Effect of ambient levels of ozone on photosynthetic components and radical scavenging system in leaves of African cowpea varieties

Tropospheric ozone (O3), a main component of photochemical oxidants, adversely affects not only human health but also vegetation. To clarify the long-term effects of ambient levels of tropospheric ozone (O3) on photosynthetic components and radical scavenging system in the leaves of cowpea ( Vigna unguiculata L.), two African varieties, Blackeye and Asontem, were grown in open-top chambers and exposed to filtered air (FA), non-filtered air (NF) or non-filtered air with additional O3 of approximately 50 nl l-1. Ambient levels of O3 significantly reduced chlorophyll concentration, quantum yield and activity of ribulose 1,5-bisphosphate carboxylase/oxygenase (Rubisco), thus contributing to the reduction in net photosynthetic rate at the reproductive growth stage of both varieties; with no significant variety difference in the sensitivity to O3. The O3-induced significant reduction in catalase activity was observed in Blackeye at vegetative and reproductive growth stages; and in Asontem at reproductive growth stage. On the other hand, exposure to O3 significantly increased ascorbate peroxidase activity in Blackeye at reproductive stage and did not significantly affect that in Blackeye at vegetative growth stage and that in Asontem at both growth stages. At reproductive growth stage, activities of monodehydroascorbate reductase and glutathione reductase were significantly increased by the exposure to O3 in both varieties. The results obtained in this study suggest that, although ascorbate peroxidase, monodehydroascorbate reductase and glutathione reductase played important roles in scavenging O3-induced reactive oxygen species in the leaves, radical scavenging ability of these enzymes is not sufficient to avoid detrimental effects of ambient levels of O3 on photosynthesis in both African cowpea varieties.

Natural plant polyphenols for alleviating oxidative damage in man: Current status and future perspectives

The balance between oxidation and reduction is important for maintaining a healthy biological system. Oxidative stress results from an imbalance between excessive formation of reactive oxygen species (ROS) and/or reactive nitrogen species (RNS) and limited endogenous defense systems, and this imbalance can adversely alter lipids, proteins and DNA, causing a number of human diseases. Thus, exogenous antioxidants that can neutralize the effect of free radicals are needed to diminish the cumulative effects of oxidative damage over human life span. Current research reveals that phenolic compounds in plants possess high antioxidant activity and free radical scavenging capacity and can prevent the body from oxidative damage over human life span. This review focuses on the present understanding of free radicals and antioxidants and their importance in human health and disease. Information about the chemical features of free radicals as well as their deleterious effects on cell structures is reviewed. The chemical structure and anti-oxidative mechanisms of essential polyphenols and their potential health benefits are presented. In addition, the limitation of natural antioxidants and a perspective on likely future trends in this field are also discussed.

Anti-cancer and antioxidant properties of phenolics isolated from Toona sinensis A Juss acetone leaf extract

Purpose: To investigate the antioxidant and anticancer activities of phenolics from the leaf extract of Toona sinensis (TS). Methods: Acetone leaf extract of TS was screened for total phenolic and flavanoid contents, and the flanonoids were subjected to high performance liquid chromatographic (HPLC) analysis. Antioxidant properties were assessed via oxygen radical absorbance capacity (ORAC), peroxyl radical scavenging capacity (PSC) and cellular antioxidant activity (CAA), while anti-proliferative activity ins HepG2 cell line was assessed using methylene blue assay. Results: The extract contained 36.02 ± 0.24 mg of gallic acid equiv/g dry weight (DW) and 20.24 ± 1.73 mg of catechin equiv/g DW of total phenolic and total flavonoid, respectively. The levels of rutin and quercitrin were 0.51 and 19.55 mg/g, respectively. Epicatechin, gallic acid, quercitin, isoquercetin were not detected. The extract showed significant antioxidant potential and high anti-proliferation capacity with low cytotoxicity against HepG2 cell in vitro. The underlying mechanism of anti-proliferative effect was induction of apoptosis. Conclusion: TS leaf extract possesses significant in vitro antioxidant properties and anti-proliferative effect against HepG2 cells, which make it a potential anticancer drug source.

Antioxidant and antimicrobial activities of solvent fractions of Vernonia cinerea (L.) Less leaf extract.

Background: Vernonia cinerea (L.) Less is used in folk medicine as a remedy for various diseases. Objectives: The present study reports antioxidant and antimicrobial activities of solvent fractions of Vernonia cinerea. Methods: The antioxidant properties of solvent fractions of V. cinerea were evaluated by determining radicals scavenging activity, total flavonoid and phenolic contents measured with the 2,2-diphenyl-1-picryl hydrazyl (DPPH) test, the aluminum chloride and the Folin-ciocalteau methods, respectively. Antimicrobial activities were tested against human pathogenic microorganisms using agar diffusion method. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of each active extract were determined. Results: The ethyl acetate fraction having the IC50 value of 6.50 μg/mL demonstrated comparable DPPH radical-scavenging activity with standard antioxidants, gallic acid and quercetin included in the study. All fractions displayed moderate antimicrobial potential against the tested pathogens with the zone of inhibition that ranged from 9.0 to 13.5 mm. The MIC (1.56 mg/mL) and MBC (3.13 mg/mL) indicated highest susceptibility of Candida albicans in all fractions. Conclusion: The results of this study showed that the solvent fractions of V. cinerea possess antioxidant and antimicrobial activities, hence justifying the folkloric use of the plant for the treatment of various ailments in traditional medicine.

GC-MS Analysis, Antimicrobial and Antioxidant Activities of Extracts of the Aerial Parts of Conyza sumatrensis

Phytochemical analyses as well as antimicrobial and antioxidant activities of the extracts of C. sumatrensis aerial parts were investigated in this study. METHODS: The aerial parts of C. sumatrensis were air dried, weighed and exhaustively extracted with hexane, ethyl acetate and methanol successively. The crude extracts were screened for metabolites. These extracts of the plant were evaluated for antimicrobial and antioxidant activities using agar diffusion and DPPH method respectively. The extracts were also analysed using Gas chromatography – Mass spectrometry, and the chromatogram coupled with mass spectra of the compounds were matched with a standard library. RESULTS: Preliminary phytochemical investigation of crude n-hexane, ethyl acetate and methanol extracts of the aerial parts of Conyza sumatrensis revealed the presence of anthraquinones, flavonoids, terpenoids, phenolics, tannin, glycosides and carbohydrate. All the crude extracts gave a clear zone of inhibition against the growth of the test bacteria ( Staphylococcus aureus , Escherichia coli , Bacillus subtilis , Pseudomona aeruginosa, Salmonella typhi , Klebsiellae pneumonae ) at moderate to high concentrations, as well as test fungi ( Candida albicans , Aspergillus niger , penicillium notatum and Rhizopus stolonifer ) at high concentration. Methanolic extract exhibited significant radical scavenging property with IC50 of 17.08 μg/mL while n-hexane and ethyl acetate extracts showed no significant antioxidant activity. GC-MS of N-hexane extract showed a total number of eleven chemical constituents with α-Farnesene and spathulenol being the most abundance compounds constituting 20.27 and 22.28% of the extract respectively. Ethyl acetate extract revealed thirteen compounds with two most abundant compounds, cis-β-farnesene (16.64 %) and cis-pinane (21.09 %). While methanolic extract affords seventeen compounds with Ephytol being the most abundant compound (19.36 %).

Anti-oxidative and anti-neuroinflammatory effects of ethyl acetate extract fractions of Suaeda asparagoides MIq

Purpose: To evaluate the in vitro antioxidant and anti-neuroinflammatory effects of Suaeda asparagoides ethylacetate extract (SAE) in lipopolysaccharide (LPS)-stimulated BV-2 microglial cells. Methods: The antioxidative activity of SAE was evaluated by measuring 1, 1-diphenyl-2-picryl-hydrazyl (DPPH) radical scavenging activity spectrometrometrically. Cell viability was evaluated by 3-(4, 5dimethylthiazol-2-yl)-2, 5- diphenyl-tetrazolium bromide (MTT) assay, while LPS-stimulated BV-2 microglia were used to study the expression and production of inflammatory mediators, including nitric oxide (NO), inducible NO synthase (iNOS) and tumor necrosis alpha (TNF-α). Results: Pretreatment with SAE prior to LPS treatment significantly inhibited excessive production of NO (p < 0.001 at 20, 40, 80 and 100 μg/mL) in a dose-dependent manner, and was associated with down-regulation of expression of inducible nitric oxide synthase (iNOS). SAE also suppressed the LPSinduced increase in TNF-α level (p < 0.01at concentrations of 40 and 80 μg/mL) in BV-2 cells. Furthermore, DPPH-generated free radicals were inhibited by SAE in a concentration-dependent manner. Conclusion: These results indicate that SAE possesses strong anti-oxidant properties, and inhibits excessive production of pro-inflammatory mediators, including NO, iNOS and TNF-α, in LPS-stimulated BV-2 cells

Phytochemical profile and some biological activities of three Centaurea species from Turkey

Purpose: To characterise the phytochemical profile of whole plants of Centaurea balsamita, C. depressa and C. lycopifolia with LC-ESI-MS/MS, and as well as their antioxidant, anticholinesterase and antimicrobial activities. Methods: Organic and aqueous extracts of the three Centaurea species were evaluated for DPPH free radical, ABTS cation radical scavenging and cupric reducing antioxidant capacity (CUPRAC). Acetyland butyryl-cholinesterase enzyme inhibition abilities of the extracts using petroleum ether, acetone, methanol and water were studied to determine anticholinesterase activity, while antimicrobial activity was determined by disc diffusion method using appropriate antimicrobial standards and organisms. The phytochemical components of the methanol extracts were assessed by LC-MS/MS. Results: The methanol extract of C. balsamita exhibited much higher DPPH free and ABTS cation radicals scavenging activities (with IC50 of 62.65 ± 0.97 and 24.21 ± 0.70 mg/ml, respectively) than the other extracts. The petroleum ether extracts of the plant species exhibited moderate inhibitory activity against butyrylcholinesterase enzymes while the acetone extract of C. balsamita showed good antifungal activity against Candida albicans. Quinic acid (17513 ± 813 μg/g, 63874 ± 3066 μg/g and 108234 ± 5195 μg/g) was the major compound found in the methanol extracts of C. balsamita, C. depressa and C. Lycopifolia, respectively. Conclusion: These results indicate quinic acid is the major compound in the three plant species and that Centaurea balsamita has significant antioxidant, anticholinesterase and antimicrobial properties. Further studies to identify the compounds in the extracts responsible for the activities are required.

Radioprotective effect and other biological benefits associated with flavonoids

Ionizing radiation has the potential to cause extensive damage to living organisms. It can directly act on DNA, proteins and lipids, resulting in ionizing excitation and chemical bond cleavage, which can lead to molecular and cellular damage. Ionizing radiation can hydrolyze water molecules in the body, resulting in increased numbers of free radicals with strong oxidation ability. This process indirectly leads to tissue degeneration and necrosis, which can possibly result in cancer. In this paper, the intervention mechanism of flavonoids on ionizing radiation was analyzed. It has been revealed that the intervention mechanism associated with flavonoids may offer protective properties for DNA, prevent scavenging free radicals, and protect against auto-immune damage. In addition, this invention mechanism can protect the hematopoietic system and reduce inflammation.

In vitro antioxidative activity of moss extract, and effect of moss on serum lipid level of mice fed with high-fat diet

Purpose: To evaluate the potential of active compounds derived from moss in the prevention and treatment of various diseases. Methods: Three species of moss were extracted with deionized water at 95 °C, and with 70.5 % ethanol at 85 °C. Analysis of total phenolic contents (TPC) of the extracts were performed by FolinCiocalteu (FC) method. The antioxidant activity of the extracts were determined using three methods, namely, by 2,2\'-azino-bis(3-ethylbenzothiazoline-6-sulphonic) acid (ABTS), 1,1-diphenyl-2-picrylhydrazyl (DPPH) and ferric reducing antioxidant power (FRAP). In vivo effects were evaluated in mice fed high fat diet (HFD) supplemented with 20 % ground moss. Cholesterol levels in HFD were evaluated by ophthalaldehyde method. Serum triglyceride levels were measured using triglyceride (TG) kit, while blood insulin level and leptin concentration were measured by enzyme-linked immunosorbent assay (ELISA) kit. Results: The moss extracts exhibited antioxidative effects, as evidenced of . TPC of 47.20 ± 11.20 to 119.87 ± 11.51 mg GAE/mg, respectively. ABTS scavenging activity was 1078.11 ± 18.95 to 2587.33 ± 46.19 μmol Trolox/mg, DPPH scavenging activity of were 42.11 ± 8.22 to 298.78 ± 20.02 μmol Trolox/mg, and FRAP value of 393.19 ± 24.64 to 1070.14 ± 17.92 μmol Trolox/mg, respectively. Mice fed with 20 % ground moss did not show any significant effect (p < 0.05) on visceral weight and blood lipid levels of HFD, while leptin concentrations reduced significantly to 4.74 ± 0.00 and 0.20 ± 0.00 ng/dL) relative to HFD alone (26.72 ± 6.53 ng/dL). Conclusion: Moss can potentially be used as an antioxidative ingredient, for the improvement of overall human health, suggesting that important medical benefits associated with moss consumption. However, further investigations are required to ascertain this.

Effect of Astragalus membranaceus (Fisch) Bunge extract on streptozocin-induced diabetic in rats

Purpose: To investigate the effect of Astragalus membranaceus (Fisch.) Bunge. extract (AMBE) on streptozotocin-induced diabetic rats. Methods: The aqueous extract of AMB was obtained by steeping the dried Astragalus membranaceus (Fisch.) Bunge. in water at 60 oC three times, each for 1 h, before first drying in an oven at 100 oC and then freeze-drying the last extract thus obtained. Diabete model rats was induced by a single intraperitoneal injection of a freshly prepared solution of streptozotocin (50 mg/kg). The rats were randomly divided into 6 groups of ten rats each: negative control group, normal control group, reference group (glibenclamide1 mg/kgbody weight) as well as AMB extract groups, namely, 40, 80 and 160 mg/kg body weight. Antihyperglycemic effect was measured by blood glucose and plasma insulin levels. Oxidative stress was evaluated in liver and kidney by antioxidant markers, viz, lipidperoxidation (LPO), superoxide dismutase (SOD), reduced glutathione (GSH), glutathione peroxidase (GPx) and catalase (CAT), while blood serum levels of creatinine and urea were also determined in both diabetic control and treated rats. Results: Compared with diabetic rats, oral administration of AMBE at a concentration of 160 mg/kg daily for 30 days showed a significant decrease in fasting blood glucose (109.438 ± 3.52, p < 0.05) and increased insulin level (13.96 ± 0.74, p < 0.05). Furthermore, it significantly reduced biochemical parameters (serum creatinine, 0.86 ± 0.29, p < 0.05) and serum urea (45.14 ± 1.79, p < 0.05). The treatment also resulted in significant increase in GSH (49.21 ± 2.59, p < 0.05), GPx (11.96 ± 1.16, p < 0.05), SOD (14.13 ± 0.49, p < 0.05), CAT (83.25 ± 3.14, p < 0.05) level in the liver and kidney of diabetic rats. Conclusion: The results suggest that AMBE may effectively normalize impaired antioxidant status in streptozotocin-induced diabetes in a dose-dependent manner. AMBE has a protective effect against lipid peroxidation by scavenging free radicals and is thus capable of reducing the risk of diabetic complications.