Phytochemical mediated gold nanoparticles and their PTP 1B inhibitory activity

Current discovery demonstrates the rapid formation of gold nanoparticles with guavanoic acid a phytochemical of Psidium guajava (Pg). The pharmacological capabilities of the phytochemicals present in the leaves of Pg and their ability to generate gold nanoparticles is presented herein. The new genre of green nanoparticles exhibit remarkable Protein Tyrosine Phosphatase 1B (PTP 1B) inhibitory activity and in vitro stability in various physiological medium including saline, histidine, cysteine, bovine serum albumin (BSA), human serum albumin (HSA) and buffers (pH 5, 7 and 9). It is predicted that this new technology will be felt greatly in several routes of pharmaceuticals.     

Synthesis of mangiferin derivates and study their potent PTP1B inhibitory activity

Protein tyrosine phosphatase 1B (PTP1B) has received considerable attention from the drug industry as a potential treatment for diabetes mellitus.Mangiferin has been reported to possess significant antidiabetic activity.Based on the previous study,eight new mangiferin derivates were synthesized and evaluated for their PTP1B inhibitory activity.Some of them displayed good inhibitory activity on PTP1B.     

Four new isoflavonoids from the stem bark of Erythrina variegata

Bioassay-directed fractionation of the stem bark extract of Erythrina variegata L. has resulted in the isolation of three new isoflavones: 5,4'-dihydroxy-8-(3,3-dimethylallyl)-2'-methoxyisopropylfurano[4,5:6,7]isoflavone (1), 5,7,4'-trihydroxy-6-(3,3-dimethylallyloxiranylmethyl)isoflavone (2), 5,4'-dihydroxy-8-(3,3-dimethylallyl)-2'-hydroxymethyl-2'-methylpyrano[5,6:6,7]isoflavone (3) and a new isoflavanone, 5,4'-dihydroxy-2'-methoxy-8-(3,3-dimethylallyl)-2',2'-dimethylpyrano[5,6:6,7]isoflavanone (4) together with seven known compounds, euchrenone b10 (5), isoerysenegalensein E (6), wighteone (7), laburnetin (8), lupiwighteone (9), erythrodiol (10), and oleanolic acid (11). The structures were determined on the basis of spectroscopic analyses and chemical evidence. The effect of these compounds on the proliferation of rat osteogenic sarcoma (UMR106) is also reported.     

5-Alkylpyrrole-2-carboxaldehyde derivatives from the Chinese sponge Mycale lissochela and their PTP1B inhibitory activities

Two new 5-alkylpyrrole-2-carboxaldehyde derivatives,mycalenitrile-15(1) and mycalenitrile-16(2),along with five known related ones(3-7),were isolated from the South China Sea sponge Mycale lissochela.The structures of the new compounds were elucidated on the basis of extensive spectroscopic analysis and by comparison of their NMR data with those reported in the literature.In bioassay,compounds 1 and 7 exhibited significant PTPIB(Protein-tyrosine phosphatase 1B,a recognized target for diabetes and obesity) inhibitory activities with IC_(50) values of 8.6 and 3.1 μmoI/L,respectively.A preliminary SAR analysis of the isolated compounds with their PTP1 B inhibitory effects was described.     

Prenylated flavonoids from the leaves of Derris malaccensis and their cytotoxicity

A new prenylated isoflavone, pomiferin-4'-O-methyl ether, and a new prenylated chalcone, 2',4'-dihydroxy-4-methoxy-3'-(2-hydroxy-3-methylbut-3-enyl)chalcone, together with four known flavonoids, were isolated from the leaves of Derris malaccensis. All isolated compounds were evaluated for their cytotoxicity.     

Isoflavone glycosides from the root wood of Erythrina latissima

The molecular structures of 3 isoflavone glycosides isolated from the root wood of Erythrina latissima were established as 4'-hydroxyisoflavone-7-O-beta-D-glucopyranoside (compound 1); 4'-hydroxyisoflavone-7-O-alpha-L-rhamnosyl (1-->6)-beta-D-glucopyranoside (compound 2); and a new compound 4', 8-dimethoxy isoflavone-7-O-alpha-L-rhamnosyl (1-->6) glucopyranoside (8-O-methylretusin-7-O-alpha-L-rhamnosyl (1-6)-beta-D-glucopyranoside) (compound 3).     

Cucurbitacin B 2-sulfate and cucurbitacin glucosides from the root bark of Helicteres angustifolia

A new sulfated cucurbitacin, cucurbitacin B 2-sulfate (1) and a new cucurbitacin glucoside, cucurbitacin G 2-O-beta-D-glucopyranoside (2) together with two known cucurbitacin glucosides, arvenin I and arvenin III were isolated from the root bark of Helicteres angustifolia. The structures of these compounds were established on the basis of spectroscopic and chemical evidence. These four compounds taste of strong bitterness. Compound 1 is a first sulfated cucurbitacin found in plants.     

Diarylheptanoids from the root bark of Juglans cathayensis

A new diarylheptanoid glucoside,（8R,9R）-17-methoxy-2-oxatricyclo[13.2.2.1^3.7]icosa-l（17）,3（20）,4,6, 15,18-hexaene-4,9,10-triol-9-O-β-D-glucopyranoside（1）,namely jugcathayenoside,together with two known diarylheptanoids,（+）-galeon（2） and 4-hydroxy-17-methoxy-2-oxatricyclo[13.2.2.1^3,7 ]icosa-1（17）,3（20）,4,6,15,18-hexaene-9-one（3）,were isolated from the root bark of Juglans cathayensis. Their structures were elucidated on the basis of extensive spectroscopic data analysis.     

A chemical model for redox regulation of protein tyrosine phosphatase 1B (PTP1B) activity

Growing evidence indicates that endogenously produced hydrogen peroxide acts as a cellular signaling molecule that (among other things) can regulate the activity of some protein phosphatases. Recent X-ray crystallographic studies revealed an unexpected chemical transformation underlying the redox regulation of protein tyrosine phosphatase 1B, in which oxidative inactivation of the enzyme yields an intrastrand protein cross-link between the catalytic cysteine residue and its neighboring amide nitrogen. This work describes a small organic molecule that serves as an effective model for the redox-sensing assembly of functional groups at the active site of PTP1B. Findings obtained using this model system suggest that the oxidative transformation of PTP1B to its "crosslinked" inactive form can proceed directly via oxidation of the active-site cysteine to a sulfenic acid (RSOH). The remarkably facile nature of this protein cross-link-forming reaction, along with the widespread cellular occurrence of protein sulfenic acids generated via oxidation of cysteine residues, suggests that the type of oxidative protein cross-link formation first seen in the context of PTP1B represents a potentially general mechanism for redox "switching" of protein function. Thus, the chemistry characterized here could have broad relevance to both redox-regulated signal transduction and the toxic effects of oxidative stress.     

A new alkylene dihydrofuran glycoside with antioxidation activity from the root bark of Morus alba L.

<正>A new alkylene dihydrofuran glycoside(1) was isolated from the root bark ofMorus alba L.,along with moracin M-3′-O-β-D-glucopyranoside (2),and moracin M-6,3′-di-O-β-D-glucopyranoside(3).Compound 1 was identified as 2-methylene-3-methoxy-2, 5-dihydrofuran-4-O-β-D-glucopyranoside on the basis of chemical and spectroscopic data including 1D and 2D NMR spectral analysis.In addition,the antioxidant activity of 1 was evaluated using the 1,1-diphenyl-2-picrylhydrazyl(DPPH) and 2,2′-azinobis- 3-ethylbenzothiazoline-6-sulphonic acid(ABTS) assay.The IC_(50) values were 2.49 and 0.45 mg/mL,respectively.     

An overview of techniques and strategies for isolation of flavonoids from the genus Erythrina

Plants in the genus Erythrina is a potential source of chemical constituents, one of which is flavonoids, which have diverse bioactivities. To date, literature on the flavonoids from the genus Erythrina has only highlighted the phytochemical aspects, so this review article will discuss isolation techniques and strategies for the first time. More than 420 flavonoids have been reported in the Erythrina genus, which are grouped into 17 categories. These flavonoid compounds were obtained through isolation techniques and strategies using polar, semi-polar, and non-polar solvents. Various chromatographic techniques have been developed to isolate flavonoids using column flash chromatography, quick column chromatography, centrifugally accelerated thin-layer chromatography, radial chromatography, medium-pressure column chromatography, semi-preparative high-performance liquid chromatography, and preparative high-performance liquid chromatography. Chromatographic processes for isolating flavonoids can be optimized using multivariate statistical applications such as response surface methodology with central composite design, Box–Behnken design, Doehlert design, and mixture design.     

Antihyperlipidemic glycosides from the root bark of Lycium chinense

Three new glycosides (1–3), together with six known ones (4–9), were isolated from the root bark of Lycium chinense. Their structures were elucidated on the basis of MS and NMR spectroscopic data. Five compounds (3, 5, 6, 8, and 9) exhibited potent antihyperlipidemic activities in HepG2 cells as assessed by Oil Red O staining and significant inhibition of intracellular triglyceride (TG) levels, whereas two compounds (5 and 9) significantly reduced total cholesterol (TC) levels.     

多管藻中具有PTP1B酶抑制活性的新化合物

应用正相硅胶、凝胶SephadexLH20柱色谱和反相HPLC等方法,从多管藻(Polysiphoniaurceolata)中分离得到6个溴酚类化合物,通过IR、MS、1D和2DNMR等波谱技术分析鉴定,发现一个有明显的PTP1B抑制活性(IC50=4·9μg/mL)的新化合物:3-溴-4-[3-溴-4,5-二羟基苯基]甲基-5-羟甲基-1,2-二苯酚(1)。另5个已知化合物分别为3-溴-4,5-二羟基苄基乙基醚(2)、3-溴-4,5-二羟基苯甲醇(3)、3-溴-4,5-二羟基苯甲醛(4)、3,5-二溴-4-羟基苯甲醛(5)、3,5-二溴-4-羟基苯甲醇(6)。     

HPLC-DAD-SPE-NMR isolation of tetracyclic spiro-alkaloids with antiplasmodial activity from the seeds of Erythrina latissima

Abstract

Seven tetracyclic spiro-alkaloids, i.e. glucoerysodine (1), erysodine (2), epi-erythratidine (3), erysovine (4), erythratidine (5), erysotrine (6) and erythraline (7) were isolated from the seeds of Erythrina latissima by means of conventional separation methods and HPLC-DAD-SPE-NMR. Their structures were elucidated by spectroscopic means. This is the first report on the isolation of compounds 3, 5 and 6 from this plant. Antiplasmodial activity against the chloroquine-resistant strain Plasmodium falciparum K1 and cytotoxicity against MRC-5 cells (human fetal lung fibroblast cells) was assessed in vitro. Erysodine (2) and erysovine (4) showed moderate activity (IC₅₀ 6.53?µM and 4.05?µM, respectively), compared with the standard chloroquine (IC₅₀ = 0.14?µM). No cytotoxicity was observed in a concentration up to 64.0?µM.     

Cytotoxic flavonoids and other constituents from the stem bark of Ochna schweinfurthiana

Seven flavonoids, hemerocallone (1), 6,7-dimethoxy-3′,4′-dimethoxyisoflavone (2), amentoflavone (4), agathisflavone (6), cupressuflavone (8), robustaflavone (9) and epicatechin (10), together with three other compounds, lithospermoside (3), β-D-fructofuranosyl-α-D-glucopyranoside (5) and 3β-O-D-glucopyranosyl-β-stigmasterol (7), were isolated from the ethyl acetate extract of the stem bark of Ochna schweinfurthiana F. Hoffm. All the compounds were characterised by spectroscopic and mass spectrometric methods, and by comparison with literature data. Cytotoxicity of the extracts and compounds against cervical adenocarcinoma (HeLa) cells was evaluated by MTT assay. Compounds 4 and 6 exhibited good cytotoxic activity, with IC₅₀ values of 20.7 and 10.0 μM, respectively.     

Four new saponins from the root bark of Aralia elata

Four new saponins, 3-O-[beta-D-glucopyranosyl(1-->3)-alpha-L-arabinopyranosyl]-16a lpha-hydroxyoleanolic acid 28-O-beta-D-glucopyranosyl ester (called aralia-saponin I), 3-O-[beta-D-glucopyranosyl(1-->3)-alpha-L-arabinopyranosyl]-16a lpha-hydroxyhederagenin 28-O-beta-D-glucopyranosyl ester (aralia-saponin II), 3-O-[beta-D-glucopyranosyl(1-->3)-beta-D-glucopyranosyl(1-->3)-alpha-L-+ ++arabinopyranosyl]-16alpha-hydroxyoleanolic acid 28-O-beta-D-glucopyranosyl ester (aralia-saponin III), 3-O-[beta-D-glucopyranosyl(1-->3)-beta-D-gucopyranosyl(1-->3)-beta -D-glucucopyranosyl]-16alpha-hydroxyoleanolic acid 28-O-beta-D-glucopyranosyl ester (aralia-saponin IV), were isolated from the root bark of Aralia elata (Miq.) Seem., together with nineteen known compounds including glycosides of (20S)-protopanaxadiol and (20S)-protopanaxatriol. Their structures were determined on the basis of chemical and spectroscopy methods.     

New cytotoxic isoflavone from the root bark of Brosimum utile

A new isoflavone 5,7,4'-trihydroxy-3'-(3-hydroxy-3-methylbutyl)isoflavone (isowigtheone hydrate) (1), together with six known isoflavones 2-7 and (-)epicatechin, were isolated from the root barks of Brosimum utile. Their structures were established on the basis of spectroscopic evidence. The in vitro cytotoxic activity of the new compound 1 was evaluated against cell lines MCF7 (human breast carcinoma), PC3 (human prostate carcinoma), HT29 (human colon cancer) and human dermis fibroblasts.     

Two new phenolic constituents from the root bark of Morus alba L. and their cardioprotective activity

A new biphenyl-furocoumarin, named morescoumarin A (1), and a new prenylated flavanone, named morflavanone A (2) were isolated from the root bark of Morus alba L., together with four known compounds (3–6). Their structures were determined by extensive spectroscopic analyses and comparison with literature data. The cardioprotective effects of these compounds against doxorubicin-induced cell death were evaluated by MTT method.     

Prenylated xanthone derivatives with antiplasmodial activity from Allanblackia monticola STANER L.C

Further study of the methanol extract of the stem bark of Allanblackia monticola STANER L.C. resulted in the isolation of a new prenylated xanthenedione, designated allanxanthone C, together with the five known xanthones, garciniafuran, tovophyllin A, rubraxanthone, norcowanin and mangostin and one saponin, stigmasterol-3-O-beta-D-glucopyranoside. The structure of the new compound was established by detailed spectroscopic analysis to be 1,2-dihydro-3,6,8-trihydroxy-1,1,7-tri(3-methylbut-2-enyl)xanthen-2,9-dione (3-hydroxyapetalinone C). The methanol extract and pure compounds were tested on two strains of Plasmodium falciparum, F32 (chloroquine sensitive) and FcM29 (chloroquine resistant). The IC50 values obtained ranged from 0.6 to 8.9 microg/ml. Their cytotoxicity was estimated on human melanoma cells (A375) and the cytotoxicity/antiplasmodial ratio was found to be between 15.45 and 30.46. The antimicrobial activities against a range of microorganisms of the crude extract and some of these compounds are also reported.     

Prenylated flavonoids and dihydrophenanthrenes from the leaves of Epimedium brevicornu and their cytotoxicity against HepG2 cells

Phytochemical study on the leaves of Epimedium brevicornu finally led to the isolation of four prenylated flavonoids (1–4) and three dihydrophenanthrenes (5–7), of which 1, 2, 5 and 7 were new compounds. The structures of these compounds were established mainly by spectroscopic techniques, including NMR spectroscopy and mass spectrometry. These isolates exhibited the cytotoxic activities against HepG2 cells with the IC₅₀ values of 32.8–87.3 μM.