Antioxidant activities and xanthine oxidase inhibitory effects of phenolic phytochemicals from Acacia confusa twigs and branches

An Improved Test Method for Assaying the Inhibition of Bioflavonoids on Xanthine Oxidase Activity in vitro

The difference on inhibitory effects of bioflavonoids inhibiting XOD activity assayed by varying test methods cause of us to be further in consideration. The reported test method creating a micro-environment surrounding XOD in the absence of ⋅O2 -, which is seemly different from the assay in vivo. So, the vitro test method for assaying XOD activity is necessary to be improved for selection of potential inhibitors in the presence of ⋅O2 -. The inhibitory results demonstrated that bioflavonoids of MY, DMY, QUE and LUT are capable to be on effective IC50 values, but others are not. As well, their resulting inhibitions determined by the improved test method are much less than that reported in the literature, indicating that their chemical affinities with XOD become weaker. Moreover, DMY assayed on the inhibitions of XOD in the improved test method performs to be a better inhibitor, as compared to the assay of the reported test methods. Abasing on the transformation of DMY into MY in the presence of ⋅O2 -, the good inhibition of DMY on XOD activity can be explained by the synergistic effect of MY.

Mechanistic Understanding of Tyrosinase Inhibition by Polymeric Proanthocyanidins from Acacia confusa Stem Bark and Their Effect on the Browning Resistance of Fresh-Cut Asparagus Lettuce

Tyrosinase inhibitors are capable of preventing unfavorable enzymatic browning of fruits and vegetables. In this study, the capacity of Acacia confusa stem bark proanthocyanidins (ASBPs) to inhibit tyrosinase activity was evaluated. ASBPs were shown to be a high-potential inhibitor of tyrosinase with IC50 values of 92.49 ± 4.70 and 61.74 ± 8.93 μg/mL when using L-tyrosine and L-DOPA as the substrate, respectively. The structural elucidation performed with UV-vis, FT-IR spectroscopy, ESI-MS and thiolysis coupled to HPLC-ESI-MS suggested that ASBPs had structural heterogeneity in monomer units and interflavan linkages and consisted mainly of procyanidins dominant with B-type linkages. To gain insights into the inhibitory mechanisms of ASBPs against tyrosinase, different spectroscopic and molecular docking methods were further conducted. Results validated that ASBPs possessed the ability to chelate copper ions and could prevent the oxidation process of substrates by tyrosinase. The hydrogen bond formed with Lys-376 residue played a key role in the binding force of ASBPs with tyrosinase that induced a certain alteration in the microenvironment and secondary structure of tyrosinase, resulting in the enzymatic activity being ultimately restricted. It was also observed that ASBPs treatment effectively inhibited the activities of PPO and POD to retard the surface browning of fresh-cut asparagus lettuce and thus extended their shelf-life. The results provided preliminary evidence supporting the exploitation of ASBPs into potential antibrowning agents for the fresh-cut food industry.

The Effects of Adding Heartwood Extractives from Acacia confusa on the Lightfastness Improvement of Refined Oriental Lacquer

In this study, a renewable polymeric material, refined oriental lacquer (ROL), used as a wood protective coating, and the Acacia confusa Merr. heartwood extractive, which was added as a natural photostabilizer for improving the lightfastness of ROL, were investigated. The best extract conditions for preparing heartwood extractives and the most suitable amount of addition (0, 1, 3, 5, and 10 phr) were investigated. The lightfastness index including brightness difference (ΔL *), yellowness difference (ΔYI), and color difference (ΔE *), and their applied properties of coating and film were measured. In the manufacture of heartwood extractives, the yield of extractives with acetone solvent was 9.2%, which was higher than that from toluene/ethanol solvent of 2.6%, and also had the most abundant total phenolic contents (535.2 mgGAE/g) and total flavonoid contents (252.3 μgRE/g). According to the SEM inspection and FTIR analysis, the plant gums migration to the surface of films and cracks occurred after UV exposure. The phenomena for photodegradation of ROL films were reduced after the addition of heartwood extractives. Among the different amounts of the heartwood extractives, the 10 phr addition was the best choice; however, the 1 phr heartwood extractive addition already showed noticeable lightfastness improvement. The drying times of ROL were extended and film performances worse with higher additions of heartwood extractives. Among the ROL films with different heartwood extractive additions, the ROL film with 1 phr addition had superior films properties, regarding adhesion and thermal stability, compared with the films of raw oriental lacquer.

Antioxidant and Cytoprotective effects of Pyrola decorata H. Andres and its five phenolic components

Background

Pyrola decorata H. Andres, is exclusively distributed in China and a source of traditional Chinese herbal medicine Luxiancao for more than 2000 years. Here, we evaluated the antioxidant and cytoprotective effects of P. decorata and its five phenolic components (protocatechuic acid, gallic acid, hyperoside, 2′′-O-galloylhyperin, and quercetin), and discussed their antioxidant chemistry.

Methods

A lyophilized aqueous extract of P. decorata (LAEP) was prepared and analyzed with high-performance liquid chromatography (HPLC). LAEP and its five phenolic components were comparatively investigated using five antioxidant assays, including ferric-reducing antioxidant power, cupric ion-reducing antioxidant capacity, 2-phenyl-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide radical (PTIO^•)-scavenging, 1,1-diphenyl-2-picryl-hydrazl radical (DPPH^•)-scavenging, and 2,2′-azino-bis(3-ethylbenzo-thiazoline-6-sulfonic acid) radical (ABTS^+•)-scavenging activities. The reaction products of the five phenolic components with 4-methoxy-2,2,6,6-tetramethylpiperidine-1-oxyl radical (4-methoxy-TEMPO^•) were determined with ultra-performance liquid chromatography coupled with electrospray ionization quadrupole time-of-flight tandem mass spectrometry (UPLC-ESI-Q-TOF-MS/MS) analysis. LAEP and its five phenolic components were incubated with bone marrow-derived mesenchymal stem cells (bmMSCs) subjected to oxidative stress to demonstrate their cytoprotective effects with a flow cytometry assay.

Results

In the five antioxidant assays, LAEP and its five phenolic components dose-dependently increased the radical-scavenging (or reducing power) activities. However, the IC₅₀ values of hyperoside were consistently higher than those of 2′′-O-galloylhyperin. UPLC-ESI-Q-TOF-MS/MS analysis results indicated that the five phenolics could yield dimer products in the presence of 4-methoxy-TEMPO^• via the radical adduct formation (RAF) pathway. Flow cytometry assay results confirmed the cytoprotective activity of LAEP and its five phenolic components toward stressed bmMSCs. In particular, 2′′-O-galloylhyperin could more effectively reduce the percentage of damaged bmMSCs than hyperoside.

Conclusion

LAEP and its five phenolic components may undergo redox-based pathways (such as electron transfer and H⁺ transfer) and covalent-based pathway (i.e., RAF) to exhibit antioxidant activity. One consequence of RAF is the generation of phenolic-phenolic dimer. In both organic and aqueous media, 2′′-O-galloylhyperin exhibited higher redox-based antioxidant levels (or cytoprotective levels) than those with hyperoside. The differences could be attributed to 2′′-O-galloylation reaction.

Extraction of Proanthocyanidins from Chinese Wild Rice (Zizania latifolia) and Analyses of Structural Composition and Potential Bioactivities of Different Fractions

Due to the importance of proanthocyanidin bioactivity and its relationship with chemical structure, ultrasound-assisted extraction and purification schemes were proposed to evaluate the proanthocyanidin content and analyze the structural composition and potential bioactivities of different proanthocyanidin fractions from Chinese wild rice (Zizanialatifolia). Following an optimized extraction procedure, the crude wild rice proanthocyanidins (WRPs) were purified using n-butanol extraction, chromatography on macroporous resins, and further fractionation on Sephadex LH-20 to yield six specific fractions (WRPs-1–WRPs-6) containing proanthocyanidin levels exceeding 524.19 ± 3.56 mg/g extract. Structurally, (+)-catechin, (−)-epicatechin, and (−)-epigallocatechin were present as both terminal and extension units, and (−)-epicatechin was the major extension unit, in each fraction. This is the first preparation of WRP fractions with a different mean degree of polymerization (mDP), ranging from 2.66 ± 0.04 to 10.30 ± 0.46. A comparison of the bioactivities of these fractions revealed that fractions WRPs-1−WRPs-5 had significant DPPH radical scavenging activities, whereas fraction WRPs-6 with a high mDP showed better α-glucosidase and pancreatic lipase inhibitory effects. These findings should help define possible applications of WRPs to functional foods or nutraceuticals.

A review of antioxidant and pharmacological properties of phenolic compounds in Acacia confusa

In the present review article, the phytochemical, antioxidant and pharmacological studies are congregated and summarized concerning the current knowledge of the phenolic compounds of a traditional medical plant Acacia confusa in Taiwan. This plant is native to Taiwan and South-East Asia. It possesses major pharmacological activities, including antioxidant and radical scavenging activity, hepatoprotective effect, xanthine oxidase inhibition, semicarbazide-sensitive amine oxidase inhibition, angiotensin I converting enzyme inhibition, antihyperuricemic effect and anti-inflammatory activity. Phenolic compounds, especially flavonoids, flavonol glycoside and phenolic acid derivatives, are the main phytochemical compounds isolated from different plant parts of A. confusa. Recent interest in this species has focused on pharmacological investigations of the phytochemicals which exhibit potent antioxidant activity based on the multiple phenolic functionalities. The consequence of this review will further extend the potential applications of this plant and offer persuasive support to its future use in the fields of clinical medicine and health functional food.

Flavonoids, gallotannins and ellagitannins in Syzygium guineense and the traditional use among Malian healers

ETHNOPHARMACOLOGICAL RELEVANCE

Syzygium guineense has been traditionally used in Mali in West Africa for the treatment of different diseases such as stomach problems, wounds, inflammations and various female disorders.

AIMS OF THE STUDY

(1) To perform an ethnopharmacological survey on the traditional use of S. guineense among Malian healers. (2) To isolate and identify chemical constituents from S. guineense leaves and to study their radical scavenging and enzyme inhibitory effects.

MATERIALS AND METHODS

In four different districts in Mali, 44 healers were interviewed about their medicinal use of S. guineense. A methanol extract of the leaves of this tree was prepared and further fractionated using different chromatographic methods. Isolated compounds were identified by 1D and 2D NMR spectroscopy. Extracts and isolated compounds were investigated as DPPH radical scavengers and as inhibitors of xanthine oxidase and 15-lipoxygenase, and the methanol extract was tested for toxicity towards Artemia salina nauplii.

RESULTS

Major uses by Malian healers were against dermatosis, pain, malaria/fever and for wound healing. There was little consensus about the use in the different districts. Leaves were most commonly used. From the methanol leaf extract, the flavonoids gallocatechin (1), myricetin (2), myricetin-3-O-glucoside (3), myricetin-3-O-rhamnoside (4), myricetin-3-O-glucuronide (5) and myricetin-3-O-β-D-(6″-galloyl)galactoside (6), the gallotannins 1,2,3,6-tetra-O-galloyl-β-D-glucose (7) and 1,2,3,4,6-penta-O-galloyl-β-D-glucose (8), and the ellagitannins casuarictin (9) and casuarinin (10) were isolated. These ten polyphenols are all new for the species. The crude methanol extract was active as a radical scavenger and as an inhibitor of xanthine oxidase and 15-lipoxygenase. Among the isolated compounds, pentagalloylglucose was the best enzyme inhibitor (IC₅₀ 25±4μM for 15-lipoxygenase, 8±1μM for xanthine oxidase), while casuarictin (IC₅₀ 3.9±0.1μM), casuarinin (IC₅₀ 4.5±0.3μM) and pentagalloylglucose (IC₅₀ 5±1μM) showed the highest radical scavenging activity. The methanol extract was non-toxic to Artemia salina nauplii.

CONCLUSION

S. guineense leaves are commonly used among Malian healers, however the traditional practice varies a lot between different regions. The leaves of S. guineense are rich in polyphenols; several are galloylated, either as galloylated flavonoids, gallotannins or ellagitannins. The high content of biologically active polyphenols might be important for medicinal effects of this plant and might give a rationale for the widespread usage of S. guineense in Mali.

Structural characterization and bioactivity of proanthocyanidins from indigenous cinnamon (Cinnamomum osmophloeum)

BACKGROUND

Barks and twigs of common species of cinnamon with abundant proanthocyanidins are used as a spice, fold medicine or supplement. Cinnamomum osmophloeum is an endemic species in Taiwan and coumarin was not detected in the oil of the C. osmophloeum twig. The present study aimed to evaluate the relationship between the bioactivities and proanthocyanidins of C. osmophloeum twig extracts (CoTE). The n-butanol soluble fraction from CoTE was divided into 10 subfractions (F1-F10) by Sephadex LH-20 gel chromatography. The antihyperglycemic activities were examined by α-glucosidase, α-amylase and protein tyrosine phosphatase 1B inhibitory assays. Total antioxidant activities were examined by 2,2-diphenyl-1-picrylhydrazyl free radical scavenging and ferrous ion-chelating assays.

RESULTS

The results revealed that subfractions F6-F10, with high proanthocyanidin contents, showed excellent antihyperglycemic and antioxidant activities. Subfractions F6-F10 were analyzed further by matrix-assisted laser desorption/ionization-time of flight/mass spectrometry and thiolysis-reversed-phase high-performance liquid chromatography/tandem mass spectrometry methods. The results showed that the mean degrees of polymerization of proanthocyanidins in subfractions F6-F10 ranged from 3.5 to 5.1, with the highest degrees of polymerization of proanthocyanidins reaching 8 in subfractions F8-F10. Two compounds in F6 were identified as cinnamtannin B1 and parameritannin A1. These proanthocyanidins contained at least one A-type and major B-type linkages.

CONCLUSION

These results demonstrate that proanthocyanidins are associated with their antihyperglycemic and antioxidant activities in CoTE. © 2016 Society of Chemical Industry.

Antioxidant Activities and Reduced Amyloid-β Toxicity of 7-Hydroxycalamenene Isolated from the Essential Oil of Zelkova serrata Heartwood

The in vitro and in vivo antioxidant activities and its potential to protect against amyloid-β toxicity of essential oils from Zelkova serrata (Thunb.) Makino were investigated in the model organism Caenorhabditis elegans. The results revealed that the essential oil of Z. serrata heartwood exhibited great radical scavenging activities and high total phenolic content. In vivo assays showed significant inhibition of oxidative damage in wild-type C. elegans under juglone-induced oxidative stress and heat shock. Based on results from both in vitro and in vivo assays, the major compound in essential oil of heartwood, (-)-(1 S, 4 S)-7-hydroxycalamenene (1 S, 4 S-7HC), may contribute significantly to the observed antioxidant activity. Further evidence showed that 1 S, 4 S-7HC significantly delayed the paralysis phenotype in amyloid beta-expressing transgenic C. elegans. These findings suggest that 1 S, 4 S-7HC from the essential oil of Z. serrata heartwood has potential as a source for antioxidant or Alzheimer's disease treatment.

Antihyperglycemic and antioxidant activities of twig extract from Cinnamomum osmophloeum

This is the first report concerning the α-glucosidase, α-amylase and protein tyrosine phosphatase 1B (PTP1B) inhibitory activities of cinnamon twig extracts. Comparing the antihyperglycemic activity of renewable plant parts, indigenous cinnamon (Cinnamomum osmophloeum; tǔ ròu guì) twig extracts (CoTE) showed better α-glucosidase and α-amylase activities than leaf, 2-cm branch and 5-cm branch extracts. Chemotype of C. osmophloeum has no influence on the antihyperglycemic activities and proanthocyanidin contents of CoTE. Among four soluble fractions obtained from CoTE by following bioactivity-guided fractionation procedure, the n-butanol soluble fraction (BSF) with abundant proanthocyanidins and condensed tannins, exhibited the best antihyperglycemic and PTP1B inhibitory activities. In addition, the BSF displayed the excellent DPPH free-radical scavenging and ferrous ion-chelating activities. The antihyperglycemic and antioxidant activities of all four soluble fractions from CoTE showed high correlation coefficient with their proanthocyanidin and condensed tannin contents. Furthermore, CoTE had no toxicity on 3T3-L1 preadiocytes. Results obtained demonstrated that CoTE has excellent antihyperglycemic, antioxidant and PTP1B inhibitory activities, and thus has great potential as a source for natural health products.

Biological evaluation of secondary metabolites from the roots of Myrica adenophora

Bioassay-guided fractionation of the roots of Myrica adenophora led to isolation of 24 known compounds and hitherto unknown compounds, including three A-type proanthocyanidins [adenodimerins A-C], two esters of sucrose [myricadenins A and B ], and the phenolic glycoside 6'-O-galloyl orbicularin. Spectroscopic analyses were used to determine their structures. Adenodimerin A, myricananin C, and myricetin showed strong 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activities, with SC50 values of 7.9, 16.3, and 15.9 μM, respectively. Adenodimerin A, myricanone, myricananin C, (-)-myricanol, myricanol 11-O-β-D-glucopyranoside, and myricetin showed stronger 2,2'-azino-bis-3-ethylbenzthiazoline-6-sulphonic acid (ABTS) radical scavenging activities than the positive control, with SC50 values of 7.5, 19.6, 12.0, 22.3, 19.6, and 15.6 μM, respectively. 5-Deoxymyricanone, porson, 12-hydroxymyricanone (-)-myricanol, and (+)-galeon exhibited anti-tubercular activity against Mycobacterium tuberculosis H37Rv in vitro and MICs values of 25.8, 40.0, 35.8, 30.0, and 15.0 μg/mL, respectively. Myricadenin A, myricanone, myricananin C, and (-)-myricanol exhibited anti-inflammatory activities in the iNOS assay with EC50 values of 18.1, 1.00, 13.0, and 7.5 μM, respectively.

Inhibition of xanthine oxidase by Rhodiola crenulata extracts and their phytochemicals

Using a fractionation technique, four phytochemicals were isolated from Rhodiola crenulata extracts. These compounds were identified as 4'-hydroxyacetophenone (4-HAP), epicatechin-(4β,8)-epicatechin gallate (B2-3'-O-gallate), salidroside, and p-tyrosol using mass spectrometry and nuclear magnetic resonance spectroscopy. The inhibition of xanthine oxidase (XO) activity by these purified compounds was then evaluated and compared to that of a known XO inhibitor (allopurinol; IC50 = 12.21 ± 0.27 μM). Both 4-HAP and B2-3'-O-gallate showed an XO inhibitory effect, for which the half maximal inhibitory concentration (IC50) values were 15.62 ± 1.19 and 24.24 ± 1.80 μM, respectively. However, salidroside and p-tyrosol did not show significant inhibitory effects on XO at 30 μM. Furthermore, an inhibition kinetics study indicated that 4-HAP and B2-3'-O-gallate are mixed competitive inhibitors. The inhibition constants (Ki) of 4-HAP and B2-3'-O-gallate were 8.41 ± 1.03 and 6.16 ± 1.56 μM, respectively. These results suggest that 4-HAP and B2-3'-O-gallate are potent XO inhibitors.

Mitigation of starch-induced postprandial glycemic spikes in rats by antioxidants-rich extract of Cicer arietinum Linn. seeds and sprouts

Introduction:

Consumption of highly processed calories dense diet leads abrupt increase in postprandial blood glucose level, which in turn induces immediate oxidative stress. Postprandial hyperglycemia (PPHG) and resultant oxidative stress is one of the earliest detectable abnormalities in diabetes prone individuals, independent risk factor for development of cardiovascular disorders (CVD), a major pathophysiological link between diabetes and CVD and an important contributing factor in atherogenesis even in non-diabetic individuals. Therefore, dietary supplements mitigating PPHG spikes along with potent antioxidant activities may help decrease development of PPHG and oxidative stress induced pathogenesis.

Objectives:

The study evaluated free radicals scavenging, antioxidant properties and intestinal α-glucosidase inhibitory activity in methanol extract of two varieties of Cicer arietinum Linn viz. Bengal gram and Kabuli chana and green gram (Vigna radiata Linn. Wilczek) raw grains and their sprouts and studied their influence on starch-induced postprandial glycemic excursion in rats.

Materials and Methods:

Healthy grains were procured from local markets. Free radicals scavenging antioxidant and glucose-induced hemoglobin (Hb)-glycation inhibition activities were analyzed using standard in vitro procedures. In vitro antihyperglycemic activity was evaluated by assessing rat intestinal α-glucosidase inhibitory activity. Influence on starch-induced postprandial glycemic excursion in rats was studied by pre-treatment of rats with extracts.

Results:

Compared with raw seeds increase in total polyphenol and flavonoids concentration in green gram sprouts and Kabuli chana sprouts (KCs) were observed. Total protein concentrations in sprouts did not differ from non-sprouted grains. 2,2’- Azinobis (3-ethyl benzthiazoline-6-sulphonic acid) cation scavenging activity was more than twice in Bengal gram sprouts of (BGs) and KCs than their raw seeds. 2,2-diphenyl-1-picrylhydrazyl, hydrogen peroxide scavenging, nitro blue tetrazolium reducing and glucose-induced Hb-glycation inhibitory activity did not differ from non-sprouted raw grains. Increase in rat intestinal α-glucosidase inhibitory activity was observed in BGs and KCs. BGs significantly mitigated 1^st 30 min starch-induced postprandial glycemic excursions and reduced 2 h postprandial glycemic load.

Conclusion:

Sprouting leads dynamic changes in free radicals scavenging potentials and antioxidant activities in grains. Consumption of seeds as well as BGs before the starch-rich meal can significantly mitigate 1^st 30 min postprandial glycemic excursion and reduce 2 h postprandial glycemic burden.

Longan seed extract reduces hyperuricemia via modulating urate transporters and suppressing xanthine oxidase activity

Hyperuricemia causes gouty arthritis, kidney disease, heart disease, and other diseases. Xanthine oxidase (XOD) and urate transporters play important roles in urate homeostasis. Numerous plants have been identified as XOD inhibitors. Longan seeds are known to contain high levels of polyphenols such as corilagin, gallic acid and ellagic acid. We examined the effect of longan seed extract on XOD inhibition and urate transporters GLUT1 and GLUT9 using both in vitro and in vivo assays. The results showed that dried longan seed extract (LSE) and its active components inhibited XOD dose-dependently in vitro. LSE inhibited uric acid production and XOD activity in normal liver cells (clone-9 cells) and was not cytotoxic under the concentration of 200 μg/ml. For the in vivo study, Sprague-Dawley (SD) rats were given intraperitoneally for thirty minutes with or without allopurinol (a XOD inhibitor, 3.5 mg/kg) or LSE (80 mg/kg) and then injected intraperitioneally with 250 mg/kg of oxonic acid and 300 mg/kg of hypoxanthine intragastrically. LSE was able to reduce serum uric acid level and XOD activity in hyperuricemic rats. However, LSE or allopurinol did not inhibit the liver XOD activities. On the other hand, GLUT1 protein was suppressed in kidney and GLUT9 was induced in liver from experimental rats and LSE or allopurinol decreased GLUT9 but increased GLUT1 protein level in the liver and kidney, respectively. These results confirmed the claimed effect of longan seeds on gout and other complications and suggested that its urate reducing effect might be due to modulation of urate transporters and inhibition of circulating xanthine oxidase.

Evaluation of antioxidant and free radical scavenging capacities of polyphenolics from pods of Caesalpinia pulcherrima

Thirteen polyphenolics were isolated from fresh pods of Caesalpinia pulcherrima using various methods of column chromatography. The structures of these polyphenolics were elucidated as gallic acid (1), methyl gallate (2), 6-O-galloyl-d-glucoside (3), methyl 6-O-galloyl-β-d-glucoside (4), methyl 3,6-di-O-galloyl-α-d-glucopyranoside (5), gentisic acid 5-O-α-d-(6'-O-galloyl)glucopyranoside (6), guaiacylglycerol 4-O-β-d-(6'-O-galloyl)glucopyranoside (7), 3-methoxy-4-hydroxyphenol 1-O-β-d-(6'-O-galloyl) glucopyranoside (8), (+)-gallocatechin (9), (+)-catechin (10), (+)-gallocatechin 3-O-gallate (11), myricetin 3-rhamnoside (12), and ampelopsin (13). All isolated compounds were tested for their antioxidant activities in the 1,1-diphenyl-2-picrylhydrazyl (DPPH), hydroxyl, and peroxynitrite radicals scavenging assays. Among those compounds, 11, 12, and 2 exhibited the best DPPH-, hydroxyl-, and peroxynitrite radical-scavenging activities, respectively. Compound 7 is a new compound, and possesses better scavenging activities towards DPPH but has equivalent hydroxyl radical scavenging activity when compared to BHT. The paper is the first report on free radical scavenging properties of components of the fresh pods of Caesalpinia pulcherrima. The results obtained from the current study indicate that the free radical scavenging property of fresh pods of Caesalpinia pulcherrima may be one of the mechanisms by which this herbal medicine is effective in several free radical mediated diseases.

Influence of antioxidant rich fresh vegetable juices on starch induced postprandial hyperglycemia in rats

This research analyzed the major chemical components and multiple antioxidant activities present in the fresh juice of eight vegetables, and studied their influence on starch induced postprandial glycemia in rats. A SDS-PAGE based protein fingerprint of each vegetable juice was also prepared. The yields of juice, chemical components like total proteins, total polyphenols, total flavonoids, total anthocyanins and free radicals like the ABTS˙(+) cation, DPPH, H(2)O(2), scavenging activities and reducing properties for NBT and FeCl(3) showed wide variations. Vegetable juice from brinjal ranked first in displaying total antioxidant capacity. Pretreatment of rats with vegetable juices moderated starch induced postprandial glycemia. The fresh juice from the vegetables ridge gourd, bottle gourd, ash gourd and chayote significantly mitigated postprandial hyperglycemic excursion. Total polyphenol concentrations present in vegetable juices positively influenced ABTS˙(+) scavenging activity and total antioxidant capacity. However, NBT reducing activity of juices was positively affected by total protein concentration. Contrarily, however, high polyphenol content in vegetable juice was observed to adversely affect the postprandial antihyperglycemic activity of vegetable juices. This is the first report exploring antihyperglycemic activity in these vegetable juices and highlights the possible adverse influence of high polyphenol content on the antihyperglycemic activity of the vegetable juices.

Antioxidant activities of fractions of polymeric procyanidins from stem bark of Acacia confusa

The polymeric procyanidins extracted from Acacia confusa stem bark were fractionated with a step gradient of water, methanol and acetone on a Sephadex LH-20 column. The antioxidant activity of the collected fractions was investigated by the 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging and ferric reducing/antioxidant power (FRAP) assays. All fractions possessed potent antioxidant activity with the highest activity observed for fraction F9. The matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) and reversed-phase high performance liquid chromatography (RP-HPLC) analyses suggested that the collected fractions consisted primarily of oligomeric and polymeric procyanidins, with different polymer ranges and most abundant polymer size. For each fraction, catechin and epicatechin were present as both terminal and extension units, and epicatechin was the major component in the extended chain. The mean degree of polymerization (mDP) of each fraction differed, ranging from 1.68 (fraction F2) to 17.31 (fraction F11). There was a relationship between antioxidant activity (IC50/DPPH and FRAP) and mDP (R(2) (DPPH) = 0.861, P = 0.006 and R(2) (FRAP) = 0.608, P = 0.038), respectively. However, the highest antioxidant activity of fraction (F9) was not coincident with the maximum mDP of fraction (F11).

MALDI-TOF MS analysis of condensed tannins with potent antioxidant activity from the leaf, stem bark and root bark of Acacia confusa

The structures of the condensed tannins from leaf, stem bark and root bark of Acacia confusa were characterized by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) analysis, and their antioxidant activities were measured using 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical scavenging and ferric reducing/antioxidant power (FRAP) assays. The results showed that the condensed tannins from stem bark and root bark include propelargonidin and procyanidin, and the leaf condensed tannins include propelargonidin, procyanidin and prodelphinidin, all with the procyanidin dominating. The condensed tannins had different polymer chain lengths, varying from trimers to undecamers for leaf and root bark and to dodecamers for stem bark. The condensed tannins extracted from the leaf, stem bark and root bark all showed a very good DPPH radical scavenging activity and ferric reducing power.