Free-radical scavengers and antioxidants from Peumus boldus Mol. ("Boldo")

The dry leaves of Peumus boldus (Monimiaceae) are used in infusion or decoction as a digestive and to improve hepatic complains. Preliminary assays showed free-radical scavenging activity in hot water extracts of boldo leaves, measured by the decoloration of a methanolic solution of the 1,1-diphenyl-2-picryl-hydrazyl radical (DPPH). Assay-guided isolation led to the active compounds. Catechin proved to be the main free-radical scavenger of the extracts. Lipid peroxidation in erythrocytes was inhibited by boldo extracts and fractions at 500 μg/ml with higher effect for the ethyl acetate soluble and alkaloid fractions. The IC 50 for catechin and boldine in the lipid peroxidation test were 75.6 and 12.5 μg/ml, respectively. On the basis of dry starting material, the catechin content in the crude drug was 2.25% while the total alkaloid calculated as boldine was 0.06%. The activity of boldine was six times higher than catechin in the lipid peroxidation assay. However, the mean catechin:total alkaloid content ratio was 37:1. The relative concentration of alkaloids and phenolics in boldo leaves and their activity suggest that free-radical scavenging effect is mainly due to catechin and flavonoids and that antioxidant effect is mainly related with the catechin content. The high catechin content of boldo leaves and its bioactivity suggest that quality control of Boldo folium has to combine the analysis of catechin as well as their characteristic aporphine alkaloids.     

Antioxidant and nitric oxide synthase activation properties of Auricularia auricula

In vitro evaluation of antioxidant activities of Auricularia auricula showed significant inhibition of lipid peroxidation, and potent hydroxyl radical scavenging activity when compared with standard drug catechin. IC5o value of crude, boiled and ethanolic extracts of A. auricula represented 403, 510, and 373 microg/ml respectively in case of hydroxyl radical scavenging activity and 310, 572 and 398 microg/ml respectively in case of lipid peroxidation. Furthermore, crude, boiled and ethanolic extracts also increase significantly nitric oxide production (664, 191 and 850 pmole/mg dry wt/hr respectively) over the control. The present results revealed that A. auricula had potential therapeutic use.     

Antioxidant and nitric oxide synthase activation properties of Ganoderma applanatum

In vitro evaluation of antioxidant activities of Ganoderma applanatum showed significant inhibition of lipid peroxidation, and potent hydroxyl radical scavenging activity when compared with standard drug catechin. IC50 values of crude, boiled and ethanolic extracts of G. applanatum were 604.8, 624 and 267 microg/ml, respectively in case of hydroxyl radical scavenging activity, and 441, 520.5 and 166.16 microg/ml, respectively in case of lipid peroxidation. Furthermore, crude, boiled and ethanolic extracts also increased significantly nitric oxide production (156.67, 121.88 and 742 pmole/mg dry wt/hr, respectively) over the control. The results of present investigation revealed that G. applanatum have potential therapeutic use.     

Bioflavonoids as antiradicals,antioxidants and DNA cleavage protectors

Flavonoids have recently aroused considerable interest because of their broad pharmacological activity. In fact, flavonoids have been reported to have antiviral, antiallergic, antiplatelet, anti-inflammatory and antitumoral activities. The pharmacological properties of bioflavonoids have been ascribed both to the concomitant inhibition of enzymes involved in the production of free radicals and to their free-radical scavenging and iron chelating capacity. However the antioxidant capacity of bioflavonoids due to free-radical scavenging and/or to iron chelating is still controversial. In this study, we have investigated the free-radical scavenging capacity of bioflavonoids (rutin, catechin, and naringin). In addition, the effects of these polyphenols on xanthine oxidase activity, spontaneous lipid peroxidation, and DNA cleavage were investigated. The bioflavonoids under examination showed a dose-dependent free-radical scavenging effect, a significant inhibition of xanthine oxidase activity, and an antilipoperoxidative capacity. In addition, they showed a protective effect on DNA cleavage. This revised version was published online in July 2006 with corrections to the Cover Date.     

Free-radical scavenging by Ouratea parviflora in experimentally-induced liver injuries

The antioxidant potential of crude extracts and fractions from leaves of Ouratea parviflora, a Brazilian medicinal plant used for the treatment of inflammatory diseases, was investigated in vitro through the scavenging of radicals 2-diphenyl-1-picryl-hydrazyl-hydrate (DPPH), hydroxyl radical (HO*), superoxide anion (O2*-), and lipid peroxidation in rat liver homogenate. The crude extract (CEOP) and hydro-alcoholic fraction (OP4) showed strong inhibitory activity toward lipid peroxidation induced by tert-butyl peroxide (IC50 = 2.3 +/- 0.2 and 1.9 +/- 0.1 microg/ml, respectively). The same products exhibited a strong concentration-dependent inhibition of deoxyribose oxidation (14.9 +/- 0.2 and 0.2 +/- 0.1 microg/ml, respectively), and also showed a considerable antioxidant activity against O2*- (87.3 +/- 0.1 and 73.1 +/- 0.4 microg/ml, respectively) and DPPH radicals (55.4 +/- 0.3 and 38.3 +/- 0.4 microg/ml, respectively). The protective effects of CEOP and OP4 were also studied in mouse liver. CCl4 significantly increased (by 90%) levels of lipid hydroperoxides, carbonyl protein content (64%), DNA damage index (133%), aspartate aminotransferase (261%), alanine aminotransferase (212%), catalase activity (23%), and also caused a decrease of 60% in GSH content. The results showed that CEOP and OP4 exerted cytoprotective effects against oxidative injury caused by CCl4 in rat liver, probably related to the antioxidant activity showed by the in vitro free radical scavenging property.     

Antioxidant activity of extract from Polygonum cuspidatum

Numerous diseases are induced by free radicals via lipid peroxidation, protein peroxidation and DNA damage. It has been known that a variety of plant extracts have antioxidant activities to scavenge free radicals. Whether Polygonum cuspidatum Sieb. et Zuce has antioxidant activity is unknown. In this study, dried roots of Polygonum cuspidatum were extracted by ethanol and the extract was lyophilized. Free radical scavenging assays, superoxide radical scavenging assays, lipid peroxidation assays and hydroxyl radical-induced DNA strand scission assays were employed to study antioxidant activities. The results indicate that the IC50 value oí Polygonum cuspidatum extract is 110 microg/ml in free radical scavenging assays, 3.2 microg/ml in superoxide radical scavenging assays, and 8 microg/ml in lipid peroxidation assays, respectively. Furthermore, Polygonum cuspidatum extract has DNA protective effect in hydroxyl radical-induced DNA strand scission assays. The total phenolics and flavonoid content of extract is 641.1 +/- 42.6 mg/g and 62.3 +/- 6.0 mg/g. The results indicate that Polygonum cuspidatum extract clearly has antioxidant effects.     

Antioxidant activities of cultured Armillariella mellea

This study aimed to evaluate the antioxidant activities of a cultured medicinal fungus--Armillariella mellea (Vahl. ex Fr.) Karst. (AM). Three antioxidant assay systems, namely cytochrome c, xanthine oxidase inhibition and FeCl2-ascorbic acid stimulated lipid peroxidation in rat tissue homogenate tests, were used. Total flavonoid and phenol contents of AM extracts were also analyzed. Results showed that both aqueous (AM-H2O) and ethanolic (AM-EtOH) extracts of solid state cultured AM showed antioxidant activities in a concentration-dependent manner. At concentrations 1-100 microg/ml, the free radical scavenging activity was 73.7-92.1% for AM-H2O, and 60.0-90.8% for AM-EtOH. These extracts also showed an inhibitory effect on xanthine oxidase activity, but with a lesser potency (IC50 - 9.17 microg/ml for AM-H2O and 7.48 microg/ml for AM-EtOH). In general, AM-H2O showed a stronger anti-lipid peroxidation activity on different rat's tissues than AM-EtOH. However, both AM extracts displayed a weak inhibitory effect on lipid peroxidation in plasma. Interestingly, the anti-lipid peroxidation activity of AM-H2O (IC50 - 6.66 microg/ml) in brain homogenate was as good as alpha-tocopherol (IC50 - 5.42 microg/ml). AM-H2O (80.0 mg/g) possessed a significant higher concentration of total flavonoids than AM-EtOH (30.0 mg/g), whereas no difference was noted in the total phenol content between these two extracts. These results conclude that AM extracts possess potent free radical scavenging and anti-lipid peroxidation activities, especially the AM-H20 in the brain homogenate.     

Antioxidant activity and protective effect on DNA cleavage of extracts from Cistus incanus L. and Cistus monspeliensis L.

The genus Cistus includes many typical species of Mediterranean flora; Cistus species are used as antidiarrheics, as general remedies for treatment of various skin diseases in folk medicine and as anti-inflammatory agents. These species contain flavonoids that are considered to be chain-breaking antioxidants. In this work, we have investigated the effects of crude aqueous extracts from Cistus incanus and Cistus monspeliensis on DNA cleavage and their free-radical scavenging capacity. In addition, their effect on lipid peroxidation in rat liver microsomes was evaluated. These extracts showed a protective effect on DNA cleavage and a dose-dependent free-radical scavenging capacity; Cistus monspeliensis was more active than Cistus incanus; these results were confirmed by a significant inhibition of lipid peroxidation in rat liver microsomes. The experimental evidence, therefore, suggests that because of their antioxidant activity these extracts may offer excellent photoprotection for skin and may be useful in the treatment of human diseases where oxidative stress plays a key role. This revised version was published online in July 2006 with corrections to the Cover Date.     

Spatio‐Temporal Variation of Alkaloids in Annona purpurea and the Associated Influence on Their Antifungal Activity

Annona purpurea grows in the areas of low elevation in deciduous forests of Mexico, those areas have marked rainy and dry seasons. This species produces more than 30 bioactive alkaloids that could have potential in the control of phytopathogens. This research provides data on the variation of the content and number of alkaloids during an annual cycle and the associated inhibitory potential of the compounds against three phytopathogenic fungi. For one year, alkaloidal extracts of stems and leaves were obtained every two months. The extract profiles were determined by gas chromatography with tandem mass spectrometry and their antifungal activity was examined in vitro. The alkaloids, annomontine and oxopurpureine, obtained from the roots and leaves, respectively, were also evaluated individually. The yields, profiles and activities of the extracts, as well as the abundance of annomontine and oxopurpureine in the extracts, were contrasted with the seasonality and phenological phases of the plant. The data indicate that the alkaloid content was higher at the height of the dry season. High yields also occurred during flowering. The strongest inhibitory effect was obtained from the root extracts during the last month of dry season. This finding seems to be explained by the higher chemodiversity of alkaloids in extracts from this season. Annomontine and oxopurpureine inhibited all three phytopathogens; however, they were not solely responsible for the activity of A. purpurea.     

Antioxidant activity of extract from Polygonum aviculare L

Free radicals induce numerous diseases by lipid peroxidation, protein peroxidation, and DNA damage. It has been reported that numerous plant extracts have antioxidant activities to scavenge free radicals. Whether Polygonum aviculare L. (Polygonaceae) has antioxidant activity is unknown. In this study, dried Polygonum aviculare L. was extracted by ethanol, and the extract was lyophilized. The antioxidant activities of extract powder were examined by free radical scavenging assays, superoxide radical scavenging assays, lipid peroxidation assays and hydroxyl radical-induced DNA strand scission assays. The results show that the IC50 value of Polygonum aviculare L. extract is 50 microg/ml in free radical scavenging assays, 0.8 microg/ml in superoxide radical scavenging assays, and 15 microg/ml in lipid peroxidation assays, respectively. Furthermore, Polygonum aviculare L. extract has DNA protective effect in hydroxyl radical-induced DNA strand scission assays. The total phenolics and flavonoid content of extract is 677.4 +/- 62.7 microg/g and 112.7 +/- 13 microg/g. The results indicate that Polygonum aviculare L. extract clearly has antioxidant effects.     

<Emphasis Type="Italic">Peumus boldus</Emphasis> (Boldo) Aqueous Extract Present Better Protective Effect than Boldine Against Manganese-Induced Toxicity in <Emphasis Type="Italic">D. melanogaster</Emphasis>

The cellular, intracellular and molecular mechanism(s) underlying the toxicity of Mn are still incompletely understood, although several points concerning Mn neurotoxicity have been addressed. Importantly, oxidative changes have been reported to be involved in Mn-induced toxicity. As a consequence, antioxidants are expected to offer protection in Drosophila melanogaster exposed to this metal. So, in this study we evaluated the hypothesis that the aqueous extract of boldo (Peumus boldus), and its alkaloids boldine, could prevent/ameliorate behavioral and oxidative alterations induced by Mn in a D. melanogaster intoxication model. Adult wild-type flies were concomitantly exposed to Mn (3 mM) and boldo aqueous extract (5 mg/mL) or boldine (327.37 µg/mL) in the food during 9 days. Mn-fed flies had a worse performance in the negative geotaxis assay and in the open-field test, as well as a higher incidence of mortality and TBARS levels in head and body, when compared to control group. Boldo aqueous extract was found to reduce the mortality rate of the flies exposed to Mn. In turn, boldine was ineffective against Mn-induced mortality and significantly increases mortality per se. Additionally, Mn-induced locomotors dysfunction were fully ameliorated by boldo crude extract and only partially ameliorated by boldine. Likewise, boldo completely normalize head and body TBARS levels, whereas boldine only partially normalize in body. Finally, we found that flies treated with Mn presented significantly decrease in dopamine levels. Our results suggest that boldo crude extract can exert protective effect against Mn-induced toxicity in D. melanogaster, whereas boldine do not. Moreover, our data confirm the utility of this model to investigate potential therapeutic strategies on movement disorders, such as that caused by Mn.     

In vitro antioxidant studies in leaves of Annona species

Antioxidant potential of leaves of three different species of Annona was studied by using different in vitro models eg., 1,1-diphenyl-2-picryl hydrazyl (DPPH), 2,2-azinobis-(3-ethylbenzothizoline-6-sulphonate) (ABTS), nitric oxide, superoxide, hydroxy radical and lipid peroxidation. The ethanolic extract of A. muricata at 500 microg/ml showed maximum scavenging activity (90.05%) of ABTS radical cation followed by the scavenging of hydroxyl radical (85.88%) and nitric oxide (72.60%) at the same concentration. However, the extract showed only moderate lipid peroxidation inhibition activity. In contrast, the extract of A. reticulata showed better activity in quenching DPPH (89.37%) and superoxide radical (80.88%) respectively. A.squamosa extract exhibited least inhibition in all in vitro antioxidant models excepting hydroxyl radical (79.79%). These findings suggest that the extracts of A. muricata possess potent in vitro antioxidant activity as compared to leaves of A. squamosa and A. reticulata suggesting its role as an effective free radical scavenger, augmenting its therapeutic     

Antioxidant Action of Benzylisoquinoline Alkaloids

The antioxidant action of a series of benzylisoquinoline alkaloids has been investigated. Laudanosoline, protopapaverine, anonaine, apomorphine, glaucine, boldine, bulbocapnine, tetrahydroberberine and stepholidine produced a dose-dependent inhibition of microsomal lipid peroxidation induced by Fe²⁺/ascorbate, CCl₄/NADPH or by Fe³⁺ADP/NADPH. Apomorphine exerted the highest inhibitory effects in the three systems of induction used, with a potency higher than propyl gallate. Laudanosoline was particularly effective in the first system, while bulbocapnine and anonaine were more potent when CCl₄/NADPH or Fe³⁺ -ADP/NADPH were used as inducers. Laudanosoline, protopapaverine, apomorphine, tetrahydroberberine and stepholidine were also potent inhibitors of nitroblue tetrazolium (NBT) reduction. The presence of a free hydroxyl group or preferably of a catechol group is a feature relevant for inhibition of lipid peroxidation and NBT reduction, nevertheless the antioxidant activity of benzylisoquinoline alkaloids cannot be only ascribed to the formation of phenoxy radicals and other free radical species may be formed during aporphine and tetrahydroprotoberberine oxidation. The influence of this series of compounds on the time course of lipid peroxidation suggests that some of them, like apomorphine and boldine act as chain-breaking antioxidants.     

Free-radical scavenging by Ouratea parviflora in experimentally-induced liver injuries

Abstract

The antioxidant potential of crude extracts and fractions from leaves of Ouratea parviflora, a Brazilian medicinal plant used for the treatment of inflammatory diseases, was investigated in vitro through the scavenging of radicals 2-diphenyl-1-picryl-hydrazyl-hydrate (DPPH), hydroxyl radical (HO^?), superoxide anion (O₂^??), and lipid peroxidation in rat liver homogenate. The crude extract (CEOP) and hydro-alcoholic fraction (OP4) showed strong inhibitory activity toward lipid peroxidation induced by tert-butyl peroxide (IC₅₀ = 2.3 ± 0.2 and 1.9 ± 0.1 μg/ml, respectively). The same products exhibited a strong concentration-dependent inhibition of deoxyribose oxidation (14.9 ± 0.2 and 0.2 ± 0.1 μg/ml, respectively), and also showed a considerable antioxidant activity against O₂^??(87.3 ± 0.1 and 73.1 ± 0.4 μg/ml, respectively) and DPPH radicals (55.4 ± 0.3 and 38.3 ± 0.4 μg/ml, respectively). The protective effects of CEOP and OP4 were also studied in mouse liver. CCl₄ significantly increased (by 90%) levels of lipid hydroperoxides, carbonyl protein content (64%), DNA damage index (133%), aspartate aminotransferase (261%), alanine aminotransferase (212%), catalase activity (23%), and also caused a decrease of 60% in GSH content. The results showed that CEOP and OP4 exerted cytoprotective effects against oxidative injury caused by CCl₄ in rat liver, probably related to the antioxidant activity showed by the in vitro free radical scavenging property.     

Boldine and its antioxidant or health-promoting properties

The increasing recognition of the participation of free radical-mediated oxidative events in the initiation and/or progression of cardiovascular, tumoural, inflammatory and neurodegenerative disorders, has given rise to the search for new antioxidant molecules. An important source of such molecules has been plants for which there is an ethno-cultural base for health promotion. An important example of this is boldo (Peumus boldus Mol.), a chilean tree whose leaves have been traditionally employed in folk medicine and is now widely recognized as a herbal remedy by a number of pharmacopoeias. Boldo leaves are rich in several aporphine-like alkaloids, of which boldine is the most abundant one. Research conducted during the early 1990s led to the discovery that boldine is one of the most potent natural antioxidants. Prompted by the latter, a large and increasing number of studies emerged, which have focused on characterizing some of the pharmacological properties that may arise from the free radical-scavenging properties of boldine. The present review attempts to exhaustively cover and discuss such studies, placing particular attention on research conducted during the last decade. Mechanistic aspects and structure-activity data are discussed. The review encompasses pharmacological actions, which arise from its antioxidant properties (e.g., cyto-protective, anti-tumour promoting, anti-inflammatory, anti-diabetic and anti-atherogenic actions), as well as those that do not seem to be associated with such activity (e.g., vasorelaxing, anti-trypanocidal, immuno- and neuro-modulator, cholagogic and/or choleretic actions). Based on the pharmacological and toxicological data now available, further research needs and recommendations are suggested to define the actual potential of boldine for its use in humans.     

Effect of phytochemical concentrations on biological activities of cranberry extracts

Plants of cranberry (Vaccinium macrocarpon) furnish edible fruits and derivates that have been used for the prevention and treatment of urinary tract infections. In the present work we compare two commercial extracts that contain proanthocyanins (PACs) at 4 percent and 20 percent for antimicrobial, antiproliferative, antiradical and protective properties against oxidative stress on cell lines. Both extracts showed antimicrobial activity (MIC values range 3-100 microg/ml). Extract at 20 percent PACs showed higher antiproliferative activity against HepG2 and MCF7 cells, but not against C2C12 cells. Both extracts showed a dose-dependent free-radical scavenging capacity, and a protective effect on the cell damage was also revealed by reduction of intracellular active oxygen species release. Cranberry extracts confirmed antioxidative properties and efficacy in reduction of cell viability that resulted stronger against tumor cells. The pretreatment with cranberry extracts, furthermore, reveal an increase of cell resistance against oxidative stress, suggesting a potential role as a dietary supplement in preventing free-radical damage. The proanthocyanidin content is critical to determine the extract efficacy. In cellular experiments the extracts resulted clearly differentiated in their activity, and the activity was strongly influenced by PACs content. Only in DPPH test the free radical scavenging activity seemed to be directly related to proanthocyanidins content.     

Inhibition of nonenzymic lipid peroxidation by benzylisoquinoline alkaloids.

A group of benzylisoquinoline alkaloids, including five simple benzylisoquinolines, three phtalideisoquinolines, six aporphines, three protoberberines, and two benzophenanthridines, have been studied as inhibitors of lipid peroxidation stimulated by Fe2+/cysteine in rat liver microsomal fractions. Protopapaverine, apomorphine, laudanosoline, tetrahydroberberine, isoboldine, bulbocapnine, boldine, anonaine, glaucine, and stepholidine showed antiperoxidative effects, and structure-activity relationships were established. In simple benzylisoquinolines, the presence of phenolic hydroxyls or similar reactive groups is necessary for inhibition of peroxidation, while in aporphines and protoberberines nonhydroxylated compounds can exert antiperoxidative effects. The phtalideisoquinolines and benzophenanthridines tested were inactive.     

Anti-inflammatory and antioxidant activities of cat's claw (Uncaria tomentosa and Uncaria guianensis) are independent of their alkaloid content.

Cat's claw is an herbal medicine from the Amazon that is used widely to treat inflammatory disorders. The purpose of this study was to characterize the antioxidative and antiinflammatory properties of cat's claw, Uncaria tomentosa (UT) and Uncaria guianensis (UG). Alkaloids and flavanols were determined using reversed-phase HPLC; scavenging of 1,1-diphenyl-2-picrilhydrazyl (DPPH), hydroxyl radicals, and lipid peroxidation by spectrophotometry; and TNFalpha production by ELISA. Anti-inflammatory activity was assessed in vitro by inhibition of TNFalpha and nitrite production from RAW 264.7 cells exposed to LPS (50 ng/ml) and in vivo using the indomethacin-induced gastritis model. Apoptosis was assessed using the TUNEL technique and TNFalpha mRNA by in situ RT-PCR. In each of the antioxidant assays tested, UG was more potent than UT (P < 0.01). The total oxindole and pentacyclic alkaloid content of UT was 35-fold > UG. The IC50 value for inhibition of TNFalpha production was significantly (P < 0.01) higher for UT (14.1 ng/ml) vs UG (9.5 ng/ml), yet at concentrations that were considerable lower than that required for antioxidant activity. Non-alkaloid HPLC fractions from UT decreased LPS-induced TNFalpha and nitrite production in RAW 264.7 cells (P < 0.01) at a concentration range comparable to the parent botanical. Oral pretreatment for 3 d with UT protected against indomethacin-induced gastritis, and prevented TNFalpha mRNA expression and apoptosis. These results indicate that while both species of cat's claw provide effective antioxidant and anti-inflammatory activities, U. guianensis is more potent. In conclusion, the presence of oxindole or pentacyclic alkaloids did not influence the antioxidant and anti-inflammatory properties of cat's claw.     

Cytoprotective and antioxidant effects of boldine on tert-butyl hydroperoxide—induced damage to isolated hepatocytes

Boldine, an aporphine alkaloid, was recently shown by us to exhibit potent antioxidant properties. We report here that boldine concentration-dependently inhibited the peroxidative (accumulation of thiobarbituric acid reactive substances) and lytic damage (trypan blue exclusion and lactate dehydrogenase leakage) to isolated rat hepatocytes induced by tert-butyl hydroperoxide (TBOOH). Boldine (200 mol/L) fully cytoprotected and completely prevented the peroxidation induced by TBOOH a concentrations equal to or lower than 0.87 mmol/L. However, at a peroxide concentration of 0.91 mmol/L, although boldine completely inhibited lipid peroxidation it largely failed to afford cytoprotection against TBOOH. TBOOH alone (0.83 mmol/L) caused an early (within 60 s) sudden decline of reduced glutathione (by 50%) and an equivalent increase in the levels of oxidized glutathione. Neither of these effects was prevented by the simultaneous addition of a cytoprotective and antioxidant concentration of boldine (200 mol/L). The delayed addition of boldine to the suspension (after 10 or 20 min), while effectively blocking any further increase in thiobarbituric acid reactive substances, totally failed to prevent the peroxide-induced loss in cell viability. Conversely, preincubation of the hepatocytes with boldine for 150 min (at which time no boldine could be detected in either intra- or extracellular spaces) prevented lipid peroxidation and was as effective in protecting the cells against the damage caused by the subsequent addition of TBOOH as the simultaneous addition of boldine and TBOOH to hepatocytes preincubated for 150 min under control conditions.Abbreviations DMSO dimethyl sulfoxide - GSH reduced glutathione - GSSG oxidized glutathione - LDH lactic dehydrogenase - TBARS thiobarbituric acid reactive substances - TBOOH tert-butyl hydroperoxide     

Antioxidant properties of <Emphasis Type="Italic">Galium verum</Emphasis> L. (Rubiaceae) extracts

The antioxidant properties of methanol extracts of Lady’s Bedstraw (Galium verum L., Rubiaceae) herb from two different localities in Serbia were evaluated. Antioxidant activity was assessed in four different model systems. Free radical scavenging capacity (RSC) was examined by measuring the scavenging activity of extracts on 2,2-diphenyl-1-pycrylhydrazil (DPPH) and hydroxyl radical (OH), as well as on hydrogen peroxide. In addition, the protective effects of lipid peroxidation (LP) in corn oil were evaluated by the TBA-assay using the Fe²⁺/ascorbate system of induction. The amount of dried extract, the content of total phenolics, flavonoids and chlorophylls was also determined. Extracts from both locations expressed very strong scavenger activity, reducing the DPPH^⊙ (IC₅₀=3.10 μg/mland 8.04 μg/ml) and OH radical formation (IC₅₀=0.05 μg/ml and 0.54 μg/ml) and neutralising H₂O₂ (IC₅₀=4.98 μg/ml and 3.80 μg/ml), in a dose dependant manner. Also, examined extracts showed notable inhibition of LP (IC₅₀=11.69 μg/ml and 19.47 μg/ml). The observed differences in antioxidant activity could be partially explained by the levels of phenolics (2.44–4.65 mg and 4.57–5.16 mg gallic acid equivalents/g dry extract), flavonoids (6.38–10.70 μg and 15.56–17.96 μg quercetin equivalents/g dry extract) and chlorophylls in the investigated Lady’s Bedstraw extracts.