Antioxidant and free-radical scavenging activity of constituents of the leaves of Tachigalia paniculata

Two new myricetin glycosides, myricetin 7-O-beta-D-glucopyranosyl-(1-->6)-beta-D-glucopyranoside (1) and myricetin 7-O-alpha-L-rhamnopyranosyl-(1-->6)-beta-D-glucopyranoside (2), together with the known compounds quercetin 3-O-beta-D-glucopyranoside (3), quercetin 3-O-alpha-L-rhamnopyranoside (4), quercetin 3-O-beta-D-galactopyranoside (5), methyl gallate (6), isovanillin (7), 4-hydroxymethylbenzoate (8), 3,4-dihydroxymethylbenzoate (9), and caffeoyl aldehyde (10) were isolated from the leaves of Tachigalia paniculata. The structures of these compounds were determined by spectroscopic methods. Their antioxidant activity was determined by measuring free-radical scavenging effects using three different assays, namely, the Trolox Equivalent Antioxidant Capacity (TEAC) assay, the coupled oxidation of beta-carotene and linoleic acid (autoxidation assay), and the inhibition of xanthine oxidase activity. Compounds 1, 2, and 6 showed activity in the TEAC test, compounds 5-7 and 10 were moderately active in the autoxidation assay, while compounds 1 and 2 were the most potent of the isolates in the xanthine oxidase test.     

Yucca schidigera bark: phenolic constituents and antioxidant activity

Two new phenolic constituents with unusual spirostructures, named yuccaols D (1) and E (2), were isolated from the MeOH extract of Yucca schidigera bark. Their structures were established by spectroscopic (ESIMS and NMR) analysis. The new yuccaols D and E, along with resveratrol (3), trans-3,3',5,5'-tetrahydroxy-4'-methoxystilbene (4), yuccaols A-C (5-7), yuccaone A (8), larixinol (9), the MeOH extract of Yucca schidigera bark, and the phenolic portion of this extract, were assayed for antioxidant activity by measuring the free radical scavenging effects using two different assays, namely, the Trolox Equivalent Antioxidant Capacity (TEAC) assay and the coupled oxidation of beta-carotene and linoleic acid (autoxidation assay). The significant activities exhibited by the phenolic fraction and its constituents in both tests show the potential use of Y. schidigera as a source of antioxidant principles.     

Antioxidant chalcone glycosides and flavanones from Maclura (Chlorophora) tinctoria

Four chalcone glycosides (1-4), including three new natural products, and three flavanones (5-7) were isolated from the methanol extract of stem bark of Maclura tinctoria. The new compounds have been characterized as 4'-O-beta-D-(2' '-p-coumaroyl)glucopyranosyl-4,2',3'-trihydroxychalcone (1), 4'-O-beta-D-(2' '-p-coumaroyl-6' '-acetyl)glucopyranosyl-4,2',3'-trihydroxychalcone (2), and 3'-(3-methyl-2-butenyl)-4'-O-beta-D-glucopyranosyl-4,2'-dihydroxychalcone (3); the known derivatives were elucidated as 4'-O-beta-D-(2' '-acetyl-6' '-cinnamoyl)glucopyranosyl-4,2',3'-trihydroxychalcone (4), eriodictyol 7-O-beta-D-glucopyranoside (5), naringenin (6), and naringenin 4'-O-beta-D-glucopyranoside (7). Their structures were determined by 1D and 2D NMR and ESIMS. The antioxidant activity of all the isolated compounds was determined by measuring free-radical-scavenging effects using two different assays, namely, the Trolox Equivalent Antioxidant Capacity (TEAC) assay and the coupled oxidation of beta-carotene and linoleic acid (autoxidation assay). The results showed that compound 3 was the most active in both antioxidant assays.     

Antioxidant and free radical scavenging activity of flavonol glycosides from different Aconitum species

Bioassay-guided fractionation by 1,1-diphenyl-2-dipicrylhydrazyl (DPPH) radical scavenging test of polar extracts of some Italian Aconitum species (A. napellus subsp. tauricum, A. napellus subsp. neomontanum, A. paniculatum, A. vulparia) led to the isolation of 13 flavonol glycosides: quercetin 3-O-(6-trans-caffeoyl)-beta-glucopyranosyl-(1-->2)-beta-glucopyranoside-7-O-alpha-rhamnopyranoside (1), kaempferol 3-O-(6-trans-caffeoyl)-beta-glucopyranosyl-(1-->2)-beta-glucopyranoside-7-O-alpha-rhamnopyranoside (2), quercetin 3-O-(6-trans-p-coumaroyl)-beta-glucopyranosyl-(1-->2)-beta-glucopyranoside-7-O-alpha-rhamnopyranoside (3), kaempferol 3-O-(6-trans-p-coumaroyl)-beta-glucopyranosyl-(1-->2)-beta-glucopyranoside-7-O-alpha-rhamnopyranoside (4), quercetin 7-O-(6-trans-caffeoyl)-beta-glucopyranosyl-(1-->3)-alpha-rhamnopyranoside-3-O-beta-glucopyranoside (5), kaempferol 7-O-(6-trans-caffeoyl)-beta-glucopyranosyl-(1-->3)-alpha-rhamnopyranoside-3-O-beta-glucopyranoside (6), kaempferol 7-O-(6-trans-p-coumaroyl)-beta-glucopyranosyl-(1-->3)-alpha-rhamnopyranoside-3-O-beta-glucopyranoside (7), kaempferol 3-O-beta-(2"-acetyl)galactopyranoside (8), kaempferol 3-O-beta-(2"-acetyl)galactopyranoside-7-O-alpha-arabinopyranoside (9), quercetin 3-O-beta-(2"-acetyl)galactopyranoside-7-O-alpha-arabinopyranoside (10), quercetin 3,7-di-O-alpha-rhamnopyranoside (11), kaempferol 3,7-di-O-alpha-rhamnopyranoside (12) and quercetin 3-O-beta-glucopyranoside-7-O-alpha-rhamnopyranoside (13). Their antioxidant activity (AA) was determined by measuring free radical scavenging activity by DPPH test and the coupled oxidation of beta-carotene and linoleic acid assay. The results showed that 5 is the most active compound in the DPPH free-radical scavenging test (IC(50) 1.9 microM) while in the coupled oxidation of beta-carotene and linoleic acid assay compound 1 has the highest inhibitory ratio after 1h (58.9%). Some structure-activity relationships on the AA were obtained.     

Antioxidant and free radical scavenging activities of 5,7,3'-trihydroxy-3,6,4'-trimethoxyflavone from Brickellia veronicaefolia

The antioxidant and antiradical activities of 5,7,3'-trihydroxy-3,6,4'-trimethoxyflavone or centaureidin isolated and characterized from Brickellia veronicaefolia were elucidated by heat-induced oxidation in a beta-carotene and linoleic acid system and by the 1,1-diphenyl-2-picrylhydrazyl decoloration test. The centaureidin (32.1%) exhibited antioxidative activity less than that of BHT (95.5%) and alpha-tocopherol (95.9%) on oxidation in a beta-carotene and linoleic acid system. A moderate antiradical effect (47.6%) compared with BHT (96.7%) and alpha-tocopherol (94.6%) in DPPH decoloration test was found.     

Brominated arginine-derived alkaloids from the red sea sponge Suberea mollis

Investigation of a new collection of the Red Sea sponge Suberea mollis afforded two new brominated arginine-derived alkaloids, subereamines A (1) and B (2), a new brominated phenolic compound, subereaphenol D (3), and the known compounds dichloroverongiaquinol (4), aerothionin (5), and purealdin L (6). The structures of the isolated compounds were assigned using one- and two-dimensional NMR spectra and HRFABMS data. The absolute configurations of subereamines A (1) and B (2) were determined by acid hydrolysis followed by chiral-phase LC-MS. The antimicrobial and antioxidant activities of the isolated compounds have been evaluated. Dichloroverongiaquinol and subereaphenol D displayed significant antimicrobial activity. Using the DPPH TLC autographic rapid screen for free radical scavenging effects, subereaphenol D displayed a significant antioxidant effect. In addition, the cytotoxic activities of the isolated compounds were investigated.     

The antioxidant activity of a triterpenoid glycoside isolated from the berries of Hedera colchica: 3-O-(beta-D-glucopyranosyl)-hederagenin

The antioxidant activity of a triterpenoid glycoside [3-O-(beta-D-glucopyranosyl)-hederagenin; OGH] isolated from the berries of Hedera colchica, an ivy species endemic in Georgia, was investigated. The antioxidant properties of OGH were evaluated using different antioxidant assays: 1,1-diphenyl-2-picryl-hydrazyl free radical (DPPH.) scavenging, total antioxidant activity, reducing power, superoxide anion radical (O2*-)) scavenging, hydrogen peroxide (H2O2) scavenging and metal chelating activities. The total antioxidant activity was measured according to the ferric thiocyanate method. alpha-Tocopherol and trolox, a water-soluble analogue of tocopherol, were used as reference antioxidant compounds. At a 30 microg/mL concentration, the inhibitory effects of OGH on the peroxidation of linoleic acid emulsion was found to be 95.3%, whereas alpha-tocopherol and trolox exhibited 88.8% and 86.2% inhibition of peroxidation in the system, respectively. In addition, OGH had effective DPPH. scavenging, superoxide anion radical scavenging, hydrogen peroxide scavenging, total reducing power and metal chelation of ferrous ions activities. These various antioxidant activities were compared with alpha-tocopherol and trolox.     

Antiradical and antioxidant activity of total anthocyanins from Perilla pankinensis decne

The purpose of this work comprise the assessment of the antioxidant activity of total anthocyanins from Perilla pankinensis samples (TAPP) by different analytical methods: 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical scavenging, total antioxidant activity, total reducing activity, superoxide anion radical scavenging, hydrogen peroxide scavenging and metal chelating activities. Total antioxidant activity was measured according to ferric thiocyanate method. alpha-Tocopherol and trolox, which water-soluble analogue of tocopherol were used as references antioxidant compounds. At the concentrations of 30 and 45 microg/mL, TAPP showed 91.9 and 96.4% inhibition on lipid peroxidation of linoleic acid emulsion, respectively. In comparison, 45 microg/mL of standard antioxidant such as alpha-tocopherol and trolox exhibited 88.8 and 86.2% inhibition on peroxidation of linoleic acid emulsion, respectively. In addition, TAPP have found effective on DPPH scavenging, superoxide anion radical and hydrogen peroxide scavenging, total reducing power and metal chelating on ferrous ions activities. Also, these various antioxidant effects were compared to alpha-tocopherol and trolox.     

Antioxidant activity of caffeoyl quinic acid derivatives from the roots of Dipsacus asper Wall

The methanol extract from Dipsacus asper Wall (Dipsacaceae) was found to show antioxidant activity against free radical and Cu(2+)-mediated LDL oxidation. In further study, to identify active constituents from the plant, six caffeoyl quinic acid derivatives: 3,4-di-O-caffeoylquinic acid (1), methyl 3,4-di-O-caffeoyl quinate (2), 3,5-di-O-caffeoylquinic acid (3), methyl 3,5-di-O-caffeoyl quinate (4), 4,5-di-O-caffeoylquinic acid (5) and methyl 4,5-di-O-caffeoyl quinate (6) were isolated. Their structures were identified by spectroscopic methods including 2D-NMR. The isolated compounds, 1-6, were found to be potent scavengers of the free radical 1,1-diphenyl-2-picrylhydrazyl (DPPH), and are more potent than butylated hydroxyl toluene (BHT) used as a positive control. The compounds 1-6 also inhibited Cu(2+)-mediated low-density lipoprotein (LDL) oxidation. They increased the lag time of conjugated dienes formation and inhibited the generation of thiobarbituric acid reactive substances (TBARS) in a dose-dependent manner. These results suggested that Dipsacus asper due to its antioxidant constituents, 1-6, may have a role to play in preventing the development and progression of atherosclerotic disease.     

黔产乌药化学成分研究

目的:研究樟科山胡椒属植物乌药块根Lindera aggregata的化学成分和抗氧化活性.方法:采用硅胶柱色谱、Sephadex LH-20色谱、D-101大孔树脂色谱等方法进行分离、纯化,通过光谱分析法鉴定它们的结构并对化合物进行抗氧化活性测试.结果:分离得到12个化合物,分别为hernangerine(1),syringgaresinol (2),香草醛(vanilin,3),α-cadinol (4),对羟基苯甲醛(p-hydroxybenzaldehyde,5),β-谷甾醇亚油酸酯(β-sistosterol linoleate,6),表儿茶素(epicatechin,7),boldine (8),norboldine(9),norboldine acetate (10),胡萝卜苷(daucosterol,11)和β-谷甾醇(β-sitosterol,12).用DPPH法测定化合物1,2,3,4,7,9,10的抗氧化活性.结论:化合物1～6均为首次从该植物中分离得到,化合物2,7有一定的抗氧化活性.     

In vitro antioxidant and free radical scavenging activity of Nardostachys jatamansi DC

In this study, the antioxidative potential of a hydroalcoholic extract of Nardostachys jatamansi (NJE) rhizomes was evaluated by various antioxidant assays, including antioxidant capacity by the phosphomolybdenum method, total antioxidant activity in linoleic acid emulsion systems, 1,1-diphenyl-2-picrylhydrazyl (DPPH), superoxide, hydroxyl radicals, nitric oxide (NO) scavenging, metal chelating and reducing power activity. These various antioxidant activities were compared with standard antioxidants such as butylated hydroxytoluene, tocopherol, catechin, and L-ascorbic acid. Total phenolic and flavonoid content of NJE was also determined by a colorimetric method. The extract exhibited high reduction capability and powerful free radical scavenging, especially against DPPH and superoxide anions as well as a moderate effect on NO. Moreover, the peroxidation inhibiting activity of NJE was demonstrated in the linoleic acid emulsion system. The results obtained in the present study clearly established the antioxidative potency of NJE, which may account for some of the medical claims attributed to this plant.     

紫花地丁化学成分分析及其体外抗氧化活性考察

目的:对堇菜科堇菜属植物紫花地丁中的化学成分及其抗氧化活性进行研究。方法:取紫花地丁5 kg,加3倍量95%乙醇回流提取3次,合并提取液,过滤,减压浓缩得总浸膏,上60~100目硅胶柱色谱,用石油醚、二氯甲烷、二氯甲烷-甲醇(50∶1,10∶1,5∶1,2∶1)及甲醇洗脱,得到7个相应馏分。各部位依次运用正相硅胶柱色谱,十八烷基硅烷键合硅胶(ODS)柱色谱,LH-20型羟丙基葡聚糖凝胶(Sephadex LH-20)柱色谱和制备型高效液相色谱(HPLC)等方法进行分离纯化,得到的化合物经核磁共振波谱(NMR),质谱(MS),红外光谱(IR)等波谱学方法进行鉴定。同时,对从紫花地丁分离得到的部分化合物进行清除1,1-二苯基-2-三硝基苯肼(DPPH)自由基实验。结果:从紫花地丁95%乙醇提取物中分离得到14个化合物,分别为N-acetyl-1-ethyl ester glutamic acid(1),N-acetyl glutamic acid-1-ethyl-5-methyl ester(2),橙黄胡椒酰胺(3),rel-(2α,3β)-7-O-methylcedrusin(4),齐墩果酸(5),α-tocopherol-quinone(6),杨芽黄素(7),异莨菪亭(8),七叶内酯(9),24-ethylcholesta-4,24(28)Z-dien-3-one(10),stigmasta-4,25-dien-3-one(11),β-sitostenone(12),β-谷甾醇(13),豆甾-5-烯-3β-醇-7-酮(14)。结论:化合物2为新的天然产物,化合物1,4,6,7,10~12为首次从堇菜属植物分离得到。化合物9具有显著的抗氧化活性,化合物2,6,8具有一定的DPPH自由基清除活性。     

灯心草抗氧化活性成分研究

采用DPPH法对两种灯心草属植物不同溶剂提取物进行抗氧化活性研究。结果表明灯心草乙酸乙酯提取物的抗氧化活性最强。评价了从该活性部位分离出的四个化合物清除DPPH自由基的活性，化合物3显示了一定的清除DPPH自由基的活性。     

Determination of antioxidant and radical scavenging activity of Basil (Ocimum basilicum L. Family Lamiaceae) assayed by different methodologies

The antioxidant properties of plants have been investigated, in the light of recent scientific developments, throughout the world due to their potent pharmacological activities and food viability. Basil (Ocimum basilicum L. Family Lamiaceae) is used as a kitchen herb and as an ornamental plant in house gardens. In the present study, the possible radical scavenging and antioxidant activity of the water (WEB) and ethanol extracts (EEB) of basil was investigated using different antioxidant methodologies: 1,1-diphenyl-2-picryl-hydrazyl (DPPH) free radical scavenging, scavenging of superoxide anion radical-generated non-enzymatic system, ferric thiocyanate method, reducing power, hydrogen peroxide scavenging and metal chelating activities. Experiments revealed that WEB and EEB have an antioxidant effects which are concentration-dependent. The total antioxidant activity was performed according to the ferric thiocyanate method. At the 50 microg/mL concentration, the inhibition effects of WEB and EEB on peroxidation of linoleic acid emulsion were found to be 94.8% and 97.5%, respectively. On the other hand, the percentage inhibition of a 50 microg/mL concentration of BHA, BHT and alpha-tocopherol was found to be 97.1%, 98.5% and 70.4% inhibition of peroxidation of linoleic acid emulsion, respectively. In addition, WEB and EEB had effective DPPH radical scavenging, superoxide anion radical scavenging, hydrogen peroxide scavenging, reducing power and metal chelating activities. Additionally, these various antioxidant activities were compared with BHA, BHT and alpha-tocopherol as reference antioxidants. The additional total phenolic content of these basil extracts was determined as the gallic acid equivalent and were found to be equivalent.     

Antioxidant and hepatoprotective effects of Orthosiphon stamineus Benth. standardized extract

Orthosiphon stamineus (OS), Benth. (Lamiaceae) is widely used in Malaysia for treatments of various kidney and liver ailments. In the experiment, DPPH* radicals scavenging, Fe(3+)-induced lipid peroxidation inhibiting activities and trolox equivalent antioxidant capacity (TEAC) of methanol/water extract of Orthosiphon stamineus (SEOS) were determined. The results indicated that SEOS exhibited antioxidant, lipid peroxidation inhibition and free radical scavenging activities. The hepatoprotective activity of the SEOS was studied using CCl(4)-induced liver toxicity in rats. The activity was assessed by monitoring liver function tests through the measurement of alanine transaminase (ALT) and aspartate transaminase (AST). Furthermore, hepatic tissues were also subjected to histopathological studies. Pretreatment of SEOS (125, 250, 500 and 1000 mg/kg p.o.) dose-dependently reduced the necrotic changes in rat liver and inhibited the increase of serum ALT and AST activities. The results of the present study indicated that the hepatoprotective effect of Orthosiphon stamineus might be ascribable to its antioxidant and free radical scavenging property.     

Evaluation of Antioxidant Potential of Melanthera scandens

A methanol extract of dried leaves of Melanthera scandens was examined for antioxidant activities using a variety of assays, including 1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging, reducing power, ferrous chelating, and ferric thiocyanate methods with ascorbic acid and EDTA as positive controls. The extract showed noticeable activities in most of these in vitro tests. The amount of phenolic compounds in the extract expressed in gallic acid equivalent was found to be 52.8 mg/g. The extract demonstrated inhibition of linoleic acid lipid peroxidation, active reducing power, and DPPH radical scavenging activities which were less than that of the positive controls. The extract also showed weaker iron chelating effect when compared with the EDTA positive control. The present results showed that M. scandens leaf extract possessed antioxidant properties and this plant is a potential useful source of natural antioxidants.     

Antioxidant xanthones from Garcinia vieillardii

Two new xanthones, 6-O-methyl-2-deprenylrheediaxanthone B (1) and vieillardixanthone (2), were isolated from the stem bark of Garcinia vieillardii, as were four known compounds (4-7). The structures of 1 and 2 were determined by means of spectroscopic analysis and chemical derivatization. Each isolate was tested for its antioxidant properties based on a scavenging activity study using the stable 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical.     

Antioxidant benzoylated flavan-3-ol glycoside from Celastrus orbiculatus

A new flavan-3-ol glycoside, (-)-epicatechin-5-O-beta-D-glucosyl-3-benzoate (1), and two known compounds, (-)-epicatechin and (-)-epiafzelechin, were isolated from an EtOAc extract of Celastrus orbiculatus aerial parts that exhibited significant antioxidant effect in a 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical assay. The structure of 1 was elucidated by spectroscopic analyses, and compound 1 and its aglycon, (-)-epicatechin-3-benzoate (2), were found to be moderately active as antioxidants in the DPPH assay.     

Benzophenones and biflavonoids from Rheedia edulis

Two new polyisoprenylated benzophenones, 32-hydroxy-ent-guttiferone M (1) and 6-epi-guttiferone J (2), along with seven known compounds, 6-epi-clusianone (3), guttiferone A (4), xanthochymol (5), guttiferone E (6), isoxanthochymol (7), (+)-volkensiflavone (8), and (+)-morelloflavone (9), were identified from the seeds and rinds of Rheedia edulis. Compounds 1-3 and 5-9 have been isolated and identified from this species for the first time. The structures of the new compounds were elucidated mainly by analysis of their 1D and 2D NMR spectroscopic data, and their absolute configurations were determined by comparison of their experimental optical rotation and electronic circular dichroism measurements with those values predicted by DFT calculations. Compound 1 showed significant antioxidant activity in both DPPH and ABTS free radical scavenging assays, whereas compound 2 was inactive.     

Prostaglandin inhibitory and antioxidant components of Cistus laurifolius, a Turkish medicinal plant

As Cistus laurifolius has been used traditionally to treat inflammatory and rheumatic disorders, its leaves were tested for prostaglandin (PG) inhibitory and antioxidant activities. The leaf extract showed both activities, i.e., inhibitory effect at 300 microg/ml on PGE1- and E2-induced contractions in guinea pig ileum and 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging effect. The separation guided by the activities shown by these dual assays provided sixteen compounds, 1-16. Known compounds 1-12 and 15 were identified as 3-O-methyl quercetin (1), 3,7-O-dimethyl quercetin (2), genkwanin (3), 3,7-O-dimethyl kaempferol (4), 3,4'-O-dimethyl quercetin (5), apigenin (6), 3,4'-O-dimethyl kaempferol (7), ellagic acid (8), beta-sitosterol-3-O-beta-glucoside (9), quercetin 3-O-alpha-rhamnoside (10), 5-O-p-coumaroyl quinic acid methyl ester (11), 1-(4-hydroxy-3-methoxyphenyl)-2-[4-(3-alpha-l-rhamnopyranoxypropyl)-2-methoxyphenoxy]-1,3-propanediol (12) and 2,3-dihydro-2-(4'-alpha-l-rhamnopyranosyloxy-3'-methoxyphenyl)-3-hydroxymethyl-7-methoxy-5-benzofuranpropanol (15). New lignan glycosides 13 and 14 were determined to be olivil 9-O-beta-D-xyloside and berchemol 9-O-rhamnoside, respectively. Compound 16 was isolated as a 2:1 mixture of two diastereomers, the major one of which was determined to be (7S,8R)-dihydrodehydrodiconiferyl alcohol 9'-O-alpha-L-rhamnoside. The structures were determined by detailed 2D NMR analysis together with NOEDF and CD. PG inhibitory effect was observed in 1, 5, 10, 12 and 16 at 30 microg/ml and antioxidant activity, in 1, 2, 8, 10, 12-14 and 16.