A flavonol glycoside-lignan ester and accompanying acylated glucosides from Monochaetum multiflorum

α-Glucosidase inhibitory flavonol glycosides from Cyclocarya paliurus (Batalin) Iljinskaja and their kinetics characteristics

Seven previously undescribed flavonol glycosides including four rare flavonol glycoside cyclodimers, dicyclopaliosides A-C (1-3) with truxinate type and dicyclopalioside D (4) with truxillate type, as well as three kaempferol glycoside derivatives cyclopaliosides A-C (5-7), were obtained from the leaves of Cyclocarya paliurus. Their structures were elucidated by extensive spectroscopic methods and chemical analyses. All compounds were evaluated for their inhibitory α-glucosidase activities. Among them, compounds 1-4 display strong inhibitory activities with IC50 values of 82.76 ± 1.41, 62.70 ± 4.00, 443.35 ± 16.48, and 6.31 ± 0.88 nM, respectively, while compounds 5-7 showed moderate activities with IC50 values of 4.91 ± 0.75, 3.64 ± 0.68, and 5.32 ± 0.53 μΜ, respectively. The structure-activity relationship analysis assumed that the cyclobutane cores likely contribute to the enhancement of α-glucosidase inhibitory activities of dimers. Also, the interaction mechanism between flavonol glycoside dimers and α-glucosidase were explored by the enzyme kinetic assay, indicating that compounds 1-3 exhibited mixed-type inhibition, while 4 showed uncompetitive inhibition. Additionally, the active compounds have also undergone molecular docking evaluation.

New Megastigmane and Polyphenolic Components of Henna Leaves and Their Tumor-Specific Cytotoxicity on Human Oral Squamous Carcinoma Cell Lines

Polyphenols have a variety of phenolic hydroxyl and carbonyl functionalities that enable them to scavenge many oxidants, thereby preserving the human redox balance and preventing a number of oxidative stress-related chronic degenerative diseases. In our ongoing investigation of polyphenol-rich plants in search of novel molecules, we resumed the investigation of Lawsonia inermis L. (Lythraceae) or henna, a popular ancient plant with aesthetic and therapeutic benefits. The leaves' 70% aq acetone extract was fractionated on a Diaion HP-20 column with different ratios of H2O/an organic solvent. Multistep gel chromatographic fractionation and HPLC purification of the Diaion 75% aq MeOH and MeOH fractions led to a new compound (1) along with tannin-related metabolites, benzoic acid (2), benzyl 6'-O-galloyl-β-D-glucopyranoside (3), and ellagic acid (4), which are first isolated from henna. Repeating the procedures on the Diaion 50% aq MeOH eluate led to the first-time isolation of two O-glucosidic ellagitannins, heterophylliin A (5), and gemin D (6), in addition to four known C-glycosidic ellagitannins, lythracin D (7), pedunculagin (8), flosin B (9), and lagerstroemin (10). The compound structures were determined through intensive spectroscopic investigations, including HRESIMS, 1D (1H and 13C) and 2D (1H-1H COSY, HSQC, HMBC, and NOESY) NMR, UV, [α]D, and CD experiments. The new structure of 1 was determined to be a megastigmane glucoside gallate; its biosynthesis from gallic acid and a β-ionone, a degradative product of the common metabolite β-carotin, was highlighted. Cytotoxicity investigations of the abundant ellagitannins revealed that lythracin D2 (7) and pedunculagin (8) are obviously more cytotoxic (tumor specificity = 2.3 and 2.8, respectively) toward oral squamous cell carcinoma cell lines (HSC-2, HSC-4, and Ca9-22) than normal human oral cells (HGF, HPC, and HPLF). In summary, Lawsonia inermis is a rich source of anti-oral cancer ellagitannins. Also, the several discovered polyphenolics highlighted here emphasize the numerous biological benefits of henna and encourage further clinical studies to profit from their antioxidant properties against oxidative stress-related disorders.

In Vitro and in Silico Analysis of Phytochemicals From Fallopia dentatoalata as Dual Functional Cholinesterase Inhibitors for the Treatment of Alzheimer’s Disease

Current studies have found that butyrylcholinesterase (BuChE) replaces the biological function of acetylcholinesterase (AChE) in the late stage of Alzheimer’s disease. Species in the genus of Fallopia, rich in polyphenols with diverse chemical structures and significant biological activities, are considered as an important resource for screening natural products to against AD. In this study, thirty-four compounds (1–34) were isolated from Fallopia dentatoalata (Fr. Schm.) Holub, and their inhibitory effects against AChE and BuChE were assessed. Compounds of the phenylpropanoid sucrose ester class emerged as the most promising members of the group, with 31–33 displaying moderate AChE inhibition (IC50 values ranging from 30.6 ± 4.7 to 56.0 ± 2.4 µM) and 30–34 showing potential inhibitory effects against BuChE (IC50 values ranging from 2.7 ± 1.7 to 17.1 ± 3.4 µM). Tacrine was used as a positive control (IC50: 126.7 ± 1.1 in AChE and 5.5 ± 1.7 nM in BuChE). Kinetic analysis highlighted compounds 31 and 32 as non-competitive inhibitors of AChE with Ki values of ∼30.0 and ∼34.4 µM, whilst 30–34 were revealed to competitively inhibit BuChE with Ki values ranging from ∼1.8 to ∼17.5 µM. Molecular binding studies demonstrated that 30–34 bound to the catalytic sites of BuChE with negative binding energies. The strong agreement between both in vitro and in silico studies highlights the phenylpropanoid sucrose esters 30–34 as promising candidates for use in future anti-cholinesterase therapeutics against Alzheimer’s disease.

Chemical constituents from the flowers of Hypericum monogynum L. with COX-2 inhibitory activity

Hypericum monogynum L. (Hypericaceae) has been used as a folk Chinese medicine for the treatment of inflammatory related diseases. Cyclooxygenase-2 (COX-2) is a crucial target for the development of agents to treat inflammation. To search for anti-inflammatory compounds from traditional Chinese medicines, a chemical constituent study along with COX-2 inhibitory activity analysis was performed for this plant. In this study, sixteen chemical monomers, including three undescribed oxidative degradation polycyclic polyprenylated acylphloroglucinols (PPAPs, hypemoins C-E), two undescribed PPAPs (hypemoins A and B), and 11 known compounds, were identified from the flowers of H. monogynum. Their structures were characterized by HRESIMS, NMR techniques, ECD, and single crystal X-ray diffraction. Four flavonoid derivatives showed remarkable COX-2 inhibitory activities, with IC₅₀ values ranging from 0.220 ± 0.006 to 1.655 ± 0.098 μM. Among these compounds, the possible recognition mechanism between quercetin 3-(6″-O-caffeoyl)-β-3-D-galactoside and COX-2 was predicted by molecular docking analysis. Moreover, the multidrug resistance reversal activities for the selected compounds were evaluated.

The "Traditional Chinese medicine regulating liver regeneration" treatment plan for reducing mortality of patients with hepatitis B-related liver failure based on real-world clinical data

On the basis of real-world clinical data, the study aimed to explore the effect and mechanisms of the treatment plan of “traditional Chinese medicine (TCM) regulating liver regeneration.” A total of 457 patients with HBV-related liver failure were retrospectively collected. The patients were divided into three groups: the modern medicine control group (MMC group), patients treated with routine medical treatment; the control group combining traditional Chinese and Western medicine (CTW), patients treated with routine medical treatment plus the common TCM formula; and the treatment group of “TCM regulating liver regeneration” (RLR), patients treated with both routine medical treatment and the special TCM formula of RLR. After 8 weeks of treatment, the mortality of patients in the RLR group (12.31%) was significantly lower than those in the MMC (50%) and CTW (29.11%) groups. Total bilirubin level significantly decreased and albumin increased in the RLR group when compared with the MMC and CTW groups (P < 0.05). In addition, there were significant differences in the expression of several cytokines related to liver regeneration in the RLR group compared with the MMC group. RLR treatment can decrease jaundice, improve liver function, and significantly reduce the mortality in patients with HBV-related liver failure. The mechanism may be related to the role of RLR treatment in influencing cytokines related to liver regeneration.

The isolation, structure and fragmentation characteristics of natural truxillic and truxinic acid derivatives in Abrus mollis leaves

Five undescribed compounds were separated from Abrus mollis leaves, including two truxillate forms (abrusamide D, H) and three truxinate forms (abrusamide E, F, G). The absolute configuration of abrusamide D was determined by X-ray crystallography. Abrusamide A was reassessed and corrected to be β-truxinate configuration rather than α-form. LC-MS/MS and CD spectroscopy were applied to determine and analyze ten compounds, including four truxillate forms (abrusamide B ~ D and H), four truxinate forms (abrusamide E ~ G and A), and two precursors [(E)-N-(4-hydroxycinnamoyl) tyrosine, (Z)-N-(4-hydroxycinnamoyl) tyrosine]. It showed that the fragmentation pattern of truxillate was symmetric, while that of truxinate was asymmetric and irregular. The CD Cotton effect was related to cyclobutane configuration. These findings provided strong evidence for the cyclobutane dimers to discriminate their configuration. In addition, the bioactivity assay showed that the compounds had low toxicity and anti-inflammatory effect.

Palhinosides A-H: Flavone Glucosidic Truxinate Esters with Neuroprotective Activities from Palhinhaea cernua

Palhinosides A-H (1-8), new flavone glucosidic truxinate esters, including β-truxinate and μ-truxinate forms, were isolated from Palhinhaea cernua. Their structures were elucidated by extensive spectroscopic methods and chemical analyses. The flavone glucoside cyclodimers possess a unique cyclobutane ring in their carbon scaffolds. Compounds 2-7 represent three pairs of stereoisomers (2/3, 4/5, 6/7). The protective effects of 1-8 against the damage of HT-22 cells induced by l-glutamate were evaluated, and compounds 4 and 5 showed better neuroprotective effects than the positive control, Trolox.

Inhibitory effect of ethanol extract of Ampelopsis brevipedunculata rhizomes on atopic dermatitis-like skin inflammation

ETHNOPHARMACOLOGICAL RELEVANCE

Extracts from various parts of Ampelopsis brevipedunculata has been used as anti-inflammatory agents in Asian folk medicine.

AIM OF THE STUDY

To demonstrate the medicinal effect of the A. brevipedunculata in skin inflammation, specifically atopic dermatitis (AD).

MATERIALS AND METHODS

The effect of ethanol extract of A. brevipedunculata rhizomes (ABE) on AD was examined using an AD-like skin inflammation model induced by repeated exposure to house dust mite (Dermatophagoides farinae extract, DFE) and 2,4-dinitrochlorobenzene (DNCB). The mechanism study was performed using tumor necrosis factor (TNF)-α and interferon (IFN)-γ-activated human keratinocytes (HaCaT). Serum histamine and immunoglobulin levels were quantified using enzymatic kits, while the gene expression of cytokines and chemokines was analyzed using quantitative real time polymerase chain reaction. The expression of signaling molecules was detected using Western blot.

RESULTS

Oral administration of ABE alleviated DFE/DNCB-induced ear thickening and clinical symptoms, as well as immune cell infiltration (mast cells and eosinophils) into the dermal layer. Serum Immunoglobulin (Ig) E, DFE-specific IgE, IgG2a, and histamine levels were decreased after the administration of ABE. ABE also inhibited CD4⁺IFN-γ⁺ and CD4⁺IL-4⁺ lymphocyte polarization in lymph nodes and expression of TNF-α, IFN-γ, IL-4, IL-13, and IL-31 in the ear tissue. In TNF-α/INF-γ-stimulated keratinocytes, ABE inhibited the gene expression of TNF-α, IL-6, IL-1β, and CCL17. In addition, ABE decreased the nuclear localization of signal transducer and activator of transcription 1 and nuclear factor-κB, and the phosphorylation of extracellular signal-regulated kinase and p38 mitogen-activated protein kinase.

CONCLUSION

Collectively, our data demonstrate the pharmacological role and signaling mechanism of ABE in the regulation of skin allergic inflammation, which supports our suggestion that ABE could be developed as a potential therapeutic agent for the treatment of AD.

Inhibitory Effects of Compounds and Extracts from Ampelopsis brevipedunculata on IL-6-Induced STAT3 Activation

Ampelopsis brevipedunculata (Maxim.) Trautv. (AB), a traditional East Asian medicine, exhibits protective effects against several inflammatory diseases. Our search for an inhibitor of IL-6-induced JAK2/STAT3 activation revealed that AB ethanolic extract (ABE) had a significant inhibitory effect on IL-6-induced STAT3 expression in Hep3B cells. The isolation and purification of an EtOAc-soluble fraction of ABE (ABEA) using reversed-phase high-performance liquid chromatography (RP-HPLC) afforded 17 compounds. The structures of these compounds (1-17) were elucidated based on ¹H and ¹³C nuclear magnetic resonance (NMR) spectroscopy as well as electrospray-ionization mass spectrometry (ESI-MS) data. ABE and ABEA were screened by a luciferase assay using Hep3B cells transfected with the STAT3 reporter gene. ABEA exhibited potent inhibitory effects on IL-6-induced STAT3 expression; moreover, these effects arose from the inhibition of the phosphorylation of the STAT3, JAK2, and ERK proteins in U266 cells. In addition, the compounds isolated from ABEA were measured for their inhibitory effects on IL-6-stimulated STAT3 expression. Of the compounds isolated, betulin showed the greatest inhibitory effects on IL-6-induced STAT3 activation in the luciferase assay (IC₅₀ value: 3.12 μM). Because of its potential for inhibiting STAT3 activation, A. brevipedunculata could be considered a source of compounds of pharmaceutical interest.

Biginkgosides A-I, Unexpected Minor Dimeric Flavonol Diglycosidic Truxinate and Truxillate Esters from Ginkgo biloba Leaves and Their Antineuroinflammatory and Neuroprotective Activities

Nine unexpected new flavonol glycoside cyclodimers in the truxinate (1-7, biginkgosides A-G, respectively) or truxillate [biginkgosides H (8) and I (9)] forms were isolated as minor components from the extract of Ginkgo biloba leaves. The new dimers possess an unusual cyclobutane ring formed by a [2+2]-cycloaddition between two symmetric (for compounds 1-5 and 7-9) or nonsymmetric (for 6) flavonol coumaroyl glucorhamnosides. A plausible biosynthetic pathway for these new compounds based on the frontier molecular orbital theory of cycloaddition reactions is briefly discussed. An antineuroinflammatory screening revealed that biginkgosides E (5) and H (8) inhibited nitric oxide production in lipopolysaccharide-activated BV-2 microglial cells, with IC50 values of 2.91 and 17.23 μM, respectively. Additionally, biginkgoside F (6) showed a significant neuroprotective effect (34.3% increase in cell viability at 1 μM) against Aβ25-35-induced cell viability decrease in SH-SY5Y neuroblastoma cells.

Phenolics and Polyphenolics from Melastomataceae Species

The Melastomataceae family, the seventh largest flowering plants, has been studied in several fronts of natural product chemistry, including terpenoids, simple phenolics, flavonoids, quinones, lignans and their glycosides, as well as a vast range of tannins or polyphenols. This review concerns the phenolic and polyphenolic metabolites described in the literature for several genera of this family, the mode of isolation and purification, and the structure elucidation of these new natural products that has been achieved by extensive spectral analyses, including ESI-MS, ¹H-, (13)C-NMR spectra and two-dimensional experiments, COSY, TOCSY, J-resolved, NOESY, HMQC, DEPT, and HMBC, as well as chemical and enzymatic degradations and the chemotaxonomic meaning. Finally, a general biogenetic pathway map for ellagitannins is proposed on the bases of the most plausible free radical C-O oxidative coupling.

α-Glucosidase Inhibitors from Vauquelinia corymbosa

The α-glucosidase inhibitory activity of an aqueous extract and compounds from the aerial parts of V. corymbosa was demonstrated with yeast and rat small intestinal α-glucosidases. The aqueous extract inhibited yeast α-glucosidase with a half maximal inhibitory concentration (IC50) of 28.6 μg/mL. Bioassay-guided fractionation of the extract led to the isolation of several compounds, including one cyanogenic glycoside [prunasin (1)], five flavonoids [(-)-epi-catechin (2), hyperoside (3), isoquercetin (4), quercitrin (5) and quercetin-3-O-(6''-benzoyl)-β-galactoside (6)] and two simple aromatic compounds [picein (7) and methylarbutin (8)]. The most active compound was 6 with IC50 values of 30 μM in the case of yeast α-glucosidase, and 437 μM in the case of the mammalian enzyme. According to the kinetic analyses performed with rat and yeast enzymes, this compound behaved as mixed-type inhibitor; the calculated inhibition constants (Ki) were 212 and 50 μM, respectively. Molecular docking analyses with yeast and mammalian α-glucosidases revealed that compound 6 bind differently to these enzymes. Altogether, the results of this work suggest that preparations of V. corymbosa might delay glucose absorption in vivo.

Chemical constituents from Sonneratia ovata Backer and their in vitro cytotoxicity and acetylcholinesterase inhibitory activities

Sonneratia ovata Backer, Sonneratiaceae, is a widespread plant in mangrove forests in Vietnam, Cambodia, Thailand, Indonesia. Sonneratia ovata's chemical composition remains mostly unknown. Therefore, we now report on the structural elucidation of three new phenolics, sonnerphenolic A (1), sonnerphenolic B (2), and sonnerphenolic C (23), a new cerebroside, sonnercerebroside (3) together with nineteen known compounds, including nine lignans (5-13), two steroids (14, 15), two triterpenoids (16, 17), three gallic acid derivatives (18-20), two phenolic derivatives (4, 22) and a 1-O-benzyl-β-d-glucopyranose (21) isolated from the leaves of Sonneratia ovata. Their chemical structures were established by spectroscopic data, as well as high resolution mass spectra and comparison with literature data. The in vitro acetylcholinesterase (AChE) inhibition and cytotoxic activities against HeLa (human epithelial carcinoma), NCI-H460 (human lung cancer), MCF-7 (human breast cancer) cancer cell lines and PHF (primary human fibroblast) cell were evaluated on some extracts and purified compounds at a concentration of 100 μg/mL. Compounds (5, 6, 23) exhibited cytotoxicity against the MCF-7 cell line with the IC50 values of 146.9±9.0, 114.5±7.2, and 112.8±9.4 μM, respectively, while they showed nontoxic with the normal cell (PHF) with IC50s >277 μM. Among 15 tested compounds, (S)-rhodolatouchol (22) showed inhibition against AChE with an IC50 value of 96.1±14.5 μM.

Two new phenolic glucosides from Lagerstroemia speciosa

Two new phenolic glucosides, 1-O-benzyl-6-O-E-caffeoyl-β-d-glucopyranoside and 1-O-(7S,8R)-guaiacylglycerol-(6-O-E-caffeoyl)-β-d-glucopyranoside, were isolated from the aerial parts of Lagerstroemia speciosa, along with ten known compounds. The structures of the isolated compounds were determined based on 1D- and 2D-NMR, Q-TOF MS and optical rotation spectroscopic data. All of the compounds showed moderate inhibitory activities against nitric oxide production in lipopolysaccharide-treated RAW264.7 cells, with IC₅₀ values of 69.5–83.3 μM.

Electrospray ionization and collision-induced dissociation tandem mass spectrometric discrimination of polyphenolic glycosides: exact acylation site determination of the O-acylated monosaccharide residues

RATIONALE

Acylated monosaccharide residues are structural subunits of natural products or synthetic intermediates that have received much attention in past years. Determination of the acylation sites of these residues still relies heavily on the comparison of their characteristic NMR signals with those of known standards and synthesized acylated glycosides. It is important to develop a rapid analytical method for determining the acylation sites for these compounds, and this is described in this study.

METHODS

Six known polyphenolic glycosides were used for the electrospray ionization and collision-induced dissociation tandem mass spectrometry (ESI-CID-MS/MS) discrimination of the acylated monosaccharide residues with different acylation sites. A combination of ESI-CID-MS/MS, using a triple quadrupole mass spectrometer, with ultra-performance liquid chromatography (UPLC) and photo-diode array (PDA) detection (UPLC-PDA) has been applied to the identification or characterization of polyphenolic glycosides in Polygonum capitatum that possess an acylated monosaccharide residue.

RESULTS

An ESI-MS and CID-MS/MS method has been developed for the determination of the acylation sites of polyphenolic glycosides that possess an acylated monosaccharide residue. Twelve polyphenolic glycosides including four new ones have been identified or characterized in P. capitatum. Eight (including the new ones) of the twelve glycosides were reported for the first time from this plant.

CONCLUSIONS

The developed ESI-MS and CID-MS/MS method provided a very useful strategy for the determination of the sites of polyphenolic glycosides that possess an acylated monosaccharide residue. The acylation site could be determined by the characteristic product ion spectra of the in-source CID-generated O-acyl monosaccharide ion [B(1)](+). The presented work may facilitate the structural characterization of these types of compounds.

Iridoid and phenylethanoid glycosides in the New Zealand sun hebes (Veronica; Plantaginaceae)

The sun hebes are a small clade of New Zealand Veronica formerly classified as Heliohebe. The water-soluble compounds of Veronica pentasepala, Veronica raoulii and Veronica hulkeana were studied and 30 compounds including 15 iridoid glucosides, 12 phenylethanoid glycosides, the acetophenone glucoside pungenin, the mannitol ester hebitol II and mannitol were isolated. Of these, five were previously unknown in the literature: dihydroverminoside and 3,3',4,4'-tetrahydroxy-α-truxillic acid 6-O-catalpyl diester, named heliosepaloside, as well as three phenylethanoid glycoside esters heliosides D, E and F, all derivatives of aragoside. The esters of cinnamic acid derivatives with iridoid and phenylethanoid glycosides and an unusually high concentration of verminoside were found to be the most distinctive chemotaxonomic characters of the sun hebes. The chemical profiles of the species were compared and used to assess the phylogenetic relationships in the group.

HPLC-ESIMS(n) profiling, isolation, structural elucidation, and evaluation of the antioxidant potential of phenolics from Paepalanthus geniculatus

The methanol extract of the flowers of Paepalanthus geniculatus Kunth. showed radical-scavenging activity in the TEAC assay. An analytical approach based on HPLC-ESIMS(n) was applied to obtain the metabolite profile of this extract and led to the rapid identification of 19 polyphenolic compounds comprising flavonoids and naphthopyranones. The new naphthopyranone (10, 16), quercetagetin (1, 5, 7, 13), and galetine derivatives (9, 11, 17, 19), and a flavonol glucoside cyclodimer in the truxillate form (12), were identified. Compounds 2, 6, and 7 showed the highest antioxidant capacity and ability to affect the levels of intracellular ROS in human prostate cancer cells (PC3).

Characterisation of galloylated cyanogenic glucosides and hydrolysable tannins from leaves of Phyllagathis rotundifolia by LC-ESI-MS/MS

INTRODUCTION

Phyllagathis rotundifolia (Jack) Bl. (Melastomataceae) is a creeping herb found in Peninsular Malaysia and Sumatra. Traditionally, a decoction of the leaves is used in the treatment of malaria, fever and stomach ache.

OBJECTIVE

To provide ESI-MS(n) data which are applicable for chemical fingerprinting of P. rotundifolia to obviate laborious isolation and purification steps.

METHODOLOGY

The mass spectral data for the compounds isolated from the leaves of P. rotundifolia were obtained by liquid chromatography-electrospray ionisation tandem mass spectrometry.

RESULTS

The MS fragmentation patterns were obtained for galloylated cyanogenic glucosides based on prunasin (prunasin 6′‐O‐gallate 1, prunasin 2′,6′‐di‐O‐gallate 2, prunasin 3′,6′‐di‐O‐gallate 3, prunasin 4′,6′‐di‐O‐gallate 4, prunasin 2′,3′,6′‐tri‐Ogallate 5, prunasin 3′,4′,6′‐tri‐O‐gallate 6 and prunasin 2′,3′,4′,6′‐tetra‐O‐gallate 7), gallotannins (6‐O‐galloyl‐D‐glucose 8, 3,6‐di‐O‐galloyl‐D‐glucose 9, 1,2,3‐tri‐O‐galloyl‐β‐D‐glucose 10, 1,4,6‐tri‐O‐galloyl‐β‐D‐glucose 11, 3,4,6‐tri‐O‐galloyl‐D‐glucose 12, 1,2,3,6‐tetra‐O‐galloyl‐β‐D‐glucose 13 and 1,2,3,4,6‐penta‐O‐galloyl‐β‐D‐glucose 14), ellagitannins [6‐O‐galloyl‐2,3‐O‐(S)‐hexahydroxy‐diphenoyl‐D‐glucose 15, praecoxin B 16 and pterocarinin C 17], ellagic acid derivatives (3′‐O‐methyl‐3,4‐methylenedioxyellagic acid 4′‐O‐β‐D‐glucopyranoside 18 and 3,3′,4‐tri‐O‐methylellagic acid 4′‐O‐β‐D‐glucopyranoside 19) and gallic acid 20 that were isolated from the leaves of P. rotundifolia.

CONCLUSION

The ESI-MS(n) technique facilitates identification of galloylated cyanogenic glucosides, hydrolysable tannins and ellagic acid derivatives that were isolated from the leaves of P. rotundifolia. It yields MS(n) spectra that are useful for identification of these compounds in complex samples and permit more complete fingerprinting of plant materials.

Phenolic Compounds from Eucalyptus Gomphocephala with Potential Cytotoxic and Antioxidant Activities

Two new phenolic compounds, 2,4,6-trihydroxy-5-methyl-acetophenone 2- O-β-D-glucopyranoside (3), and benzyl alcohol 7- O-(3’,4’,6’-tri- O-galloyl)-β-D-glucopyranoside (8), together with eight known phenolic compounds, were isolated from the 70% aqueous acetone extract of Eucalyptus gomphocephala DC. (Myrtaceae). The isolated compounds were elucidated based on their 1H, 13C, DQF-COSY, selective 1D-TOCSY, HSQC, and HMBC NMR spectroscopic; and ESIMS data. The antioxidant effect of the phenolic compounds was tested using 1,1-diphenyl-2-picrylhydrazyl (DPPH.), hydroxyl radical and super oxide anion radical scavenging assays. The cytotoxicity of the isolated compounds was evaluated using HeLa cell line.

Flavonol glycosides and monoterpenoids from Potentilla anserina

Potentilin A (1), a rare diflavonol ester of mu-truxinic acid and a new normonoterpenoid, 2,6-dimethyl-2,3-dihydro-4-oxo-4H-pyran-2-acetic acid (2), was isolated from Potentilla anserina, together with 19 known flavonol glycosides (3-21) and 2 known monterpenoids (22,23). Their structures were elucidated by means of UV, IR, HR-ESI-MS, 1D and 2D NMR spectroscopic data.

Antihyperglycemic activity of phenylpropanoyl esters of catechol glycoside and its dimers from Dodecadenia grandiflora

Bioactivity-guided separation of an antihyperglycemic extract from the leaves of Dodecadenia grandiflora afforded two phenylpropanoyl esters of catechol glycosides (1 and 4) and two lignane bis(catecol glycoside)esters (2 and 3). Their structures were established on the basis of extensive spectroscopic analysis (1D and 2D-NMR, MS). Compounds 2 and 3 are believed to be derived from dimerization via the two phenylpropanoid units of 1. Compounds 1-4 showed significant antihyperglycemic activity in streptozotocin-induced (STZ) diabetic rats, which is comparable to the standard drug metformin. Our results provide support to explain the use of D. grandiflora as antihyperglycemic agent by the traditional medical practitioners.

Caffeoyl arbutin and related compounds from the buds of Vaccinium dunalianum

Dunalianosides A-I (1-9), esters of arbutin and related phenolic glucosides, were isolated from the buds of Vaccinium dunalianum Wight (Ericaceae) together with 20 known compounds, and their structures were established on the basis of 1- and 2D NMR spectroscopic evidence. Dunalianosides F-H were dimers of p-hydroxyphenyl 6-O-trans-caffeoyl-beta-D-glucopyranoside (10). The latter was obtained in extraordinary high yield (22% of dry weight), and dunalianoside I (9) was found to be a conjugate of arbutin with an iridoid glucoside.

Flavonol Caffeoylglycosides as alpha-Glucosidase Inhibitors from Spiraea cantoniensis Flower

In the screening experiments for rat intestinal alpha-glucosidase inhibitors in 218 plants cultivated in the Japanese temperate region, potent maltase-inhibiting activity was found in the extract of flowers of Spiraea cantoniensis. The enzyme assay guided fractionation of the extract led to the isolation of three flavonol caffeoylglycosides, quercetin 3- O-(6- O-caffeoyl)-beta-galactoside ( 1), kaempferol 3- O-(6- O-caffeoyl)-beta-galactoside ( 2), and kaempferol 3- O-(6- O-caffeoyl)-beta-glucoside ( 3), as rat intestinal maltase inhibitors. This is the first report on the alpha-glucosidase-inhibitory activity of those flavonol caffeoylglycosides. Comparison in the activity of the isolates indicated the importance of caffeoyl substructures in the molecule for the alpha-glucosidase-inhibiting activity. The relatively high contents of the active isolates in the plant suggest that S. cantoniensis could be physiologically useful for treatment of diabetes.

Two new flavonol glycosides from Sarcopyramis bodinieri var. delicate

Detailed chemical investigation of the herb Sarcopyramis bodinieri var. delicate resulted in the isolation of two new flavonol glycosides, namely, isorhamnetin-3-O-(6''-OE-feruloyl)-beta-D-glucopyranoside (1) and isorhamnetin-3-O-(6''-O-E-feruloyl)-beta-Dgalactopyranoside (2). In addition, four known compounds, quercetin-3-O-(6''-acetyl)-beta-Dglucopyranoside (3), isorhamnetin-3-O-(6''-acetyl)-beta-D-glucopyranoside (4), quercetin-3-O-(6''-O-E-p-coumaroyl)-beta-D-glucopyranoside (5), and isorhamnetin-3-O-(6''-O-E-pcoumaroyl)-beta-D-glucopyranoside (6) were obtained. The structures of the new isolates were determined by extensive spectroscopic analysis.

A galloylated cyanogenic glycoside from the Australian endemic rainforest tree Elaeocarpus sericopetalus (Elaeocarpaceae)

A cyanogenic glycoside - 6'-O-galloylsambunigrin - has been isolated from the foliage of the Australian tropical rainforest tree species Elaeocarpus sericopetalus F. Muell. (Elaeocarpaceae). This is the first formal characterisation of a cyanogenic constituent in the Elaeocarpaceae family, and only the second in the order Malvales. 6'-O-galloylsambunigrin was identified as the principal glycoside, accounting for 91% of total cyanogen in a leaf methanol extract. Preliminary analyses indicated that the remaining cyanogen content may comprise small quantities of sambunigrin, as well as di- and tri-gallates of sambunigrin. E. sericopetalus was found to have foliar concentrations of cyanogenic glycosides among the highest reported for tree leaves, up to 5.2 mg CN g(-1) dry wt.

Pentameric ellagitannin oligomers in melastomataceous plants--chemotaxonomic significance

The pantropical plant family Melastomataceae produces characteristic hydrolyzable tannin oligomers. The latter in this family are distinguished from those in other plant families by the fact that the oligomers from dimers to tetramers are composed of two different alternating monomeric units: casuarictin and pterocaryanin C. These oligomers are metabolites that are produced by intermolecular C-O oxidative coupling between the monomers (or their desgalloyl-or des-hexahydroxydiphenoyl derivatives) forming a valoneoyl group as the link between monomers. The chemotaxonomically significant oligomerization pattern of melastomataceous plants provided helpful suggestions for determining the structures of new oligomers (nobotanins Q-T and melastoflorins A-D) isolated from Monochaetum multiflorum, which belongs to this family. Melastoflorins A-D were characterized as pentamers, which are the largest hydrolyzable tannins composed of different monomeric units.

Cypellogins A, B and C, Acylated Flavonol Glycosides from Eucalyptus cypellocarpa

Three new acylated flavonol glycosides, cypellogins A (1), B (2) and C (3), along with eight known phenolic compounds, were isolated from the dried leaves of Eucalyptus cypellocarpa, and their structures were elucidated using spectroscopic methods, including 2D NMR experiments and chemical evidence.

A new ursane triterpene from Monochaetum vulcanicum that inhibits DNA polymerase beta lyase

Bioassay-directed fractionation of a butanone extract of Monochaetum vulcanicum resulted in the isolation of a new triterpene (1) and four known compounds, ursolic acid (2), 2alpha-hydroxyursolic acid (3), 3-(p-coumaroyl)ursolic acid (4), and beta-sitosteryl-beta-d-galactoside (5). The structure of the new compound 1 was established as 3beta-acetoxy-2alpha-hydroxyurs-12-en-28-oic acid on the basis of extensive 1D and 2D NMR spectroscopic interpretation and chemical derivatization. Compounds 1-3 and 5 exhibited polymerase beta lyase activity.

Oligomeric hydrolyzable tannins from Monochaetum multiflorum

Four hydrolyzable tannins, nobotanins Q, R, S, and T, were isolated from the aqueous acetone extract of the dried leaves of Monochaetum multiflorum (Melastomataceae), a plant indigenous to Colombia. Their dimeric and tetrameric structures were elucidated by spectral and chemical methods. Eight known hydrolyzable tannin monomers and eight ellagitannin oligomers characteristic of melastomataceous plants were also characterized as tannin constituents of the plant.

Polyphenolic compounds from the leaves of Koelreuteria paniculata Laxm

From the fresh leaves of Koelreuteria paniculata Laxm (Sapindaceae), four new compounds, named ethyl p-trigallate (1), 3''-O-galloyl-4'-O-galloyl-4-O-galloyl-gallic acid (2), ethyl p-heptagallate (3) and 3''-galloylquercitrin (4), together with 12 known compounds namely catechin (5), galloylepicatechin (6), isorhamnetin (7), kaempferol-3-O-arabinopyranoside (8), quercetin-3'-O-beta-D-arabinopyranoside (9), quercitrin (10), methyl p-digallate (11), methyl m-digallate (12), p-digalloyl acid (13), m-digalloyl acid (14), hyperin (15) and kaempferol-3-O-alpha-L-rhamnoside (16) were isolated by extensive column chromatographic separation. Their structures were elucidated on the basis of chemical and spectroscopic methods. Compound 9 was not reported previously with pyranoside of arabinose at C-3'. Compounds 4 and 9 possessed the activity for PTK inhibition.

New cyanogenic and alkyl glycoside constituents from Phyllagathis rotundifolia

Methanolic extracts of the leaves, stems, and roots of Phyllagathis rotundifolia collected in Malaysia yielded seven galloylated cyanogenic glucosides based on prunasin, with six of these being new compounds, prunasin 2',6'-di-O-gallate (3), prunasin 3',6'-di-O-gallate (4), prunasin 4',6'-di-O-gallate (5), prunasin 2',3',6'-tri-O-gallate (6), prunasin 3',4',6'-tri-O-gallate (7), and prunasin 2',3',4',6'-tetra-O-gallate (8). Also obtained was a new alkyl glycoside, oct-1-en-3-yl alpha-arabinofuranosyl-(1-->6)-beta-glucopyranoside (9). For compounds 3-8, the galloyl groups were individually linked to the sugar moieties via ester bonds. All new structures were established on the basis of NMR and MS spectroscopic studies. In addition, prunasin (1), gallic acid and its methyl ester, beta-glucogallin, 3,6-di-O-galloyl-D-glucose, 1,2,3,6-tetra-O-galloyl-beta-D-glucose, strictinin, 6-O-galloyl-2,3-O-(S)-hexahydroxydiphenoyl-D-glucose, praecoxin B, and pterocarinin C were isolated and identified. The isolation of 1 and its galloyl derivatives (3-8) from a Melastomataceous plant are described for the first time.