Antitumor effects of novel compound, guttiferone K, on colon cancer by p21Waf1/Cip1-mediated G(0) /G(1) cell cycle arrest and apoptosis.

Low selectivity is one of the major problems of currently used anticancer drugs, therefore, there is a high demand for novel, selective antitumor agents. In this study, the anticancer effects and mechanisms of guttiferone K (GUTK), a novel polyprenylated acylphloroglucinol derivative isolated from Garcinia cowa Roxb., were examined for its development as a novel drug targeting colon cancer. GUTK concentration- and time-dependently reduced the viability of human colon cancer HT-29 cells (IC(50) value 5.39 ± 0.22 µM) without affecting the viability of normal human colon epithelial CCD 841 CoN cells and induced G(0) /G(1) cell cycle arrest in HT-29 cells by down-regulating cyclins D1, D3 and cyclin-dependent kinases 4 and 6, while selectively restoring p21Waf1/Cip1 and p27Kip1 to levels comparable to those observed in normal colon cells, without affecting their levels in normal cells. GUTK (10.0 µM) induced cleavage of PARP, caspases-3, -8 and -9 and chromatin condensation to stimulate caspase-3-mediated apoptosis. The addition of a JNK inhibitor, SP600125, partially reversed GUTK-induced caspase-3 activity, indicating the possible involvement of JNK in GUTK-induced apoptosis. Furthermore, GUTK (10 mg/kg, i.p.) significantly decreased the tumor volume in a syngeneic colon tumor model when used alone or in combination with 5-fluorouracil without toxicity to the mice. Immunohistochemical staining of the tumor sections revealed a mechanism involving an increase in cleaved caspase-3 and a decrease in cell proliferation marker Ki-67. Our results support GUTK as a promising novel, potent and selective antitumor drug candidate for colon cancer.

Study of the anti-proliferative effects and synergy of phthalides from Angelica sinensis on colon cancer cells.

UNLABELLED: Angelica sinensis is a Chinese medicinal herb for treating gynecological and gastrointestinal disorders, and also in conjunction with cancer chemotherapy. AIM OF THE STUDY: In the present study, the cytotoxic and anti-proliferative effects of three main Angelica sinensis phthalides, namely n-butylidenephthalide (BLP), senkyunolide A (SKA) and z-ligustilide (LGT), and their synergy on colon cancer HT-29 cells were investigated. Moreover, the results obtained in both human colon cancer HT-29 and normal colon CCD-18Co cells were compared for the investigation of selectivity. MATERIALS AND METHODS: MTT and [3H] thymidine incorporation assays were used for the evaluation of cytotoxic and anti-proliferative effects, respectively. Interactions among phthalides were determined by median-effect analysis. RESULTS: All three phthalides dose-dependently decreased cell viability more potently in HT-29 than in CCD-18Co cells. The IC50 values for inhibition of cell proliferation for SKA, LGT and BLP were 54.17+/-5.10, 60.63+/-6.79 and 236.90+/-18.22microM, respectively, in HT-29 cells. Angelica sinensis extract demonstrated significant synergy in inhibiting cell proliferation. CONCLUSIONS: The three phthalides might have anti-cancer potential, yet the phthalides, in combination with other ingredients in Angelica sinensis extract, display significant synergy leading to a stronger anti-tumor effect.

Sulfur fumigation reducing systemic exposure of ginsenosides and weakening immunomodulatory activity of ginseng.

ETHNOPHARMACOLOGICAL RELEVANCE: Ginseng (Ginseng Radix et Rhizoma) is used worldwide for its miracle tonic effects, especially for its immunomodulatory activities. Sulfur fumigation, a fast and convenient method to prevent pesticidal and bacterial contamination in the food industry, has been recently employed during post-harvest processing of ginseng. Our previous studies demonstrated that sulfur fumigation significantly altered the chemical profile of the bioactive ingredients in ginseng. However, the effects of sulfur fumigation on the pharmacokinetics and bioactivities of ginseng remain unknown. AIM OF THE STUDY: To examine the effects of sulfur fumigation on the pharmacokinetics and immunomodulatory activities of ginseng. MATERIALS AND METHODS: For pharmacokinetic studies, male Sprague-Dawley rats exposed to single/multiple dosages of non-fumigated ginseng (NFG) and sulfur fumigated ginseng (SFG) were investigated using HPLC-MS/MS analysis. For bioactivity studies, male ICR mice were used to compare the immunomodulatory effects of NFG or SFG under both normal and cyclophosphamide (CY)-induced immunocompromised conditions using white blood cell counts, serum cytokine levels, and spleen and thymus weight indices. RESULTS: Sulfur fumigation significantly reduced the contents of the bioactive ginsenosides in ginseng, which resulted in drastically low systemic exposure of ginsenosides in SFG-treatment group compared to NFG-treatment group. This observation was consistent with the bioactivities obtained in NFG- and SFG-treatment groups. The bioactivity studies also demonstrated the immunomodulatory effects of NFG but not SFG in the CY-induced immunosuppressed mice. CONCLUSION: Sulfur fumigation significantly reduced contents of bioactive ginsenosides in ginseng, leading to dramatic decrease in the systemic exposure of these ginsenosides in the body and detrimental reduction of immunomodulatory effects of ginseng. Our results provided scientific evidences and laid a solid foundation for the needs of thorough evaluation of the significant impact of sulfur fumigation on ginseng and other medicinal herbs.

Assessment of pyrrolizidine alkaloid-induced toxicity in an in vitro screening model.

ETHNOPHARMACOLOGICAL RELEVANCE: Pyrrolizidine alkaloids (PAs) are a group of heterocyclic phytotoxins present in a wide range of plants. The consumption of PA-containing medicinal herbs or PA-contaminated foodstuffs has long been reported to cause human hepatotoxicity. However, the degrees of hepatotoxicity of different PAs are unknown, which makes it difficult to determine a universal threshold of toxic dose of individual PAs for safe regulation of PA-containing natural products. The aim of the present study is to develop a simple and convenient in vitro model to assess the hepatotoxicity of different PAs. MATERIAL AND METHODS: Six common cytotoxicity assays were used to evaluate the hepatotoxicity of different PAs in human hepatocellular carcinoma HepG2 cells. RESULTS: The combination of MTT and bromodeoxyuridine incorporation (BrdU) assays demonstrated to be a suitable method to evaluate the toxic potencies of various PAs in HepG2 cells, and the results indicated that otonecine-type PA (clivorine: IC20=0.013 ± 0.004 mM (MTT), 0.066 ± 0.031 mM (BrdU)) exhibited significantly higher cytotoxic and anti-proliferative effects than retronecine-type PA (retrorsine: IC20=0.27 ± 0.07 mM (MTT), 0.19 ± 0.03 mM (BrdU)). While as expected, the known less toxic platyphylline-type PA (platyphylline: IC20=0.85 ± 0.11 mM (MTT), 1.01 ± 0.40 mM (BrdU)) exhibited significantly less toxicity. The different cytotoxic and anti-proliferative potencies of various PAs in the same retronecine-type could also be discriminated by using the combined MTT and BrdU assays. In addition, the developed assays were further utilized to test alkaloid extract of Gynura segetum, a senecionine and seneciphylline-containing herb, the overall cytotoxicity of two PAs in the extract was comparable to that of these two PAs tested individually. CONCLUSION: Using the developed in vitro model, the cytotoxicity of different PAs and the extract of a PA-containing herb were investigated in parallel in one system, and their different hepatotoxic potencies were determined and directly compared for the first time. The results suggested that the developed model has a great potential to be applied for the quick screening of the toxicity of PAs and PA-containing natural products.

Reversal of P-glycoprotein-mediated multidrug resistance by a synthetic α-aminoxy peptidomimetic.

The lack of selectivity and adequate potency of currently known P-glycoprotein (P-gp) inhibitors obscured their further development for clinical use to circumvent P-gp-mediated multidrug resistance (MDR), which necessitates the investigation of novel ones with higher potency and better specificity. The present study investigated the reversal effect of a new synthetic α-aminoxy lysine-peptidomimetic (Lys-P) on P-gp-mediated MDR. Effects of Lys-P on cytotoxicity of P-gp substrate doxorubicin (Dox) and intracellular accumulation of another P-gp substrate rhodamine 123 were examined in HEK293 cells. Its interaction mechanism and effect on P-gp expression were further investigated using ATPase assay and Western blot in Caco-2 cells, respectively. Lys-P restored the cytotoxicity of Dox toward the resistant MDR1-transfected HEK293 and MCF-7 TX400 cells without affecting their corresponding parental cells. It also significantly increased intracellular accumulation (21-fold) of rhodamine 123 in HEK293 MDR1 cells. Further mechanistic studies demonstrated that in the Caco-2 cell monolayer model, Lys-P abolished the P-gp-mediated efflux of Dox due to uncompetitive inhibition of P-gp ATPase without altering P-gp expression. Our findings demonstrated that Lys-P can be used as a promising lead compound for further development into selective and efficient MDR reversing agents for combination use with P-gp substrate drugs in cancer chemotherapy.

Sulfur fumigation processing of traditional chinese medicinal herbs: beneficial or detrimental?

Majority of traditional Chinese medicine (TCM) herbs need to undergo post-harvesting processing to convert raw material into the form readily used for prescription. In general, processing procedures are either according to China Pharmacopeia or based on traditional methods. Recently sulfur fumigation is increasingly used to replace traditional sun-drying for its pesticidal and anti-bacterial properties in a cheap and convenient manner. However, to date information on effects of sulfur fumigation on herbal safety and efficacy are limited. This article addresses potential destructive effects of sulfur fumigation on herbal efficacy and safety through reviewing currently available information. Since recently increased numbers of studies have demonstrated that sulfur fumigation-induced dramatic changes in chemical profiles of various sulfur-fumigated herbs, consequent alteration of efficacy, and/or potential incidence of toxicity are suspected. Therefore comprehensive investigations on effects of sulfur fumigation on toxicity, chemical profiles, pharmacokinetics, and bioactivities of TCM herbs are timely to provide scientific basis for standardization and regulation of this currently common but potentially harmful processing method.