Deoxyribose Degradation Assay Research Articles

Diminution of free radical induced DNA damage by extracts/fractions from bark of Schleichera oleosa (Lour.) Oken

The present study was undertaken to investigate the effect of extracts of Schleichera oleosa (Sapindaceae) for its cytotoxic and hydroxyl radical-scavenging activities. The bark of the tree was used to prepare extracts with different solvents (i.e., hexane, chloroform, ethyl acetate, methanol, and water). The extracts were initially assessed for their in vitro cytotoxicity potential in the sulforhodamine B dye assay against cell lines, such as 502713 (colon), SW-620 (colon), HCT-15 (colon), A-549 (lung), HEP-2 (liver), SK-NS-H (central nervous system), and IMR-32 (neuroblastoma). It was observed that the water extract was effective against all the three colon cancer cell lines, while only methanol and water extracts were effective against A-549 (lung) and HEP-2 (liver), respectively. As DNA damage is one of the hallmarks of cell death, so the extracts were assessed for their ability to scavenge hydroxyl radicals, in the deoxyribose degradation assay (site- and nonsite specific) as well as their protective effect against the hydroxyl radical–induced DNA damage in the plasmid nicking assay, using pBR322. It was observed that all the extracts, except chloroform and hexane, exhibited relatively greater antioxidant activity in the nonsite-specific than in the site-specific assay. Similarly, the extracts were also found to be effective in inhibiting the hydroxyl radical–induced unwinding of supercoiled DNA, which further confirmed the hydroxyl radical–scavenging ability of the extracts in the deoxyribose degradation method.

Chemical Composition and Antioxidant Activities of the Essential Oils of Different Parts of Cupressus arizonica Greene

The essential oils of different parts of Cupressus arizonica were examined for their potential radical scavenging activity. Fresh leaves and fruits of C. arizonica were steam distilled and the oils were analyzed qualitatively and quantitatively by GC and GC/MS. Different methods of rapid TLC screening, DPPH assay, desoxyribose assay, assay for site-specific reaction and non-enzymatic lipid peroxidation were employed to evaluate possible antioxidant activity of the oils and their main components, as well as the positive controls. The main components of these essential oils were α-pinene, cymene, myrcene, limonene, sabinene hydrate, cedrane and germacrene D. In rapid TLC screening, the tested compounds mainly showed antioxidant activity. In DPPH assay the stronger antioxidant effects were shown by the fruit oil of C. arizonia. In deoxyribose degradation assay test, most of the tested compounds showed some antioxidant effects. In non-enzymatic lipid peroxidation test, most antioxidant activity was shown by the fruit oil.

In vitro antioxidant activity of Vetiveria zizanioides root extract

Free radicals induce numerous diseases by lipid peroxidation and DNA damage. It has been reported that some of the extracts from plants possess antioxidant properties capable of scavenging free radicals in vivo. Vetiveria zizanioides belonging to the family Gramineae, is a densely tufted grass which is widely used as a traditional plant for aromatherapy, to relieve stress, anxiety, nervous tension and insomnia. In this regard, the roots of V zizanioides was extracted with ethanol and used for the evaluation of various in vitro antioxidant activities such as reducing power ability, superoxide anion radical scavenging activity, deoxyribose degradation assay, total antioxidant capacity, total phenolics and total flavonoid composition. The various antioxidant activities were compared with suitable antioxidants such as butyl hydroxy toluene, ascorbic acid, quercetin, alpha tocopherol, pyrocatechol and curcumin respectively. The generation of free radicals O2, H2O2 OH and N O were effectively scavenged by the ethanolic extract of V zizanioides. In all these methods, the extract showed strong antioxidant activity in a dose dependent manner. The results obtained in the present study clearly indicates that V zizanioides scavenges free radicals, ameliorating damage imposed by oxidative stress in different disease conditions and serve as a potential source of natural antioxidant. The study provides a proof for the ethnomedical claims and reported biological activities. The plant has, therefore, very good therapeutic and antioxidant potential.

Simultaneous Detection of Pro- and Antioxidative Effects in the Variants of the Deoxyribose Degradation Assay

Interest in the redox properties of natural products has led to the development of various assays for the detection of antioxidant activities and ROS-scavenging properties. Here, additional modifications of the 2-deoxy-d-ribose degradation assay are introduced that specifically allow the determination of interactions of the test compound with the autoxidation of ascorbic acid and the autoxidation of the test compound itself. To illustrate this, juglone and quercetin were used as examples. The modified assay systems provide insights into their specific antioxidative and pro-oxidative properties. In additional, an extensive characterization of the redox properties of their complex with iron is possible, if iron ions are added in the free form or complexed with EDTA. The juglone−iron complex proved to be pro-oxidative in a wider range of milieus than the quercetin−iron complex.

Antioxidant activity of some edible plants of the Turkmen Sahra region in northern Iran

The antioxidant properties of 10 edible plants of the Turkmen Sahra region in Golestan province in northern Iran, including Allium paradoxum, Allium rubellum, Foeniculum vulgare, Mentha longifolia, Origanum vulgare, Prunus divaricata, Rubus sanctus, Rumex tuberosus, Satureja mutica and Spinacia turkestanica were evaluated by four different methods; free radical scavenging using 2,2-diphenyl-1-picrylhydrazyl (DPPH), evaluation of xanthine-oxidase activity, inhibition of lipid peroxidation by the ferric thiocyanate method, and the deoxyribose degradation assay. All species tested except A. paradoxum and P. divaricata showed antioxidant activity at least in one assay. The pro-oxidant activities were also assayed for these species and S. mutica, M. longifolia, and O. vulgare showed significant pro-oxidant activity.

(+/-)-catechin: chemical weapon, antioxidant, or stress regulator?

(±)-Catechin is a flavan-3-ol that occurs in the organs of many plant species, especially fruits. Health-beneficial effects have been studied extensively, and notable toxic effects have not been found. In contrast, (±)-catechin has been implicated as a ‘chemical weapon’ that is exuded by the roots of Centaurea stoebe, an invasive knapweed of northern America. Recently, this hypothesis has been rejected based on (±)-catechin’s low phytotoxicity, instability at pH levels higher than 5, and poor recovery from soil. In the current study, (±)-catechin did not inhibit the development of white and black mustard to an extent that was comparable to the highly phytotoxic juglone, a naphthoquinone that is allegedly responsible for the allelopathy of the walnut tree. At high stress levels, caused by sub-lethal methanol concentrations in the medium, and a 12 h photoperiod, (±)-catechin even attenuated growth retardation. A similar effect was observed when (±)-catechin was assayed for brine shrimp mortality. Higher concentrations reduced the mortality caused by toxic concentrations of methanol. Further, when (±)-catechin was tested in variants of the deoxyribose degradation assay, it was an efficient scavenger of reactive oxygen species (ROS) when they were present in higher concentrations. This antioxidant effect was enhanced when iron was chelated directly by (±)-catechin. Conversely, if iron was chelated to EDTA, pro-oxidative effects were demonstrated at higher concentrations; in this case (±)-catechin reduced molecular oxygen and iron to reagents required by the Fenton reaction to produce hydroxyl radicals. A comparison of cyclic voltammograms of (±)-catechin with the phytotoxic naphthoquinone juglone indicated similar redox-cycling properties for both compounds although juglone required lower electrochemical potentials to enter redox reactions. In buffer solutions, (±)-catechin remained stable at pH 3.6 (vacuole) and decomposed at pH 7.4 (cytoplasm) after 24 h. The results support the recent rejection of the hypothesis that (±)-catechin may serve as a ‘chemical weapon’ for invasive plants. Instead, accumulation and exudation of (±)-catechin may help plants survive periods of stress.

The role of iron chelation activity of wheat grass juice in patients with myelodysplastic syndrome

7012 Background: A pilot study with wheat grass juice in major thalassaemia patients was done by a group of clinicians in IPGMR, Chandigarh, India. We performed a study of 200 patients of intermediate thalassaemia with wheat grass juice and found 80% patients becoming transfusion independent. During the study in majority of the patients, serum ferritin level was significantly less as compared to pretreatment values. The aim of our study was to see the effect of wheat grass juice in reducing Ferritin level in myelodysplastic syndrome and also do the biochemical analysis of the wheat grass juice. Methods: During period from January 2003 to December 2007 we selected 20 patients of transfusion dependent myelodysplastic syndrome in the oncology department of Netaji Subhash Chandra Bose Cancer Research Institute. The age range of the patients was 42 years to 72 years (median 55 years). The fresh leaves of 5–7-day-old wheat grasss including stems were made fresh juice and had given 30 mL of juice daily to all 20 patients for continuous 6 months. Wheat grass juice was analyzed by column chromatography and found to be rich in oxalic and malic acid which might have some role in dietary absorption of iron from intestine. Beside that the wheat grass juice was found to contain two unique active ingredients with iron chelating property which was performed by deoxyribose degradation assay. We compared aqueous soluble extract of 5–7-day-old plant and dose-dependent study showed a significant iron chelating activity of crude extract in comparison to known standard iron chelator desferroxamine (DFO). The active compounds of crude extract of wheat grass may chelate catalytic iron in iron overload disorders when taking systematic dose. Result: The mean serum Ferritin level of the patients was 2,250 (range 650–4,800) before wheat grass treatment. The mean reduced to 950 (range 68–1680) (p < 0.0001). The performance status was improved from 60% to 80% (Karnofsky) after wheat grass treatment. The mean interval between transfusions was found increased. Conclusions: Wheat grass juice is an effective iron chelator and its use in reducing serum ferritin should be encouraged in myelodysplastic syndrome and other diseases where repeated blood transfusion is required. No significant financial relationships to disclose.

Anti-free radical activities of kaempferol isolated from Acacia nilotica (L.) Willd. Ex. Del.

In the present study the polyphenolic compound has been isolated from methanol extract of Acacia nilotica Willd. Ex. Del. which has been identified as kaempferol (AN-5) by NMR and mass spectroscopy. The antioxidant potential of the AN-5 was demonstrated in several in vitro assays: measuring the proton radical scavenging activity (DPPH scavenging assay), hydroxyl radical scavenging activity (deoxyribose degradation assay), metal chelating activity, reducing power and inhibition of lipid peroxidation. It was found that the effect of the compound AN-5 was strongly dose dependent up to the concentrations 1-50 microg/ml in DPPH assay and 1-100 microg/ml in deoxyribose degradation assay but did not show further change above the highest concentrations.

Essential Oil Composition, Antibacterial and Antioxidant Activities of <i>Mentha aquatica</i> Growing in Ethiopia

The in vitro antibacterial and antioxidant activities of the essential oil of Mentha aquatica L. (Lamiaceae) growing in Ethiopia were studied. The chemical composition of the oil was also investigated by using capillary gas chromatography-mass spectrometry. A total of 34 compounds representing 99.4% of the oil have been identified. Menthofuran (70.5%) was characterized as the main component with limonene and pmenthone constituting 9.42 and 7.20% of the oil, respectively. In general, the oil showed a remarkable activity against the Gram-positive bacteria tested of which Staphylococcus aureus 29737, S. aureus ML267, Sarcina luteus 9341 and Bacilus pumilus 8241 strains were the most susceptible. The minimum inhibitory concentration (MIC) values of the oil against these organisms were found to be less than 5 μg/ml. The antioxidant activity of the oil was evaluated using 2,2-diphenyl-1-picrylhydrazyl (DPPH) and deoxyribose degradation assays and was found to possess good radical scavenging activity with IC50 values of 11.2 and 3.74 μl/ml, respectively. Keywords: antibacterial, antioxidant, Mentha aquatica, essential oil, capillary gas chromatography-mass spectrometryEthiopian Pharmaceutical Journal Vol. 26 (1) 2008: pp. 9-16

A study on antioxidant, free radical scavenging, anti-inflammatory and hepatoprotective actions of Aegiceras corniculatum (stem) extracts

Aim of the study The present study was conducted to evaluate the antioxidant, anti-inflammatory and hepatoprotective potential of Aegiceras corniculatum Linn. Blanco (Aegicerataceae). Methods and results The n-hexane, ethyl acetate and methanol extracts, derived from Aegiceras corniculatum stems, scavenged superoxide anions (O 2 −) and hydroxyl radicals ( OH) in nitro blue tetrazolium reduction and deoxyribose degradation assays, respectively. All the extracts inhibited the process of lipid peroxidation at its initiation step. Additionally, in rat liver microsomes n-hexane and ethyl acetate extracts also caused termination of radical chain reaction supporting their scavenging action towards lipid peroxy radicals (LOO ). Moreover, increased production of O 2 − in human neutrophils, stimulated by phorbol-12-myristate-13-acetate (PMA) and/or opsonized zymosan were also suppressed (IC 50 ∼3–20 μg/mL). Thereby, revealing the ability of plant extracts to antagonize the oxidative stress via interference with NADPH oxidase metabolic pathway. These in vitro results coincide with the reduction in the glucose oxidase-induced paw edema in mice in the presence of ethyl acetate and methanol extracts (10, 50, and 100 mg/kg, i.p.). Plant extracts (250, 500 and 1000 mg/kg, p.o.) also significantly protected the carbon tetrachloride (CCl4)-induced oxidative tissue injury in rat liver. This was reflected by a ∼60% decline in the levels of serum aminotransferase enzymes. Conclusion Aegiceras corniculatum extracts found to possess pronounced antioxidant effect that may be at least in part related to its anti-inflammatory and hepatoprotective activities. This study provides a scientific basis for the ethnomedical claims that Aegiceras corniculatum is effective against inflammation and liver injury.

Antioxidant activity of the phenol rich fractions of leaves of Chukrasia tabularis A. Juss.

The present study was designed to explore the antioxidant potential of chloroform, ethyl acetate, n-butanol and water fractions of 80% methanol extract of leaves Chukrasia tabularis by 2,2′-diphenyl-1-picrylhydrazyl (DPPH), deoxyribose degradation (non-site specific and site specific), reducing power and DNA nicking assays. The different fractions showed significant activities in all the free radical scavenging tests and these findings have also shown direct relationship between antioxidant activity and phenolic content. Among the fractions, ethyl acetate fraction exhibited highest inhibition of 93.14%, 89.99%, 87.04% in DPPH, non-site specific and site specific deoxyribose degradation assays, respectively and 91.20% reduction of ferricyanide to give Prussian blue coloured complex in reducing power assay at maximum concentration tested. This preliminary study indicates the antioxidant activity of the leaves of Chukrasia tabularis, and moreover the results showed correlation with the amount of phenolic content present in different fractions.

Essential Oil Composition, Antibacterial and Antioxidant Activities of Four <i>Mentha</i> Species Growing in Ethiopia

The essential oils obtained by hydrodistillation from the leaves of Mentha arvensis L., M. longifolia L., M. piperita L., and M. spicata L., were analyzed by gas chromatography (GC-FID) and gas chromatography/ mass spectrometry (GC/MS). In addition, the antibacterial activities of the oils were evaluated against 20 bacterial strains and their radical scavenging potentials were determined in 2,2-diphenyl-1-picrylhydrazyl (DPPH) and deoxyribose degradation assays. Oxygenated monoterpenes were found to be major constituents of all the oils. The essential oil of M. spicata exhibited a significant wide spectrum antibacterial activity against all test strains including multiresistant strains of Pseudomonas aeruginosa and Escherichia coli. The essential oil of M. piperita displayed powerful in vitro radical scavenging activities in both DPPH and deoxyribose degradation assays, with IC50 values of 5.96 μl/ml and 0.57 μl/ml, respectively. The other essential oils also produced concentraion dependant radical scavenging activities with IC50 values ranging between 5.96 and 37.01 μl/ml, and 0.57 and 3.88 μl/ml, in DPPH and deoxyribose degradation assays, respectively. The present study revealed that all the essential oils have the potential to be used as naturally occurring antibacterial and antioxidant agents. Keywords: essential oils, Mentha spp, capillary gas chromatography-mass spectrometry, radical scavenging activity, antibacterial activityEthiopian Pharmaceutical Journal Vol. 25 (2) 2007: pp. 91-102

Antioxidant Activities of Three Rubus Species Growing in Ethiopia

In Ethiopian traditional medical practices some species of the genus Rubus (Rosaceae) are used for the treatment of diabetes mellitus, one of the disease conditions in which free radicals and oxidative stress have been implicated. In the present study extracts prepared from three members of the genus, namely Rubus apetalus Poir, R. niveus Thunb and R. steudneri Schweinf were investigated for their in vitro radical scavenging activities using 2,2-diphenyl-1-picrylhydrazyl (DPPH) and deoxyribose degradation assays. The 80% methanol extract, and acetone and methanol soxhlet fractions of the three plants tested showed antioxidant activity in a concentration-dependent manner. The 80% methanolic extract of R. steudneri showed the strongest activity in the DPPH radical scavenging assay (IC50 = 6.5 mg/ml). In the deoxyribose degradation assay the 80% methanol, acetone and methanol extracts of R. niveus displayed potent activity with IC50 values of 0.64, 0.6 and 0.61 μg/ml, respectively. Ascorbic acid (vitamin C) was used as a positive control in the DPPH assay (IC50 = 4.5 μg/ml) and butylhydroxytoluene, in the deoxyribose degradation assay (IC50 = 4.76 μg/ml). The results of the present study suggest that the antioxidant activity of the studied plants may contribute to their purported uses as antidiabetic agents. The work further indicated that the antioxidant active principles of the plants reside in the polar fraction of the extracts. Keywords: Rubus spp., Rosaceae, radical scavenging activity, DPPH assay, deoxyribose degradation assayEthiopian Pharmaceutical Journal Vol. 25 (2) 2007: pp. 103-110

The Role of Iron Chelation Activity of Wheat Grass Juice in Blood Transfusion Requirement of Intermediate Thalassaemia.

Background: Previously it was thought that the chlorophyll of wheat grass (Triticum astevum) may be the substitute of haemoglobin of RBC having resemblance of similar structure. A group of Austrelian scientists tried to prove that wheat grass juice increases the foetal haemoglobin level 3–5 folds in intermediate thalassaemia patients. A pilot study with wheat grass juice in major thalassaemia patients were done by Dr. Marwa et al in IPGMR, Chandigarh, India. But there is no satisfactory explanation behind the reduced blood transfusion requirements after consumption of wheat grass juice for a long period. The aim of our study was to see the effect of wheat grass juice in blood transfusion requirement in intermediate thalassaemia patients and also do the biochemical analysis of the wheat grass juice.Material & Methods: During period from January 2003 to December 2006 we selected 200 intermediate thalassaemia patients (E-thalassaemia, E-Beta & Sickle thal) in the paediatric oncology department of Netaji Subhash Chandra Bose Cancer Research Institute. The age range of the patients was 1 year to 35 years (median age 18 years). The different types of thalasssaemia were E-Beta Thalassaemia 80% (160 patients), E-Thalassaemia 15% (30 patients) and Sickle Thalassaemia 5% (10 patients). When the wheat grasses were 5–7 days old, the fresh leaves including steams were made fresh juice and had given 30ml of juice daily to all our 200 patients for continuous 6 months. Wheat grass juice was analysed by column chromatography and found to be rich in oxalic acid and malic acid which might have some role in dietary absorption of iron from intestine. Beside that the wheat grass juice was found to contain a unique iron chelating property which was performed by deoxyribose degradation assay. We compared aqueous soluble extract of 5–7th day plant and our dose dependant study showed a significant iron chelating activity of crude extract in comparison to known standard iron chelator desferroxamine (DFO). The active compounds of crude extract of wheat grass may chelate catalytic iron in iron overload disorders when taking systematic dose.Result: The mean levels of haemoglobin before starting wheat grass juice were 6.2gm%. After 6months of wheat grass therapy the mean value for haemoglobin was 7.8gm% (pvalue <. 005). Twenty four patients (12%) require blood transfusion (haemoglobin < 6gm%). The performance status was improved from 60% to 80% (Karnofsky) after wheat grass treatment. The ferritin level of all patients before the study was found to be decreased significantly after wheat grass juice consumption. The mean interval between transfusion were found increased. Being a natural potent iron chelator and H2O2 quencher, it prevents the hydroxyl radical production by Fenton reaction in the RBC. Thus it may prevent the breakdown of plasma membrane of RBC and haemoglobin level becomes stable for a prolonged period.Conclusion: We may conclude that wheat grass juice is an effective alternative of blood transfusion. It's use in intermediate thalassaemia patients should be encouraged.

In vitro scavenging activity for reactive oxygen species by N‐substituted indole‐2‐carboxylic acid esters

The hydroxyl radical (HO*)- and superoxide anion radical (O* (2))-scavenging activity, as well as the singlet oxygen ((1)O(2))-quenching property of N-substituted indole-2-carboxylic acid esters (INDs) were investigated by deoxyribose degradation assay, a chemiluminescence method and the electron spin resonance (ESR) spin-trapping technique. This novel group of compounds was developed as a search for cyclooxygenase-2 (COX-2)-selective enzyme inhibitors. The results obtained demonstrated that of the 16 compounds examined, five inhibited light emission from the superoxide anion radical (O* (2))-DMSO system by at least 60% at a concentration of 1 mmol/L, nine prevented the degradation of deoxyribose induced by the Fenton reaction system (range 3-78%) or scavenged hydroxyl radicals (HO*) directly (range 8-93%) and 14 showed the (1)O(2)-quenching effect (range 10-74%). These results indicate that majority of the indole esters tested possess the ability to scavenge O(-) (2) and HO radicals and to quench (1)O(2) directly, and consequently may be considered effective antioxidative agents.

Antioxidant Activity of the Essential Oils of Different Parts of Juniperus communis. subsp. hemisphaerica. and Juniperus oblonga.

The essential oils of different parts of Juniperus communis. subsp. hemisphaerica. (Presl) Nyman (Cupressaceae) and Juniperus oblonga. M. B. were examined for their potential radical scavenging activity. The compositions of the essential oils of these plants were studied qualitatively and quantitatively by GC and GC-MS. The main components of the essential oils as well as positive controls were subjected to antioxidant testing. A rapid evaluation for antioxidants, using two TLC screening methods, showed that all tested oils and their main components have antioxidant activity. The abilities of the volatile oils to act as nonspecific donors for hydrogen atoms for electron were checked in the diphenylpicrylhydrazyl (DPPH) assay. In the DPPH assay, the strongest effect among the essential oils was measured for the oil of leaves of male J. communis. subsp. hemisphaerica. at a concentration of 4 µL/mL (24.0%) In the deoxyribose degradation assay, the essential oils, pure components, and positive controls were tested at different concentrations. Most of the tested compounds showed some antioxidant effects. The fruit oil of J. oblonga. has the strongest effect among the tested volatile oils.The deoxyribose assay was modified in three different ways to assess whether the oils exhibited site-specific effects. The results of the current study, which demonstrate the DPPH scavenging activity of the essential oils of the of leaves of male J. communis. subsp. hemisphaerica. and the OH radical scavenging effects of the fruit oil of J. oblong. suggest the use of these two essential oils in very low concentrations for preserving food materials.

Antioxidant effect of oregano ( Lippia berlandieri v. Shauer) essential oil and mother liquors

The conventional steam distillation process for oregano ( Lippia berlandieri v. Shauer) essential oil extraction produces large volumes of mother liquor. This residual liquid represents a potential value because the soluble antioxidants it contains. Essential oil and ethyl acetate mother liquor extracts (MLEs) were evaluated for antioxidant activity. Total phenolic content and antioxidant activities by the 2-2′-diphenyl-1-picrylhydrazyl (DPPH) method, by the deoxyribose degradation assay, and by oxidation of low density lipoproteins (LDL) with CuSO 4 were evaluated. Oil yield was 4.34%. Total phenolic content was 151 ± 2.00 and 150.5 ± 0.98 mg of GAE (gallic acid equivalents)/mL for the essential oil and MLEs, respectively. DPPH assay showed a low radical scavenging activity (RSA) for oregano essential oil. Meanwhile MLEs exhibited no significant RSA at low concentrations, but at higher concentrations (100 μg/mL), it was superior to those exhibited by the controls ascorbic acid and butylated hydroxytoluene (BHT). Deoxy- d-ribose assay results for both essential oil and MLEs showed a good hydroxyl radical RSA at the concentrations tested. Essential oil and MLEs delayed induction time effectively. Solubility problems, chemical constituents, and their hydrophilic–lipophilic distribution are key factors that explain samples behavior for an eventual use of these natural products.

Antioxidant activity of Gymnema inodorum Decne. (Pak chiang daa) and its effect on DNA damage in TK6 human lymphoblastoid cells

Gymnema inodorum Decne. (Pak chiang daa, GI) is one of Thai herbs that have been popularly consumed and used as herbal remedy in the northern Thailand. It has been shown that GI contains high amount of phenolic compounds as well as beta-carotene, vitamin E and C. This study was conducted to determine the antioxidant activity of GI and whether it protects cells against DNA damage. Edible parts of GI were prepared as fresh juice (GIJ) and dried forms, which were extracted further with either water (GIW) or 50% ethanol (GIE). The antioxidant activity of all extracts was determined by 1,1-diphenyl-2-picryl-hydrazil (DPPH) radical scavenging assay, deoxyribose degradation assay, and hemolysis assay. The effect of the GI extracts on DNA damage was examined by the comet assay in TK6 human lymphoblastoid cells. The results showed that GIJ had the highest antioxidant activity compared with GIW and GIE (IC50 values were 0.25 ± 0.02, 0.40 ± 0.02, and 0.33 ± 0.04 mg/mL (DPPH assay); 0.15 ± 0.07, 0.29 ± 0.03, and 0.27 ± 0.05 mg/mL (deoxyribose assay); 0.15 ± 0.23, 0.24 ± 0.37, and 0.29 ± 0.21 mg/mL (hemolysis assay), respectively). The highest inhibitory effect on DNA damage was found in GIJ compared with GIW and GIE (78.02%, 40.38% and 50.54%, respectively). This study suggests that the fresh preparation of GI can be used as an effective antioxidant.

Antioxidant and Pro-oxidant Activities of Aqueous Extracts and Crude Polyphenolic Fractions of Rooibos (Aspalathus linearis)

Unfermented rooibos tea is known to contain higher levels of total polyphenols and flavonoids than its fermented counterpart, making it the obvious choice for the preparation of flavonoid-enriched fractions. Evaluation of aqueous extracts and crude polyphenolic fractions of unfermented and fermented rooibos showed anti- and/or pro-oxidant activities, using a linoleic acid-Tween-buffer emulsion for lipid peroxidation and the deoxyribose degradation assay, based on a Fenton reaction model system containing FeCl3-EDTA and H2O2 for the generation of hydroxyl radicals. Except for the ethyl acetate fraction, with the highest total polyphenol (TP) content and offering the least protection presumably due to pro-oxidant activity, the inhibition of lipid peroxidation by the samples correlated moderately with their TP content in a linear relationship (r = 0.896, P < 0.01). Using the deoxyribose degradation assay, the pro-oxidant activity of the aqueous extracts and their crude polymeric fractions (0.1 mg/mL in the reaction mixture) was linear with respect to their dihydrochalcone (aspalathin and nothofagin) (r = 0.977, P = 0.023) and flavonoid (r = 0.971, P = 0.029) content. Pro-oxidant activity was demonstrated for pure aspalathin. Using the same assay, but with ascorbate added to regenerate Fe3+ to Fe2+, the aqueous extract and crude polymeric fraction of fermented rooibos displayed hydroxyl radical scavenging activity. Fermentation (i.e., oxidation) of rooibos decreased the pro-oxidant activity of aqueous extracts, which was contributed to a decrease in their dihydrochalcone content. The in vitro pro-oxidant activity displayed by flavonoid-enriched fractions of rooibos demonstrates that one must be aware of the potential adverse biological properties of potent antioxidant extracts utilized as dietary supplements.

3-O-β-ᴅ-Galactopyranoside of Quercetin as an Active Principle from High Altitude Podophyllum hexandrum and Evaluation of its Radioprotective Properties

The aqueous-ethanolic extract (AEE) of high altitude Podophyllum hexandrum has earlier been reported to render a radioprotective effect against lethal gamma radiation in in vitro model. AEE has also been reported to possess metal chelating and DNA protecting properties. The present study was undertaken to isolate and characterize the bioactive principle present in AEE and investigate its role in radiation protection. A novel molecule was found to be present in AEE and was assigned as 3-O-beta-D-galactoside of quercetin by acid hydrolysis, LC-MS, LC-APCI-MS/MS and 13C NMR spectra. Various biological activities were investigated at in vitro level. The antioxidant potential of AEE in lipid and aqueous phase was determined against numerous stresses. AEE was found to be significantly (p < 0.05) protective, i.e., against Fe2+ and Cu2+-induced linoleic acid degradation, respectively. Radiation-induced lipid oxidation studies revealed that AEE maximally works at a [lignan]/0.25 kGy ratio 400 (ratio of concentration of AEE divided by the radiation dose, i.e., 0.25 kGy) and no drug-induced lipid oxidation at all concentrations tested was found. In a time-dependent study, total antioxidant activity was maximally exhibited at 1 mg/ml. The site-specific and non-site-specific deoxyribose degradation assay exhibited a dose-dependant hydroxyl scavenging potential of AEE (0.05-500 microg/ml). The anti-lipid peroxidation ability of AEE against radiation (0.25 kGy)-induced lipid peroxidation was higher in case of neural tissue homogenate as compared to kidney homogenate [activity ratio: 0.039 (brain) < 0.24 (kidney)]. The protein protection study using bovine serum albumin was also done for two time intervals (2 h and 4 h) and significant (p < 0.05) protection was observed at 500 microg/ml (> 97%). This study implies that 3-O-beta-D-galactoside present in AEE renders radioprotection by protecting lipids, proteins in renal and neural model system against supra-lethal (0.25 kGy) gamma radiation.