Acylated flavonol glycoside from Platanus orientalis

The ethylacetate and n-butanol fractions of ethanolic extract of Platanus orientalis leaves led to the isolation of new acylated flavonol glycoside as 3',5,7-trihydroxy-4'-methoxyflavonol 3-[O-2-O-(2,4-Dihydroxy)-E-cinnamoyl-α-L-rhamnopyranosyl-(1→6)-β-D-glucopyranosyl (1→2)]-β-D-glucopyranoside, along with seven known compounds. All the compounds were characterized by NMR including 2D NMR techniques. The isolates were evaluated for NF-κB, nitric oxide (NO), aromatase and QR2 chemoprevention activities and some of them appeared to be modestly active.     

New flavonol glycosides from Aconitum burnatii Gáyer and Aconitum variegatum L.

Six flavonol glycosides, compounds 1-3 from A. burnatii Gáyer and 4-6 from A. variegatum L., were obtained from their methanol extracts of aerial parts. The identified structures were quercetin 3-O-β-d-glucopyranoside-7-O-(6-E-p-coumaroyl)-β-d-glucopyranosyl-(1 → 3)-α-l-rhamnopyranoside (1), quercetin 3-O-β-d-glucopyranoside-7-O-β-d-glucopyranosyl-(1 → 3)-α-l-rhamnopyranoside (2), quercetin 3-O-β-d-glucopyranoside-7-O-(6-E-caffeoyl)-β-d-glucopyranosyl-(1 → 3)-α-l-rhamnopyranoside (3), kaempferol 3-O-β-d-galactopyranoside-7-O-α-l-arabinopyranoside (4), quercetin 3-O-β-d-glucopyranoside (5), and kaempferol 3-O-β-d-glucopyranoside (6). Compounds 1, 2 and 4 were isolated for the first time. The antioxidant potential of the methanol extracts and pure compounds was tested with different assays.     

New coumarin glycosides from the leaves of Diospyros crassiflora (Hiern)

Two new 5-methylcoumarin glycosides named diosfeboside A (1) and B (2) and five known compounds namely kaempferol 3-O-α-l-rhamnopyranosyl-(1→2)-β-d-glucopyranoside (3), ursolic acid (4), betulinic acid (5), stigmasterol (6) and stigmasterol 3-O-β-d-glucopyranoside (7) were isolated from the leaves of Diospyros crassiflora (Hiern). Their structures were established through interpretation of 1 and 2D NMR, mass spectra analysis and comparison with reported data. In vitro cytotoxic activity of the new compounds against human carcinoma cell lines (HL-60, Bel-7402, BGC-823, and KB) was evaluated and no cytotoxicity was observed for each of them.     

DPPH radical scavenging activity of two flavonol glycosides from Aconitum napellus sp. lusitanicum

The DPPH radical scavenging activity of two flavonol glycosides obtained from ethanolic extracts of Aconitum napellus sp. lusitanicum was studied. The results showed a high DPPH antiradical activity of compound 1 (quercetin 3-O-(6-trans-caffeoyl)-beta-glucopyranosyl-(1-->2)-beta-glucopyranosyl-7-O-alpha-rhamnopyranoside) when compared with compound 2 (quercetin-3-sophoroside-7-rhamnopyranoside), rutin and ascorbic acid. The relationship between the caffeoyl and rhamnopyranoside groups in the flavonol glycosides structures and the DPPH antiradical activity was also discussed.     

New monoterpene glycosides from Paeonia lactiflora

Three new monoterpene glycosides named 4-O-methyl-paeoniflorin (1), isopaeoniflorin (2), and isobenzoylpaeoniflorin (3), together with two known monoterpene glycosides, paeoniflorin (4) and benzoylpaeoniflorin (5), were isolated from the roots of Paeonia lactiflora. Their structures were established on the basis of spectral and chemical evidence.     

Antiproliferative steroidal glycosides from Digitalis ciliata

Two new compounds, a furostanol glycoside (1) and a pregnane glycoside (4), along with eight known compounds, belonging to the classes of spirostane (2,3), pregnane (5–7) and cardenolide (8–10) glycosides, were isolated from the seeds of Digitalis ciliata. Their structures were elucidated by 1D and 2D-NMR experiments as well as ESI-MS analysis. For the first time pregnane glycosides of the diginigenin series have been isolated from D. ciliata. The cytotoxic effects of compounds 1–10 on cell viability of several cancer cell lines, namely human breast cancer (MCF-7), human glioblastoma (T98G), human lung adenocarcinoma (A549), human colon carcinoma (HT-29), and human prostate cancer (PC-3) cell lines were evaluated. Compounds 1, 4, 7 and 8 showed antiproliferative effects against MCF-7, HT-29 and A549 cancer cells with IC₅₀ values ranging from 8.3 to 20 μM. The effects of compounds 1–10 on cell proliferation were evaluated on these three cancer cell lines by cell cycle analysis of DNA content using flow cytometry. Compounds 7, 8 and 10 induced significant changes in G₂/M cell cycle phase of all analyzed cells. The obtained results indicate that compounds 7, 8 and 10 are cytostatic compounds effective in reducing cell proliferation by inducing accumulation of the cells in the G₂/M phase of the cell cycle.     

Antiparasitic antioxidant phenylpropanoids and iridoid glycosides from Tecoma mollis

A radical scavenging guided phytochemical study on the stem bark of Tecoma mollis afforded seven active phenylpropanoid glycosides (1–7), including a new one (4), and one iridoid (8). The structures of the isolated compounds were elucidated on the basis of spectroscopic evidences and correlated with known compounds. Compounds (1–7) displayed promising antioxidant activity (DPPH assay) in relation to ascorbic acid (positive control). The antimicrobial activity for compounds (1–8) was evaluated against five bacterial and five fungal strains. The isolated compounds exhibited nonselective weak to moderate antimicrobial activity. The highest antileishmanial activity against Leishmania donovani was observed for compound (7) with an IC₅₀ value of 6.71 μg/ml, using pentamidine and amphotericin B as drug controls. Compound (5) exhibited moderate antimalarial activity (45% inhibition) against chloroquine sensitive (D6) clones of Plasmodium falciparum.     

Potent antiviral flavone glycosides from Ficus benjamina leaves

Crude ethanol extracts from Ficus benjamina leaves strongly inhibit Herpes Simplex Virus 1 and 2 (HSV-1/2) as well as Varicella Zoster Virus (VZV) cell infection in vitro. Bioassay-guided fractionation of the crude extract demonstrated that the most efficient inhibition of HSV-1 and HSV-2 was obtained with the flavonoid fraction. The present study was aimed to further isolate, purify and identify substances with potent antiviral activity from the flavonoid fraction of F. benjamina extracts. Flavonoids were collected from the leaf ethanol extracts through repeated purification procedure and HPLC analysis. The antiviral activity of each substance was then evaluated in cell culture. Three known flavone glycosides, (1) quercetin 3-O-rutinoside, (2) kaempferol 3-O-rutinoside and (3) kaempferol 3-O-robinobioside, showing highest antiviral efficiency were selected and their structure was determined by spectroscopic analyses including NMR and mass spectrometry (MS). These three flavones were highly effective against HSV-1 reaching a selectivity index (SI) of 266, 100 and 666 for compound 1, 2 and 3, respectively, while the SI of their aglycons, quercetin and kaempferol amounted only in 7.1 and 3.2, respectively. Kaempferol 3-O-robinobioside showed similar SI to that of acyclovir (ACV), the standard anti-HSV drug. Although highly effective against HSV-1 and HSV-2, these flavone glycosides did not show any significant activity against VZV.     

beta-Glucosidase inhibitory activities of phenylpropanoid glycosides, vanicoside A and B from Polygonum sachalinense rhizome

The phenylpropanoid glycosides, vanicoside A and B, isolated from rhizomes of giant knotweed (Polygonum sachalinense) showed beta-glucosidase inhibitory activity, with IC(50) values of 59.8 and 48.3 mug/ml (59.9 and 50.5 muM), respectively. In contrast, p-coumaric acid and ferulic acid, corresponding to phenylpropanoyl moieties of vanicosides, exhibited very little inhibition.     

Iridoid, phenylethanoid and flavonoid glycosides from Sideritis trojana

From the MeOH extract of Sideritis trojana, a new iridoid glycoside, 10-O-(E)-feruloylmelittoside (1) was obtained in addition to four known iridoid glycosides [melittoside (2), 10-O-(E)-p-coumaroylmelittoside (3), stachysosides E (4) and G (5)]. Moreover, five phenylethanoid glycosides [verbascoside (6), isoacteoside (7), lamalboside (8), leonoside A (9), isolavandulifolioside (10), three flavone glycosides (isoscutellarein 7-O-[6'-O-acetyl-β-allopyranosyl-(1→2)]-β-glucopyranoside (11), 4'-O-methyisoscutellarein 7-O-[6'-O-acetyl-β-allopyranosyl-(1→2)]-β-glucopyranoside (12), 3'-hydroxy-4'-O-methyisoscutellarein 7-O-[6'-O-acetyl-β-allopyranosyl-(1→2)]-β-glucopyranoside (13) and a benzylalcohol derivative (di-O-methylcrenatin) were obtained and identified. The structures were elucidated on the basis of NMR and HRMS data. All compounds were tested for their antioxidant activity by in vitro TEAC assay and some of them exhibited moderate activity (0.97-1.44 mM) when compared with the reference compound (quercetin 1.86 mM). Glycosides 6-13, the most active compounds in the TEAC assay, were also tested by flow cytometry to evaluate their ability to affect the levels of reactive oxygen species (ROS) in human prostate cancer cells (PC3).     

Sedative activity of stem bark of the Sri Lankan endemic plant, Vateria copallifera

An aqueous bark extract of Vateria copallifera showed marked sedative activity, which supports the therapeutic effects claimed by Sri Lankan traditional physicians.     

Two new secolignan glycosides from the roots of Urtica triangularis Hand.-Mazz.

Two secolignan glycoside isomers, urticaside A (1) and urticaside B (2), were isolated from the roots of Urtica triangularis Hand.-Mazz. Their structures were elucidated by means of spectral analyses including 1D, 2D NMR and HR-EI-MS.     

Nepetalactone content in shoot cultures of three endemic Nepeta species and the evaluation of their antimicrobial activity

Rapid micropropagation of Nepeta rtanjensis, N. sibirica and N. nervosa was performed. Qualitative and quantitative nepetalactone content in methanol extracts of in vitro grown plants was analysed by reverse-phase HPLC coupled with UV and MS detection. Only trans,cis-nepetalactone was detected in shoots of N. rtanjensis, while cis,trans-nepetalactone stereoisomer was present in N. sibirica. No nepetalactone was observed in shoots of N. nervosa. The antimicrobial activity of methanol extracts, against eight bacterial and eight fungal species, was evaluated. All the tested extracts showed significant antibacterial and strong antifungal activity. However, N. rtanjensis extract exhibited the best antimicrobial potential.     

Two new chalcone glycosides from the stems of Entada phaseoloides

Two new chalcone glycosides 4′-O-(6″-O-galloyl-β-d-glucopyranosyl)-2′,4-dihydroxychalcone (1) and 4′-O-(6″-O-galloyl-β-d-glucopyranosyl)-2′-hydroxy-4-methoxychalcone (2) together with one known chalcone glycoside 4′-O-β-d-glucopyranosyl-2′-hydroxy-4-methoxychalcone (3) were isolated from the stems of Entada phaseoloides. The structures of the new compounds were elucidated on the basis of extensive spectroscopic analysis, including HSQC, HMBC, ¹H–¹H COSY, and chemical evidences. This is the first report of chalcone-type compounds isolated from the genus Entada.     

Predisposition to bark beetle attack by root herbivores and associated pathogens: Roles in forest decline,gap formation,and persistence of endemic bark beetle populations

Bark beetles are largely known for their ability to undergo intermittent population eruptions that transform entire landscapes and pose significant economic hardships. However, most species do not undergo outbreaks, and eruptive species usually exert only minor disturbances. Understanding the dynamics of tree-killing noneruptive species can provide insights into how beetles persist at low densities, and how some spatiotemporal patterns of host predisposition may more likely favor breaching eruptive thresholds than others. Elucidating mechanisms behind low-density populations is challenging, however, due to the requirement of long-term monitoring and high degrees of spatial and temporal covariance. We censused more than 2700 trees annually over 7 years, and at the end of 17 years, in a mature red pine plantation. Trees were measured for the presence of bark beetles and wood borers that breed within the primary stem, root weevils that breed in root collars, and bark beetles that breed in basal stems. We quantify the sequence of events that drive this decline syndrome, with the primary emergent pattern being an interaction between below- and above-ground herbivores and their fungal symbionts. This interaction results in an expanding forest gap, with subsequent colonization by early-successional vegetation. Spatial position strongly affects the likelihood of tree mortality. A red pine is initially very likely to avoid attack by tree-killing Ips beetles, but attack becomes increasingly likely as the belowground complex spreads to neighboring trees and eventually make trees susceptible. This system is largely internally driven, as there are strong gap edge, but not stand-edge, effects. Additional stressors, such as drought, can provide an intermittent source of susceptible trees to Ips beetles, and elevated temperature slightly accentuates this effect. New gaps can arise from such trees as they subsequently become epicenters for the full complex of organisms associated with this decline, but this is not common. As Ips populations rise, there is some element of positive feedback, in that the proportion of killed trees that were not first colonized by root organisms increases. This positive feedback is very weak, however, and we propose the slope between beetle population density and reliance on host stress as a quantitative distinction along a gradient from noneruptive through eruptive species. Almost all trees colonized by Ips were subsequently colonized by wood borers, likely a source of negative feedback. We discuss implications to our overall understanding of cross-scale interactions, between-guild interactions, forest declines, and eruptive thresholds.     

Millaurine A, a new guanidine alkaloid from seeds of Millettia laurentii

A new guanidine alkaloid, millaurine A (1), was isolated from the methanol extract of the seeds of Millettia laurentii. The structure of the new compound was elucidated on the basis of spectral analysis.     

New anthraquinone glycosides from the roots of Morinda citrifolia

Six new anthraquinone glycosides: digiferruginol-1-methylether-11-O-β-gentiobioside (1); digiferruginol-11-O-β-primeveroside (2); damnacanthol-11-O-β-primeveroside (3); 1-methoxy-2-primeverosyloxymethyl-anthraquinone-3-olate (4); 1-hydroxy-2-primeverosyloxymethyl-anthraquinone-3-olate (5); and 1-hydroxy-5,6-dimethoxy-2-methyl-7-primeverosyloxyanthraquinone (6) were isolated from Morinda citrifolia (Rubiaceae) roots together with four known anthraquinone glycosides. The structures of the new compounds were established using spectral methods. For five of the new compounds, the sugar is attached via the hydroxymethyl group of the anthraquinone C-2 carbon. This type of bond is rarely found for anthraquinone glycosides isolated from natural sources.     

Linalool production from the leaves of Bursera aloexylon and its antimicrobial activity

The oil of the leaves of Bursera aloexylon was found to contain a high linalool level (96.7 %). The antimicrobial activity tests indicated that the oil was effective against Rhodococcus equi (0.60 mg/ml) and Staphylococcus epidermides (0.15 mg/ml).     

Phenylpropionic acid derivates from the bark of Cerbera manghas

Two new phenylpropionic acid derivates, cerberic acids A (1) and B (2), were isolated from the bark of Cerbera manghas. Their structures were established on the basis of spectroscopic methods including IR, ESI-FT-ICR-MS, 1D and 2D NMR. Primary bioassays showed that compound 1 possessed weak cytotoxic activity against HepG2, MCF-7, and HeLa cell lines with IC₅₀ values of 44.7, 52.3, 48.7 μg/ml, respectively.     

Two new triterpene saponins from the aerial parts of Paraquilegia microphylla

Two new triterpene saponins, paraquinosides A (1) and B (2) were isolated from the aerial parts of Paraquilegia microphylla (Royle) Dromm. et Hutch, a Tibetan ethnic medicine distributed in the Qinghai–Tibet Plateau. On the basis of 1D and 2D NMR evidence, their structure was elucidated as 3-O-α-L-rhamnopyranosyl (1→2)-β-D-glucopyranosyl-15-dehydroxyl-16-O-methyl-24, 25-deoxy-26-hydroxylshengmanol-26-O-β-D-glucopyranoside (1) and 3-O-α-L-Rhamnopyranosyl (1→2)-[β-D-glucopyranosyl(1→3)]-β-D-glucopyranosyl-15-dehydroxyl-16-O-methyl-24, 25-deoxy-26-hydroxylshengmanol-26-O-β-D- glucopyranoside (2), respectively.