Inhibition of malonaldehyde formation from lipids by an isoflavonoid isolated from young green barley leaves

Saponarin, a Di-glycosyl Flavone from Barley (Hordeum vulgare L.): An Effective Compound for Plant Defense and Therapeutic Application

Saponarin (SA) is a major di-C-glycosyl-O-glycosyl flavone, which is predominantly accumulated in the young green leaves of barley (Hordeum vulgare L.), with numerous biological functions in plants, such as protection against environmental stresses. Generally, SA synthesis and its localization in the mesophyll vacuole or leaf epidermis are largely stimulated in response to biotic and abiotic stresses to participate in a plant's defense response. In addition, SA is also credited for its pharmacological properties, such as the regulation of signaling pathways associated with antioxidant and anti-inflammatory responses. In recent years, many researchers have shown the potential of SA to treat oxidative and inflammatory disorders, such as in protection against liver diseases, and reducing blood glucose, along with antiobesity effects. This review aims to highlight natural variations of SA in plants, biosynthesis pathway, and SA's role in response to environmental stress and implications in various therapeutic applications. In addition, we also discuss the challenges and knowledge gaps concerning SA use and commercialization.

Antidiabetic effect of Equisetum giganteum L. extract on alloxan-diabetic rabbit

ETHNOPHARMACOLOGICAL RELEVANCE

Equisetum giganteum has been traditionally used as an anti-diabetic herbal remedy to treat diabetes in the southern state of Rio Grande do Sul in Brazil.

AIM OF THE STUDY

Considering the ethonopharmacology and historical importance of E. giganteum, its potential antidiabetic effect was evaluated in alloxan induced diabetic rabbits.

MATERIAL AND METHODS

Samples of Equisetum giganteum were collected in the city of Ouro Preto, Minas Gerais, Brazil. Butanolic and aqueous extracts were prepared and subsequently evaluated for anti-diabetic properties in vivo using albino male rabbits. At the end of the treatment period, the animals were euthanized, and histopathological analysis were carried out. The following biochemical parameters were studied: glucose, triacylglycerol, cholesterol, albumin, creatinine, glycosylated hemoglobin and lipase. The phytochemical profile of the extracts was studied by liquid chromatography techniques coupled to a UV/VIS detector and high-resolution mass spectrometry.

RESULTS

Both aqueous and butanolic extracts were capable of reducing significantly the levels of glucose, cholesterol and triacylglycerol and thus demonstrating their hypolipidemic and hypoglycemiant effects. Furthermore, the extracts prevented the occurrence of hepatic complications during treatment. The phytochemical profile of the extracts was investigated, and the natural products detected were in agreement with those that had been previously described in the literature.

CONCLUSION

Based on the significant reductions in biochemical parameters and the histologic evidence for the absence of complications in the liver, pancreas of the treated animals, Equisetum giganteum can be a therapeutically relevant resource in the treatment of diabetes and hyperlipidemia.

Young Barley Indicates Antitumor Effects in Experimental Breast Cancer In Vivo and In Vitro

The effect of dietary administered young barley containing a mixture of phytochemicals to female rats for the prevention of N-methyl-N-nitrosourea-induced mammary carcinogenesis was evaluated. After carcinogen administration (14 wk), mammary tumors were removed and prepared for histopathological and immunohistochemical analysis. Moreover, in vitro evaluation of possible mechanisms in MCF-7 breast cancer cell line was performed. Barley (0.3%) demonstrated mild antitumor effect in mammary carcinogenesis, yet 3% barley did not further improve this effect. Immunohistochemical analysis of rat tumor cells in treated groups showed significant increase in caspase-3 expression and significant reduction in Ki67 expression. In addition, 3% barley significantly decreased dityrosine levels versus control. Barley in higher dose significantly decreased serum low-density lipoprotein-cholesterol in rats. In vitro studies showed that barley significantly decreased survival of MCF-7 cells in 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay and significantly decreased 5-bromo-20-deoxyuridine incorporation versus control. Barley prevented cell cycle progression and extended incubation with barley showed significant increase in the percentage of annexin V/propidium iodide-positive MCF-7 cells. Our results propose an antitumor effect for the mixture of phytochemicals present in young barley in a breast cancer model.

A novel gas chromatographic method for determination of malondialdehyde from oxidized DNA

Malondialdehyde (MA) is known to form from various lipids upon oxidation as one of secondary oxidation products. Determination of MA formed from lipid peroxidation has been used to examine occurrence of oxidative damages associated with many diseases, such as cancer, Alzheimer's, arthritis, inflammation, diabetes, atherosclerosis, and AIDS as well as aging. Analysis of MA is, however, extremely difficult because it is highly reactive and readily polymerized and forming adducts with biological substances such as proteins, phospholipids, and DNA (Shibamoto, J Pharm Biomed Anal 41:12-25, 2002). Gas chromatographic method using stable derivative, 1-methylpyrazole was advanced and has been successfully used to analyze MA in various lipids and lipid-rich foods. This method was also applied to determine MA formed from DNA and related compounds. The amounts found in oxidized 2'-deoxyribonucleotides were 213.8 nmol/16 mmol in 2'-deoxyguanosine, 130.6 nmol/16 mmol in 2'-deoxycytidine, 85.1 nmol/16 mmol in 2'-deoxyadenosine, and 84.5 nmol/16 mmol in thymidine. When the antioxidant activity of flavonoids and anthocyanins against calf thymus DNA oxidized with Fenton's reagent was examined using this newly developed gas chromatographic method, antioxidant activity of flavonoids and anthocyanins ranged from 48.5% (catechin) to 29.9% (apigenin) and from 45.0% (callistephin) to 10.2% (cyaniding), respectively.

Flavonoids with potent antioxidant activity found in young green barley leaves

Saponarin, a flavonoid found in young green barley leaves, possesses potent antioxidant activities, which are determined by its inhibition of malonaldehyde (MA) formation from various lipids oxidized by UV light or Fenton's reagent. Lipids used were squalene, ethyl linoleate, ethyl linolenate, ethyl arachidonate, octadecatetraenoic acid (ODTA), eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA), cod liver oil, lecithin I, lecithin II, and blood plasma. The addition of saponarin inhibited the formation of MA from squalene upon UV irradiation at the level of 2 μmol/mL by almost 100%, whereas BHT inhibited its formation by 75% at the same level. Saponarin showed potent antioxidant activity toward fatty acid ethyl esters at levels >100 μg/mL. Saponarin inhibited MA formation in ODTA by 60%, in EPA by 50%, and in DHA by 43% at the level of 15 μmol/mL. Saponarin exhibited strong antioxidant activities with dose-response levels toward cod liver oil and lipoproteins (lecithins I and II), higher than those of α-tocopherol. A mixture of saponarin/lutonarin (4.5:1, w/w) inhibited MA formation appreciably from all lipids tested with dose response. This mixture exhibited highest effect toward cod liver oil (86%), followed by DHA, lecithin II, blood plasma, EPA, and lecithin I. Supplementation of young green barley leaves containing saponarin should be beneficial to health and may prevent diseases caused by oxidative damage such as various cancers, inflammations, and cardiovascular diseases.

Antioxidant activity of flavonoids isolated from young green barley leaves toward biological lipid samples

Natural plant flavonoids, saponarin/lutonarin=4.5/1, isolated from young green barley leaves were examined for their antioxidant activity using cod liver oil, omega-3 fatty acids, phospholipids, and blood plasma. The saponarin/lutonarin (S/L) mixture inhibited malonaldehyde (MA) formation from cod liver oil by 76.47+/-0.11% at a level of 1 micromol and 85.88+/-0.12% at a level of 8 micromol. The S/L mixture inhibited MA formation from the omega-3 fatty acids eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) by 45.60+/-1.08 and 69.24+/-0.24%, respectively, at a level of 8 micromol. The S/L mixture inhibited MA formation from the phospholipids lecithin I and II by 43.08+/-0.72 and 69.16+/-2.92%, respectively, at a level of 8 micromol. It also inhibited MA formation from blood plasma by 62.20+/-0.11% at a level of 8 micromol. The antioxidant activities obtained from the S/L mixture were comparable to those obtained from alpha-tocopherol and butylated hydroxy toluene (BHT) in all lipids tested.

Analytical methods for trace levels of reactive carbonyl compounds formed in lipid peroxidation systems

Analysis of trace levels of reactive carbonyl compounds (RCCs), including formaldehyde, acetaldehyde, acrolein, malonaldehyde, glyoxal, and methyl glyoxal, is extremely difficult because they are highly reactive, water soluble, and volatile. Determination of these RCCs in trace levels is important because they are major products of lipid peroxidation, which is strongly associated with various diseases such as cancer, Alzheimer's disease, aging, and atherosclerosis. This review covers the development and application of various derivatives for RCC analysis. Among the many derivatives which have been prepared, cysteamine derivatives for formaldehyde and acetaldehyde; N-hydrazine derivatives for acrolein, 4-hydroxy-2-nonenal, and malonaldeyde; and o-phenylene diamine derivatives for glyoxal and methyl glyoxal were selected for extended discussion. The application of advanced instruments, including gas chromatograph with nitrogen-phosphorus detector (GC/NPD), mass spectrometer (MS), high performance liquid chromatograph (HPLC), GC/MS, and LC/MS, to the determination of trace RCCs in various oxidized lipid samples, including fatty acids, skin lipids, beef fats, blood plasma, whole blood, and liver homogenates, is also discussed.

Formation and inhibition of genotoxic malonaldehyde from DNA oxidation controlled with EDTA

The attack of DNA by reactive oxygen species, such as hydroxyl radical, causes several types of damage, which subsequently promote diseases. Determination of oxidized products, such as malonaldehyde (MA), from DNA would provide theoretical and practical information on the mechanisms of DNA oxidation following DNA damage and this information could be used to prevent DNA damage caused by oxidation. In the present study, calf thymus DNA was oxidized by Fenton's reagent/EDTA with or without natural antioxidants-flavonoids and anthocyanins-and synthetic antioxidants, Trolox and 2H-pyrrole, 3,4-dihydro-2,2-dimethyl-, 1-oxide (DMPO). Amounts of MA formed, which was determined by gas chromatography, in oxidized DNA with the presence of antioxidants, ranged from 7.35+/-0.88 nmol/mg (2''-O-GIV) to 12.6+/-0.24 nmol/g (cyanidin). Except for cyanidin, all antioxidants tested inhibited MA formation. DMPO and Trolox inhibited MA formation by 12.4% and 27.3%, respectively from oxidized DNA. The decreasing order of inhibitory effect by the anthocyanins was callistephin (30.2%)>keracyanin (27.3%)>Pelargonindin (10.1%)>cyanidin (0%). The decreasing order of inhibitory effect by the flavonoids was 2''-O-GIV (42.7%)>catechin (8.8%)>quercetin (36.4%)>apigenin (34.4%). It is hypothesized that EDTA controlled formation of hydroxyl radicals via trapping Fe(II) ions reversibly.

Inhibition of malonaldehyde formation in oxidized calf thymus DNA with synthetic and natural antioxidants

Calf thymus DNA was oxidized by Fenton's reagent with or without synthetic antioxidants (Trolox and DMPO) and natural antioxidants-quercetin, apigenin, 2''-O-glycosylisovitexin (2''-O-GIV), (+)-catechin, cyanidin, pelargonidin, keracyanin, and callistephin. Malonaldehyde (MA) formed in oxidized DNA was analyzed using gas chromatography. MA formed from oxidized DNA without antioxidants was 4.0 +/- 0.53 nmol/mg of DNA in buffer solution, 3.7 +/- 0.34 nmol/mg of DNA in NaOH solution, and 4.6 +/- 0.19 nmol/mg of DNA in HCl solution. MA formed from DNA with antioxidants (at the level of 0.1 micromol/mL) ranged from 1.90 +/- 0.18 (catechin) to 4.10 +/- 0.18 nmol/mg of DNA (cyanidin). Trolox and DMPO inhibited MA formation from DNA by 41.2% and 18.6%, respectively, at the level of 0.1 micromol/mL. Trolox (water-soluble vitamin E) exhibited dose-dependent inhibition. The decreasing order of inhibitory effect by flavonoids at the level of 0.1 micromol/mL was catechin (48.5%) > quercetin (47.1%) > 2''-O-GIV (40.5%) > apigenin (29.9%) and by the anthocyanins at the level of 0.1 micromol/mL was callistephin (45%) > keracyanin (33.2%) > pelargonidin (25.1%) > cyanidin (10.2%).

Determination of antioxidant potential of volatile extracts isolated from various herbs and spices

Antioxidant activities of volatile extracts isolated from thyme, basil, rosemary, chamomile, lavender, and cinnamon were evaluated by two independent assays: the aldehyde/carboxylic acid assay and the conjugated diene assay. The volatile extracts were prepared from dried herbs and spices using liquid-liquid continuous extraction following steam distillation under reduced pressure (55 degrees C and 95 mmHg). The antioxidant activities of the extracts decreased in the following order in both of the lipophilic assay systems: thyme > basil > rosemary > chamomile > lavender and cinnamon. Thyme and basil extracts inhibited the oxidation of hexanal for 40 days at the levels of 10 microg/mL and 50 microg/mL, respectively. The extracts of thyme and basil were effective in retarding methyl linoleate deterioration at 40 degrees C, with activity increasing with concentration in the range 10-200 microg/mL. At a concentration of 50 microg/mL, thyme extract was similar in antioxidant activity to BHT and alpha-tocopherol in the conjugated diene assay. The antioxidant potentials of the volatile extracts used in this study were accurately measured by the lipophilic systems, such as the aldehyde/carboxylic acid assay and the conjugated diene assay.

Effect of the natural antioxidant 2"-O-glycosylisovitexin on superoxide and hydroxyl radical generation

The inhibitory effect of 2"-O-glycosyl isovitexin (2"-O-GIV) isolated from green barley leaves on superoxide and hydroxyl radical generation was investigated using electron spin resonance spectroscopy. 2"-O-GIV exhibited dose-related inhibitory activity both towards superoxide generation and hydroxyl radical generation. 2"-O-GIV inhibited superoxide formation by 97% at a level of 25 mM and inhibited hydroxyl radical formation by 91% at a level of 500 microM. The results suggest that the inhibitory activity of 2"-O-GIV is due to trapping radicals.

Inhibition of lipid peroxidation and the active oxygen radical scavenging effect of anthocyanin pigments isolated from Phaseolus vulgaris L

No attention has been paid to anthocyanin pigments from the viewpoint of inhibitors of lipid peroxidation and scavengers of active oxygen radicals; therefore, we investigated the antioxidative, radical scavenging, and inhibitory effects on lipid peroxidation by UV light irradiation of three anthocyanin pigments, pelargonidin 3-O-beta-D-glucoside (P3G), cyanidin 3-O-beta-D-glucoside (C3G), and delphinidin 3-O-beta-D-glucoside (D3G), isolated from the Phaseolus vulgaris L. seed coat, and their aglycons, pelargonidin chloride (Pel), cyanidin chloride (Cy), and delphinidin chloride (Del). All pigments had strong antioxidative activity in a liposomal system and reduced the formation of malondialdehyde by UVB irradiation. On the other hand, the extent of antioxidative activity in a rat liver microsomal system and the scavenging effect of hydroxyl radicals (-OH) and superoxide anion radicals (O2-) were influenced by their own structures.