Biomedical subjects

Sibao Chen

Publications and source records attributed to Sibao Chen.

7 recordsLinked to original sources

PubMed2006

Chromatographic fingerprint analysis--a rational approach for quality assessment of traditional Chinese herbal medicine.

Traditional Chinese Herbal Medicine (TCHM) contain multiple botanicals, each of which contains many compounds that may be relevant to the medicine's putative activity. Therefore, analytical techniques that look at a suite of compounds, including their respective ratios, provide a more rational approach to the authentication and quality assessment of TCHM. In this paper we present several examples of applying chromatographic fingerprint analysis for determining the identity, stability, and consistency of TCHM as well as the identification of adulterants as follows: (1) species authentication of various species of ginseng (Panax ginseng, Panax quinquefolium, Panax noto-ginseng) and stability of ginseng preparations using high performance thin-layer chromatography (HPTLC) fingerprint analysis; (2) batch-to-batch consistency of extracts of Total Glycosides of Peony (TGP), to be used as a raw material and in finished products (TGP powdered extract products), using high performance liquid chromatography (HPLC) fingerprint analysis with a pattern recognition software interface (CASE); (3) documenting the representative HPLC fingerprints of Immature Fruits of Terminalia chebula (IFTC) through the assessment of raw material, in-process assay of the extracts, and the analysis of the finished product (tablets); (4) HPLC fingerprint study demonstrating the consistent quality of total flavonoids of commercial extracts of ginkgo (Ginkgo biloba) leaves (EGb) along with detection of adulterations. The experimental conditions as well as general comments on the application of chromatographic fingerprint analysis are discussed.

Chromatography, High Pressure Liquid↗

PubMed2006

Anti-cancer activity and mechanisms of 25-anhydrocimigenol-3-O-beta-D-xylopyranoside isolated from Souliea vaginata on hepatomas.

Our previous study first revealed the cytotoxicity and relative selectivity of 25-anhydrocimigenol-3-O-beta-D-xylopyranoside (ACX) on HepG2 and R-HepG2 cells. In the present study, the anti-cancer activity and mechanisms of ACX isolated from S. vaginata were investigated both in vitro and in vivo. ACX showed significant, consistent anti-proliferative activity on hepatoma bel-7402 cells by MTT and clone formation assays with an IC50 value of 18 mumol/l. Morphological observation and flow cytometry results showed that apoptosis and G0/G1 cell cycle arrest contributed to the cytotoxic and cytostatic effects. Further studies showed that Bax and p21 protein expression were upregulated, Bcl-2 protein expression was downregulated, and poly(ADP-ribose) polymerase protein was cleaved. Moreover, ACX also exhibited a dose-dependent inhibition of tumor growth on mice implanted with H22 in vivo. These findings implicate ACX as a promising anti-cancer agent for chemotherapy of certain cancers.

Animals↗

PubMed2005

The cytotoxicity of naturally occurring styryl lactones.

We extracted and isolated three natural styryl lactones from Goniothalamus griffithii Hook f. Thoms and investigated their cytotoxicity on a panel of three hepatocyte cell lines, HepG2, drug resistant HepG2 (HepG2-R) and primary cultured normal mice hepatocyte in order to find candidates of potential anti-cancer drugs which have low toxicity on normal cells and high effect on tumors or drug resistant tumors. All the three styryl lactones showed evident cytotoxic activities on both HepG2 and HepG2-R cell lines; however, gonithalamin and goniodiol shows less toxicity on normal mice hepatocyte as the IC(50) values of them on normal mice hepatocyte were about three times of that on HepG2. Morphological observation and cell cycle analysis were employed to elucidate the mechanisms of cytotoxicity of the tested compounds. Many apoptotic cells were observed in gonithalamin- and altholactone-treated cells, whereas, cells with chromosomes gathered at the equator were easily found in goniodiol-treated cultures. The analysis of cell cycle showed that G(2)/M arrest contributed to goniothalimin- and gonidiol-caused cell death and apoptosis was the cause of gonithalamin- and altholactone-induced cell death. Our results suggest that the three styryl lactones may be prospectively developed into anti-tumor drugs, especially on treating drug-resistance tumor after structure modification.

Animals↗

PubMed2005

Controlled delivery of testosterone from smart polymer solution based systems: in vitro evaluation.

The objective of this research is to develop injectable polymers solution based controlled release delivery systems for testosterone (TSN), using phase sensitive and thermosensitive polymers. A combination of poly(lactide) (PLA) and solvents mixture of benzyl benzoate (BB) and benzyl alcohol (BA) was used in the phase sensitive polymer delivery system. The effects of solvents system and drug loading on the in vitro TSN release were evaluated. In the case of thermosensitive polymer delivery systems, a series of low-molecular-weight poly(lactide-co-glycolide)-poly(ethylene glycol)-poly(lactide-co-glycolide) (PLGA-PEG-PLGA) triblock copolymers with varying ratio of lactide/glycolide (LA/GA, 2.0-3.5) were studied to control the release of TSN. The effects of varying block length of copolymers 1-4 on the in vitro TSN release were evaluated. Phosphate buffer saline (pH 7.4) containing 0.5% (w/v) Tween-80 was used as in vitro release medium. The amount of the released TSN was determined by an HPLC method. A controlled (zero-order) in vitro release of TSN was observed from both the phase sensitive and thermosensitive polymer delivery systems. Addition of BA (15%, v/v) in solvents system significantly (p<0.05) increased the release rate of TSN (0.33+/-0.01 mg/ml) from phase sensitive delivery system in comparison to solvent without BA (0.27+/-0.00 mg/day). Increasing drug loading also increased release rate. In the case of thermosensitive polymer delivery system, increasing the hydrophobic PLGA block length of copolymers significantly (p<0.05) decreased the release rate of TSN. It is evident from this study that the phase sensitive and thermosensitive polymers are suitable for developing prolong-release injectable implant delivery systems for TSN.

Drug Delivery Systems↗

PubMed2005

In vitro release of levonorgestrel from phase sensitive and thermosensitive smart polymer delivery systems.

The objective of this research is to develop injectable controlled delivery systems for the contraceptive hormone, levonorgestrel (LNG), using phase sensitive and thermosensitive polymers. A combination of poly (lactide) (PLA) and a solvent mixture of benzyl benzoate (BB) and benzyl alcohol (BA) was used in the phase-sensitive polymer delivery systems. The effects of solvent systems and polymer concentrations on the in vitro LNG release were evaluated. In the case of thermosensitive polymer delivery systems, a series of low-molecular-weight poly (lactide-co-glycolide)-poly (ethylene glycol)-poly (lactide-co-glycolide) (PLGA-PEG-PLGA) triblock copolymers with varying ratios of lactide/glycolide (LA/GA, 2.0-3.5) were used. The effects of varying block length of copolymers 1, 2, 3, and 4 on the in vitro LNG release were evaluated. Phosphate buffer saline (pH 7.4) containing 0.5% w/v Tween-80 was used as in vitro release medium. The amount of the released LNG was determined by an high pressure liquid chromatography (HPLC) method. A controlled (zero-order) in vitro release of LNG was observed from both phase-sensitive and thermosensitive-polymer delivery systems. Increasing the concentration of the phase-sensitive polymer from 5% to 30% significantly (p < 0.05) decreased the release rate of LNG from 38.32 microg/day to 31.45 microg/day; and increasing the hydrophilic fraction of the solvents mixture (i.e., BA) significantly (p < 0.05) increased the release rate of LNG. In the case of the thermosensitive polymer delivery system, increasing the hydrophobic PLGA block length of copolymers significantly (p < 0.05) decreased the release rate of LNG (98.65 microg/day to 67.60 microg/day). It is evident from this study that both the phase sensitive and thermosensitive polymers are suitable for developing prolonged-release injectable delivery systems for the contraceptive hormone.

Benzoates↗

PubMed2004

Cytotoxicity of three cycloartane triterpenoids from Cimicifuga dahurica.

We first investigated the cytotoxicity of three cycloartane triterpenoids isolated from the aerial part of C. dahurica. Their cytotoxic activity was investigated on several cancer cell lines including solid tumor (HepG2), blood tumor (HL-60), drug resistant tumor (R-HepG2) and primary cultured normal mouse and rat hepatocytes in order to find efficient anti-tumor agents against both parental and drug-resistant tumor with reduced toxicity. Evident cytotoxicity of these compounds on all tested neoplastic cell lines revealed that they are efficient on both drug-resistant tumor and parental tumor. Furthermore, they all showed relatively selective cytotoxicity on cancerous cells based on the higher IC(50) values of them on normal cells than that on tumor cells. Morphological observation and cell cycle analysis were employed to elucidate the cytotoxicity of the tested compounds. They brought out similar apoptotic morphological changes and G(2)/M cell cycle arrest in HepG2, R-HepG2 and HL-60 cells. Moreover, they suppressed the expression of cdc2 and COX-2 protein. These results imply that the three compounds possess potential anti-tumor activities and they exert their cytotoxicity via apoptosis and G(2)/M arrest. In addition, inhibition of cdc2 protein expression correlates with mechanism of G(2)/M arrest.

Animals↗

PubMed2004

Triblock copolymers: synthesis, characterization, and delivery of a model protein.

The purpose of this study was to synthesize and characterize biodegradable and thermosensitive triblock copolymers for delivering protein at controlled rate in biologically active form for longer duration of time. A series of thermosensitive triblock copolymers with different block lengths (PLGA-PEG-PLGA) were synthesized by ring-opening polymerization of d,l-lactide and glycolide with polyethylene glycol (PEG) in the presence of stannous octoate. Compositions and molecular weight of triblock copolymers were characterized by 1H NMR spectrometry and gel permeation chromatography, respectively. A single test-tube inverting method was employed to determine the sol-gel transition temperature. Lysozyme was used as a model protein. Lysozyme solution formulation was prepared with different triblock copolymers for in vitro release. Lysozyme concentration and its biological activity in the released sample were determined using a standard MicroBCA method and bacterial cell lysis method, respectively. The effects of varying block lengths and concentrations of copolymers on the in vitro release of lysozyme were evaluated. The release profiles from formulations showed a higher initial release followed by slower release up to 4 weeks. Increasing the block lengths of copolymers decreased burst release of lysozyme from 41.2+/-5.4% to 16.1+/-3.9%. Increasing copolymer concentrations decreased the drug release. Lysozyme in the 4 weeks released samples retained most of its biological activity (>80%). It is feasible to deliver protein in biologically active form for longer duration by varying block lengths and concentrations of triblock copolymers.

Animals↗