Aldehyde dehydrogenase, aldose reductase, and free radical scavengers in cataract

Human lens was found to contain aldehyde dehydrogenase at a level of activity similar to that of bovine lens, namely 1.76 +/- 0.51 IU/g. The enzyme, which appears to be a tetramer of 229 kD, was less susceptible to inhibition by cataractogenic agents than the bovine enzyme. The lipid peroxidation product malondialdehyde was a good substrate of the human lens enzyme. The in vitro aldose reductase reaction, which we have shown is caused by glyceraldehyde-stimulated free-radical NADPH oxidation, is inhibited by the potential anti-cataract agents, bendazac acid and bendazac lysine; these compounds also inhibit ferricytochrome c reduction in the presence of DL-glyceraldehyde and scavenge superoxide radicals. These results are consistent with the hypotheses that aldehyde dehydrogenase is a protective enzyme in the human lens, and that the peroxy radical scavenging effects of bendazac acid and bendazac lysine contribute to their anti-cataract activity.     

In-vitro evaluation of selected chalcones for antioxidant activity

Synthetic chalcones (SCs) having different side chains on the 1-(2-Hydroxy-3-(2-hydroxy-cyclohexyl)-4,6 dimethoxy-phenyl(-methanone structure were examined in-vitro for their antioxidant abilities by DPPH (2,2-diphenyl-1-picryl hydrazine) radical scavenging activity, reducing ability, OH radical scavenging activity, inhibition of polyphenol oxidase (PPO) and formation of diene conjugates. Overall, with few exceptions, all the SCs showed moderate biological activity in all the parameters examined. The SCs were found to be reactive towards DPPH radical and had considerable reducing ability. With few exceptions, all the test compounds under study were found to possess moderate to poor OH radical scavenging activity and inhibited PPO significantly and all were found to be effective inhibitors of hydroperoxide formation. These findings suggest that these SCs can be considered as potential antioxidant agents which might be further explored for the design of lead antioxidant drug candidates.     

In-vitro evaluation of selected chalcones for antioxidant activity

Synthetic chalcones (SCs) having different side chains on the 1-(2-Hydroxy-3-(2-hydroxy-cyclohexyl)-4,6 dimethoxy-phenyl(-methanone structure were examined in-vitro for their antioxidant abilities by DPPH (2,2-diphenyl-1-picryl hydrazine) radical scavenging activity, reducing ability, OH radical scavenging activity, inhibition of polyphenol oxidase (PPO) and formation of diene conjugates. Overall, with few exceptions, all the SCs showed moderate biological activity in all the parameters examined. The SCs were found to be reactive towards DPPH radical and had considerable reducing ability. With few exceptions, all the test compounds under study were found to possess moderate to poor OH radical scavenging activity and inhibited PPO significantly and all were found to be effective inhibitors of hydroperoxide formation. These findings suggest that these SCs can be considered as potential antioxidant agents which might be further explored for the design of lead antioxidant drug candidates.     

A rapid method for evaluation of analgesic and anti-inflammatory activity in rats

Carrageenin (2%) was used to produce edema and hyperalgesia; indomethacin, phenylbutazone, aspirin, ibuprofen, analgin, paracetamol and phenacetin were tested at different doses for anti-inflammatory and analgesic activity in the same rats as the peak for the edema reached at the end of 3rd hr and for the hyperalgesia at the end of 4th hr. Indomethacin, phenylbutazone and ibuprofen reduced edema and increased the pain threshold. Analgin and aspirin increased the pain threshold relatively at a low dose. Paracetamol and phenacetin were inactive in the doses tested. Carrageenin (2%) was observed to possess both phlogistic and allogenic properties.     

Alkyl esters of hydroxycinnamic acids with improved antioxidant activity and lipophilicity protect PC12 cells against oxidative stress

Hydroxycinnamic acids (HCAs) are phenolic compounds present in dietary plants, which possess considerable antioxidant activity. In order to increase the lipophilicity of HCAs, with the aim of improving their cellular absorption and expansion of their use in lipophilic media, methyl, ethyl, propyl and butyl esters of caffeic acid and ferulic acid have been synthesized. All caffeate esters had a slightly lower DPPH IC(50) (13.5-14.5 μM) and higher ferric reducing antioxidant power (FRAP) values (1490-1588 mM quercetin/mole [mMQ/mole]) compared to caffeic acid (16.6 μM and 1398 mMQ/mole, respectively) in antioxidant assays. In contrast, ferulate esters were less active in DPPH (56.3-74.7 μM) and FRAP assays (193-262 mMQ/mole) compared to ferulic acid (44.6 μM and 324 mMQ/mole, respectively). Redox properties of HCAs were in line with their antioxidant capacities, so that compounds with higher antioxidant activities had lower oxidation potentials. Measurement of partition coefficients disclosed the higher lipophilicity of the esters compared to parent compounds. All esters of caffeic acid significantly inhibited hydrogen peroxide-induced neuronal PC12 cell death assessed by MTT assay at 5 and 25 μM. However, caffeic acid, ferulic acid and ferulate esters were not able to protect the cells. In conclusion, these findings suggest that alkyl esterification of some HCAs augments their antioxidant properties as well as their lipophilicity and as a consequence, improves their cell protective activity against oxidative stress. These compounds could have useful applications in conditions where oxidative stress plays a pathogenic role.     

Biological evaluation of several coumarin derivatives designed as possible anti-inflammatory/antioxidant agents

Several linear and angular coumarins designed and synthesised as possible anti-inflammatory and antioxidant agents were evaluated for their biological activities, using the carrageenin-induced rat paw oedema model. In general, the compounds were found to be potent anti-inflammatory agents. Compound (4) was found to possess protective properties in adjuvant-induced arthritis in rats. The compounds were found to interact with 1,1-diphenyl-2-picryl-hydrazyl stable free radical (DPPH) whereas most of them were essentially inactive in other tests. The anti-inflammatory activity seemed to be connected with their reducing activity. R(M) values were determined as an expression of their lipophilicity which was also calculated as clog P. Only a poor relationship existed between lipophilicity and anti-inflammatory activity.     

Biological Evaluation of Several Coumarin Derivatives Designed as Possible Anti-inflammatory/Antioxidant Agents

Several linear and angular coumarins designed and synthesised as possible anti-inflammatory and antioxidant agents were evaluated for their biological activities, using the carrageenin-induced rat paw oedema model. In general, the compounds were found to be potent anti-inflammatory agents. Compound (4) was found to possess protective properties in adjuvant-induced arthritis in rats. The compounds were found to interact with 1,1-diphenyl-2-picryl-hydrazyl stable free radical (DPPH) whereas most of them were essentially inactive in other tests. The anti-inflammatory activity seemed to be connected with their reducing activity. R M values were determined as an expression of their lipophilicity which was also calculated as clog P. Only a poor relationship existed between lipophilicity and anti-inflammatory activity.     

Synthesis, stereochemical assignments, and biological activities of homoisoflavonoids

A series of four naturally occurring homoisoflavonoids and eight analogs have been synthesized starting from an appropriately substituted phenol through chroman-4-one, in four steps. The products were assigned as E-isomers based on NMR spectroscopic data. The E-isomers were converted into Z-isomers by photoisomerization. The E- and Z-isomers showed distinct chemical shifts and the differences between (E) and (Z)-homoisoflavonoids in the proton NMR spectra afford a useful method for ascertaining the stereochemistry. The antioxidant activity of homoisoflavonoids was determined by superoxide (NBT) and DPPH free radical scavenging methods. The analog 7-hydroxy-3-[(3,4,5-trihydroxyphenyl)methylene]chroman-4-one displayed excellent activity followed by sappanone A in both the methods and were several times potent than the commercial antioxidants like BHA, BHT, etc. These compounds were evaluated in vitro for their inhibitory activities against 5-lipoxygenase (5-LOX) enzyme. The analog 7-hydroxy-3-[(N,N-dimethylaminophenyl)methylene]chroman-4-one was found to possess potent inhibitory activity and was comparable to that of the standard, nordihydroguiaretic acid. These results suggest that these homoisoflavonoids, with their potent antioxidant and 5-LOX inhibitory activities, may have useful applications as antioxidants and lead compounds for asthma and inflammatory diseases.     

Specificity of an HPETE peroxidase from rat PMN

The 15,000xg supernatant of sonicated rat PMN contains 5-lipoxygenase that converts arachidonic acid to 5-hydroperoxyeicosatetraenoic acid (5-HPETE) and leukotriene A4 and an HPETE peroxidase that catalyzes reduction of the 5-HPETE. The specificity of this HPETE peroxidase for peroxides, reducing agents, and inhibitors has been characterized to distinguish this enzyme from other peroxidase activities. In addition to 5-HPETE, the HPETE peroxidase will catalyze reduction of 15-hydroperoxyeicosatetraenoic acid, 13-hydroperoxyoctadecadienoic acid, and 15-hydroperoxy-8,11,13-eicosatrienoic acid, but not cumene or t-butylhydroperoxides. The HPETE peroxidase accepted 5 of 11 thiols tested as reducing agents. However, glutathione is greater than 15 times more effective than any other thiol tested. Other reducing agents, ascorbate, NADH, NADPH, phenol, p-cresol, and homovanillic acid, were not accepted by HPETE peroxidase. This enzyme is not inhibited by 10 mM KCN, 2 mM aspirin, 2 mM salicylic acid, or 0.5 mM indomethacin. When 5-[14C]HPETE is generated from [14C]arachidonic acid in the presence of unlabeled 5-HPETE and the HPETE peroxidase, the 5-[14C]HETE produced is of much lower specific activity than the [14C]arachidonic acid. This indicates that the 5-[14C]HPETE leaves the active site of 5-lipoxygenase and mixes with the unlabeled 5-HPETE in solution prior to reduction and is a kinetic demonstration that 5-lipoxygenase has no peroxidase activity. Specificity for peroxides, reducing agents, and inhibitors differentiates HPETE peroxidase from glutathione peroxidase, phospholipid-hydroperoxide glutathione peroxidase, a 12-HPETE peroxidase, and heme peroxidases. The HPETE peroxidase could be a glutathione S-transferase selective for fatty acid hydroperoxides.     

蚁巢膝束霉次级代谢产物及生物活性

菌株L342分离自中国四川省的废弃白蚁巢,rDNA序列分析表明L342为蚁巢膝束霉Geniculisynnema termiticola。抗氧化活性评价结果显示其PDB发酵产物的乙酸乙酯提取物具有很强的还原能力和中等强度的DPPH清除能力。采用硅胶柱色谱、ODS柱色谱、Sephadex LH-20柱色谱、HPLC等分离方法,从G. termiticola的PDB发酵粗提物中分离鉴定了6个化合物：3,4-Dihydro-6,8-dihydroxy-3-methylisocoumarin (1), regiolone (2), (3S, 4S)-3,4,6,8-tetradydroxy-3,4-Dihydronaphthalen-1(2H)-one (3), ergosta-4,6,8(14),22-tetraen-3-one (4), cerebroside A (5), and cerebroside C (6)。其中化合物4-6具有中等强度的铁离子还原能力,化合物4还具有一定的HeLa细胞毒活性（IC50=98.3μmol/L）。G. termiticola发酵产物具有产生有生物活性次级代谢产物的潜力,有望开发成为一种新型的功能性食品。     

裸花紫珠提取物及其主要成分抗氧化活性研究

裸花紫珠是海南一种道地药材,具有消炎止血的功效。裸花紫珠富含黄酮类和苯乙醇苷类化学成分,它们已经被证实是天然抗氧化剂的主要来源之一。为了考察裸花紫珠药材的抗氧化活性,该研究采用DPPH.自由基清除法测定裸花紫珠醇提物、4个不同极性部位(石油醚、乙酸乙酯、正丁醇、水)及其7个主要成分的抗氧化作用。结果表明：裸花紫珠醇提物、醇提物的水部位、正丁醇部位、乙酸乙酯部位和化合物木犀草素、木犀草苷、毛蕊花糖苷具有较强的抗氧化活性,而5-羟基-3,7,3′,4′-四甲氧基黄酮的抗氧化活性则较弱。该研究结果为裸花紫珠的保健功能开发提供了依据。     

Dual antioxidant structures with potent anti-inflammatory,hypolipidemic and cytoprotective properties

Novel amide derivatives of trolox, 3,5-di-tert-butyl-4-hydroxybenzoic acid, (E)-3-(3,5-di-tert-butyl-4-hydroxyphenyl)acrylic acid and cinnamic acid with cysteamine and l-cysteine ethyl ester were synthesised. In four cases, the disulfide derivatives were also isolated and tested. All compounds were examined for antioxidant activity, expressed as their ability to inhibit lipid peroxidation and to scavenge free radicals. They were found to demonstrate up to 17-fold better activity than that of the parent antioxidant acids. They could reduce acute inflammation up to 87%. The most active antioxidant compounds were further tested for their in vivo hypolipidemic effect, which ranged from 47% to 73%, and for their ability to protect the liver against oxidative toxicity caused by high paracetamol dose. The disulfide derivatives of 3,5-di-tert-butyl-4-hydroxybenzoic acid and cinnamic acid had no antioxidant activity and presented equal or lower anti-inflammatory effect than their thiol analogues, indicating that their molecular characteristics may not permit biological barrier penetration.     

Inhibition of camel lens zeta-crystallin by aspirin and aspirin-like analgesics.

Camel lens zeta-crystallin was reversibly inhibited to various degrees by aspirin (acetyl salicylic acid) and the aspirin-like analgesics: paracetamol (acetaminophen) and ibuprofen (2-(4-isobutyl phenyl)-propionic acid). Among these, aspirin was the most potent inhibitor, causing nearly complete inhibition in a dose-dependent, but time-independent manner. Analysis of inhibition kinetics revealed that aspirin was uncompetitive inhibitor (K(i) 0.64 mM) with respect to NADPH and non-competitive inhibitor (K(i) 1.6 mM) with respect to the substrate, 9,10-phenanthrenequinone (PQ). Multiple-inhibition analysis showed that aspirin and pyridoxal 5' phosphate (PAL-P), a lysine specific reagent, simultaneously bound to a critical lysine residue located towards the NADPH binding region. Consistent with this, NADPH was able to substantially protect zeta-crystallin against aspirin, whereas PQ did not provide any protection. The results suggested that an essential lysine residue was the locus of aspirin binding. The inhibition of zeta-crystallin by aspirin and aspirin-like analgesics was reversible thus eliminating acetylation as a mechanism for inhibition. Reversible binding of aspirin to this lysine may cause steric hindrance resulting in uncompetitive inhibition with respect to NADPH.     

Specificity of an HPETE peroxidase from rat PMN

The 15,000xg supernatant of sonicated rat PMN contains 5-lipoxygenase that converts arachidonic acid to 5-hydroperoxyeicosatetraenoic acid (5-HPETE) and leukotriene A₄ and an HPETE peroxidase that catalyzes reduction of the 5-HPETE. The specificity of this HPETE peroxidase for peroxides, reducing agents, and inhibitors has been characterized to distinguish this enzyme from other peroxidase activities. In addition to 5-HPETE, the HPETE peroxidase will catalyze reduction of 15-hydroperoxyeicosatetraenoic acid, 13-hydroperoxyoctadecadienoic acid, and 15-hydroperoxy-8,11,13-eicosatrienoic acid, but not cumene or t-butylhydroperoxides. The HPETE peroxidase accepted 5 of 11 thiols tested as reducing agents. However, glutathione is >15 times more effective than any other thiol tested. Other reducing agents, ascorbate, NADH, NADPH, phenol, p-cresol, and homovanillic acid, were not accepted by HPETE peroxidase. This enzyme is not inhibited by 10 mM KCN, 2 mM aspirin, 2 mM salicylic acid, or 0.5 mM indomethacin. When 5-[¹⁴C]HPETE is generated from [¹⁴C]arachidonic acid in the presence of unlabeled 5-HPETE and the HPETE peroxidase, the 5-[¹⁴C]HETE produced is of much lower specific activity than the [¹⁴C]arachidonic acid. This indicates that the 5-[¹⁴C]HPETE leaves the active site of 5-lipoxygenase and mixes with the unlabeled 5-HPETE in solution prior to reduction and is a kinetic demonstration that 5-lipoxygenase has no peroxidase activity. Specificity for peroxides, reducing agents, and inhibitors differentiates HPETE peroxidase from glutathione peroxidase, phospholipid-hydroperoxide glutathione peroxidase, a 12-HPETE peroxidase, and heme peroxidases. The HPETE peroxidase could be a glutathione S-transferase selective for fatty acid hydroperoxides.     

Antioxidant,Anti-Skin-Aging,Anti-Inflammatory,and Anti-Acetylcholinesterase Activities of Rourea oligophlebia Extracts

The objective of this study was to evaluate the antioxidant, anti-skin-aging, anti-inflammatory, and anti-acetylcholinesterase activities of the hexane (n-hex), AcOEt, BuOH, MeOH, and aqueous extracts from R. oligophlebia roots. The total phenolic and flavonoid contents (TPC and TFC) were determined using Folin-Ciocalteu and AlCl₃ colorimetric assays. The antioxidant capacity was examined by reducing power (RP), ferric reducing antioxidant power (FRAP), ABTS⋅⁺, and DPPH⋅⁺ radical cation assays. All extracts potentially exhibited antioxidant activity with IC₅₀ values ranging from 2.93 to 5.73 μg/mL for ABTS⋅⁺ and from 5.69 to 7.65 μg/mL for DPPH⋅⁺ except the n-hex extract. The BuOH, MeOH, and aqueous extract possess promising anti-skin-aging activities, as observed by an attenuation of UV-A toxicity on human keratinocytes. We proposed that these anti-skin-aging properties are possibly due to direct scavenging activity against reactive oxygen species and upregulate cellular antioxidant machinery. Moreover, we found that the antioxidant capacity was well correlated with anti-inflammatory capacity against nitric oxide (NO) production in terms of the n-hex, AcOEt, and BuOH extracts with IC₅₀ values from 23.21 to 47.1 μg/mL. In contrast, these activities were found to be poorly correlated with AchE activity. To the best of our knowledge, this is the first report of the antioxidant, anti-skin-aging, anti-inflammatory, and anti-acetylcholinesterase activities of the extracts of R. oligophlebia roots. These findings indicated that this species could be a potential source of natural antioxidant, anti-aging, and anti-inflammatory agents. Consequently, it may be suggested as a medicinal plant that prevents diseases related to oxidative stress and inflammatory responses.     

Novel indole-based melatonin analogues substituted with triazole,thiadiazole and carbothioamides: studies on their antioxidant,chemopreventive and cytotoxic activities

Melatonin (MLT) is a well-known free-radical scavenger, involving in the prevention of cellular damage that can lead to cancer, ageing and a variety of neurodegenerative diseases. Research on MLT-related compounds has been required to optimise the maximum pharmaceutical activity with the lowest side effects. In our ongoing research, we have synthesized new indole-based MLT analogues as potential antioxidant agents by modifying the MLT molecule. In this study, we build on previous findings, through the synthesis, characterization and in vitro antioxidant profiling of a series of new indole-based MLT analogues which possess triazole, thiadiazole and carbothioamides on the third position on the indole ring. In vitro antioxidant activity was investigated by evaluating their reducing effect against oxidation of a redox sensitive fluorescent probe and their radical scavenging activity was assessed via the DPPH assay. In addition, in vitro cytotoxic effects of newly synthesized compounds were investigated in CHO-K1 cells using the MTT assay.     

Antioxidative activities of novel diphenylalkyl piperazine derivatives with high affinities for the dopamine transporter

A new series of diphenylalkyl piperazine derivatives with high affinities for the dopamine transporter (DAT), which were modified at both the diphenylalkyl moiety and the phenyl ring in the phenylamino moiety of 1-[4,4-bis(4-fluorophenyl)butyl]-4-[2-hydroxy-3-(phenylamino)propyl]piperazine 1, was evaluated for their inhibitory activities against auto-oxidative lipid peroxidation in canine brain homogenates. Some of these were approximately equivalent in activity to alpha-tocopherol as a potent antioxidant with IC(50) values of low micromolar order, and the 4-hydroxyphenyl derivative 11 showed the most potent antioxidative activity with an IC(50) value of 0.32 microM, exhibiting approximately 5-fold more potent activity than alpha-tocopherol. The structure-activity relationship (SAR) studies of the antioxidative activity of these derivatives are presented.     

The Impact of Different Antioxidant Agents alone or in Combination on Reactive Oxygen Species,Antioxidant Enzymes and Cytokines in a Series of Advanced Cancer Patients at Different Sites: Correlation with Disease Progression

In the present study we tested the ability of different antioxidant agents, used alone or in combination, to reduce the reactive oxygen species (ROS) levels and to increase the glutathione peroxidase (GPx) activity. Moreover, we tested the ability of such antioxidant agents to reduce the serum levels of proinflammatory cytokines IL-6 and TNF &#102 . Fifty-six advanced stage cancer patients with tumors at different sites were included in the study: they were mainly stage III (12.5%) and stage IV (82.1%). The study was divided into two phases. In the 1 st phase 28 patients were divided into five groups and a single different antioxidant agent was administered to each group. The selected antioxidant agents were: alpha lipoic acid or carboxycysteine-lysine salt, amifostine, reduced glutathione, vitamin A plus vitamin E plus Vitamin C. In the 2 nd phase of the study 28 patients were divided into five groups and a combination of two different antioxidant agents was administered to each group. The antioxidant treatment was administered for 10 consecutive days. The patients were studied at baseline and after antioxidant treatment. Our results show that all single antioxidants tested were effective in reducing the ROS levels and three of them in increasing GPx activity, too. Among the combinations of antioxidant agents, three were effective in reducing ROS, while three were effective in increasing GPx activity (arm 4 was effective in both instances). Comprehensively, the "antioxidant treatment" was found to be effective both on ROS levels and GPx activity. Moreover, the antioxidant treatment was able to reduce serum levels of IL-6 and TNF &#102 . Furthermore, a correlation was shown between the Eastern Cooperative Oncology Group Performance Status of patients and blood levels of ROS, GPx activity, serum levels of proinflammatory cytokines.     

The impact of different antioxidant agents alone or in combination on reactive oxygen species,antioxidant enzymes and cytokines in a series of advanced cancer patients at different sites: correlation with disease progression

In the present study we tested the ability of different antioxidant agents, used alone or in combination, to reduce the reactive oxygen species (ROS) levels and to increase the glutathione peroxidase (GPx) activity. Moreover, we tested the ability of such antioxidant agents to reduce the serum levels of proinflammatory cytokines IL-6 and TNFalpha. Fifty-six advanced stage cancer patients with tumors at different sites were included in the study: they were mainly stage III (12.5%) and stage IV (82.1%). The study was divided into two phases. In the 1st phase 28 patients were divided into five groups and a single different antioxidant agent was administered to each group. The selected antioxidant agents were: alpha lipoic acid or carboxycysteine-lysine salt, amifostine, reduced glutathione, vitamin A plus vitamin E plus Vitamin C. In the 2nd phase of the study 28 patients were divided into five groups and a combination of two different antioxidant agents was administered to each group. The antioxidant treatment was administered for 10 consecutive days. The patients were studied at baseline and after antioxidant treatment. Our results show that all single antioxidants tested were effective in reducing the ROS levels and three of them in increasing GPx activity, too. Among the combinations of antioxidant agents, three were effective in reducing ROS, while three were effective in increasing GPx activity (arm 4 was effective in both instances). Comprehensively, the "antioxidant treatment" was found to be effective both on ROS levels and GPx activity. Moreover, the antioxidant treatment was able to reduce serum levels of IL-6 and TNFalpha. Furthermore, a correlation was shown between the Eastern Cooperative Oncology Group Performance Status of patients and blood levels of ROS, GPx activity, serum levels of proinflammatory cytokines.     

Molecular docking analysis of selected pyrimidine derivatives with human cyclin-dependent kinase 2

A series of pyrimidine were synthesized, characterized and evaluated for their antioxidant properties using the human cyclin-dependent kinase-2 protein model. Data shows that the pyrimidine derivatives (compound ID 4G) with para fluoro groups substitution at phenyl ring attached to the 4th position (IC50: 98.5µg/ml), compound 4B bearing hydroxy group at para position of phenyl ring (IC50: 117.8 µg/ml) have significant antioxidant activity. Docking data infer that compounds 4c, 4a, 4h and 4b possess binding energy (-7.9, -7.7, -7.5 and -7.4 kcal.mol-1) with 1HCK (PDB ID) receptor.