Yong-Bo Peng

Anti-diabetic agents from natural products--an update from 2004 to 2009.

Diabetes mellitus (DM), the third killer of the mankind health along with cancer, cardiovascular and cerebrovascular diseases, is one of the most challenging diseases facing health care professionals today. The World Health Organization (WHO) has declared that a DM epidemic is underway. Primary DM and its complications are costly to manage, not only for affected individuals, but also for healthcare systems around the world. Screening of anti-diabetic agents has been extensively investigated in the past decades. Natural products (NPs) have served as a major source of drugs for centuries, and about half of the pharmaceuticals in use today are derived from natural substances. Many natural products especially plants-derived medicines have been recommended for the treatment of DM. The present paper reviews NPs appeared in the literature with potential for DM and also identifies the research needs in this area. It mainly covers the time period from January 2004 to October 2008. The current review is divided into three major sections based on classification of the natural materials involved. The first part focuses on known and some new chemical entities isolated mainly from medicinal plants possessing anti-diabetic properties, including saponins, flavonoids, alkaloids, anthraquinones, terpenes, coumarins, phenolics, polysaccharides, and some other compounds. The second part summarizes crude extract of medicinal plants which are commonly used in the traditional Chinese medical system and have been demonstrated experimental or/and clinical anti-diabetic effectiveness, mainly including Leguminosae, Cucurbitaceae, Araliaceae, Liliaceae, Chenopodiaceae, Solanaceae, Compositae, Campanulaceae, Cornaceae, Rhamnaceae, Scrophulariaceae, Euphorbiaceae, Ginkgoceae, Gramineae, Myrtaceae, Sterculiaceae, Annonaceae, Labiatae, Crassulaceae, and Miscellaneous. The third part lists some compound formulae consisting of extracts of several plants that have been reported as beneficial for the treatment of DM, major involving Xiaokeling tablet, Ba-Wei-Di-Huang-Wan and Formula 1.

6-Shogaol Induces Apoptosis in Human Hepatocellular Carcinoma Cells and Exhibits Anti-Tumor Activity In Vivo through Endoplasmic Reticulum Stress

6-Shogaol is an active compound isolated from Ginger (Zingiber officinale Rosc). In this work, we demonstrated that 6-shogaol induces apoptosis in human hepatocellular carcinoma cells in relation to caspase activation and endoplasmic reticulum (ER) stress signaling. Proteomic analysis revealed that ER stress was accompanied by 6-shogaol-induced apoptosis in hepatocellular carcinoma cells. 6-shogaol affected the ER stress signaling by regulating unfolded protein response (UPR) sensor PERK and its downstream target eIF2α. However, the effect on the other two UPR sensors IRE1 and ATF6 was not obvious. In prolonged ER stress, 6-shogaol inhibited the phosphorylation of eIF2α and triggered apoptosis in SMMC-7721 cells. Salubrinal, an activator of the PERK/eIF2α pathway, strikingly enhanced the phosphorylation of eIF2α in SMMC-7721 cells with no toxicity. However, combined treatment with 6-shogaol and salubrinal resulted in significantly increase of apoptosis and dephosphorylation of eIF2α. Overexpression of eIF2α prevented 6-shogaol-mediated apoptosis in SMMC-7721 cells, whereas inhibition of eIF2α by small interfering RNA markedly enhanced 6-shogaol-mediated cell death. Furthermore, 6-shogaol-mediated inhibition of tumor growth of mouse SMMC-7721 xenograft was associated with induction of apoptosis, activation of caspase-3, and inactivation of eIF2α. Altogether our results indicate that the PERK/eIF2α pathway plays an important role in 6-shogaol-mediated ER stress and apoptosis in SMMC-7721 cells in vitro and in vivo.

Advances of Modern Chromatographic and Electrophoretic Methods in Separation and Analysis of Flavonoids

Flavonoids, one of the largest groups of secondary metabolites, are widespread in vegetable crops such as herbs, fruits, vegetables, grains, seeds and derived foods such as juices, wines, oils, etc. They receive considerable attention due to their biological and physiological importance. Hundreds of publications on the analysis of flavonoids have appeared over the past decade. Traditional and more advanced techniques have come to prominence for sample preparation, separation, detection, and identification. This review intends to provide an updated, concise overview on the recent development and trends of separation, identification and quantification for flavonoids by modern chromatographic and spectrophotometric analytical techniques, including gas chromatography (GC), liquid chromatography (LC), and capillary electrophoresis (CE). The sample preparation before analysis is also briefly summarized.

High‐speed separation and characterization of major constituents in Radix Paeoniae Rubra by fast high‐performance liquid chromatography coupled with diode‐array detection and time‐of‐flight mass spectrometry

A fast high-performance liquid chromatography (HPLC) method coupled with diode-array detection (DAD) and electrospray ionization time-of-flight mass spectrometry (ESI-TOFMS) has been developed for rapid separation and sensitive identification of major constituents in Radix Paeoniae Rubra (RPR). The total analysis time on a short column packed with 1.8-microm porous particles was about 20 min without a loss in resolution, six times faster than the performance of a conventional column analysis (115 min). The MS fragmentation behavior and structural characterization of major compounds in RPR were investigated here for the first time. The targets were rapidly screened from RPR matrix using a narrow mass window of 0.01 Da to restructure extracted ion chromatograms. Accurate mass measurements (less than 5 ppm error) for both the deprotonated molecule and characteristic fragment ions represent reliable identification criteria for these compounds in complex matrices with similar if not even better performance compared with tandem mass spectrometry. A total of 26 components were screened and identified in RPR including 11 monoterpene glycosides, 11 galloyl glucoses and 4 other phenolic compounds. From the point of time savings, resolving power, accurate mass measurement capability and full spectral sensitivity, the established fast HPLC/DAD/TOFMS method turns out to be a highly useful technique to identify constituents in complex herbal medicines.

Anticancer agents derived from natural products.

Advances in the prevention and treatment of cancer require the continued development of novel and improved chemopreventive and chemotherapeutic agents. Throughout history, natural products have afforded a rich source of anticancer agents with diverse chemical structures and bioactivities. Recent technological and methodologic advances in structure elucidation, organic synthesis, and biological assay have resulted in the isolation and clinical evaluation of various novel anticancer agents. In this review, we will present the anticancer activities, mechanism of action, structure and activity relationships of six important anticancer agents from natural products, that is, taxol, betulinic acid, camptothecin, resveratrol, podophyllotoxin and curcumin.

Rapid separation and identification of 54 major constituents in Buyang Huanwu decoction by ultra-fast HPLC system coupled with DAD-TOF/MS.

Buyang Huanwu Decoction (BYHWD), is a well-known traditional Chinese preparation consisting of Radix Astragali, Radix Angelicae Sinensis, Rhizoma Ligustici Chuanxiong, Radix paeoniae Rubra, Flos Carthami, Semen Persicae and Lumbricus. An ultra-fast high-performance liquid chromatography (HPLC) method coupled with diode array detection (DAD) and electrospray ionization time-of-flight mass spectrometry (ESI-TOF/MS) has been developed for rapid separation and structural identification of constituents in BYHWD. Using an ultra-fast HPLC system with short columns (4.6 x 50 mm, 1.8 microm), the total analysis time for this complex prescription is less than 30 min. With various fragmentor voltages in TOF/MS, accurate mass measurements (less than 5 ppm error) for molecular ions and characteristic fragment ions could represent reliable identification criteria for these compounds. Fifty-four major constituents from BYHWD sample, including four C-glycosyl quinochalcones, four flavonoid O-glycosides, sixteen isoflavones, six monoterpene glycosides, eight saponins, four organic acids and five amino acids, were identified or tentatively characterized based on their retention times, DAD and TOF/MS data. All the compounds were further assigned in the seven individual crude drugs. In conclusion, the ultra-fast HPLC with DAD-TOF/MS is a highly useful and efficient technique to separate and identify constituents in complex matrices of herbal medicines or preparations.

The Cytotoxicity Mechanism of 6-Shogaol-Treated HeLa Human Cervical Cancer Cells Revealed by Label-Free Shotgun Proteomics and Bioinformatics Analysis

Cervical cancer is one of the most common cancers among women in the world. 6-Shogaol is a natural compound isolated from the rhizome of ginger (Zingiber officinale). In this paper, we demonstrated that 6-shogaol induced apoptosis and G2/M phase arrest in human cervical cancer HeLa cells. Endoplasmic reticulum stress and mitochondrial pathway were involved in 6-shogaol-mediated apoptosis. Proteomic analysis based on label-free strategy by liquid chromatography chip quadrupole time-of-flight mass spectrometry was subsequently proposed to identify, in a non-target-biased manner, the molecular changes in cellular proteins in response to 6-shogaol treatment. A total of 287 proteins were differentially expressed in response to 24 h treatment with 15 μM 6-shogaol in HeLa cells. Significantly changed proteins were subjected to functional pathway analysis by multiple analyzing software. Ingenuity pathway analysis (IPA) suggested that 14-3-3 signaling is a predominant canonical pathway involved in networks which may be significantly associated with the process of apoptosis and G2/M cell cycle arrest induced by 6-shogaol. In conclusion, this work developed an unbiased protein analysis strategy by shotgun proteomics and bioinformatics analysis. Data observed provide a comprehensive analysis of the 6-shogaol-treated HeLa cell proteome and reveal protein alterations that are associated with its anticancer mechanism.

6-Shogaol induces apoptosis in human leukemia cells through a process involving caspase-mediated cleavage of eIF2α

Background6-Shogaol is a promising antitumor agent isolated from dietary ginger (Zingiber officinale). However, little is known about the efficacy of 6-shogaol on leukemia cells. Here we investigated the underlying mechanism of 6-shogaol induced apoptosis in human leukemia cells in vitro and in vivo.MethodsThree leukemia cell lines and primary leukemia cells were used to investigate the apoptosis effect of 6-shogaol. A shotgun approach based on label-free proteome with LC-CHIP Q-TOF MS/MS was employed to identify the cellular targets of 6-shogaol and the differentially expressed proteins were analyzed by bioinformatics protocols.ResultsThe present study indicated that 6-shogaol selectively induced apoptosis in transformed and primary leukemia cells but not in normal cells. Eukaryotic translation initiation factor 2 alpha (eIF2α), a key regulator in apoptosis signaling pathway, was significantly affected in both Jurkat and U937 proteome profiles. The docking results suggested that 6-shogaol might bind well to eIF2α at Ser51 of the N-terminal domain. Immunoblotting data indicated that 6-shogaol induced apoptosis through a process involving dephosphorylation of eIF2α and caspase activation–dependent cleavage of eIF2α. Furthermore, 6-shogaol markedly inhibited tumor growth and induced apoptosis in U937 xenograft mouse model.ConclusionThe potent anti-leukemia activity of 6-shogaol found both in vitro and in vivo in our study make this compound a potential anti-tumor agent for hematologic malignancies.

Simultaneous determination of twelve bioactive constituents in Buyang Huanwu decoction by HPLC-DAD-ELSD and HPLC-TOF/MS.

Buyang Huanwu Decoction (BYHYD) is a classical traditional Chinese medicinal prescription that has been widely used for treating cerebrovascular illnesses for hundreds of years. In this study, a comprehensive analytical method has been developed for quantitative analysis of the major constituents in BYHWD. This method was based on high-performance liquid chromatography coupled to a diode array and evaporative light scattering detectors (HPLC-DAD-ELSD) on a common reverse-phase C(18) column. HPLC coupled with on-line time-of-flight mass spectrometry (HPLC-TOF/MS) was additionally adopted to provide further validation for the constituents. It was found that 0.3% aqueous formic acid and acetonitrile was the optimum mobile phase for gradient elution. This method, which showed excellent precision and accuracy, was successfully applied to quantify the bioactive constituents in six BYHWD products. The validated HPLC-DAD-ELSD method, together with the HPLC-TOF/MS analysis, provided a new basis for assessing the quality of traditional Chinese medicinal prescription consisting of many bioactive components.

Proteomic Analysis for Malonylastragaloside I in U937 Leukemia Cells by Modified Label-free Quantitative Strategy with LC Chip Q-TOF MS/MS

Abstract Aim To study the differentially-expressed proteins for malonylastragaloside I in human leukemia U937 cells. Methods A suitable protein quantitative mode of label-free technique was established by LC Chip Q-TOF. It was found that the mode of peptide spectral intensity based on label-free quantification strategy of LC Chip Q-TOF showed high reproducibility, wide dynamic range, as well as simplicity and convenience. The optimized quantification mode of the peptide spectral intensity, normalization algorithm was applied to screen the differentially-expressed proteins for malonylastragaloside I (MA-I), a novel astragaloside from Astragalus sp., in human leukemia U937 cells. Results Fifteen differentially-expressed proteins with up or down-regulation over 2.0 folds were identified, six of which including HSC70, RPLP2, PHB2, PCNA, TCTP and ANXA11 were confirmed by Western blotting. We also observed significant activation of PARP1 and cleavage of caspases-3 and −9 by MA-I in U937 cells, and the pan-caspase inhibitor Z-VAD-FMK could reduce MA-I inhibited cell proliferation, indicating that caspase activation may be involved in MA-I induced cell toxicity. Conclusion This study has generated potentially functional proteins important for MA-I inhibited U937 cells proliferation by the optimized quantification mode of peptide spectral intensity.