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Background

In this report the phytochemical profile of Nitraria. Retusa (N. Retusa) leaf extracts were identified and their ability to induce apoptosis in human chronic myelogenous erythroleukaemia (K562) was evaluated.

Methods

Apoptosis of the human chronic myelogenous erythroleukaemia (K562) was evidenced by investigating DNA fragmentation, PARP cleavage and caspases 3 and 8 inducing activities, in the presence of N. retusa extracts.

Results

Our study revealed that the tested extracts from N. Retusa contain many useful bioactive compounds. They induced in a time-dependent manner the apoptosis the tested cancerous our cell line. This result was confirmed by ladder DNA fragmentation profile and PARP cleavage, as well as a release in caspase-3 and caspase-8 level.

Conclusion

Our results indicate that the tested compounds have a significant antiproliferative effect which may be due to their involvement in the induction of the extrinsic apoptosic pathway.

The methanolic extract of Sida retusa Linn.(Malvaceae),Urena lobata Linn.(Malvaceae)and Triumfetta rhomboidea Jacq.(Teliaceae) roots were found to inhibit lipid peroxidation, scavenge hydroxyl and superoxide radicals in vitro. The quantity of S.retusa root extract required for 50% inhibition of lipid peroxidation, scavenging hydroxyl radical and superoxide radical was 1130.24 ug/ml respectively. IC 50 of root extract of U.lobata was 470.60 ug/ml, 1627.35ug/ml and 1109.24 ug/ml for superoxide radical scavenging, hydroxyl radical scavenging and lipid peroxidation respectively. T.rhomboidea root extract required for IC 50 was 336.65 ug/ml, 1346.03 ug/ml and 1004.22 ug/ml for superoxide scavenging, hydroxyl radical scavenging and lipid peroxidation respectively. The present investigation indicated that S. retusa, U.lobata and T.rhomboidea possessed significant antioxidant activity.

The metabolic interactions and signaling between neurons and glial cells are necessary for the development and maintenance of brain functions and structures and for neuroprotection, which includes protection from chemical attack. Astrocytes are essential for cerebral detoxification and present an efficient and specific cytochrome P450 enzymatic system. Whilst Crotalaria (Fabaceae, Leguminosae) plants are used in popular medicine, they are considered toxic and can cause damage to livestock and human health problems. Studies in animals have shown cases of poisoning by plants from the genus Crotalaria, which induced damage to the central nervous system. This finding has been attributed to the toxic effects of the pyrrolizidine alkaloid (PA) monocrotaline (MCT). The involvement of P450 enzymatic systems in MCT hepatic and pulmonary metabolism and toxicity has been elucidated, but little is known about the pathways implicated in the bioactivation of these systems and the direct contribution of these systems to brain toxicity. This review will present the main toxicological aspects of the Crotalaria genus that are established in the literature and recent findings describing the mechanisms involved in the neurotoxic effects of MCT, which was extracted from Crotalaria retusa, and its interaction with neurons in isolated astrocytes.

Background

Plants play a significant role in maintaining human health and improving the quality of human life. They serve humans well as valuable components of food, as well as in cosmetics, dyes, and medicines. In fact, many plant extracts prepared from plants have been shown to exert biological activity in vitro and in vivo. The present study explored antioxidant and antigenotoxic effects of Daphne gnidium leaf extracts.

Methods

The genotoxic potential of petroleum ether, chloroform, ethyl acetate, methanol and total oligomer flavonoid (TOF) enriched extracts from leaves of Daphne gnidium, was assessed using Escherichia coli PQ37. Likewise, the antigenotoxicity of the same extracts was tested using the “SOS chromotest test”. Antioxidant activities were studied using non enzymatic and enzymatic method: NBT/Riboflavine and xantine oxidase.

Results

None of the different extracts produced a genotoxic effect, except TOF extract at the lowest tested dose. Our results showed that D. gnidium leaf extracts possess an antigenotoxic effect against the nitrofurantoin a mutagen of reference. Ethyl acetate and TOF extracts were the most effective in inhibiting xanthine oxidase activity. While, methanol extract was the most potent superoxide scavenger when tested with the NBT/Riboflavine assay.

Conclusions

The present study has demonstrated that D. gnidium leaf extract possess antioxidant and antigenotoxic effects. These activities could be ascribed to compounds like polyphenols and flavonoid. Further studies are required to isolate the active molecules.

Reduced coenzyme Q10 (CoQ10H2) is known as a potent antioxidant in biological systems. However, it is not yet known whether CoQ9H2 could act as an antioxidant in human cells. The aim of this study is to assess whether exogenously added CoQ9 can protect human liver cells against injuries induced by a water-soluble radical initiator, 2,2'-azobis(2-amidinopropane) dihydrochloride (AAPH) and a lipid-soluble radical initiator, 2,2'-azobis(2,4-dimethylvaleronitrile) (AMVN). CoQ9-enriched cells were obtained by treatment of HepG2 cells with 10 µM CoQ9 liposomes for 24 h. CoQ9-enriched cells were exposed to 10 mM AAPH and 500 µM AMVN over 4 h and 24 h, respectively. The loss of viability after treatment with AAPH or AMVN was much less in CoQ9-enriched cells than in naive HepG2 cells. The decrease in glutathione and the increase in thiobarbituric acid-reactive substance after treatment with AAPH or AMVN were also suppressed in CoQ9-enriched cells. The incubation of CoQ9-enriched cells with AAPH or AMVN led to a decrease in cellular CoQ9H2 and reciprocal increase in cellular CoQ9 resulting from its antioxidant function. Taken together, it was demonstrated for the first time that exogenously added CoQ9 could prevent oxidative stress-mediated damage to human cells by virtue of its antioxidant activity.

Preparative high-speed countercurrent chromatography (HSCCC) has been successfully used for the isolation and purification of isorhamnetin from Stigma maydis. This was achieved in two stages: the first separation was performed with a two-phase solvent system composed of n-hexane-ethyl acetate-methanol-water (HEMW) at a volume ratio of 5:5:5:5, yielding isorhamnetinat 65.6 %, which is followed by the second run using a two-phase solvent system composed of HEMW 5:5:6:4, v/v. From 700 mg of the crude extract 11.8 mg of isorhamnetin was obtained at a high purity of 98%. The final identification was performed by MS, 1H-NMR and 13C-NMR spectra.

Inflammatory bowel disease (IBD) is a chronic condition of the intestine with unknown etiology involving multiple immune, genetic and environmental factors. We were interested to examine the effect of total extract from Zataria multiflora Boiss, a folk medicinal plant on prevention and treatment of experimental IBD. Z. multiflora was administered (400, 600, 900 p.p.m.) through drinking water to IBD mice induced by intrarectal administration of acetic acid. Prednisolone was used as the standard drug for comparison. Biochemical, macroscopic and microscopic examinations of colon were performed. Biochemical evaluation of inflamed colon was done using assay of myeloperoxidase (MPO) activity and thiobarbituric acid reactive substances (TBARS) concentration as indicators of free radical activity and cell lipid peroxidation. The activity of MPO and lipid peroxidation products (TBARS) increased in acetic acid-treated groups while recovered by pretreatment of animals with Z. multiflora (400–900 p.p.m.) and prednisolone. Z. multiflora (600 and 900 p.p.m.) and prednisolone-treated groups showed significantly lower score values of macroscopic and microscopic characters when compared with the acetic acid-treated group. The beneficial effect of Z. multiflora (900 p.p.m.) was comparable with that of prednisolone. The antioxidant, antimicrobial and anti-inflammatory potentials of Z. multiflora might be the mechanisms by which this herbal extract protects animals against experimentally induced IBD. Proper clinical investigation should be carried out to confirm the activity in human.

The present study was undertaken to explore the possible biochemical activities of Hyaenanche globosa Lamb. and its compounds. Two different extracts (ethanol and dichloromethane) of four different parts (leaves, root, stem, and fruits) of H. globosa were evaluated for their possible antibacterial, antityrosinase, and anticancer (cytotoxicity) properties. Two pure compounds were isolated using column chromatographic techniques. Active extracts and pure compounds were investigated for their antioxidant effect on cultured ‘Hela cells’. Antioxidant/oxidative properties of the ethanolic extract of the fruits of H. globosa and purified compounds were investigated using reactive oxygen species (ROS), ferric-reducing antioxidant power (FRAP), and lipid peroxidation thiobarbituric acid reactive substance (TBARS) assays. The ethanolic extract of the leaves and fruits of H. globosa showed the best activity, exhibiting a minimum inhibitory concentration (MIC) of 3.1 mg/ ml and a minimum bactericidal concentration (MBC) of 1.56 and 6.2 mg/ml, respectively, against M. smegmatis. The ethanolic extract of the fruits of H. globosa (F.E) showed the highest percentage of inhibitory activity of monophenolase (90.4% at 200 μg/ml). In addition, F.E exhibited 50% inhibitory concentration (IC50) of 37.7 μg/ml on the viability of ‘HeLa cells’ using cytotoxicity MTT assay. Subsequently, F.E was fractionated using phase-partitioning with n-hexane, ethyl acetate, and n-butanol. The cytotoxicity of these fractions were determined in vitro using different cancer cell lines. The n-hexane fraction exhibited the highest activity of toxicity. Therefore, this fraction was subjected to further separation by chromatographic methods. Two pure compounds known as: ‘Tutin’ and ‘hyenanchin’ were isolated and their structures were determined by NMR spectroscopic methods. Unpredictably, none of them showed significant (P < 0.01) inhibition on cell viability/proliferation at the concentrations that were used. F.E showed significant anti-tyrosinase, antibacterial, and cytotoxicity effects, therefore it can be considered as an effective inhibitor alone or in combination with other plant extracts.

Hibiscus sabdariffa (HS) is an edible medicinal plant, indigenous to India, China and Thailand and is used in Ayurveda and traditional medicine. Alcoholic extract of HS leaves (HSEt) was studied for its anti-hyperammonemic and antioxidant effects in brain tissues of ammonium chloride-induced hyperammonemic rats. Oral administration of HSEt (250 mg kg−1 body weight) significantly normalizes the levels of ammonia, urea, uric acid, creatinine and non-protein nitrogen in the blood. HSEt significantly reduced brain levels of lipid peroxidation products such as thiobarbituric acid and reactive substances (TBARS) and hydroperoxides (HP). However, the administered extract significantly increased the levels of antioxidants such as catalase (CAT), superoxide dismutase (SOD), glutathione peroxidase (GPx) and reduced glutathione (GSH) in brain tissues of hyperammonemic rats. This investigation demonstrates significant anti-hyperammonemic and antioxidant activity of HS.

Flavonoids, a group of compounds mainly derived from vegetables and herbal medicines, share a chemical resemblance to estrogen, and indeed some of which have been used as estrogen substitutes. In searching for possible functions of flavonoids, the neuroprotective effect in brain could lead to novel treatment, or prevention, for neurodegenerative diseases. Here, different subclasses of flavonoids were analyzed for its inductive role in neurite outgrowth of cultured PC12 cells. Amongst the tested flavonoids, a flavonol aglycone, isorhamnetin that was isolated mainly from the leaves of Ginkgo biloba L. showed robust induction in the expression of neurofilament, a protein marker for neurite outgrowth, of cultured PC12 cells. Although isorhamnetin by itself did not show significant inductive effect on neurite outgrowth of cultured PC12 cells, the application of isorhamnetin potentiated the nerve growth factor- (NGF-)induced neurite outgrowth. In parallel, the expression of neurofilaments was markedly increased in the cotreatment of NGF and isorhamnetin in the cultures. The identification of these neurite-promoting flavonoids could be very useful in finding potential drugs, or food supplements, for treating various neurodegenerative diseases, including Alzheimer's disease and depression.

Background

The peptide hormone calcitonin (CT) can significantly effect the proliferation rate of CT receptor (CTR) positive human cancer cells. We wish to identify additional human cancers expressing CTRs and assay the effects of CT on their growth rates and signal transduction pathways.

Results

The expression of the human calcitonin receptor (hCTR) gene in the chronic myelogenous leukemia cell line K562 was examined. RT-PCR on total RNA extracted from K562 cells detected the presence of hCTR mRNA. Further analysis demonstrated that multiple hCTR isoforms were present. Incubation of K562 cells with salmon calcitonin (sCT), but not amylin, caused an increase in intracellular levels of cAMP similar to that induced by forskolin treatment. We further demonstrated that butyrate induced erythroid differentiation of K562 cells caused a significant decrease in hCTR mRNA levels. However, phorbol myristate acetate (PMA) induced megakaryocytic differentiation of these cells had no significant effect on hCTR mRNA levels. We demonstrated that exposure to various concentrations of sCT had no effect on the cellular proliferation of K562 cells in vitro.

Conclusion

Chronic myelogenous k562 cells express multiple CTR isoforms. However, CT does not effect K562 proliferation rates. It is likely that the small increase in intracellular levels of cAMP following CT treatment is not sufficient to interfere with cellular growth.

Background

The aim of this research was to determine the intensity and mechanisms of the cytotoxic actions of five extracts isolated from the endemic plant species Helichrysum zivojinii Černjavski & Soška (family Asteraceae) against specific cancer cell lines. In order to evaluate the sensitivity of normal immunocompetent cells implicated in the antitumor immune response, the cytotoxicity of extracts was also tested against healthy peripheral blood mononuclear cells (PBMC).

Methods

The aerial parts of the plants were air-dried, powdered, and successively extracted with solvents of increasing polarity to obtain hexane, dichloromethane, ethyl-acetate, n-butanol and methanol extracts. The cytotoxic activities of the extracts against human cervix adenocarcinoma HeLa, human melanoma Fem-x, human myelogenous leukemia K562, human breast adenocarcinoma MDA-MB-361 cells and PBMC were evaluated by the MTT test. The mode of HeLa cell death was investigated by morphological analysis. Changes in the cell cycle of HeLa cells treated with the extracts were analyzed by flow cytometry. The apoptotic mechanisms induced by the tested extracts were determined using specific caspase inhibitors.

Results

The investigated Helichrysum zivojinii extracts exerted selective dose-dependent cytotoxic actions against selected cancer cell lines and healthy immunocompetent PBMC stimulated to proliferate, while the cytotoxic actions exerted on unstimulated PBMC were less pronounced. The tested extracts exhibited considerably stronger cytotoxic activities towards HeLa, Fem-x and K562 cells in comparison to resting and stimulated PBMC. It is worth noting that the cytotoxicity of the extracts was weaker against unstimulated PBMC in comparison to stimulated PBMC. Furthermore, each of the five extracts induced apoptosis in HeLa cells, through the activation of both intrinsic and extrinsic signaling pathways.

Conclusion

Extracts obtained from the endemic plant Helichrysum zivojinii may represent an important source of novel potential antitumor agents due to their pronounced and selective cytotoxic actions towards malignant cells.

Background

This study aims to evaluate the antioxidant potential of the ethyl acetate extract of Desmodium gangeticum root for cardioprotection from ischemia reperfusion-induced oxidative stress.

Methods

The in vitro antioxidant potential of the extract was in terms of hydroxyl radical scavenging activity, lipid peroxide scavenging activity, nitric oxide scavenging activity and diphenylpicrylhydrazyl radical scavenging activity. The in vivo antioxidant potential of the extract was assessed in an isolated rat heart model.

Results

Free radicals were scavenged by the extract in a concentration-dependent manner within the range of the given concentrations in all models. Administration of the ethyl acetate extract of Desmodium gangeticum root (100 mg per kg body weight) before global ischemia caused a significant improvement of cardiac function and a decrease in the release of lactate dehydrogenase in coronary effluent, as well as the level of malondialdehyde in myocardial tissues.

Conclusion

The ethyl acetate extract of Desmodium gangeticum root protects the myocardium against ischemia-reperfusion-induced damage in rats. The effects of the extract may be related to the inhibition of lipid peroxidation.

Summary

Reactive oxygen species are implicated in many human diseases and aging process. Much of the evidence is based on experimental data indicating increasing rates of lipid peroxidation in disease states and the ameliorating effects of antioxidants. It is becoming increasingly evident that the natural antioxidants, which have basically a phenolic structure, play an important role in protecting tissues against free radical damage. Eugenol (4-allyl-2 methoxyphenol), is one among such naturally occurring phenolic compounds. The antioxidant activity of eugenol is evaluated by the extent of protection offered against free radical mediated lipid peroxidation using both in vitro and in vivo studies. The in vitro lipid peroxidation is induced in mitochondria by (Fe(II)-ascorbate) or (Fe(II) + H2O2). The lipid peroxidation is assessed colorimetrically by measuring the formation of thiobarbituric acid reactive substances (TBARS) following the reaction of oxidized lipids with TBA. Eugenol inhibits both iron and Fenton reagent mediated lipid peroxidation. The inhibitory activity of eugenol is about five fold higher than α-tocopherol and about ten fold less than the synthetic antioxidant, BHT. The in vivo antioxidant activity of eugenol is evaluated by the determination of certain biochemical parameters (SGOT, Cyt.P450, glucose-6-phosphatase), peroxidation products and histopathological examination of •CCl3 radical induced hepatotoxicity in rats. Eugenol significantly inhibits the rise in SGOT activity and cell necrosis without protecting the endoplasmic reticulum (ER) damage as assessed by its failure to prevent a decrease in glucose-6-phosphatase activity. The protective action of eugenol has been found to be due to interception of secondary radicals derived from ER lipids rather than interfering with primary radicals of CCl4 (•CCl3/CCl3OO•).

High-speed countercurrent chromatography (HSCCC) was applied for separation and purification of flavonoids from the extract of belamcanda. High efficiency of HSCCC separation was achieved on a two-phase solvent system of n-hexane–ethyl acetate–methanol–water (4:5:5:5, v/v) by eluting the lower mobile phase at a flow-rate of 1.2mL/min and a revolution speed of 800 rpm. Three well-separated peaks were obtained in the HSCCC chromatogram and their purities were determined by HPLC-UV absorption spectrometry. These peaks were characterized by ESI-MSn and NMR, and the data compared with the reference standards where three peaks were identified as isorhamnetin, irigenin and hispidulin. The purities of each peak were 94, 95 and 90% respectively. In HSCCC experiment, 100 mg of the crude extract were separated yielding 10 mg of isorhamnetin, 8 mg of irigenin and 7 mg of hispidulin. HSCCC thus provides a cost-effective alternative to preparative scale HPLC for the semi-preparative scale separation and purification of flavonoids from Belamcanda.

Effect of oral administration of 200 mg/Kg body weight of the aqueous extract ofOcimum sanctum (Tulsi) mixed with diet for eight weeks to diabetic (streptozotocin induced) rats was studied. There was significant reduction in fasting blood glucose, serum lipid profile, lipid peroxidation products, (LPO) and improvement in glucose tolerance. The aqueous extract also decreased LPO formation (thiobarbituric acid reactive substances TBARS) and increased antioxidant enzymes superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPX), glutathione transferase (GT) and one antioxidant reduced glutathione (GSH) in plasma and rat liver, lung, kidney and brain. The decrease in TBARS and increase in GSH, SOD, CAT, GPX, and GT clearly shows the antioxidant property ofOcimum sanctum.

Smenospongine, a sesquiterpene aminoquinone isolated from the marine sponge Dactylospongia elegans, was previously reported by us to induce erythroid differentiation and G1 phase arrest of K562 chronic myelogenous leukemia cells. In this study, we investigated the effect of smenospongine on the cell cycles of other leukemia cells, including HL60 human acute promyelocytic leukemia cells and U937 human histiocytic lymphoma cells by flow cytometric analysis. Smenospongine induced apoptosis dose-dependently in HL60 and U937 cells. The smenospongine treatment increased expression of p21 and inhibited phosphorylation of Rb in K562 cells, suggesting the p21-Rb pathway play an important role in G1 arrest in K562 cells. However, the p21 promoter was not activated by the smenospongine treatment based on a luciferase assay using the transfected K562 cells. Smenospongine might induce p21 expression via another mechanism than transactivation of p21 promoter.

The present study was designed to investigate the antioxidant activity of aqueous and methanol extracts of Erythrina indica Lam leaves by in vitro methods viz. 1, 1-Diphenyl-2-Picrylhydrazyl, nitric oxide radical scavenging activity, and inhibition of lipid peroxidation by thiobarbituric acid reactive substances (TBARS) method on isolated rat liver tissues. Quantitative analysis of antioxidative components like total amount of phenolics, flavonoids, and flavonols were estimated using the spectrophotometric method. Linear regression analysis was used to calculate the IC50 value. Results showed that the aqueous and methanol extracts exhibited significant DPPH radicals scavenging activity with an IC50 value 342.59 ± 19.59, 283.24 ± 12.28 µg/mL respectively. Nitric oxide radicals were significantly scavenged by the aqueous and methanol extracts (IC50 = 250.12 ± 10.66; 328.29 ± 3.74 µg/mL). Lipid peroxidation induced by the Fe2+ was inhibited by the aqueous extract with low IC50 value (97.29 ± 2.05 µg/mL) as compared to methanol extract (IC50 = 283.74 ± 5.70 µg/mL). Both the extracts were exhibited similar quantities of total phenolics. Total flavonoids were found to be in higher quantities than total flavonols in aqueous extract as compared to methanol extract. From the results, it is concluded that the aqueous and methanol extracts of E. indica leaves possesses significant antioxidant activity that may be due to the presence of flavonoids and related polyphenolic compounds.

Methanol extract of the aerial parts of Phlomis persica Boiss. (Lamiaceae) (PPE) was studied to evaluate the effects of antidiabetic potential, by measuring fasting blood glucose, insulin, total antioxidant power (TAP), using ferric reducing antioxidant power (FRAP), lipid peroxidation (using thiobarbituric acid reactive substances, TBARS), superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx) on streptozotocin-induced diabetes in rats. Male Wistar rats were randomly divided into five groups of six animals each. Oral administration of PPE at doses of 100 and 200 mg/kg once a day for 10 days resulted in a significant reduction in fasting blood glucose and an increase in serum insulin levels, in comparison with diabetic control group. It also prevented diabetes-induced loss in body weight. Hepatic TAP increased and TBARS decreased following PPE treatments. The extract at 100 and 200 mg/kg increased the activity of hepatic SOD, CAT, and GPx in diabetic rats. It is concluded that PPE has antidiabetic potential that is comparable with glibenclamide. In conclusion, the results of the present study show positive effects of P. persica on experimental diabetes and thus the antidiabetic effect of PPE is related to its potential to inhibit hepatocellular oxidative stress.

Background:

The phytochemical and pharmacological activities of Annona reticulata components suggest a wide range of clinical application in lieu of cancer chemotherapy.

Materials and Methods:

Ethanol and aqueous extracts of roots of Annona reticulata Linn were studied for their in vitro antiproliferative activity on A-549 (human lung carcinoma), K-562 (human chronic myelogenous leukemia bone marrow), HeLa (human cervix) and MDA-MB (human adenocarcinoma mammary gland) cancer cell lines by MTT [3-(4,5-dimethyl thiazol-2-yl)-2,5-diphenyl tetrazolium bromide] colorimetric assay.

Results:

The ethanol extract exhibited a prominent inhibitory effect against A-549, K-562, HeLa and MDA-MB human cancer cell lines at a concentration range between 10 and 40 μg/ml, whereas the aqueous extract showed a lower activity at the same concentration. Simultaneously, the effect of the ethanol extract toward the inhibition of Vero cell line proliferation was lower in comparison with the cancer cell lines.

Conclusion:

The significant antiproliferative activity of the ethanol extract of Annona reticulata roots against A-549, K-562, HeLa and MDA-MB human cancer cell lines may be attributed toward the collective presence of acetogenins, alkaloids and lower inhibitory effect on Vero cell line, which suggests Annona reticulata be used as a chemopreventive agent in cancer therapy.

Abstract

This study was designed to determine the contents of total polyphenols, flavonoids, flavonols, flavanols, and anthocyanins of purple corn (Zea mays L.) extracts obtained with different methanol:water concentrations, acidified with 1% HCl (1 N). Another objective was to determine the antioxidant activity by 1,1-diphenyl-2-picrylhydrazyl (DPPH), 2,2′-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), ferric reducing antioxidant power (FRAP), and deoxyribose assay, individual phenolic compounds by high-performance liquid chromatography (HPLC), and endogenous antioxidant enzyme (superoxide dismutase [SOD], catalase [CAT], and total peroxidase [TPX]) activity and lipid peroxidation activity (thiobarbituric acid–reactive substances [TBARS] assay) in isolated mouse organs. Overall, the highest total content of polyphenols, anthocyanins, flavonoids, flavonols, and flavanols was obtained with the 80:20 methanol:water extract, acidified with 1% HCl (1 N). The 50% inhibitory concentration values obtained by the DPPH and ABTS assays with this extract were 66.3 μg/mL and 250 μg/mL, respectively. The antioxidant activity by the FRAP assay was 26.1 μM Trolox equivalents/g, whereas the deoxyribose assay presented 93.6% inhibition. Because of these results, the 80:20 methanol:water extract, acidified with 1% HCl (1 N), was used for the remaining tests. Eight phenolic compounds were identified by HPLC: chlorogenic acid, caffeic acid, rutin, ferulic acid, morin, quercetin, naringenin, and kaempferol. Furthermore, it was observed that the purple corn extract was capable of significantly reducing lipid peroxidation (lower malondialdehyde [MDA] concentrations by the TBARS assay) and at the same time increasing endogenous antioxidant enzyme (CAT, TPX, and SOD) activities in isolated mouse kidney, liver, and brain. On the basis of the results, it was concluded that the purple corn extract contained various bioactive phenolic compounds that exhibited considerable in vitro antioxidant activity, which correlated well with the decreased MDA formation and increase in activity of endogenous antioxidant enzymes observed in the isolated mouse organs. This warrants further in vivo studies with purple corn extracts to assess its antioxidant activity and other bioactivities.

Flavonoids are bioactive food compounds with potential lipid-lowering effects. Commercially available enzymatic assays are widely used to determine free fatty acid (FFA) and triglyceride (TG) levels both in vivo in plasma or serum and in vitro in cell culture medium or cell lysate. However, we have observed that various flavonoids interfere with peroxidases used in these enzymatic assays, resulting in incorrect lower FFA and TG levels than actually present. Furthermore, addition of isorhamnetin or the major metabolite of the flavonoid quercetin in human and rat plasma, quercetin-3-O-glucuronide, to murine serum also resulted in a significant reduction of the detected TG levels, while a trend was seen for FFA levels. It is concluded that when applying these assays, vigilance is needed and alternative analytical methods, directly assessing FFA or TG levels, should be used for studying the biological effects of flavonoids on FFA and TG levels.

FigureInterference of different flavonoids spiked into cell culture medium on the FFA (A) and TG (B) levels, and interference of quercetin (Q) and its major metabolite, quercetin-3-O-glucuronide (Q3G), and isorhamnetin (I) spiked into murine serum on the FFA (C) and TG (D) levels, as measured by enzymatic assays. Flavonoids analysed are quercetin (Q), (+)-catechin (C), luteolin (L), genistein (G), naringenin (N), and kaempferol (K). Asterisk indicates a significant difference (p < 0.05) from the control (0 μM)

Rac2 is a Rho family GTPase that is widely expressed in hematopoietic cells and plays a critical role in host defense. This study investigates the mechanisms responsible for increased Rac2 gene expression during myeloid cell differentiation. Treatment of K562 chronic myelogenous leukemia cells with phorbol-12-myristate-13-acetate (PMA) induces megakaryocytic differentiation and Rac2 gene transcription following a lag of 6-12 hours. Promoter/luciferase reporter gene assays reveal that a 135 bp cis-element located between -4223 and -4008 bp upstream of the Rac2 transcription start site is necessary and sufficient for PMA-induced gene expression. The AP1 transcription factor binds to three cis-elements within the 135 bp Rac2 gene regulatory region both in vitro and in vivo following PMA treatment, and mutagenesis of the AP1 binding sites ablates the PMA responsiveness of the 135 bp Rac2 gene regulatory region. Over-expression of AP1 is sufficient to induce expression of a transiently transfected Rac2 promoter/luciferase plasmid, but not the endogenous Rac2 gene. Induction of AP1 in vitro DNA-binding activity is apparent within 1 hour of PMA stimulation. However, AP1 binding to the endogenous Rac2 promoter exhibits a lag of 5-9 hours, which correlates with reduced histone H3-Lys9 methylation, increased histone H3 acetylation, and increased nuclease accessibility within the 135 bp Rac2 gene regulatory region. These results demonstrate that PMA induction of Rac2 expression during terminal myeloid differentiation requires the coordinate induction of transcription factors and remodeling of Rac2 gene chromatin structure.

4-Hydroxy-trans 2-nonenal (HNE) is one of the most abundant and toxic lipid aldehydes formed during lipid peroxidation by reactive oxygen species. We have investigated the genotoxic effects of HNE and its regulation by cellular glutathione (GSH) levels in human erythroleukemia (K562) cells. Incubation of K562 cells with HNE (5–10 μM) significantly elicited a 3- to 5-fold increased DNA damage in a time and dose dependent manner as measured by comet assay. Depletion of GSH in cells by L-Buthionine-[S,R]-sulfoximine (BSO) significantly increased HNE-induced DNA damage, whereas supplementation of GSH by incubating the cells with GSH-ethyl ester significantly decreased HNE-induced genotoxicity. Further, over-expression of mGSTA4-4, a HNE detoxifying GST isozyme, significantly prevented HNE-induced DNA damage in cells, and ablation of GSTA4-4 and aldose reductase with respective siRNAs further augmented HNE-induced DNA damage. These results suggest that the genotoxicity of HNE is highly dependent on cellular GSH/GST/AR levels and favorable modulation of the aldehyde detoxification system may help in controlling the oxidative stress- induced complications.

The present study is based on the evaluation of antioxidant potential of a well known plant Lactuca sativa. Methanolic leaf extract was investigated for in vitro inhibition of oxidative damage induced by UV-radiations to the salmonella typhi bacteria and in vivo effect on the production of body enzymes i.e. catalase and superoxide dismutase. The lipid peroxidation masurement was also done in terms of thiobarbituric acid reactive substances (TBARS) in blood and brain of male albino wistar rats. The plant extract has shown significant antioxidant potential both in vitro and in vivo.