investigation of microbial communities in kefir grains and kefir beverages. Practical Application: Due to their artisan‐ and region‐dependent microflora, kefir products can be a source of interesting lactic acid bacteria, either new taxa or strains with specific functional properties, which might be used for the development of new starter cultures and innovative food products. Therefore, an increasing demand exists for new strains that show desirable effects on the product characteristics Artisan dairy products are a candidate source of such microorganisms. For this reason, in this study, the bacterial compositions of kefir grains and kefir beverages obtained from different regions of Turkey were studied using culture‐dependent and culture‐independent molecular methods.     

Investigation of nutraceutical potential of the microalgae Chlorella vulgaris and Arthrospira platensis

The microalgae Chlorella vulgaris and Arthrospira platensis were evaluated as nutraceuticals. It was observed that Arthrospira platensis is richer in saturated fatty acids (FA) and Chlorella vulgaris richer in monounsaturated FA. Within polyunsaturated FA (PUFA), n3 PUFA content was below 1% in Arthrospira sp and over 10% in Chlorella vulgaris. This microalga had the lowest polyphenolic content. The highest value was found in the aqueous extract of Arthrospira platensis, 334 ± 32 mg GAE per 100 g dw. Regarding DPPH, only aqueous extracts of Chlorella vulgaris yielded antioxidant activity with an inhibitory activity of 80 ± 1%. ABTS results showed stronger inhibition through the aqueous extracts than through the ethanolic extracts, 89%–93% vs. 24%–32%. Concerning cytotoxicity, ethanolic extracts of Chlorella vulgaris induced a cell viability decrease of approximately 80%. The biochemical characterisation and bioactivity assessment of Chlorella vulgaris and Arthrospira platensis showed that these microalgae have potential for nutraceutical applications.     

Response surface optimisation for the extraction of phenolics and flavonoids from a pink guava puree industrial by‐product

Pink guava puree industry produces huge amount of by‐products that have potential as sources for polyphenols. Response surface methodology was implemented to optimise the extraction conditions for phenolics (Y₁) and flavonoids (Y₂) from a by‐product of the guava industry. A three‐factor inscribed central composite design was employed to determine the effects of three independent variables, namely pH (X₁: 2–6), temperature (X₂: 40–60 °C) and time (X₃: 1–5 h), on the response variables. The corresponding predicted values for phenolics and flavonoids were 336.30 and 427.35 mg 100 g^?1, respectively. Predicted values for extraction rates of phenolics agreed well with experiment values; R² of 0.902. However, the model derived for flavonoids extraction was less reliable; R² of 0.983. Increase in time and temperature was found significant in increasing the extraction rate. The optimum conditions for extracting phenolics by ethanolic solvent occurred at a pH of 2 and 60 °C for a 5‐h extraction.     

Comparative evaluation of physicochemical,functional and texture properties and sensory acceptance of different instant rice varieties coated with Spirulina and edible polymers

This study aimed to determine the influence of Spirulina platensis and edible polymer coating on the physicochemical and texture properties, and sensory acceptance of coated instant rice: glutinous white rice (GWR), glutinous black rice (GBR), non-glutinous white rice (NWR) and non-glutinous black rice (NBR). Instant rice was cooked and dried, and then coated by a pan-coating process. Black rice varieties (GBR and NBR) showed higher amounts of protein, fibre, ash and bioactive compounds than white rice varieties (GWR and NWR). The Spirulina-coated rice had significantly improved texture properties, especially black rice cultivars. The hedonic rating of the coated instant rice ranged from 5 (neither like nor dislike) to 6 (slightly liked), and GBR obtained a higher acceptability score (6.93). Principal component analysis models allowed sample classification. Therefore, fortification with Spirulina as a coating on instant rice could be an alternative way to produce functional instant rice with extra health benefits.     

Inhibitory effect of phenolics extracted from sorghum genotypes on Aspergillus parasiticus (NRRL 2999) growth and aflatoxin production

The inhibitory activity of bioactive polyphenols present in six sorghum genotypes—two red (AON 486 and IS 620), two yellow (LPJ and IS 17779) and two white (SPV 86 and SPV 462) varieties—on Aspergillus parasiticus (NRRL 2999) growth and aflatoxin production was evaluated. In the first experiment the production of aflatoxins in the six sorghum genotypes after removal of surface phenolics by acidic methanol treatment was studied and compared with that in untreated grains. Aflatoxin production was found to be fourfold higher in treated grains. The total phenols and bioactive polyphenols extracted by acidic methanol were quantified using the Folin–Denis method and the bovine serum albumin–benzidine conjugate procedure respectively. In the second experiment the effect of extracted sorghum phenolics under in vitro conditions on fungal growth and aflatoxin production was studied at two concentrations (0.01% and 0.1%) of phenolics. Extracted phenolics added to yeast extract sucrose (YES) medium at 0.1% concentration showed an inhibitory effect on aflatoxin production. At 0.01% phenolic concentration, aflatoxin production was minimal on day 3 after infection. At other time points the aflatoxin content was similar to that in the control. At 9 days after infection the fungal biomass in IS 620 was significantly lower than that in the control. At 0.1% phenolic concentration, aflatoxin production was minimal and the red genotype IS 620 showed maximum resistance. Fungal biomass was lowest at all growth stages in IS 620 as compared with the control. Polyphenol oxidase (PPO) activity was not detected in A. parasiticus grown on YES medium (control). PPO activity was not induced in A. parasiticus by the addition of phenolics to the liquid culture medium (no PPO activity was detected in the culture medium). The inhibitory activity of bioactive polyphenols could be attributed to the lack of PPO enzyme in this fungus. Copyright © 2007 Society of Chemical Industry     

Effects of steeping and germination time on growth rate and phenolics content of Nigerian Sorghum bicolor and Sorghum vulgare seedlings

Moisture content and enthalpy, growth rates, and phenolics of germinating grains of Sorghum bicolor Moench (SK) and Sorghum vulgare L (LR) were evaluated as functions of steeping time, air-rest and formalin treatments, and germination time. Results obtained showed that 24-h steeping gave rise to the highest growth rate, which was greater for LR than SK. The moisture and enthalpy which gave rise to optimum germination rate were 0.48 and 0.48 kg kg^?1, 422.69 and 392.32 kJ kg^?1 for LR and SK, respectively. Air-rested steeping effected the maximum growth rate as well as high phenolics retention in the germinated grains. Formalin re-steeping imparted 71.32 and 68.88 % reduction in phenolics in LR and SK, respectively, while causing very low growth rate in the seedlings. However, no significant difference was found (P = 0.05) between FRS and low-temperature steeping for the two parameters.     

Investigation of Microbial Communities of Chinese Sourdoughs Using Culture‐Dependent and DGGE Approaches

Sourdough is typically characterized by the complex microbial communities mainly comprising of yeasts and lactic acid bacteria (LAB). The objective of this study was to explore the microbiota of Chinese traditional sourdoughs collected from different areas of China using culture‐dependent and denaturing gradient gel electrophoresis (DGGE) methods. A total of 131 yeasts, 2 molds, and 106 LAB strains were isolated and identified. Based on the culture‐dependent analysis, the populations of yeasts and LAB were at the level of 10⁵ to 10⁷ and 10⁶ to 10⁷ cfu/g, respectively. Similarly, the results of RT‐qPCR showed that the values of total yeasts and LAB populations were in the range of 10⁶ to 10⁷ and 10⁷ to 10⁸ copies/g, respectively. Using culture‐dependent method, a total of 7 yeasts, 2 molds and 7 LAB species were identified. Results showed that Saccharomyces cerevisiae and Lactobacillus plantarum were the predominant species among the yeasts and LAB microflora. Similarly, using PCR‐DGGE approach, 7 yeasts, 1 mold and 9 LAB species were detected. The yeast, S. cerevisiae, represented the predominant, while the yeast Candida tropicalis represented the subdominant species of the yeast community. Among the LAB community, Lactobacillus sanfranciscensis was the predominant species, while Lactococcus qarvieae, Enterococcus faecium, Lactobacillus delbrueckii and Enterococcus cecorum were among the less dominant species.     

Iron-chelating ability and antioxidant properties of phycocyanin isolated from a protean extract of Spirulinaplatensis

The invitro scavenger activities of different reactive oxygen species (superoxide radical, hydroxyl radical, hydrogen peroxide, hypochlorous acid and peroxyl radical), the effects on lipid peroxidation and the iron-chelating ability of a Spirulinaplatensis protean extract and the biliprotein, phycocyanin, isolated from this microalga were studied. S. platensis protean extract inhibited the generation of hydroxyl radical (IC₅₀ = 537 μg/ml for the system with EDTA and 1500 μg/ml without EDTA), the production of peroxyl radical (IC₅₀ = 230 μg/ml), and the lipid peroxidation process (IC₅₀ = 2320 μg/ml for the enzymatic system and 2180 μg/ml for the non-enzymatic system). Besides, phycocyanin inhibited hydroxyl and peroxyl radicals and the lipid peroxidation process. The iron ions decreased the maximum fluorescence emission spectra of S. platensis protean extract and phycocyanin and it was an indicator of the metal-chelating activity. The antioxidant properties of S. platensis and phycocyanin may arise from both radical-scavenging and metal chelation. Our results suggest that S. platensis could be used as a dietary supplement to prevent some diseases where free radicals are involved.     

Growth Potential of Listeria Monocytogenes and Staphylococcus Aureus on Fresh‐Cut Tropical Fruits

The objective of this study was to evaluate the fate of Staphylococcus aureus, Listeria monocytogenes, and natural microbiota on fresh‐cut tropical fruits (pitaya, mango, papaya and pineapple) with commercial PVC film at different storage temperature (5, 13, and 25 °C). The results showed that S. aureus, L. monocytogenes, and natural microbiota increased significantly on fresh‐cut tropical fruits at 25 °C. Both pathogen and natural microbiota were able to grow on fresh‐cut tropical fruits at 13 °C. The maximum population of L. monocytogenes was higher than that of S. aureus on fresh‐cut tropical fruits. L. monocytogenes and S. aureus could survive without growth on fresh‐cut pitaya, mango, and papaya at 5 °C. The population of L. monocytogenes declined significantly on fresh‐cut pineapple at all temperature, indicating composition of fresh‐cut pineapple could inhibit growth of L. monocytogenes. However, S. aureus was still able to grow on fresh‐cut pineapple at storage temperature. Thus, this study suggests that 4 kinds of fresh‐cut tropical fruits (pitaya, mango, papaya, and pineapple) should be stored at low temperature to extend shelf life as well as to ensure the safety of fresh‐cut fruits.     

Antioxidant,Antibacterial, and Antiproliferative Activities of Free and Bound Phenolics from Peel and Flesh of Fuji Apple

This study was conducted to investigate the antioxidant, antibacterial, and antiproliferative activities of flesh free (FF), flesh bound (FB), peel free (PF), and peel bound (PB) phenolics from Fuji apple. The PB, which had highest total phenolic contents (126.15 ± 2.41 mg/100 g wet weight) and lowest total carbohydrate contents (34.68 ± 2.78 mg/100 g wet weight), showed the strongest 2,2’‐azinobis‐(3‐ethylbenthiazoline‐6‐sulphonate) (ABTS) radical scavenging activity (EC₅₀ = 0.36 ± 0.02 mg/mL), 1,1‐diphenyl‐2‐picryhydrazyl (DPPH) radical scavenging activity (EC₅₀ = 0.26 ± 0.01 mg/mL), and ferric reducing antioxidant power (Ferric reducing antioxidant power; EC₅₀ = 0.19 ± 0.02 mg/mL) compared with those of FF, FB, and PF. The PB also showed the strongest antibacterial activities on Escherichia coli, Staphylococcus aureus, and Listeria monocytogenes and it also showed the highest antiproliferative effects on Caco‐2 human colonic cancer cell (EC₅₀ = 1.44 ± 0.01 mg/mL) and Hela human cervical cell (EC₅₀ = 2.81 ± 0.01 mg/mL). Both free and bound phenolics from Fuji apple showed good antioxidant, antibacterial, and antiproliferative activities in our study, and bound phenolics had significantly higher activities compared with those of free phenolics.     

Characteristics of the leaf parts of some traditional Korean salad plants used for food

BACKGROUND: Total phenolics content, antioxidant activity and cytotoxicity of the methanol extracts from leaf parts of 13 Korean traditional salad plants were investigated in order to determine their properties. RESULTS: The highest phenolics content (mg ferulic acid equivalents kg^?1 dry weight (d.w.), omit one) was found in methanol extracts from Polygonum aviculare, at 293.7 ± 6.0, followed by Euonymus alatus, at 250.7 ± 3.3, Saxifraga stolonifera, at 125.0 ± 8.1 and Ligularia fischeri, at 122.5 ± 5.9. The methanol plant extracts dose‐dependently increased free radical scavenging activity. Methanol extracts of Polygonum aviculare, Euonymus alatus and Saxifraga stolonifera, at 31 mg kg^?1, exhibited the highest 1,1‐diphenyl‐2‐picrylhydrazyl (DPPH) radical scavenging activity (%) by 90.8 ± 4.2, 85.7 ± 3.9 and 64.1 ± 3.2, respectively. According to 3‐(4,5‐dimethylthiazol‐2‐yl)‐2,5‐diphenyltetrazolium bromide (MTT) assay, the methanol extracts from Portulaca oleracea (IC₅₀ < 25.0 µg mL^?1) showed the highest cytotoxicity against Calu‐6, followed by Plantago asiatica (49.2 µg mL^?1) and Osmunda japonica (89.6 µg mL^?1). CONCLUSION: Total phenolics content of the tested plant extracts was correlated with the DPPH radical scavenging activity, suggesting the phenolics compounds are contributing to the antioxidant properties of Korean salad plants. The leaf parts of the 13 Korean traditional salad plants described here that are currently used as foods may also provide some benefit to human health, and research into their potential benefits as preventative and/or therapeutic agents is warranted. Copyright © 2008 Society of Chemical Industry