Xuelei Xin

Preparative isolation and purification of isobenzofuranone derivatives and saponins from seeds of Nigella glandulifera Freyn by high-speed counter-current chromatography combined with gel filtration

Although the medicinal plant and food Nigella glandulifera Freyn has been researched for decades, isobenzofuranones have never been isolated before. Two isobenzofuranone derivatives and two saponins were successfully separated and purified from seeds of N. glandulifera Freyn by high-speed counter-current chromatography (HSCCC) with the optimized two-phase solvent system, n-hexane-ethyl acetate-methanol-water (7:3:5:5, v/v). Salfredin B(11) (22.1mg, HPLC purity 95.3%), 5, 7-dihydroxy-6-(3-methybut-2-enyl) isobenzofuran-1(3H)-one (18.9mg, HPLC purity 97.3%) and crude sample 2 (555mg) were separated from 600mg of ethyl acetate extract of N. glandulifera Freyn. Following a cleaning-up step by chromatography on Sephadex LH-20, hederagenin (12mg) and 3-O-[beta-d-xylopyranosyl-(1-->3)-alpha-l-rhamnopyranosyl-(1-->2)-alpha-l-arabinopyranosyl]-hederagenin (45mg) were separated from sample 2. All of the fractions before peak II were collected and subjected to a Sephadex LH-20 column and eluted by methanol, two of triterpene saponins (12mg of hederagenin and 45mg of 3-O-[beta-d-xylopyranosyl-(1-->3)-alpha-l-rhamnopyranosyl-(1-->2)-alpha-l-arabinopyranosyl]-hederagenin) were isolated. The structures of peak fractions were identified by IR, electron ionization MS, (1)H NMR and (13)C NMR. 5, 7-Dihydroxy-6-(3-methybut-2-enyl) isobenzofuran-1(3H)-one was isolated for the first time from higher plant and salfredin B11 was isolated for the first time in this plant.

A LC/QTOF-MS/MS Application to Investigate Chemical Compositions in a Fraction with Protein Tyrosine Phosphatase 1B Inhibitory Activity from Rosa Rugosa Flowers

INTRODUCTION Rosa rugosa flowers used as herbal medicine possess many activities. A fraction extracted by ethyl acetate exhibited strong inhibitive activity against protein tyrosine phosphatase 1B (PTP1B) in vitro. OBJECTIVE Establish an efficient method of LC coupled to quadrupole time-of-flight (QTOF) with tandem MS/MS to investigate the compositions in the active fraction. METHODS Chemical compositions were separated and investigated by LC/QTOF-MS/MS in negative electrospray ionisation (ESI) mode at different collision energy (CE) values. The maximal structural information was obtained for the identification of components. RESULTS A total of 75 compounds including tannins, their related compounds and flavonoids were identified or partially characterised according to accurate mass and the characteristic fragments at low and high CE. Meanwhile, the fragmentation pathways of gallotannins and ellagitannins (hexahydroxydiphenoyl group and lactonised valoneoyl group) were studied and proposed and were used to trace tannins in crude extracts. CONCLUSION The results suggest that this fraction is a source of PTP1B inhibitory activity with a potential for treating diabetes.

Highly Conjugated Norditerpenoid and Pyrroloquinoline Alkaloids with Potent PTP1B Inhibitory Activity from Nigella glandulifera

Three norditerpenoid alkaloids, nigelladines A-C (1-3), and one pyrroloquinoline alkaloid, nigellaquinomine (4), all possessing new skeletons with highly conjugated systems, were isolated from Nigella glandulifera. The 8aS-configuration for 1 and 2 was determined by comparison of the experimental and calculated electronic circular dichroism spectra. These alkaloids exhibited potent protein tyrosine phosphatase 1B (PTP1B) inhibitory activity but are devoid of cytotoxicity against the A431 cell line at 100 μM.

Preparation of metallic pivot-based imprinted monolith for polar template

One of the main challenges in MIPs preparation is the proper MIP monolith design for water-soluble compounds due to the difficulty in satisfying the demands of both good column permeability and affinity to polar template. A new strategy of metallic pivot in a ternary porogenic system of dimethyl sulfoxide (DMSO)-dimethylformamide (DMF)-1-butyl-3-methylimidazolium tetrafluoroborate ([Bmim]BF4) was suggested to solve this problem. An imprinted monolithic column with high porosity and good permeability was synthesized using a mixture of methyl gallate (template), 4-vinylpyridine, ethylene glycol dimethacrylate, and cobalt acetate. Some polymerization factors, such as template-monomer molar ratio and the composition of the ionic liquid, on the imprinting effect of the resulting MIPs monoliths were systematically investigated. In a mobile phase of acetonitrile-buffer, the greatest imprinting factor of 10.9 was obtained on the MIPs monolith with the optimized polymerization parameters. Thermodynamic analysis for separation demonstrated that the separation between the template and its analogs on the ion-mediated MIPs monolith is an enthalpy-controlled process.

Anti-diabetic effect of three new norditerpenoid alkaloids in vitro and potential mechanism via PI3K/Akt signaling pathway.

Diabetes is a metabolic disease with the characteristic of high blood glucose (hyperglycemia). In our previous study, we found that nigelladines A-C (compounds A-C), three norditerpenoid alkaloids from the seeds of Nigella glandulifera Freyn (Ranunculaceae) exhibited protein of tyrosine phosphatase 1B (PTP1B) inhibitory activity in vitro. In the present study, we further investigated their anti-diabetes activities in L6 moytubes and illuminated the mechanisms of action of compounds A-C. Several parameters of glucose metabolism such as glucose consumption, glycogen content and hexokinase activity were increased by compounds A-C. The results suggested that compounds A-C improved glucose metabolism through promoting synthesis of glycogen. Expression of PTP1B protein was inhibited by compounds A-C in L6 moytubes. PI3K-dependent Akt phosphorylation was found to be activated by compounds A-C and completely blocked by wortmannin (a PI3K inhibitor). Moreover, the insulin-mediated induction of insulin receptor substrate-1 (IRS-1) and glycogen synthase kinase-3β (GSK-3β) were also suppressed by wortmannin. Western blot results indicated that compounds A-C-induced IRS-1/Akt activation was likely a consequence of PTP1B inhibition. Compounds A-C promoted glycogen synthesis through Akt-mediated GSK3 phosphorylation. Therefore, activation of PI3K/Akt insulin signaling pathway and suppression of PTP1B is the molecular mechanism that contributes to the anti-diabetic effect of compounds A-C in cellular models. The three alkaloids potentially serve as lead compounds for the development of antidiabetic drugs.

Flavonoids and phenolic compounds from seeds of the Chinese plant Nigella glandulifera

of Sciences, Peoples Republic of China, Lanzhou, 730000, China; 2) Xinjiang Technical Institute of Physics and Chemistry, Academy of Sciences of Xinjiang, 40-1, Beijing Road, Urumchi, China, 830011, e-mail: haji@ms.xjb.ac.cn; 3) Graduate School of the Academy of Sciences of the PRC, 19 Beijing Blvd., China, 100049. Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 294-295, May-June, 2008. Original article submitted February 25, 2008.

Hypoglycemic effect of the polyphenols rich extract from Rose rugosa Thunb on high fat diet and STZ induced diabetic rats

ETHNOPHARMACOLOGICAL RELEVANCE Rosa rugosa Thunb is a traditional Uygur medicine that has been used in the treatment of diabetes in Uygur ancient recipe for hundreds of years. However, the mechanism of Rosa rugosa Thunb activity is still unclear. This study was designed to address this issue by studying the polyphenols enriched extract (RPE) of Rosa rugosa Thunb in diabetic rats. MATERIALS AND METHODS RPE were tested in the inhibition of α-glucosidase and oxidative stress in vitro. RPE was administrated at dosages of 37.5, 75 and 150mg/kg body weight in the type 2 diabetic rats, which were made by high fat diet feeding plus a low dose of STZ injection (30mg/kg). The therapeutic effect was evaluated four weeks later. Oral glucose tolerance test (OGTT), insulin tolerance test (ITT) and insulin signal pathway (PI3K/AKT) were examined to determine insulin sensitivity. Blood glucose levels and body weight were measured weekly in the study. RESULTS In vitro, RPE exhibited an activity in the inhibition of α-glucosidase and had an excellent antioxidant activity in the liver of diabetic rats. RPE significantly decreased the fasting blood glucose, improved insulin sensitivity (HOMA-IR), OGTT, ITT and blood lipid profile. The glycogen synthesis and hexokinase activity were increased together with the improved signaling activity of insulin as indicated by p-IRS, p-IR, p-AKT, and p-GSK-3β. CONCLUSIONS The results suggest that RPE reduced blood glucose in type 2 diabetic rats by improvement of insulin sensitivity. The effect is likely achieved by inhibition of oxidative stress and α-glucosidase.

Diterpenoid constituents of Euphorbia macrorrhiza.

Ten diterpenoids, named macrorilone A-B, macroripremyrsinone A, macrorilathyrone A-B, macrorieuphorone A-B and macroricasbalone A-C, together with ten known diterpenoids, jatrophalone, sikkimenoids A-D, jatrophodione A, latilagascenes F, jolkinol B, 15β-O-benzoyl-5α-hydroxyisolathyrol and jatrophalactone were isolated from the whole plant of Euphorbia macrorrhiza C.A. Mey. These diterpenoids belong to six skeleton-types, including jatropholane, premyrsinane, lathyrane, euphoractin, casbene and rhamnofolane diterpenoids. Their structures were elucidated by extensive analysis of 1D, 2D NMR and HRESIMS spectroscopic data. The absolute configurations of macrorilone B, macroripremyrsinone A and macrorilathyrone A were established by comparing their experimental and calculated electronic circular dichroism (ECD) spectra. Several of the isolated compounds exhibited weak cytotoxicity against the KB and KBv200 cell lines with IC50 values ranging from 21.19 to 47.87μM. Some also showed multidrug resistance (MDR) reversal activity, among which macrorilathyrone B exhibited a remarkable inhibitory effect on P-gp-mediated drug exclusion.

Anti-Inflammatory Effect of Rosa rugosa Flower Extract in Lipopolysaccharide-Stimulated RAW264.7 Macrophages.

Rosa rugosa Thunb, a deciduous shrub of the genus Rosa, has been widely used to treat stomach aches, diarrhoea, pain, and chronic inflammatory disease in eastern Asia. In recent years, our research team has extensively studied the Rosa rugosa flower extract, and specifically undertook pharmacological experiments which have optimized the extraction process. Our methods have yielded a standard extract enriched in phenolic compounds, named PRE. Herein, we expand our efforts and evaluated the anti-inflammatory activity of PRE on lipopolysaccharide (LPS)-induced inflammation in RAW 264.7 macrophages. PRE significantly inhibited production of nitric oxide (NO), prostaglandin E2 (PGE2), tumor necrosis factor (TNF)-a, interleukin (IL)-6, and interleukin 1β (IL-1β), as well as expression of their synthesizing enzymes, inducible nitric oxide synthase (iNOS) and cyclooxygenase2 (COX-2). Furthermore, PRE inhibited activity of mitogen-activated protein kinases (MAPK) as well as nuclear factor-kappa B (NF-κB) signaling pathway. Our findings are the first to explain the anti-inflammatory mechanism by PRE in LPS-stimulated macrophages. Given these results, we propose that PRE has therapeutic potential in the prevention of inflammatory disorders.

A sample pretreatment strategy for pH-zone-refining counter-current chromatography.

A sample pretreatment method using acid-base extraction was established for pH-zone-refining counter-current chromatography (CCC) to increase the yield of the target compound. As the most important step, selection of two-phase solvent system for pH-zone-refining CCC should follow some rules. One of these rules is that when pH of two-phase solvent system is around 2 (for an acidic analyte) or 10 (for a basic analyte), partition coefficient values of K(acid) or K(base) should be much greater than 1. According to this rule, a new pretreatment method was developed that could substantially increase the yield of the target compound in pH-zone-refining CCC. The separation of the crude alkaloids extracted from the seeds of Sophora alopecuroides was selected as an example to show the advantage of this method. Before CCC separation, 20 g of crude sample was extracted 3 times with the selected two-phase solvent system composed of MtBE-CH₃CN-H₂O (2:2:3, v/v), where pH of the upper phase was adjusted with triethylamine to 10. A 10 g amount of the second basic extract thus obtained was subjected to pH-zone-refining CCC separation. As a result, 169 mg of sophoramin and 696 mg of sophoearpin were isolated from the second basic extract, where the yields have been doubled compared with those of the untreated sample (crude sample). Experimental results showed that the present method for pretreating the crude sample could produce substantially higher yields of target compounds in pH-zone-refining CCC.