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Verbascoside, pedicularioside A, cistanoside C, salidroside, 6-O-(E)-feruloyl-glucose and 6-O-(E)-p-hydroxycinnamoyl-glucose were isolated from Pedicularis species and other plants. The scavenging activities of these phytophenols towards hydrated electron, the strongest reducing radical, were investigated by pulse radiolysis. With the exception of salidroside, the other phytophenols react with hydrated electrons (e(aq)(-)) at rate constants close to the diffusion-controlled rate (4.9-7.5 x 10(9)M(-1) s(-1)), indicating that these phytophenols are effective e(aq)(-) scavengers. This property is consistent with the phytophenols' ability to quickly repair DNA radical anions. The comparison of the reaction rate constants indicates that the conjugated carbonyl group is essential to the e;(1 scavenging activities, whereas the phenolic hydroxyl groups, which determine the antioxidant capacity, have no significant effect on the e(aq)(-) scavenging activities. We propose that the reducing radical-scavenging activity of the phytophenols is a novel pharmacological mechanism for prevention and treatment of diseases in which reducing radicals play a key role. Our finding provides a criterion for screening the scavengers of reducing radicals. (C) 2010 Elsevier Ltd. All rights reserved.

From the acetone extract of the root of Euphorbia sieboldiana, a new ent-atis-16-ene type diterpenol was isolated and its structure was demonstrated as ent-atis-16-ene-13 α-hydroxy-3,14-dione (1) based on the chemical as well as NMR and MS spectroscopic evidences, and finally confirmed by X-ray diffraction.

Five new acyclic 12-hydroxygeranylgeraniol-derived diterpenoids, i.e., 1-5, were isolated from the seeds of Carpesium triste. The structures including the absolute configurations of the new compounds were elucidated by spectroscopic methods. All the compounds, except for 2, were evaluated for their in vitro cytotoxic activity against cultured SMMC-7721 (human hepatoma), HL-60 (human promyclocytic leukemia), and L02 (human hepatocyte) cells.

One new triterpene and seven new eremophilane-type sesquiterpenes were isolated from the roots of Ligularia sagitta, among them la, an O-acetylated oleanane type triterpene, 2a and 3a, two 11-nor eremophilane-type sesquiterpenes, 4a, 5, and 6, three standard eremophilane-type sesquiterpenes, and 7 and 8, two tri-nor eremophilane-type sesquiterpenes. Their structures were established by extensive spectral analyses (1D, 2D-NMR, IR, and MS). Compound la showed moderate cytotoxicity against two tumor cell lines.

Virgaurols A-D (1-4), four novel asymmetric eremophilane sesquiterpene dimers were isolated from the roots of Ligularia virgaurea. Especially, virgaurols A (1) and B (2) possessed novel carbon skeleton in which the two sesquiterpene units are uniquely connected by a single C-C bond directly. The structures of these dimers were determined on the basis of comprehensive spectral analysis. Compounds 1 and 3 were found to exhibit weak cytotoxicity against human leukemia (HL-60), human hepatoma (SMMC-7721), and human cervical carcinoma (HeLa) cells.

A phytochemical study of the ethanolic extract of the leaves of Ligularia virgaurea led to the isolation of a new eremophilane-type sesquiterpene lactone, (4S,5R,6S,8S, 10R)-6 beta-angeloyloxy-eremophil-7(11)-en-10 beta H-8 alpha,12-olide (1), along with a known eremophilane-type sesquiterpene, (4S,5R,6S,10S)-6 beta-angeloyloxy-10 beta H-furanoeremophil-9-one (2). Their structures were elucidated by extensive spectroscopic methods, including 1D and 2D nuclear magnetic resonance and high-resolution electrospray ionization mass spectrometry experiments, and the absolute configurations were confirmed by single-crystal X-ray diffraction analysis using the anomalous scattering of Cu K alpha radiation.

The repair activities and reaction mechanisms of phenylpropanoid glycosides (PPGs) and their analogues, isolated from Chinese folk medicinal herbs, towards oxidative DNA damage were studied with pulse radiolytic technique. On pulse irradiation of nitrogen-saturated 4 mM poly C aqueous solution containing one of the tested polyphenols, 40 mM K2S2O8 and 200 mM t-BuOH, the transient absorption spectrum of the oxidative radical of poly C decays with the concurrent formation of the phenoxyl radical of the tested polyphenols within several tens of microseconds after the electron pulse irradiation. The result indicated that there was a repair reaction between oxidative radical of poly C and the tested polyphenols. The repair activities also were observed for the tested polyphenols towards the radical cations of single-stranded DNA (ssDNA) and double-stranded DNA (dsDNA). The rate constants were determined to be 3.7-6.4 x 10(9), 4.8-5.5 x 10(8) and 8.8-10.3 x 10(8) M(-1).sec(-1) for the repair reactions of oxidative radical of poly C and radical cations of ssDNA and dsDNA, respectively. The result of this study together with those of our previous studies demonstrates that PPGs and their analogues can fast repair not only the damage of deoxynucleoside and deoxynucleotide but also the damage of integral DNA, with the latter being closer to a cellular condition.

From the whole plants of Conyza canadensis (Compositae), a new C-10 acetylene, namely 8R, 9R-dihydroxymatricarine methyl ester (1), and a new triterpenoid, namely 3beta, 16beta, 20beta-trihydroxytaraxast-3-O-palmitoxyl ester (4), were isolated along with eleven known compounds (2, 3, 5-13). The structures of all 13 compounds were elucidated on the basis of their spectral data. The antibacterial activities of compounds 1-3 were evaluated.

Two new ent-kaurenoids,19-acetoxyl-ent-3beta,17-dihydroxykaur-15-ene (1), 19-acetoxyl-ent-3beta-hydroxykaur-15-en-17-al (2), together with seven known ent-kaurenoids: ent-kaur-16-en-19-al (3), ent-kaur-16-en-19-oic acid (4), ent-kauran-16beta,17-diol (5), ent-15beta, 16beta-epoxy-17-hydroxykauran-19-oic acid (6),19-acetyl-ent-3beta-hydroxyl-kaur-16-ene (7), ent-3beta,19-dihydroxykaur-16-ene (8), ent-17-hydroxykaur-15-ene (9), were isolated from Cacalia pilgeriana. Their structures were elucidated by spectroscopic methods including 2D NMR spectral analysis.

A new iridoid (1) and thirteen known compounds 2-14 were isolated from Pedicularis kansuensis forma albiflora Li., and their structures were elucidated by spectroscopic methods including 2D-NMR techniques.

Phytochemical investigation of the roots of Patrinia rupestris afforded a new triterpenoid patrirupin A (1) and a new iridoid patrirupin B (2), as well as three known triterpenoids: 3-oxo-olean-12-en-28-oic acid (3), ursolic acid (4), alpha-amyrin (5), three known iridoids: isovaltratum (6), 11-ethoxyviburtinal (7), homobaldrinal (8), five known steroids: ergosterol (9), ergost-6,22-diene-3 beta,5 alpha,8 alpha-triol (10), 6-hydroxenone (11), beta-sitosterol (12), daucosterol (13), and two known flavones: 1-hydroxy-5-methoxy xanthen-9-one (14), 3',4',5,7-tetrahydroxyflavanone (15). The new compounds were characterized by means of spectroscopic methods including UV, IR, 1D, 2D NMR and HRESIMS, and the known ones were established on the basis of comparing their NMR data with those of the corresponding compounds in the literature.

Two new apianen lactones, named as guanyeliaoine I (1) and guanyeliaoine II (2), have been isolated along with seven known compounds from Polygonum perforliatum L. (Chinese name "Guanyeliao", Berberidaceae). Their structures were deduced on the basis of spectral data and chemical methods.

Three new apianen lactones Maomailiaoine I (1), Maomailiaoine II (2) and Maoimaliaoine III (3), together with one known apianen lactone, five known flavonoids and three other known compounds were isolated from Polgonum ciliinerve Ohwi. Their structures were deduced from spectroscopic methods and 2D NMR techniques.

Using the MTT assay and the telomeric repeat amplification protocol (TRAP)-based PCR-ELISA assay, the cytotoxicity and telomerase inhibiting ability of 17 sesquiterpenes (extracted from Chinese herbs) were tested in the human ovarian cancer cell line HO-8910. The results indicated that seven sesquiterpenes inhibited cell proliferation without having an effect on telomerase activity; two sesquiterpenes inhibited neither cell proliferation nor telomerase activity; and the other eight sesquiterpenes inhibited both cell proliferation and telomerase activity to a certain extent. Without exception, none of these 17 sesquiterpenes could only inhibit telomerase activity without inhibiting cell proliferation. This indicated that the telomerase inhibiting activity is not a universal mechanism for all anticancer drugs but is only one of several possible mechanisms. The structure-activity relationships of 5 groups of sesquiterpenes are also discussed. This study may help to develop anticancer drugs.

Three new triterpenoids, 19-hydroxy-2,3-secours-12-ene-2,3,28-trioic acid 3- methyl ester (1), 19-hydroxy-1-oxo-2-nor-2,3-secours-12-ene-3,28-dioic acid (2), and (3beta,18alpha,19alpha)-3,28-dihydroxy-20,28-epoxyursan-24-oic acid (3), were isolated from the roots of Potentilla multicaulis. Their structures were elucidated on the basis of spectroscopic methods (IR, HR-ESI-MS, and 1D- and 2D-NMR). Compound 2b exhibited moderate cytotoxic activity against human promyelocytic leukemia (HL-60) cells.

Six new compounds were isolated from the whole plant of Sonchus uliginosus, including three eudesmane-type sesquiterpenoids (1β,6α)-1,6,14-trihydroxyeudesm-3-en-12-oic acid γ-lactone (1), (1β,6α)-1,6,14-trihydroxyeudesma-3,11(13)-dien-12-oic acid γ-lactone (2), and (1β,6α)-1,6-dihydroxy-14-O-[(4-hydroxyphenyl)acetyl]eudesma-3,11(13)-dien-12-oic acid γ-lactone (3), and three phenylpropane derivatives, 4-hydroxy-γ,3,5-trimethoxybenzenepropanol (6), γ,3,4,5-tetramethoxybenzenepropanol (7), and γ,3,4,5-tetramethoxybenzenepropanol acetate (8), together with the two known compounds 4 and 5. The new structures were elucidated by means of spectroscopic methods, such as IR, EI-MS, HR-ESI-MS, 1D- and 2D-NMR, and by comparison of the spectroscopic data with those reported for structurally related compounds.

Four new, highly oxygenated oplopane-type sesquiterpenes (3–6) were isolated from the roots of Ligularia narynensis, together with four known compounds, and their structures were elucidated by spectroscopic methods and comparison with literature data. Selected congeners were evaluated for their in vitro cytotoxic activities against cultured SMMC-7721 (human hepatoma), L02 (human hepatocyte), and HL-60 (human promyelocytic leukemia) cells, but were found to be inactive.

The present study was designed to investigate the acute relaxing effect of phytoestrogen resveratrol on isolated porcine coronary arteries and to determine the mechanisms underlying its vasodilatation. Rings of porcine coronary arteries were suspended in organ baths containing Krebs-Henseleit solution, and then isometric tension was measured. Resveratrol concentration-dependently relaxed arterial rings precontracted with 30 mM KCl. The IC(50) value of resveratrol was 38.67+/-3.21 microM. Incubation with N(omega)-L-nitro-arginine (L-NNA), endothelium removal or the presence of a potent inhibitor of protein tyrosine phosphatase sodium orthovanadate partly decreased the relaxation induced by resveratrol. However, the relaxation induced by resveratrol was unaffected by the estrogen receptor antagonist tamoxifen, the inhibitor of prostanoid synthesis indomethacin, the antagonist of beta-adrenoceptors propranolol or the protein synthesis inhibitor, cycloheximide. In addition, resveratrol significantly decreased the contractile responses of 5-HT, KCl and CaCl(2), and shifted their cumulative concentration-response curves to the right. These results suggest that the mechanisms of vasorelaxation induced by resveratrol are heterogeneous, two mechanisms participating partially in the relaxation of porcine coronary artery were detected in the study, one being the nitric oxide released from the endothelium, the other causing inhibition of Ca(2+) influx, but estrogen receptors were not involved in resveratrol-induced relaxation.

Four new benzofuran derivatives were isolated from the roots of Ligularia stenocephala; they were named as ligustenin A (1), B (2), C (3) and D (4), and the structures were established by spectroscopic methods including 2D NMR techniques. Ligustenin A (1) was found to exhibit potent anti-tumor activity against HL-60 (human leukemia cells), Bel-7402 (human hepatoma cells) and HO-8910 (human ovarian neoplasm cells) with IC 5 0 values of 18.6, 27.6 and 57.5 μM, respectively.

From the roots of Asparagus gobicus, four new nor-lignans, 3'-methoxynyasin, iso-agatharesinol, gobicusins A, B and one new steroidal saponin, 3-O-[beta-D-xylopyranosyl(1-4)-beta-D-glucopyranosyl(1-2)-beta-D-glucopyranosyl]-(25S)-5beta-spirostan-3beta-ol (11) were isolated, together with twelve known compounds. The structures of the new compounds were established by spectroscopic methods including 2D-NMR techniques (1H-1H COSY, HMBC, HMQC) and chemical transformations. Nyasol (5) and 11 exhibited remarkable in vitro cytotoxic activity against cultured HO-8910 (human ovarian carcinoma) and Bel-7402 (human hepatoma) cells with IC50 vales of 30.6 and 29.4 microM, 5.2 and 5.2 microM, respectively.

A thorough investigation of Ligulariopsis shichuana afforded five new sesquiterpenes, including 1β,10β-epoxy-3α-angeloyloxy-9β-acetoxy-8α,11β-dihydroxybakkenolide (1), 1β,7-dihydroxy-3β-acetoxy-noreremophil-6(7),9(10)-dien-8-one (2), 8α-hydroxy-3-oxoeremophil-1(2),7(11),9(10)-trien-8β(12)-olide (3), 1β,10β-dihydroxy-3β-acetoxyeremophil-7(11),8(9)-dien-8(12)-olide (4) and 1β,10β-epoxy-8,12-dihydroxy-3β-acetoxy-9β-angeloyloxyeremophil-7(11)-en-8,12-disemiketal (5). Their structures were established by spectroscopic methods and 2D NMR techniques. In addition, bakkenolide (1) and eremophilenolides (5) showed antibacterial and cytotoxic activities.

Six new dihydro-beta-agarofuran [5,11-epoxy-5beta,10alpha-eudesm-4 (14)-ene] sesquiterpenes were isolated from the seeds of Euonymus nanoides Loes, including five with a novel substitution pattern: (1 R,2 S,4 S,5 R,7 R,9 S,10 R)-1alpha-benzoyloxy-2alpha,15-diacetoxy-4beta-hydroxy-9beta-cinnamoyloxy-beta-dihydroagarofuran ( 1), 1alpha-(alpha-methyl)-butanoyl-2alpha,15-diacetoxy-4beta-hydroxy-9beta-(beta-)furoyloxy-beta-dihydroagarofuran ( 2), 1alpha,2alpha-di-(alpha-methyl)-butanoyl-4beta-hydroxy-9beta-(beta-)furoyloxy-15-acetoxy-beta-dihydroagarofuran ( 3), 1alpha-(alpha-methyl)-butanoyl-2alpha-(alpha-methyl)-propynoyloxy-4beta-hydroxy-9beta-(beta-)furoyloxy-15-acetoxy-beta-dihydroagarofuran ( 4) and 1alpha,2alpha, 9beta-tri-(beta-)furoyloxy-4beta-hydroxy-15-acetoxy-beta-dihydroagarofuran ( 5). The other dihydroagarofuran sesquiterpene was 1alpha,2alpha,6beta,15-tetraacetoxy-3alpha-(alpha-methyl)-butanoyl-4beta-hydroxy-9beta-(beta-)furoyloxy-beta-dihydroagarofuran ( 6). The structures of 1 - 6 were elucidated by means of (1)H- and (13)C-NMR spectroscopic studies, including 2D heteronuclear COSY (HMQC), long-range correlation spectra with inverse detection (HMBC), (1)H- (1)H COSY and NOESY. The absolute configuration of compound 1 was determined by application of the CD exciton chirality method. Six compounds were evaluated for their in vitro antitumor effects (IC (50) values: 27.71 - 50.69 microg/mL) and the structure-activity relationship is discussed.

Three new xanthanolides, 1-3, along with nine known compounds, were isolated from the aerial parts of Carpesium longifolium. The structures of the new compounds were elucidated as 1beta,4beta-epoxy-5beta-hydroxy-10alphaH-xantha-11(13)-en-12,8beta-olide (1), 1beta,4beta,4alpha,5beta-diepoxy-10alphaH,11alphaH-xantha-12,8beta-olide (2), and 4-acetoxy-1beta,5beta-epoxy-10alphaH-xantha-11(13)-en-12,8beta-olide (3) by spectroscopic methods including IR, EIMS, HRESIMS, and 1D and 2D NMR experiments. Parthenolide and michelenolide exhibited significant cytotoxic activity against cultured SMMC-7721 (human hepatoma) and HO-8910 (human ovarian carcinoma) cells.

Two new steroids Zhonghualiaoine I (1) and Zhonghualiaoine II (2) were isolated along with seven known compounds from Polygonum nodosum pers (Chinese name “Zhonghualiao”, Berberidaceae). Their structures were deduced on the basis of spectral data.

Verbascoside and rutin possess anti-cancer properties and are capable of repairing DNA damaged by oxygen radicals, acting as powerful antioxidants. Based on kinetic measurements and experiments on tumor cells, docking studies of the two ligand molecules with the receptor telomeric DNA fragments have been carried out. The docking calculations performed using JUMNA software showed that the both molecules can be docked into the minor groove of telomeric DNA and form complexes with suitable geometry for electron transfer between guanine radical and ligands. The reaction mechanism via the electron transfer process is further confirmed through energy calculations for transition states using MOPAC 93 program. Complexes can be formed without major distortion of DNA structure and are further stabilized by the interaction of DNA with the saccharide side-groups. By comparing their energies, the difference of activities of the two compounds can be explained.

Chemical investigation of the roots of Ligularia sagitta has resulted in the characterization of six eremophilenolides 6beta,8beta-dimethoxy-10beta-hydroxyeremophil-7(11)-en-12,8alpha-olide (1), 6beta-angeloyloxy-10beta-hydroxy-8beta-methoxyeremophil-7(11)-en-12,8alpha-olide (2), 6beta-(2'-methylbutanoyloxy)-10beta-hydroxy-8beta-methoxyeremophil-7(11)-en-12,8alpha-olide (3), 6beta-angeloyloxy-10beta-hydroxy-8alpha-methoxyeremophil-7(11)-en-12,8beta-olide (4), 6beta-(2'-methylbutanoyloxy)-10beta-hydroxy-8alpha-methoxyeremophil-7(11)-en-12,8beta-olide (5) and 8beta,10beta-dihydroxy-6beta-methoxyeremophil-7(11)-en-12,8alpha-olide (6), together with one monoterpene (3 R,4 R,6 S)-3,6-dihydroxy-1-menthene (7), two triterpenes lupeol (8) and ursolic acid (9), and beta-sitosterol (10). The structures of five new constituents (1-5) were elucidated by spectroscopic methods including 2D-NMR experiments. The compounds 1, 5 and 7 showed antibacterial activity by being assayed against Staphylococcus aureus, Bacillus subtilis and Escherichia coli.

A new nor-sesquiterpenoid eremophilane derivative and a new eudesmane derivative were isolated from the whole plants of Ligularia hodgsonii. Their structures were elucidated by spectroscopic methods and 2D NMR techniques.

Screening of natural products with anti-tumor activity as telomerase inhibitor is a new subject in the field of tumor therapy. Using telomerase PCR ELISA, telomere DNA hybridization and flow cytometry analysis, the effects of verbascoside, a phenylpropanoid glucoside extracted from Pedicularis striata Pall, on telomerase activity, telomere length and cell cycle of human gastric carcinoma cells MKN45 was examined in vitro. After being treated with a 50 % inhibition concentration of verbascoside (17.8 microg/ml), telomerase activity in the cells was significantly inhibited but not in the cellular supernatant, the average telomere length became remarkably short, and the sub-G0 /G1 peak and G2/M arrest were also displayed when compared to the control cells. These results suggest that verbascoside mediated-cell differentiation and apoptosis may be affected by telomere-telomerase-cell cycle dependent modulation. Thus, the antitumor mechanism of verbascoside is demonstrated once more by its inhibiting effect on telomerase activity in tumor cells, and the telomerase assay may provide a valuable screening method for antitumor activity of natural products.

Experiments show that the natural substances phenylpropanoid glycosides (PPGs) extracted from pelicularis spicata are capable of repairing DNA damaged by oxygen radicals. Based on kinetic measurements and experiments on tumor cells, a theoretical study of the interaction between PPG molecules and isolated DNA bases, as well as a DNA fragment has been performed. An interaction mechanism reported early has been refined. The docking calculations performed using junction minimization of nucleic acids (JUMNA) software showed that the PPG molecules can be docked into the minor groove of DNA and form complexes with the geometry suitable for an electron transfer between guanine radical and the ligand. Such complexes can be formed without major distortions of DNA structure and are further stabilized by the interaction with the rhamnosyl side-groups.

The effects of quercetin and rutin on the repair of the radical cations of dCMP and poly C were studied using the technique of pulse radiolysis. The radical cations of dCMP and poly C were formed by the reaction of dCMP and poly C with SO( 4)(-). After pulse irradiation of nitrogen-saturated aqueous solutions containing dCMP, 20 mM K(2)S(2)O(8), 200 mM t-BuOH and either rutin or quercetin, the initially formed radical cation of dCMP, detected spectrophotometrically, rapidly decayed with the concurrent formation of the phenoxyl radical of rutin or quercetin within 8-40 micros. The repair efficiencies of the tested compounds towards the poly C radical cation were also determined using the same procedure. The results indicate that dCMP and poly C radical cations can be rapidly repaired by quercetin and rutin. The rate constants of the repair reactions were determined to be 4.3-8.8x10(8) M/s and 1.5-3.6x10(8) M/s for dCMP and poly C radical cations, respectively. Together with findings from our previous studies, the present results demonstrate that non-enzymatic fast repair may be a universal form of repair involving phenolic antioxidants.

A new guaianolide and a new eudesmanolide were isolated from Lactuca tatarica, as well as eight known sesquiterpenoids. The new compounds were elucidated on the basis of spectroscopic methods including IR, HRESIMS, 1D and 2D NMR, and the known compounds were established by comparing their physical data with those of the corresponding compounds in the literature.

Repair effect on TMP radical anions by phenylpropanoid glycosides (PPGs) and their analogs, isolated from Chinese folk medicinal herbs, were studied using a pulse radiolysis technique. The radical anion of TMP was formed by the reaction of hydrated electron with TMP. On pulse irradiation of a nitrogen saturated TMP aqueous solution containing 0.2 mol/l t -BuOH and one of the PPGs or their analogs, the transient absorption spectrum of the radical anion of TMP decayed with the formation of that of the radical anion of PPGs or their analogs within several decades of microseconds after electron pulse irradiation. The results indicated that TMP radical anions can be repaired by PPGs or their analogs. The rate constants of the repair reactions were deduced to be 1.64–2.75×10 9 M −1 s −1 . A deeper understanding of this new repair mechanism will undoubtedly help researchers design strategies to prevent and/or intervene more effectively in free radical related diseases.

A nor-lignan and two sesquiterpenes, along with six known compounds, have been isolated from the medicinal plant Cremanthodium ellisii. Their structures were determined on the basis of spectral evidence, especially 2D NMR ( 1 H – 1 H COSY, HMQC, HMBC).

A new antibacterial bisabolane sesquiterpene, 1β-acetoxy-2β,8-diangeloyloxy-3β-hydroxy-4α-cbioro-10,11-expoxybisabol-7(14)-ene (1), was isolated from Ligularia thyrsoidea and its structure was elucidated by 2D NMR techniques.

A new triterpene, 13β-methyl isomer of bauerenol acetate, named mongolenin, has been isolated from the aerial parts of Artemisia mongolica. The structure was elucidated by spectroscopic methods. Its 13C- and 1H-NMR chemical shifts have been assigned unambiguously on the basis of detailed 2D-NMR analyses.

DNA damaged by oxygen radicals has been implicated as a causative event in a number of degenerative diseases, including cancer and aging. So it is very significant to look for ways in which either oxygen radicals are scavenged prior to DNA damage or damaged DNA is repaired to supplement the cells’ inadequate repair capacity. The repair activities and reaction mechanism of phenylpropanoid glycosides (PPGs) and their derivatives, isolated from Chinese folk medicinal herbs, towards both dGMP-OH adducts and dAMP-OH adducts were studied with the pulse radiolytic technique. On pulse irradiation of nitrous oxide saturated 2 mM dGMP or dAMP aqueous solution containing one of the PPGs or their derivatives, the transient absorption spectra of the hydroxyl adduct of dGMP or dAMP decayed with the formation of that of phenoxyl radicals of PPGs or their derivatives within several decades of microseconds after electron pulse irradiation. The result indicated that dGMP or dAMP hydroxyl adducts can be repaired by PPGs or their derivatives. The rate constants of the repair reactions were deduced to be 0.641–1.28×10 9 M −1 s −1 for dGMP-OH and 0.2–0.491×10 9 M −1 s −1 for dAMP-OH , which positively correlated to the number of phenolic hydroxyl groups in the glycoside structure. A deeper understanding of this new repair mechanism may help researchers to design strategies to prevent and/or intervene more effectively in free radical related diseases.

Two new sesquiterpenes named liguducin-A (1) and -B (4) were isolated from a Chinese medicinal plant, the dried roots of Ligularia duciformis, together with four known sesquiterpenes, 4α, 10β-dihydroxy-1β,5α-H-guai-6-ene (2), 4α-hydroxy-1β,5α,11α-H-guai-9-en-12,8α-olide (3), 1β-hydroxyeudesm-4,11-dien-3-one (5) and 1β,6α-dihydroxyeudesm-4(15)-ene (6). On the basis of the spectral evidence, their structures were determined.

The reaction of hydroxyl radical with 1 phenylpropanoid glycoside (PPG), cistanoside C, and its 3 derivatives: 1-0-beta-D-2-(p-hydroxyphenyl)-ethanyl-glucose, 6-O-(E)-femloyl-glucose and 6-O-(E)-p-hydroxy-cinnarnoylglucose isolated from folk medicinal herbs was investigated by pulse radiolysis technique respectively. The reaction rate constants were determined by analysis of built-up trace of absorption at lambda(max) of specific transient absorption spectra of PPG and its derivatives upon attacking . OH. All four compounds react with . OH at close to diffusion controlled rate (1. 03 x 10(9)-19.139 x 10(9) L . mol(-1) . s(-1)), suggesting that they are effective . OH scavengers. The results demonstrated that the numbers of phenolic hydroxyl groups of PPG and its derivatives are directly related to their scavenging activities. By comparing the reaction rates of . OH with 1-O-beta-D-2-(p-hydroxyphenyl)-ethanyl-glucose, 6-O-(E)-feruloyl-glucose or 6-O-(E)-p-hydroxy-cinnomoyl-glucose, it is evident that the phenylethyl group is more impofiant than phenylacryloyl group for scavenging . OH.

Phytochemistry investigation of the whole plants of Ligularia thyrsoidea, has led to the isolation of five new bisabolane sesquiterpenes along with three known compounds. The structures of these new compounds were elucidated by spectroscopic methods and 2D NMR techniques.

From Ligularia atroviolacea, four new eremophilendiolides, 8 beta-hydroxy-eremophil-3,7 (11)-dien-12,8 alpha(14,6 alpha)-diolide (1), 8 beta-methoxy-eremophil-3,7(11)-dien-12,8 alpha(14,6 alpha)-diolide (2), 8 alpha-hydroxy-eremophil-3,7(11)-dien-12,8 beta(14,6 alpha)-diolide (3) and eremophil-3,7(11),8-trien-12,8 (14,6 alpha)-diolide (4), as well as a known diolide (5) were isolated. Their structures were elucidated on the basis of 1D and 2D NMR as well as ESI-MS spectral data. (c) 2006 Yu Zhao. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved.

Eight pentacyclic triterpenoids have been isolated from the aerial parts of Rubus xanthocarpus and four of them are new compounds. Their structures were elucidated on the basis of spectral data and chemical transformations as: 1α,2α,3β,19α-tetrahydroxyurs-12-en-28-oic and, 2α,3α,19α,24-tetrahydroxyurs-12-en-28-oic acid-28-O-β- D -glucopyranusyl ester, 2α,3α,19α-trihydroxyurs-12-en-24-formyl-28-oic acid-28-O-β- D -glucopyranosyl ester and 2,3-O-isopropylidenyl-2α,3α,19α-trihydroxyurs-12-en-28-oic acid.

Six new compounds, an iridoid glucoside, 6- O-methyl-epiaucubin, three iridoids, artselaenins A, B, C, a phenylethanoid glycoside, artselaeroside A, and a phenylpropanoid glycoside, artselaeroside B, as well as fourteen known compounds, nine iridoid glycosides and five phenylpropanoid glycosides were isolated from the whole plants (including roots, stems, leaves and flowers) of Pedicularis artselaeri. Their structures were identified mainly by spectral evidence.

A new triterpene glycoside, 2 α ,3 β ,19 α -trihydroxyurs-12-ene-23,28-dioic acid-28- O -(6′- O -methyl- β - d -glucopyranosyl) ester and a new triterpene derivative, 24- O -butyl-2 α ,3 β ,19 α ,24-tetrahydroxyurs-12-en-28-oic acid, together with six known compounds, have been isolated from the aerial parts of Rubus pungens Camb. var oldhamii . The structures of these compounds were established mainly by spectroscopic methods.

Investigation of Ligularia duciformis roots afforded four novel coniferyl alcohol derivatives and two new sinapyl alcohol derivatives: 4- O -[6-hydroxy-7(9)-dehydro-6,7-dihydrogeranyl]-coniferyl alcohol, 4- O -[7-hydroxy-5,6 E -dehydro-6,7-dihydrogeranyl]-coniferyl alcohol, 4- O -[6-hydroperoxy-7(9)-dehydro-6,7-dihydrogeranyl]-coniferyl alcohol, 4- O -[7-hydroperoxy-5,6 E -dehydro-6,7-dihydrogeranyl]-coniferyl alcohol, 4- O -[6-hydroxy-7(9)-dehydro-6,7-dihydrogeranyl]-sinapyl alcohol and 4- O -[7-hydroxy-5,6 E -dehydro-6,7-dihydrogeranyl]-sinapyl alcohol.

The title compound, 13(R)-9β-methyl-1(10),14-dienefried­labda-13-O-α-l-2′-acetyl­rhamonopyanoside or 3-methyl-5-(1,2,5,5-tetra­methyl-1,2,3,4,4a,5,6,7-octa­hydro­naphth­yl)pent-1-en-3-yl 2-O-acetyl­rhamnopyanoside, C28H46O6, is a bicyclic diterpenoid glycoside. The rearranged methyl group (from C10 to C9) is in a β orientation and a double bond is formed between C1 and C10 in the rearrangement. The l-rhamnose group on the cyclo­hexane ring is equatorial and the configuration of the C atom to which the methyl­ene group is attached is R. The cyclo­hexene, cyclo­hexane and l-rhamnose rings in the mol­ecule adopt half-chair, chair and chair conformations, respectively. In the crystal structure, mol­ecules are linked by O—H⋯O hydrogen bonds. The l-2′-acetyl-rhamnose hydr­oxy groups serve as hydrogen-bond donors, forming mol­ecular chains along the b axis.

The title compound, 3α-hydr­oxy-11αH-guaia-4(15),10(14)-dien-12,6α-olide, C15H20O3, is a 5,7,5-tricyclic guaianol­ide. The hydr­oxy group is equatorial and the methyl group is axial. Three rings, viz. a five-membered, a seven-membered and a γ-lactone ring, are cis- and trans-fused to each other, and adopt half-chair, chair and envelope conformations, respectively. The crystal structure is stabilized by inter­molecular O—H⋯O hydrogen bonds between the hydr­oxy group and the γ-lactone carbonyl O atom along the b direction.

The roots of Ligularia intermedia yielded four benzofurans, a novel phenol derivative, 2-isopropenyl-6-acetyl-8-methoxy-1,3-benzodioxin-4-one, and three substituted geranyls, including two new hydroperoxide compounds, (E)-4-(6-hydroperoxy-3,7-dimethylocta-2,7-dienyloxy)-syringenin and (E,E)-4-(7-hydroperoxy-3,7-dimethylocta-2,5-dienyloxy)-syringenin. Structures were elucidated using chemical and spectroscopic methods.

Five pentacyclic triterpenoid glycosyl esters have been isolated from the aerial parts of Rubus pileatus and three of them are new compounds. Their structures were elucidated on the basis of spectral data and chemical transformations as 3β,19α-dihydroxyurs-12-en-24,28-dioic acid -28-O-(6′-O- methyl -β- d -glucopyranosyl ) ester, 2α,3β,19α-trihydroxyurs-12-en-24,28-dioic acid -28-O-(6′-O- methyl -β- d -glucopyranosyl ) ester and 2α,3β,19α-trihydroxyurs-12-en-24,28-dioic acid -28-O-3′-O- methyl -β- d -glucopyranosyl ) ester.

Further phytochemical investigation of the roots of Ligularia sagitta afforded two new eremophilane sesquiterpene acids (1, 2), and from the roots of Ligularia nelumbifolia, two new guaiane sesquiterpenes (3, 4) were isolated. Their structures were elucidated by spectroscopic methods including 2D NMR techniques and chemical transformations.