Antioxidative compounds from Crotalaria sessiliflora

Seven antioxidative compounds were isolated from the EtOAc extract of the aerial part of C. sessiliflora (Japanese name, tanukimame) by activity-guided fractionation with 2,2-diphenyl-1-picrylhydrazyl (DPPH). Among the isolated compounds, hydroxyeucomic acid showed the strongest free radical-scavenging activity, which was almost identical to that of epigallocatechin gallate, against DPPH. Orientin and isoorientin showed strong anti-peroxidative activities toward linoleic acid and protective effects against the bactericidal action of the tert-butyl peroxyl radical. Their activities were nearly equal to that of epigallocatechin gallate.     

Antioxidant properties of gingerol related compounds from ginger

Ginger (Zingiber officinale Roscoe) shows an antioxidant activity, and we have been engaging to determine the structures of more than 50 antioxidants isolated from the rhizomes of ginger. The isolated antioxidants are divided into two groups; gingerol related compounds and diarylheptanoids. In this study, structure-activity relationship of gingerol related compounds was evaluated. Gingerol related compounds substituted with an alkyl group bearing 10-, 12- or 14-carbon chain length were isolated from the dichloromethane extract of rhizomes using repeated chromatographic techniques. The antioxidant activities of these compounds were evaluated by the following measurements; 1) 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity, 2) inhibitory effect on oxidation of methyl linoleate under aeration and heating by the Oil Stability Index (OSI) method, and 3) inhibitory effect on oxidation of liposome induced by 2,2'-azobis(2-amidinopropane)dihydrochloride (AAPH). These results suggested that the substituents on the alkyl chain might contribute to both radical scavenging effect and inhibitory effect of autoxidation of oils, while inhibitory effects against the AAPH-induced peroxidation of liposome was somewhat influenced by the alkyl chain length; the antioxidant activity might be due to not only radical scavenging activity of antioxidants but also their affinity of the antioxidants to the substrates.     

Antidiabetic and Antioxidant Effects and Phytochemicals of Mulberry Fruit (Morus alba L.) Polyphenol Enhanced Extract

The antidiabetic and antioxidant activities of the ethyl acetate-soluble extract (MFE) of mulberry fruit (Morus alba L.) were investigated. In vitro, MFE showed potent α-glucosidase inhibitory activity and radical-scavenging activities against DPPH and superoxide anion radicals. In vivo, MFE could significantly decrease fasting blood glucose (FBG) and glycosylated serum protein (GSP), and increase antioxidant enzymatic activities (SOD, CAT, GSH-Px) in streptozotocin (STZ)-induced diabetic mice. Bioactivity-guided fractionation of the MFE led to the isolation of 25 phenolic compounds, and their structures were identified on the basis of MS and NMR data. All the 25 compounds were isolated from mulberry fruit for the first time. Also, the α-glucosidase inhibitory activity and antioxidant activity of the phenolics were evaluated. Potent α-glucosidase inhibitory and radical-scavenging activities of these phenolics suggested that they may be partially responsible for the antidiabetic and antioxidant activities of mulberry fruit.     

Lipoxygenase inhibiting and antioxidant iridoids from Buddleja crispa

Phytochemical investigations on the ethyl acetate-soluble fraction of the whole plant of Buddleja crispa led to the isolation of the iridoids 1-7. Compound 2 displayed significant inhibitory potential against enzyme lipoxygenase in a concentration-dependant fashion with IC(50) value of 39.7 +/- 0.02microM, along with DPPH radical scavenging activity with IC(50) value 0.638 mM.     

Vialinin A, a novel 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenger from an edible mushroom in China

While screening for bioactive compounds from edible mushrooms, a new potent antioxidant, vialinin A (1), together with a known compound, ganbajunin B (2), and a mixture of ganbajunins D (3) and E (4), were isolated from the dry fruiting bodies of Thelephora vialis. The structure of 1, 5',6'-bis(phenylacetoxy)-1,1':4',1'-terphenyl-2',3',4,4'-tetraol, was elucidated by spectroscopic and chemical methods. This compound had strong 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical-scavenging activity with an EC(50) value of 14.0 microM, nearly equal to that of butylated hydroxytoluene (BHT; EC(50) = 10.0 microM). A radical scavenging experiment using 1 and DPPH radicals indicated that 1 donated two hydrogen atoms to two molecules of the DPPH radical under hydrophobic conditions.     

Antioxidant potential of natural and synthesised polyprenylated hydroquinones

The metabolites 2-octaprenyl-1,4-hydroquinone (1) and 2-(24-hydroxy)-octaprenyl-1,4-hydroquinone (2), isolated from the sponge Ircinia spinosula, along with a series of synthetic derivatives, were evaluated for their antioxidant capacity, in order to establish a potential relationship between structural characteristics and antioxidant activity. The antioxidant potential of both natural and synthesised compounds was evaluated in vitro by their ability: (1) to interact with the stable free 1,1-diphenyl-2-picrylhydrazyl radical (DPPH) and (2) to inhibit the peroxidation, induced by the Fe(++)/ascorbate system, of heat inactivated hepatic microsomal membrane lipids. Metabolite 1 presented a strong interaction with DPPH and had a moderate effect on lipid peroxidation, while metabolite 2 interacted extensively with DPPH and exhibited a significant effect against lipid peroxidation. All derivatives retaining the free 1,4-hydroquinone system maintained fully or partly the free radical scavenging capacity.     

Antioxidant and cytotoxic activities of xanthones from Cudrania tricuspidata

The new catecholic xanthone, 1,3,7-trihydroxy-4-(1,1-dimethyl-2-propenyl)-5,6-(2,2-dimethylchromeno)-xanthone (1), was isolated from the root bark of Cudrania tricuspidata together with seven known xanthones. The structures were fully characterized by analysis of physical and spectral (UV, IR, mass, and NMR) data. Relationships between the structural characteristics of xanthones and their antioxidant activities (DPPH, superoxide, and hydroxyl radical) were studied. Among the range of catecholic xanthones, 6,7-dihydroxyl xanthones (3–8) exhibited a strong scavenging effect on the DPPH radical. When one of the catecholic hydroxyl groups was protected as in compounds 1 and 2, DPPH radical scavenging activity was markedly decreased (IC₅₀ > 200 μM). DPPH activities were consistent with electrochemical response by cyclic voltammetry. Interestingly, compounds (1, 2) which had the weak activities on DPPH, exhibited both potent superoxide and hydroxyl radical scavenging activities. The strong activity on the hydroxyl radical of compounds (1, 2) could be rationalized by their chelating effect with iron (Fe²⁺) due to a redshift of its complex. The catecholic xanthones (3–8), being able to convert quinone methide intermediate, showed potent cytotoxicities against human cancer cell lines (HT-29, HL-60, SK-OV3, AGS, and A549). In particular, compounds 3, 6, and 7 had strong cytotoxic activities against AGS (LD₅₀ < 5 μM). DNA fragmentation patterns induced by catecholic xanthones revealed that tumor cell death was due to apoptosis.     

New phenolic constituents from Balanophora polyandra with radical-scavenging activity

The 80% acetone extract of Balanophora polyandra Griff. (Balanophoraceae) was found to exhibit high radical-scavenging activity (SC(50)=14.48 mug/ml) towards 1,1-diphenyl-2-picrylhydrazyl (DPPH) radicals. Further chemical investigation led the isolation of two new hydrolysable tannins, balapolyphorins A (1) and B (2), together with 20 known phenolic compounds (3-22). Their structures were established by detailed spectroscopic analysis, and the radical-scavenging properties of all isolated compounds were determined by DPPH assay.     

Antioxidative activities of galloyl glucopyranosides from the stem-bark of Juglans mandshurica

Two phenolics, 1,2,6-trigalloylglucose (1) and 1,2,3,6-tetragalloylglucose (2), isolated from the stem-bark of Juglans mandshurica were evaluated for their antioxidative activities. The results showed that compounds 1 and 2 exhibited strong scavenging activities against 1,1'-diphenyl-1-picrylhydrazyl (DPPH), 2,2'-azino-bis-(3-ethylbenzenthiazoline-6-sulphonic) acid (ABTS(*+)), and superoxide radicals (O(2)(*-)), and also had a significant inhibitory effect on lipid peroxidation and low-density lipoprotein (LDL) oxidation. The strong superoxide radical scavenging of 1 and 2 resulted from the potential competitive inhibition with xanthine at the active site of xanthine oxidase (OX). In addition, compounds 1 and 2 displayed significant lipoxygenase inhibitory activity, the mode of inhibition also being identified as competitive. In comparison, the antioxidative activities of compounds 1 and 2, together with gallic acid, indicated that the number of galloyl moieties could play an important role in the antioxidative activity.     

朱红栓菌提取物抗氧化、抗肿瘤活性评价及相关化学成分分析

采用石油醚、乙酸乙酯、乙醇浸提朱红栓菌 Trametes cinnabarina 子实体干粉,得到不同极性提取物;采用清除DPPH 自由基、羟自由基、超氧阴离子自由基能力,测定提取物的体外抗氧化活性;MTT法检测提取物对人肝癌细胞株HepG2细胞增殖的抑制作用。结果表明,朱红栓菌石油醚、乙酸乙酯、乙醇提取物均具有一定的抗氧化、抗肿瘤活性;各提取物在浓度为4-5mg/mL时,对DPPH自由基、羟自由基和超氧阴离子自由基清除能力大小依次为乙酸乙酯提取物>乙醇提取物>石油醚提取物;乙酸乙酯提取物对3种自由基的最高清除率分别为60.23%、74.49%、63.84%。各提取物对人肝癌细胞株HepG2细胞增殖抑制作用大小依次为乙酸乙酯提取物>乙醇提取物>石油醚提取物;乙酸乙酯提取物的抑制率最高达55.93%。采用硅胶和凝胶等柱色谱方法结合核磁、波谱和质谱等技术对乙酸乙酯提取物的化学组分进行分析,共分离纯化出11种化合物,分别鉴定为：麦角甾醇（1）,邻苯二甲酸二丁酯（2）,对羟基苯甲酸甲酯（3）,麦角甾-7,22,二烯-3-酮（4）,1-[(12E,16E)-12,16-二十碳二烯酰基]-2-[(E,E)-7,11-十八碳二烯酰基]-3-硬脂酰基甘油（5）,cinnabarin（6）,过氧麦角甾醇（7）,尿嘧啶（8）,甘露醇（9）,腺嘌呤核苷（10）,豆甾-7,22-二烯-3β,5α,6β-三醇（11）。除化合物6外均为首次从朱红栓菌子实体中分离得到。研究结果为开发利用朱红栓菌子实体提供了科学依据。     

Phenolic compounds with antioxidant activity from Anthemis tinctoria L. (Asteraceae)

From the aerial parts of Anthemis tinctoria L. subsp. tinctoria var. pallida DC. (Asteraceae), one new cyclitol glucoside, conduritol F-1-O-(6'-O-E-p-caffeoyl)-beta-D-glucopyranoside (1), has been isolated together with four flavonoids, nicotiflorin (2), isoquercitrin (3), rutin (4) and patulitrin (5). The structures of the isolated compounds were established by means of NMR, MS, and UV spectral analyses. Methanolic extract and pure isolated compounds were examined for their free radical, scavenging activity, using the 1,1-diphenyl-2-picrylhydrazyl (DPPH) free stable radical, and for their inhibitory activity toward soybean lipoxygenase, using linoleic acid as substrate. Compounds 1 and 5 showed a strong scavenging effect in the DPPH radical assay. In addition 5 also exhibited high inhibitory activity on soybean lipoxygenase.     

Antioxidative and cytoprotective effects of Artemisia capillaris fractions

The antioxidant effects of Artemisia capillaris fractions against reactive oxygen species (ROS) were evaluated by measuring scavenging activities against 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical, superoxide (O_2(-)), hydroxyl (HO.) and nitric oxide (NO.) radical. Among five solvent fractions, ethyl acetate fraction showed the highest total polyphenol and total flavonoid contents as 648.75 and 89.09 microg/mg, respectively. Also, the ethyl acetate fraction showed the highest scavenging activity; the 50% inhibitory concentration (IC50, microg/mg) value for DPPH, O_2(-), HO. and NO. radical scavenging were 4.76, 31.54, 69.34 and 74.63, respectively. Additionally, the highest inhibition of rat liver microsomal lipid peroxidation was observed by ethyl acetate fraction. Except for free radical-mediated protein damage, ethyl acetate fraction showed the highest scavenging activity. The effect of Artemisia capillaris fractions on cell viability and DNA damage induced by H2O2 in Raw 264.7 cell were also evaluated by MTT and comet assay, respectively. The protective effect of ethyl acetate fraction, as indicated by cell viability increasing 71% and DNA breakage decreasing 51% as compared with H2O2-treated positive control. These results suggest that ethyl acetate fraction possess significant ROS scavenging and protective effect against oxidative DNA damage.     

Novel antioxidants isolated from plants of the genera Ferula, Inula, Prangos and Rheum collected in Uzbekistan

We examined the effects of 48 compounds isolated from Ferula pallida, F. penninervis, Inula macrophylla, Prangos pabularia, P. tschimganica and Rheum maximowiczii collected in Uzbekistan on ADP/Fe²⁺-induced lipid peroxidation of egg yolk phosphatidylcholine liposomes. Of those compounds, 23 inhibited ADP/Fe²⁺-induced lipid peroxidation and nine showed especially strong inhibition of lipid peroxidation. Most compounds that inhibited peroxidation scavenged the 1,1′-diphenyl-2-picrylhydrazyl (DPPH) radical, indicating that the inhibition was due to radical scavenging. However, some compounds did not scavenge DPPH but inhibited lipid peroxidation significantly, suggesting that their inhibitory effect was not due to radical scavenging but to some other mechanism, such as prevention of Fe²⁺ function. Thus, we found various new antioxidants, some of which had a unique mechanism of action, in Ferula, Inula, Prangos and Rheum plants collected in Uzbekistan as seeds used in medicine.     

Isolation and synthesis of analgesic and anti-inflammatory compounds from Ochna squarrosa L

Two new furanoflavonoids (1, 2), one new chalcone dimer (3) along with six known compounds, chrysophanol, 5-O-methyl squarrosin, 5-methoxy furano[4',5',6,7]flavone, calodenone, lophirone A and lophirone H were isolated from the ethyl acetate-soluble fraction of methanol extract of root bark of Ochna squarrosa. Chrysophanol, calodenone, lophirone A and lophirone H were isolated from this plant for the first time. The structures of all the isolated compounds were confirmed by 1D and 2D spectroscopic data. These compounds were tested for analgesic and anti-inflammatory activity. All the new compounds showed good analgesic and anti-inflammatory activity. A simple and facile method for the cleavage of benzyl ethers using I(2) in trigol is also reported.     

Antioxidant activities of phlorotannins isolated from Japanese Laminariaceae

The antioxidant activities of brown algal phlorotannins were evaluated using the inhibition of phospholipid peroxidation in the liposome system, and by determining radical scavenging activities against the superoxide anion and 1,1-diphenyl-2-picrylhydrazyl (DPPH). Oligomers of phloroglucinol (1,3,5-trihydroxybenzene), eckol (a trimer), phlorofucofuroeckol A (a pentamer), dieckol and 8,8′-bieckol (hexamers), isolated from the Laminarian brown algae Eisenia bicyclis, Ecklonia cava and Ecklonia kurome, showed potent inhibition of phospholipid peroxidation at 1 μM in the liposome system. The phlorotannins had significant radical scavenging activities against the superoxide anion (50% effective concentration values: 6.5–8.4 μM) and DPPH (50% effective concentration values: 12–26 μM), and were more effective compared to ascorbic acid and α-tocopherol. For the purpose of using phlorotannins as functional food ingredients, the antioxidant activity of a complex of crude phlorotannins and soybean protein was examined. The complex had a pronounced DPPH-radical scavenging activity. These results suggest that phlorotannins are potent anti-inflammatory substances, and that the Laminariaceous brown algae, which are abundant in phlorotannins, may be useful as a new functional foodstuff or supplement with anti-inflammatory activity.     

Antimicrobial and antioxidant flavonoids from the root wood of Bolusanthus speciosus

Three new flavonoids-5,7,4'-trihydroxy-6-[1-hydroxy-2-methylbuten-2-yl]isoflavone (isogancaonin C), 7,2'-dihydroxy-4'-methoxyisoflav-3-ene (bolusanthin III), 6,6'-dihydroxy-4'-methoxy-2-arylbenzofuran (bolusanthin IV), in addition to eight known flavonoids; derrone, medicarpan, genistein, wighteone, lupiwighteone, gancaonin C, 7-hydroxy-4'-methoxyisoflavone and 7,3'-dihydroxy-4'-methoxyisoflavone were isolated from the root wood of Bolusanthus speciosus. The compounds showed strong antimicrobial activity against Escherichia coli, Bacillus subtilis, Staphylococcus aureus and Candida mycoderma. The isolated compounds also showed moderate to strong radical scavenging properties against DPPH radical with the highest activities shown by the 2-arylbenzofuran, the isoflav-3-ene and 7,3'-dihydroxy-4'-methoxyisoflavone in decreasing order.     

Chemical constituents and biological activities of Senecio aegyptius var. discoideus Boiss

A new eremophilane sesquiterpene, 1-beta-hydroxy-8-oxoeremophila-7,9-dien-12-oic acid (1), in addition to two known flavonol glycosides, rutin (2) and quercetin-3-O-glucoside-7-O-rutinoside (3), was isolated from the ethyl acetate fraction obtained from the aqueous alcoholic extract of the aerial parts of Senecio aegyptius var. discoideus Boiss. (family Asteraceae). The chemical structures of the isolated compounds were established by 1D and 2D NMR analysis (1H, 13C, COSY, HMQC, HMBC), MS and UV data, and through comparison with the literature. The ethyl acetate fraction and the isolated rutin showed significant cytotoxic activity against colorectal carcinoma (HCT 116) and to less extent against brain (U 251) and breast carcinoma (MCF 7). The ethyl acetate fraction showed a significant level of activity against Klebsiella pneumoniae, while the total extract showed the best antifungal activity against Candida albicans and Saccharomyces cerevisiae. DPPH radical scavenging activity of the ethyl acetate fraction was significant (96.7%) when compared to ascorbic acid. It also showed anti-inflammatory activity but no diuretic effect.     

1,1-Diphenyl-2-picrylhydrazyl radical scavenging activity and tyrosinase inhibitory effects of constituents of sugarcane molasses

In the course of our work into the use of cane by-products, we have studied the isolation and structural determination of bioactive compounds in sugarcane molasses. In this study, three stereo isomers of syringyl glycerol 3'-O-beta-D-glucopyranoside, three stereo isomers of guaiacyl glycerol 3'-O-beta-D-glucopyranoside, a syringyl glycerol 2'-O-beta-D-glucopyranoside, tachioside and a 2,3-dihydro-3,5-dihydroxy-6-methyl-4-(H)-pyran-4-one (DDMP) were isolated from the 25% methanol eluate by Amberlite XAD-2 column chromatography of sugarcane molasses. The structures of these compounds were determined on the basis of spectroscopic evidence. These isolated compounds were examined for their scavenging activity against 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical species, and for their inhibitory activity against mushroom tyrosinase. All of the isolated compounds showed DPPH radical scavenging activity, while DDMP and tachioside showed mushroom tyrosinase inhibitory activity.     

Study on the inhibitory effects of Korean medicinal plants and their main compounds on the 1,1-diphenyl-2-picrylhydrazyl radical

A 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical-generating system was used to evaluate the antioxidant properties of Korean medicinal plants that have been used widely as folk medicines for several disorders, as well as compounds isolated from them. Among the Rosaceae, Rosa rugosa and Rosa davurica showed strong DPPH radical-scavenging activity. The most effective medicinal plant from families other than Rosaceae was Cedrela sinensis, followed in order by Nelumbo nucifera, Eucommia ulmoides, Zanthoxylum piperitum, Cudrania tricuspidata and Houttuynia cordata. These results serve as a good index of the free radical-scavenging activities of Korean medicinal plants. Furthermore, the polyphenols isolated from these plants, procyanidin B-3, (+)-catechin, gallic acid, methyl gallate, quercetin, quercetin-3-O-beta-D-glucoside, quercetin-3-O-beta-galactoside, quercetin-3-O-rutinose and kaempferol, exerted strong DPPH radical-scavenging activity. These results suggest that the Korean medicinal plants and the polyphenols isolated from them that exhibited effective radical-scavenging activity may be promising agents for scavenging free radicals and treating diseases associated with excess free radicals.     

DPPH free radical scavenger components from the fruits of Alpinia rafflesiana Wall. ex. Bak. (Zingiberaceae)

The methanol extract of the dried ripe fruits of Alpinia rafflesiana was investigated for its DPPH free radical scavenger constituents. 2',3',4',6'-Tetrahydroxychalcone (7), which has never been isolated from natural sources was found to be most active as a DPPH free radical scavenger with the IC50 value of 55 microM. Other known compounds isolated from this species include 5,6-dehydrokawain (1), flavokawin B (2). 1,7-diphenyl-5-hydroxy-6-hepten-3-one (3), (-)-pinocembrin (4), cardamonin (5) and (-)-pinostrobin (6). The DPPH free radical scavenger compounds were detected using TLC autographic analysis. The percentage inhibition of DPPH free radical scavenging activity was measured on isolates (5-7) using colorimetric analysis.