Aconitase activity and expression during the development of lemon fruit

Citrus fruits are characterized by the accumulation of high levels of citric acid in the juice sac cells and a decline in acid level toward maturation. It has been suggested that changes in mitochondrial aconitase (EC 4.2.1.3) activity affect fruit acidity. Recently, a cytosolic aconitase (cyt-Aco) homologous to mammalian iron-regulated proteins was identified in plants, leading us to re-evaluate the role of aconitase in acid accumulation. Aconitase activity was studied in 2 contrasting citrus varieties, sweet lime ( Citrus limettioides Tan., low acid) and sour lemon ( Citrus limon var. Eureka, high acid). Two aconitase isozymes were detected. One declined early in sour lemon fruit development, but was constant throughout sweet lime fruit development. Its reduction in sour lemon was associated with a decrease in aconitase activity in the mitochondrial fraction. Another isozyme was detected in sour lemon toward maturation, and was associated with an increase in aconitase activity in the soluble fraction, suggesting a cytosolic localization. The cyt-Aco was cloned from lemon juice sac cells, but in contrast to the changes in isozyme activity, its expression was constant during fruit development. We present a model, which suggests that reduction of the mitochondrial aconitase activity plays a role in acid accumulation, while an increase in the cyt-Aco activity reduces acid level toward fruit maturation.     

Antioxidant constituents from rhubarb: structural requirements of stilbenes for the activity and structures of two new anthraquinone glucosides

The methanolic extracts from five kinds of rhubarb were found to show scavenging activity for DPPH radical and .O2-. Two new anthraquinone glucosides were isolated from the rhizome of Rheum undulatum L. together with two anthraquinone glucosides, a naphthalene glucoside, and 10 stilbenes. In the screening test for radical scavenging activity of rhubarb constituents, stilbenes and a naphthalene glucoside showed activity, but anthraquinones and sennosides did not. In addition, most stilbenes inhibited lipid peroxidation of erythrocyte membrane by tert-butyl hydroperoxide. Detailed examination of the scavenging effect on various related compounds suggested the following structural requirements; 1) phenolic hydroxyl groups are essential to show the activity; 2) galloyl moiety enhances the activity; 3) glucoside moiety reduces the activity; 4) dihydrostilbene derivatives maintain the scavenging activity for the DPPH radical, but they show weak activity for .O2-. In addition, several stilbenes with both the 3-hydroxyl and 4'-methoxyl groups inhibited xanthine oxidase.     

Protective effects of an extract from Citrus bergamia against inflammatory injury in interferon-γ and histamine exposed human keratinocytes

AimsThe present work evaluated the anti‐inflammatory/antioxidant activity of a well characterized extract from Citrus bergamia Risso and Poiteau (CBE), containing neoeriocitrin, naringin, neohesperidin and other flavonoids, on human NCTC 2544 keratinocytes treated with interferon-gamma (IFN-γ) and histamine (H).Main methodsHigh performance liquid chromatography (HPLC) coupled with diode array detectors was used to characterize and quantify phenolic compounds in CBE. Anti‐inflammatory/antioxidant ability on keratinocytes was determined through evaluation of inter-cellular adhesion molecule-1 (ICAM-1) and inducible nitric oxide synthase (iNOS) expression by Western blot, production of nitric oxide (NO) with Griess reagent and concentration of reactive oxygen species (ROS) by fluorescent quantitative analysis with 2′,7′-dichlorfluorescein-diacetate (DCFH-DA). Cell viability was assessed using 3-(4,5-dimethyl-2 thiazoyl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assay. Antioxidant activity was also measured by oxygen radical absorbance capacity (ORAC) assay. Glycosaminoglycans (GAGs) were quantified using 1.9-dimethyl methylene blue (DMB).Key findingsCBE exhibited high antioxidant activity confirmed by elevated ORAC values related to high capacity in oxygen radical scavenging. The assays on keratinocytes demonstrated that CBE does not inhibit cell proliferation and is shown to significantly reduce dose-dependently ICAM-1, iNOS, NO, ROS and GAG production in cells exposed to IFN-γ and H.SignificanceOur study demonstrates that the pools of compounds of an extract from C. bergamia efficiently block the proinflammatory actions induced by IFN-γ and H on human keratinocytes. CBE may be used for topic employment in some inflammatory diseases of the skin and to represent an important opportunity for the essential oil processing industries.     

The role of carotenoid cleavage dioxygenases in the regulation of carotenoid profiles during maturation in citrus fruit

To investigate the relationship between a carotenoid profile and gene expression for carotenoid cleavage dioxygenases, three citrus varieties that exhibit different 9-cis-violaxanthin levels in their juice sacs, Satsuma mandarin (Citrus unshiu Marc.; a variety accumulating a low level of 9-cis-violaxanthin), Valencia orange (Citrus sinensis Osbeck; variety accumulating a high level of 9-cis-violaxanthin), and Lisbon lemon (Citrus limon Burm.f.; a variety accumulating an undetectable level of 9-cis-violaxanthin) were used. Three cDNAs (CitCCD1, CitNCED2, and CitNCED3) were cloned. The recombinant CitCCD1 protein cleaved beta-cryptoxanthin, zeaxanthin, and all-trans-violaxanthin at the 9-10 and 9'-10' positions and 9-cis-violaxanthin at the 9'-10' position. The recombinant CitNCED2 and CitNCED3 proteins cleaved 9-cis-violaxanthin at the 11-12 position to form xanthoxin, a precursor of abscisic acid (ABA). The gene expression of CitCCD1 increased in the flavedos and juice sacs of the three varieties during maturation. In Satsuma mandarin, the gene expression of CitNCED2 and CitNCED3 increased noticeably, accompanying a massive accumulation of ABA in the flavedo and juice sacs. In Valencia orange, the gene expression of CitNCED3 increased with a slight elevation of the ABA level in the flavedo, whereas neither the gene expression of CitNCED2 nor the ABA level increased noticeably in the juice sacs. In Lisbon lemon, the gene expression of CitNCED2 increased remarkably, accompanying increases in the ABA level in the flavedo and juice sacs. These results suggest that, in the juice sacs, the efficient cleavage reaction for ABA synthesis reduces the 9-cis-violaxanthin level in Satsuma mandarin and Lisbon lemon, whereas the low cleavage reaction maintains the predominant 9-cis-violaxanthin accumulation in Valencia orange.     

Isolation and measurement of quercetin glucosides in flower buds of Japanese butterbur (Petasites japonicus subsp. gigantea Kitam.)

Three quercetin glucosides were isolated from flower buds of Japanese butterbur (Petasites japonicus subsp. gigantea Kitam.) together with caffeic acid as the ingredients that had DPPH radical scavenging activity, using the DPPH-HPLC method for measuring the radical scavenging activity. These quercetin glucosides were identified as quercetin 3-O-beta-D-glucoside, quercetin 3-O-beta-D-6'-O-acetylglucoside, and rutin, and the amounts of the glucosides in flower buds were also examined by HPLC. The flower buds were harvested from four different sites, the total amount of quercetin glucosides in each site was 100-170 mg/100 g fr. wt., and there were no great differences of the amounts between growing fields.     

Quantification of polyphenolic antioxidants and free radical scavengers in marine algae

While the health benefits of antioxidant compounds from terrestrial plants are widely accepted in Western counties, there is less recognition of the health benefits of marine algal antioxidant compounds. Oceans are an abundant source of biomaterials, with many natural antioxidants derived from marine algae being investigated as potential anti-aging, anti-inflammatory, anti-bacterial, anti-fungal, cytotoxic, anti-malarial, anti-proliferative, and anti-cancer agents. The aim of this work was to quantify and compare polyphenolic content and free radical scavenging activity of algal extracts using normal phase and reverse phase thin layer chromatography. Post-chromatographic derivatization with neutral ferric chloride (FeCl₃) solution and with 2,2-diphenyl-1-picrylhydrazyl (DPPH·) free radical were used to assess total polyphenolic content and free radical scavenging activities in algal samples. Total phenolic content quantified on normal phase plates was correlated to phenolic content established on reverse phase plates. Similarly, free radical scavenging activity established on normal phase and reverse phase plates were in good agreement. However, although free radical scavenging activities determined on normal phase plates were highly correlated with polyphenolic content, this correlation was low for reverse phase plates. Lipophilic reversed phase TLC plates do not effectively separate mixtures of highly polar compounds like flavonoids, phenolic compounds and their glucosides. Thus, although reversed phase plates are recommended for assessment of free radical scavengers, as they do not influence the free radical-antioxidant reaction, they may not provide the best separation of polar phenolic compounds, especially flavonoids, and therefore may not accurately quantify polyphenolic content and free radical scavenging potential.     

Studies on the development of functional powder from citrus peel

The suitability of citrus peels, generated as a by-product of the juice industry, as a source of antioxidants was investigated. Citrus peel powder was prepared by lyophilizing 70% ethanol extract from citrus peels. Extraction was carried out at room temperature (20 degrees C) for 72 h. The extract was subjected to gamma-irradiation treatment (20 kGy). The aqueous solutions of citrus peel powder were examined for color characteristics and antioxidant potential in terms of 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging, beta-carotene bleaching and nitrite scavenging activities. There were significant changes in Hunter color values due to irradiation. The a*- and b*-values decreased due to radiation treatment. DPPH radical scavenging, beta-carotene bleaching and nitrite scavenging activities were not affected by irradiation treatment. Nitrite scavenging activity was the highest in the extract at pH 1.2 followed by pH 4.2 and 6.0. These functional properties of the aqueous solution were found to be stable in heat treatment. It could significantly improve oxidative stability of lipids in fish meat system. Based on these results there may be opportunities to use citrus peel powder as a functional component in the food processing industry with gamma irradiation treatment improving its color characteristics without adversely influencing the functional properties.     

Hepatic cold hypoxia and oxidative stress: implications for ICAM-1 expression and modulation by glutathione during experimental isolated liver preservation

Cold preservation and reperfusion of liver during transplantation are necessary steps in the procedure but which are also associated with damage to the organ. One aspect of this damage is thought to concern up-regulation of inflammatory markers, such as the adhesion molecule intercellular adhesion molecule 1 (ICAM-1) on target cells in the liver. This aids sequestration of activated leucocytes, which promote inflammation, by a complex sequence of events, including free radical mediated damage. We have studied changes in ICAM-1 in rat liver as a consequence of cold preservation for various times, and also after warm reperfusion during isolated liver perfusion. We have also investigated the effects of the free radical scavenging agent (reduced glutathione-GSH) on the modulation of ICAM-1 expression after cold hypoxia and reperfusion. Livers were subjected to various regimes of cold preservation and reperfusion. Liver biopsies were taken at three time points (initial baseline on liver exposure; after organ flushing and post-storage at 0, 8, 16, and 24h cold hypoxia in University of Wisconsin solution; in the same livers after 1h warm reperfusion). The tissues were processed for frozen biopsy work, and frozen sections were stained using immunohistochemical methods, for blinded scoring by an independent observer. Positive controls were obtained by exposure to endotoxin lipopolysaccharide before liver flushing. ICAM-1 expression was low in control livers (0.33+/-0.21), and increased to near maximal (2.83+/-0.17) after endotoxin exposure. ICAM-1 expression increased progressively with cold preservation, reaching values of 1.17+/-0.31 and 1.83+/-0.31 after 16 and 24h, respectively (P<0.05 and 0.02 versus controls). Warm reperfusuion increased ICAM-1 expression in all flushed groups and with longer cold preservation was close to maximal (2.67+/-0.21 after 16h and 2.98+/-0.02 after 24h; P<0.001 in both cases). Addition of the free radical scavenger GSH prevented up-regulation of ICAM-1 in livers reperfused after flushing and cold storage for up to 8h; beyond this time, ICAM-1 expression still increased, such that by 24h cold preservation and reperfusion absence (2.98+/-0.02) or presence (2.67+/-0.21) made no difference. We conclude that liver ICAM-1 expression is demonstrably increased by progressive cold preservation and reperfusion, and is only marginally affected by addition of GSH during reperfusion. The model can be used to investigate other agents which might be more successful in preventing post-storage inflammatory damage.     

Antioxidative pyranonigrins in rice mold starters and their suppressive effect on the expression of blood adhesion molecules

Antioxidants having a 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging capacity in rice mold starters, which are used for the preparation of various Japanese fermented foods, and their effectiveness against the expression of blood adhesion molecules were examined. An antioxidant was isolated from the rice mold starters used for shochu and identified as pyranonigrin-S (PG-S) by (1)H-NMR, (13)C-NMR, and FAB-MS analyses. It was a derivative of pyranonigrin-A (PG-A), which has been isolated as an antioxidant from the rice mold starters. Pyranonigrins PG-A and PG-S were found to exist in spores on rice mold starters which had been prepared by Aspergillus awamori, A. kawachii, and A. saitoi. PG-S exhibited a higher level of DPPH radical scavenging activity than PG-A. PG-A was found to have a significant suppressive effect on the expression of vascular cell adhesion molecule-1 (VCAM-1) in human umbilical vein endothelial cells (HUVECs) induced by tumor necrosis factor-alpha (TNF-alpha) (P<0.05).     

Aspirin prevents adhesion of T lymphoblasts to vascular smooth muscle cells

In the development of atherosclerosis, inflammatory cells adhere to and migrate into the vascular walls by interacting with vascular smooth muscle cells. To investigate the mechanism of aspirin’s anti-atherogenic activity, we examined whether aspirin inhibits the adhesion of lymphocytes to human aortic smooth muscle cells (AoSMC). Aspirin inhibited T-cell adhesion to AoSMC activated by interleukin 1β (IL-1β) in a dose-dependent manner. Antibodies to the adhesion molecules ICAM-1 or VCAM-1, but not to E-selectin, prevented T-cell adhesion. ICAM-1 and VCAM-1 expression stimulated by IL-1β was reduced by the treatment with aspirin, whereas the expression of E-selectin was unaffected. Nuclear factor κB (NF-κB) activity was enhanced by IL-1β and reduced by aspirin, indicating that decreased ICAM-1 and VCAM-1 expression was due to reduced NF-κB activity.Thus, aspirin inhibits the adhesion of Jurkat T cells to IL-1β-activated AoSMC by reducing NF-κB activity and decreasing expression of ICAM-1 and VCAM-1, and may prevent the development of atherosclerosis.     

rhG-CSF 动员对供者CD4+ T 细胞免疫表型和功能影响

目的:研究重组人粒细胞集落刺激因子(rhG-CSF)动员对供者CD4+T细胞表面分子淋巴细胞功能相关抗原-1(LFA-1)、细胞间黏附分子-1(ICAM-1)、L-选择素(LAM-1)和人整合素-4(VLA-4)的表达及其介导的CD4+T细胞功能的影响,探讨外周血干细胞移植过程中CD4+T细胞免疫耐受机制。方法:使用三色荧光标记检测动员前及动员后第5天供者外周血LFA-1、ICAM-1、LAM-1和VLA-4的表达率,ELISA方法检测动员前后CD4+T细胞分泌IFN-γ和IL-4能力,免疫磁性分选法分离纯化CD4+T细胞,检测动员前后CD4+T细胞对基质细胞衍生因子-1α(SDF-1α)的迁移能力和对ICAM-1的黏附能力。结果:动员前后CD4+T细胞LFA-1(CD11a)和VLA-4(CD49d)表达率差异无统计学意义(P>0.01),动员前后CD4+T细胞LAM-1(CD62L)和ICAM-1(CD54)的表达率差异均有统计学意义,动员前显著高于动员后(P<0.01);动员前后CD4+T淋巴细胞向SDF-1α的迁移率差异无统计学意义(P>0.01);动员后CD4+T细胞对ICAM-1的黏附率降低(P<0.01);动员后IL-4和IFN-γ两个细胞因子在外周血血清的浓度均降低(P<0.01)。结论:rhG-CSF动员不影响CD4+T细胞LFA-1和VLA-4表达及CD4+T细胞迁移,但影响CD4+T细胞ICAM-1和LAM-1表达以及CD4+T细胞通过LFA-1对ICAM-1的黏附能力影响,并可能影响CD4+T细胞分泌细胞因子IL-4及IFN-γ的功能。     

Radical scavenging activities of Rio Red grapefruits and Sour orange fruit extracts in different in vitro model systems

Antioxidant fractions from two different citrus species such as Rio Red (Citrus paradise Macf.) and Sour orange (Citrus aurantium L.) were extracted with five different polar solvents using Soxhlet type extractor. The total phenolic content of the extracts was determined by Folin-Ciocalteu method. Ethyl acetate extract of Rio Red and Sour orange was found to contain maximum phenolics. The dried fractions were screened for their antioxidant activity potential using in vitro model systems such as 1,1-diphenyl-2-picryl hydrazyl (DPPH), phosphomolybdenum method and nitroblue tetrazolium (NBT) reduction at different concentrations. The methanol:water (80:20) fraction of Rio Red showed the highest radical scavenging activity 42.5%, 77.8% and 92.1% at 250, 500 and 1000 ppm, respectively, while methanol:water (80:20) fraction of Sour orange showed the lowest radical scavenging activity at all the tested concentrations. All citrus fractions showed good antioxidant capacity by the formation of phosphomolybdenum complex at 200 ppm. In addition, superoxide radical scavenging activity was assayed using non-enzymatic (NADH/phenaxine methosulfate) superoxide generating system. All the extracts showed variable superoxide radical scavenging activity. Moreover, methanol:water (80:20) extract of Rio Red and methanol extract of Sour orange exhibited marked reducing power in potassium ferricyanide reduction method. The data obtained using above in vitro models clearly establish the antioxidant potential of citrus fruit extracts. However, comprehensive studies need to be conducted to ascertain the in vivo bioavailability, safety and efficacy of such extracts in experimental animals. To the best of our knowledge, this is the first report on antioxidant activity of different polar extracts from Rio Red and Sour oranges.     

Toxins of Bacteroides fragilis and Bacteroides thetaiotaomicron rods as stimulators of adhesion molecule expression on the surface of vascular endothelial cells

Lipopolysaccharides from four Bacteroides fragilis strains: one nonenterotoxigenic (NTBF) and three enterotoxigenic (ETBF), and from three B. thetaiotaomicron strains were extracted by hot phenol-water method and purified. B. fragilis enterotoxin was prepared according to the procedure of van Tassell et al. (1992). The influence of the examined toxins on the expression of adhesion molecules: ICAM-1, VCAM-1 and E-selectin on HMEC-1 (human dermal microvascular endothelial cells) was assayed in ELISA test with monoclonal antibodies. Four concentrations of toxins were applied: 0.01, 0.1, 1.0 and 10.0 (micrograms/ml). Endothelial cells were activated for 24 hours (ICAM-1 and VCAM-1 expression) and for 4 hours (E-selectin expression). The coloured product of immunoenzymatic reaction was measured by reading the absorbance at wavelength 492 nm. Two controls were performed in each experiment: with resting HMEC-1 and E. coli O55:B5 LPS (Sigma, USA). Bacteroides fragilis and B. thetaiotaomicron lipopolysaccharides stimulated three adhesion molecules under investigation. Their activity was comparable, but weaker than the activity of E. coli O55:B5 LPS. ICAM-1 was the most stimulated molecule. B. fragilis enterotoxin induced two adhesion molecules: VCAM-1 and E-selectin demonstrating weaker stimulatory activity than E. coli LPS. Stimulation of adhesion molecules on vascular endothelial cells should be considered to be a biological activity of B. fragilis and B. thetaiotaomicron endotoxins and B. fragilis enterotoxin.     

Antioxidative Pyranonigrins in Rice Mold Starters and Their Suppressive Effect on the Expression of Blood Adhesion Molecules

Antioxidants having a 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging capacity in rice mold starters, which are used for the preparation of various Japanese fermented foods, and their effectiveness against the expression of blood adhesion molecules were examined. An antioxidant was isolated from the rice mold starters used for shochu and identified as pyranonigrin-S (PG-S) by ¹H-NMR, ¹³C-NMR, and FAB-MS analyses. It was a derivative of pyranonigrin-A (PG-A), which has been isolated as an antioxidant from the rice mold starters. Pyranonigrins PG-A and PG-S were found to exist in spores on rice mold starters which had been prepared by Aspergillus awamori, A. kawachii, and A. saitoi. PG-S exhibited a higher level of DPPH radical scavenging activity than PG-A. PG-A was found to have a significant suppressive effect on the expression of vascular cell adhesion molecule-1 (VCAM-1) in human umbilical vein endothelial cells (HUVECs) induced by tumor necrosis factor-α (TNF-α) (P<0.05).     

Thrombin-induced expression of endothelial P-selectin and intercellular adhesion molecule-1: a mechanism for stabilizing neutrophil adhesion

Thrombin-induced expression of endothelial adhesivity toward neutrophils (PMN) was studied using human umbilical vein endothelial cells (HUVEC). HUVEC were challenged with human alpha-thrombin for varying durations up to 120 min, after which the cells were fixed with 1% paraformaldehyde and 51Cr-labeled human PMN were added to determine PMN adhesion. Endothelial adhesivity increased within 15 min after alpha-thrombin exposure, and the response persisted up to 120 min. Expression of endothelial adhesion proteins, P-selectin (GMP-140, PADGEM, CD62), and intercellular adhesion molecule-1 (ICAM-1; CD54) on the endothelial surface was quantitated by increase in the specific binding of anti-P-selectin mAb G1 and anti-ICAM-1 mAb RR1/1 labeled with 125I. P-selectin expression was maximal at 5-15 min alpha-thrombin exposure and decayed to basal levels within 90 min. In contrast, ICAM-1 activity increased at 30 min and remained elevated for 120 min after alpha-thrombin challenge. The initial endothelial adhesivity was dependent on P-selectin expression since PMN adhesion occurring within the first 30 min after alpha-thrombin challenge was inhibited by mAb G1. The later prolonged PMN adhesion was ICAM-1 dependent since this response was inhibited by mAb RR1/1 and to the same degree by the anti-CD18 mAb IB4. Anti-ELAM-1 mAb BB11 had no effect on adhesion of PMN to the alpha-thrombin-challenged cells. The initial P-selectin expression and PMN adhesion responses were reproduced by the 14-amino peptide (SFLLRNPNDKYEPF) (thrombin-receptor activity peptide; TRP-14) which comprised the NH2 terminus created by thrombin's proteolytic action on its receptors. However, TRP-14-induced PMN adhesion was transient, and TRP-14 did not cause ICAM-1 expression. The ICAM-1-dependent PMN adhesion mediated by alpha-thrombin was protein synthesis independent since ICAM-1 expression and PMN adhesion were not inhibited by cycloheximide pretreatment of HUVEC. Moreover, Northern blot analysis indicated absence of ICAM-1 mRNA signal up to 180 min after alpha-thrombin challenge. In conclusion, thrombin-induced endothelial adhesivity involves early- and late-phase responses. The initial reversible PMN adhesion is mediated by rapid P-selectin expression via TRP-14 generation. Thrombin-induced PMN adhesion is stabilized by a protein synthesis-independent upregulation of the constitutive ICAM-1 activity which enables the interaction of ICAM-1 with the CD18 beta 2 integrin on PMN.     

The effect of metronidazole on stimulation of adhesion molecule expression on the surface of vascular endothelial cells by Bacteroides fragilis endotoxins and enterotoxin]

The influence of metronidazole on the level of expression of adhesion molecules ICAM-1, VCAM-1 and E-selectin on the surface of vascular endothelial cells activated with B. fragilis endotoxins and enterotoxin was examined. Three enterotoxigenic (ETBF) strains and one nonenterotoxigenic (NTBF) strain were used for lipopolysaccharide extraction. Enterotoxin was prepared from the culture supernatant of the reference B. fragilis ATCC 43858 strain. Expression of adhesion molecules on vascular endothelial cells (HMEC-1 cell line) was determined after their stimulation with bacterial compounds at the concentration of 10 micrograms/ml in the presence of metronidazole at the concentration of 4 micrograms/ml. Endothelial cells were activated for 4 hours (E-selectin expression) and for 24 hours (ICAM-1 and VCAM-1 expression). Adhesion molecules were detected in immunoenzymatic test (ELISA) with mouse, monoclonal antibodies against human ICAM-1, VCAM-1 and E-selectin. The results of experiments suggest, that metronidazole enhances the expression of examined adhesion molecules on endothelial cells. This antimicrobial agent causes some changes in the expression of endothelial ICAM-1, VCAM-1 and E-selectin stimulated by B. fragilis endotoxins and enterotoxin.     

Antioxidant properties and phenolic profiling by UPLC-QTOF-MS of Ajwah,Safawy and Sukkari cultivars of date palm

Date palm (P. dactylifera) plays a vital role in ethnomedicinal practices in several parts of the world. There are over 2000 cultivars of date palm that differ in chemical composition and extent of bioactivity. The present study was undertaken to comparatively evaluate the antioxidant potential of three cultivars of date palm (Ajwah, Safawy and Sukkari) from Saudi Arabia and analyze their phenolic constituents in order to draw a rationale for their activity. Antioxidant activities of the date cultivars were evaluated by different quantitative methods including 2,2-diphenyl-1-picrylhydrazyl (DPPH) and hydroxyl radical scavenging assay, total antioxidant capacity, reducing power, total phenolic (TPC), flavonoid (TFC) and tannin content (TTC), while qualitative phenolic composition was determined using ultra performance liquid chromatography coupled to quadropole time of flight mass spectrometry (UPLC-QTOF-MS). All the three date extracts showed good DPPH radical scavenging (IC₅₀ 103–177 μg/mL) and hydroxyl radical scavenging (IC₅₀ 1.1–1.55 mg/mL) activity and total antioxidant capacity (IC₅₀ 87–192 μg/mL). The reducing power was also comparable to that of ascorbic acid, used as standard in above experiments. All the three samples contain significant amount of major antioxidant components (phenolic, flavonoid and tannin) that successfully correlates with the results of radical scavenging assays. UPLC-QTOF-MS revealed a total of 22 compounds in these date cultivars classified into common phenolics, flavonoids, sterols and phytoestrogens. Significant variation in the degree of antioxidant activity of these three date cultivars can be attributed to the difference in the content and composition of phenolic compounds.     

Evaluation of free radical scavenging activity of Butea monosperma Lam

In the present study, ethyl acetate, butanol and aqueous fractions derived from total methanol extract of Butea monosperma flowers were evaluated for radical scavenging activities using different in vitro models like reducing power assay, scavenging of 2,2 diphenyl-1-picrylhydrazyl (DPPH) radical, nitric oxide radical, superoxide anion radical, hydroxyl radical and inhibition of erythrocyte hemolysis using 2, 2' azo-bis (amidinopropane) dihydrochloride (AAPH). Methanol extract along with its ethyl acetate and butanol fractions showed potent free radical scavenging activity, whereas aqueous fraction was found to be devoid of any radical scavenging properties. The observed activity could be due to the higher phenolic content in the extracts (16.1, 25.29, and 17.74% w/w in methanol extract, ethyl acetate and butanol fractions respectively). HPTLC fingerprint profile of the ethyl acetate and butanol fractions were developed which would serve as reference standard for quality control of the extracts.