Biological activity of Brassica rapa L. polysaccharides on RAW264.7 macrophages and on tumor cells

Polysaccharides are a type of natural macromolecule widely existing in nature, and its pharmacological activity has attracted wide research attention. In this study, Brassica rapa L. polysaccharides were taken as the research object, and a preliminary study of the immune activity and mechanism of the antitumor activity of these polysaccharides in vitro was carried out. Five polysaccharides, namely, BRP, BRNP-1, BRNP-2, BRAP-1, and BRAP-2, were compared in terms of their ability to inhibit the growth of three types of cancer cells, namely, A549, AGS, and HepG2. The most effective polysaccharides were screened out, and their mechanism was studied. Immunoassay results showed that the five polysaccharides not only promoted the growth of RAW264.7 cells but also stimulated their endocytic/pinocytosis activity and released NO, TNF, IL-6 cytokines, especially BRP. In vitro antitumor experiments showed that BRP has a significant inhibitory effect (*P < 0.05) on the growth of A549 cells, especially at high concentrations (500–2000 μg/mL). BRP can also induce A549 cells to release reactive oxygen species, cause mitochondrial membrane potential, and effect the expression of Bax, caspase-9, caspase-3, p53, and B-cell lymphoma 2. Immunological experiments showed that the five groups of polysaccharides are not cytotoxic to normal cells and have immunostimulatory effects. Mitochondria represent one of the more important endogenous pathways in the apoptotic process. The results suggested that BRP participates in mitochondria mediated apoptosis and induces A549 cell apoptosis. This study lays a theoretical foundation for further research on the mechanisms of BRP immunoregulation and antitumor activity in vitro and in vivo.     

Enhanced antioxidant and antitumor activities of Antrodia cinnamomea cultured with cereal substrates in solid state fermentation

Growing exclusively on stout camphor trees in Taiwan, Antrodia cinnamomea is known for its extraordinary antioxidant and antitumor activities. As an alternative to the limited supply of natural source, cultured A. cinnamomea from solid state or submerged liquid fermentation still offers many of its medicinal effects. To further enhance the production of functional compounds and corresponding activities, oat, wheat, buckwheat and pearl barley were used as substrates for solid state fermentation of A. cinnamomea in this study. Among these cereal-based culturing, the methanol extract of A. cinnamomea mycelia grown on oats showed stronger overall antioxidant properties. EC₅₀ for the antioxidant activity (conjugated diene method), the DPPH radicals scavenging ability and reducing power were estimated to be around 0.57 mg/mL, 1.07 mg/mL and 0.31 mg/mL, respectively. Incubating cultured cells with 150 ppm of the oat-cultured mycelial extract for 24 h greatly reduced the viability of MCF-7 breast cancer cells and HepG2 hepatocellular carcinoma cells to 29% and 76%, while 3T3 normal fibroblasts were virtually unaffected. In general, cereal-based solid state fermentation of A. cinnamomea produced more of the secondary metabolites and their methanolic extracts showed stronger antioxidant and anti-tumor activities than extracts obtained from liquid fermentation at the same concentration.     

Synthesis and antitumor activity of bis(arylsulfonyl)dihydroimidazolinone derivatives

A series of novel bis(arylsulfonyl)dihydroimidazolinones with different aryl substitution patterns were readily synthesized and evaluated for their antitumor activities. Some of the newly synthesized compounds exhibited cytotoxicity at micromolar range against multiple cancer cell lines, including A549, HepG2, HuCCA-1, and MOLT-3. The most potent analogue contained pentafluorobenzenesulfonyl groups, which could be chemically elaborated to serve as a potential pharmacophore.     

Synthesis and antitumor activity of daunorubicin conjugates with of 3,4-methylendioxybenzaldehyde

The design of hybrid (chimeric) molecules containing two different pharmacophores connected via a spacer (linker) is a promising approach to the functionalization of natural compounds and potentially of drug molecules. These are important examples for the use of this approach with anthracycline antibiotics. The use of this methodology may help to eliminate some of the drawbacks of anthracycline drugs, e.g., high cardiotoxicity and MDR development.     

Synthesis and biological evaluation of the natural product komaroviquinone and related compounds aiming at a potential therapeutic lead compound for high-risk multiple myeloma

Alternatives of treatments for multiple myeloma (MM) have become increasingly available with the advent of new drugs such as proteasome inhibitors, thalidomide derivatives, histone deacetylase inhibitors, and antibody drugs. However, high-risk MM cases that are refractory to novel drugs remain, and further optimization of chemotherapeutics is urgently needed.We had achieved asymmetric total synthesis of komaroviquinone, which is a natural product from the plant Dracocephalum komarovi. Similar to several leading antitumor agents that have been developed from natural compounds, we describe the antitumor activity and cytotoxicity of komaroviquinone and related compounds in bone marrow cells. Our data suggested that komaroviquinone-related agents have potential as starting compounds for anticancer drug development.     

Platinum(II) compounds with chelating ligands based on pyridine and pyrimidine: DNA and protein binding studies

Four Pt(II) compounds (C1–C4) have been studied in their DNA and protein binding. The compounds contain chelating diimine ligands bis(pyridine-2-yl)amine, abbreviated dpa, and bis(pyrimidine-2-yl)amine, abbreviated dipm. The anions for the compounds C1 and C3 are chloride (coordinated) and nitrate (non-coordinated) for C2 and C4. Calf-thymus DNA and an abundant plasma protein have been taken as models for the two major targets for metallodrug interactions investigated by CD spectroscopy. The modifications in the carrier ligands (chloride or ammine) or ancillary secondary amines have been considered to reveal the mode of interactions. The simultaneous effects of coordinative binding and partial intercalation to DNA are evident from several spectroscopic studies. To evaluate the permeability of the cytoplasmic and cellular membrane and the transportation inside the cells, partition coefficients of the four platinum compounds were determined. Two compounds (C3 and C4) induce two-step single-strand DNA cleavage, initiated by partial intercalation. The combined effect of several binding modes towards different bio-molecules is elucidated, providing a rationale for their in vitro activity profile.     

Analysis of the aplyronine A-induced protein–protein interaction between actin and tubulin by surface plasmon resonance

The antitumor macrolide aplyronine A induces protein–protein interaction (PPI) between actin and tubulin to exert highly potent biological activities. The interactions and binding kinetics of these molecules were analyzed by the surface plasmon resonance with biotinylated aplyronines or tubulin as ligands. Strong binding was observed for tubulin and actin with immobilized aplyronine A. These PPIs were almost completely inhibited by one equivalent of either aplyronine A or C, or mycalolide B. In contrast, a non-competitive actin-depolymerizing agent, latrunculin A, highly accelerated their association. Significant binding was also observed for immobilized tubulin with an actin–aplyronine A complex, and the dissociation constant K_D was 1.84 μM. Our method could be used for the quantitative analysis of the PPIs between two polymerizing proteins stabilized with small agents.     

Cure of mice bearing a late-stage,highly metastatic,drug-resistant tumor by adoptive chemoimmunotherapy

We show here that in contrast to BALB/c mice bearing a late-stage, large MOPC-315 plasmacytoma, BALB/c mice bearing a late-stage, large RPC-5 plasmacytoma were not cured by cyclophosphamide therapy (15, 50, 100 or 200 mg/kg). However, most BALB/c mice bearing a late-stage RPC-5 tumor were cured by cyclophosphamide therapy (100 mg/kg) in conjunction with adoptive immunotherapy using tumor-infiltrated spleen cells (TISpC) that had been cultured with inactivated RPC-5 tumor cells plus polyethylene glycol 6000, even though this protocol was not effective for the therapy of mice bearing a barely palpable, early-stage RPC-5 tumor. Only a few of the mice that were cured of a late-stage RPC-5 tumor following adoptive chemoimmunotherapy (ACIT) were resistant to a subsequent challenge with RPC-5 tumor cells. However, the challenged mice that had developed progressively growing tumors could then be cured by cyclophosphamide alone when the tumor became large, even though this treatment was not curative for mice bearing a tumor of similar size but not previously treated by ACIT. Thus, the cure by ACIT of BALB/c mice bearing a lethal, late-stage RPC-5 tumor with extensive metastases provides a novel experimental tumor model for investigating the mechanisms by which a chemotherapeutic drug and adoptive cellular immunotherapy can cooperate in causing the complete regression of a large tumor load.Supported by research grant CA-30088 from the National Cancer Institute and IM-435 from the American Cancer Society. M. B. M. was supported by Career Development Award CA-01350 from the National Cancer InstituteThis work is a partial fulfillment of the requirements for the Ph.D. degree     

Semiquinones derived from anthraquinone-containing antitumor drugs can partition into phosphatidylcholine bilayers

Semiquinones derived from anthraquinone-containing antitumor drugs (doxorubicin, daunorobucin and 4′-epidoxorubicin) were generated by the hypoxanthine/xanthine oxidase system in argon-saturated phosphate buffer (pH 7.4) in the presence of egg-yolk phosphatidylcholine multilamellar vesicles (MLVs) containing 1 mon% of a doxylstearic acid (DSA)_isomer. The destruction of the electron spin resonance signal corresponding to 5-, 12- and 15-DSA included in the MLVs follows pseudo-first-order kinetics. Higher rates of destruction are obtained for the 12-DSA isomer which indicates that these semiquinones can localize preferentially about the depth of the 12^th position of stearic acid in membranes. It is demonstrated that DSA destruction is due to a reversible reduction of DSA to the hydroxylamine species. This work shows that anthracycline semiquinones can partition into phosphatidylcholine bilayers under anoxic conditions which may imply another pathway on their cytotoxic action.     

Enhanced expansion of the thymic CD8+ cell subset as a potential mechanism for the generation of enhanced antitumor cytotoxicity by thymocytes from low-dose melphalan-treated MOPC-315 tumor bearers

Summary We have previously shown that thymocytes from low-dose melphalan (l-phenylalanine mustard)-treated MOPC-315-tumor-bearing mice (melphalan TuB) are able to generate an enhanced level of anti-MOPC-315 cytotoxicity, as compared to thymocytes from untreated MOPC-315-tumor-bearing mice or thymocytes from untreated or low-dose melphalan-treated normal mice, upon in vitro stimulation with MOPC-315 tumor cells in the presence of a low concentration of recombinant interleukin-2 (rIL-2). Here we show that the generation of enhanced anti-MOPC-315 cytotoxicity by melphalan TuB thymocytes depends on the ability of the thymocytes to proliferate. In addition, the ability of melphalan TuB thymocytes to generate an enhanced level of anti-MOPC-315 cytotoxicity correlated with their ability to proliferate more readily than thymocytes from untreated tumor-bearing mice and thymocytes from untreated or melphalan-treated normal mice in response to stimulation with MOPC-315 tumor cells plus a low concentration of rIL-2. Moreover, although fresh melphalan TuB thymocytes do not contain a higher percentage of phenotypically mature cells (i.e., CD4^–/CD8⁺ or CD4⁺/CD8^–) than do thymocytes from normal mice or untreated tumor-bearing mice, after a 5-day culture with both MOPC-315 tumor cells and a low concentration of rIL-2, cultures of thymocytes from melphalan TuB contained a much higher percentage of CD4^–/CD8⁺ (but not CD4⁺/CD8^–) cells than did cultures of thymocytes from the other two sources. Since CD4^–/CD8⁺ cells were previously shown to be responsible for the exertion of antitumor cytotoxicity by thymocytes stimulated with MOPC-315 in vitro, our results indicate that the enhanced antitumor cytotoxicity exerted by melphalan TuB thymocytes following in vitro stimulation with MOPC-315 tumor cells in the presence of a low concentration of rIL-2 is due, at least in part, to an expansion of the pool of CD4^–/CD8⁺ effector cells.Supported by research grant CA-35 761 from the National Cancer InstituteIn partial fulfillment of the requirements for the Doctor of Philosophy degreeSupported by career development award CA-01 350 from the National Cancer Institute