Bioactivities of water-soluble polysaccharides from fruit shell of Camellia oleifera Abel: Antitumor and antioxidant activities

Polysaccharides were extracted from fruit shell of Camellia oleifera Abel. Fruit shell of Camellia oleifera Abel polysaccharide (WEP2) was a water-soluble compound. Its molecular weight was about 362 kDa. HPLC analysis showed that this polysaccharide was composed of rhamnose, fucose, arabinose, mannose, galactose and glucose in the molecular ratio of 4.05, 11.62, 1.78, 3.91, 8.76 and 27.06, respectively. The broad intense characteristic peak around 3463 cm⁻¹ due to the hydroxyl stretching vibration of the polysaccharide was observed in the polysaccharide. The characteristic absorption bands at 852 cm⁻¹ and 893 cm⁻¹ indicated that WEP2 contained both α-glycosidic and β-glycosidic linkages. WEP2 exhibited remarkable antitumor activity against Sarcoma180 cell compared to the negative control group. At the highest dose 40 mg/kg days, the tumor inhibition rate reached 65.2%. The scavenging effects of WEP2 to hydroxyl radical and superoxide radical anion were 72.5% and 86.3% at a concentration of 1.0 mg/ml, respectively.     

Synergistic antitumor activity of interleukin-2 and cimetidine against syngeneic murine tumor

Summary Cimetidine, an H2 histamine receptor antagonist, is a potent immunomodulating agent, which acts by inhibiting suppressor T lymphocyte function. The present work investigated the effect, if any, of cimetidine on interleukin-2 (IL-2)-induced natural killer (NK) and lymphokine-activated killer (LAK) cell activities, and on in vivo antitumor activity using syngeneic colon 26 adenocarcinoma as the model. Mimicking the clinical conditions, all in vitro experiments were evaluated with the splenocytes prepared from tumor-bearing BALB/c mice. Ten days after subcutaneous inoculation of tumor cells (5 × 10⁵), animals were treated intraperitoneally daily with phosphate-buffered saline (PBS), cimetidine (2 mg kg^–1 day^–1), IL-2 (300 000 IU/day), or cimetidine plus IL-2 for 7 consecutive days. The treatment of IL-2 plus cimetidine increased NK and LAK cell activities significantly and synergistically at the end of the treatment (i.e. on day 18) as well as 1 week after the treatment (i.e. on day 25), in comparison with those of the control groups (PBS, cimetidine alone, IL-2 alone). Also, in vivo antitumor activity, as analyzed by a Kaplan-Meier life table with the log-rank test, revealed a significantly prolonged survival in the group treated with IL-2 plus cimetidine compared to the control groups. Phenotyping performed on the murine splenocytes on day 18 indicated a significant reduction in Lyt2-positive cells in the cimetidine-treated group in comparison with the PBS group. A significant increase in asialo GM1-positive cells and IL-2-receptor-positive cells was detected in the group treated with IL-2 plus cimetidine in comparison with the PBS and IL-2 control groups. Therefore, this study indicates a synergistic enhancement of IL-2-induced NK and LAK cell activities in tumor-bearing hosts by cimetidine, a noncytotoxic inhibitor of suppressor T function, and a significantly prolonged survival of tumor-bearing animals treated by IL-2 plus cimetidine. It also suggests the clinical potential of combination therapy of IL-2 with cimetidine.     

Synthesis and in vitro antiproliferative evaluation of d-secooxime derivatives of 13β- and 13α-estrone

d-Secooximes were synthesized from the d-secoaldehydes in the 13β- and 13α-estrone series. The oximes were modified at three sites in the molecule: the oxime function was transformed into an oxime ether, oxime ester or nitrile group, the propenyl side-chain was saturated and the 3-benzyl ether was removed in order to obtain a phenolic hydroxy function. Triazoles were formed via Cu(I)-catalysed azide–alkyne cycloaddition (CuAAC) from 3-(prop-2-yniloxy)-d-secooximes and benzyl azides. All the products were evaluated in vitro by means of MTT assays for antiproliferative activity against a panel of human adherent cell lines (HeLa, MCF-7, A2780 and A431). Some of them exhibited activities with submicromolar IC₅₀ values, better than that of the reference agent cisplatin. The structural modifications led to significant differences in the cytostatic properties. Flow cytometry indicated that one of the most potent agents resulted in a cell cycle blockade.     

Design & synthesis of novel oxazolone & triazinone derivatives and their biological evaluation as COX-2 inhibitors

A new series of oxazolones and triazinones were designed and synthesized and evaluated against both COX-1 and COX-2 enzymes. Full structure elucidation of the new derivatives was performed using microanalyses, IR, 1H NMR, 13C NMR and mass spectra. Most of the derivatives showed good inhibitory activity against COX-2 enzyme specifically compounds IIIc, IIIe, IVd and IVg with IC50 values 0.024, 0.019, 0.011 and 0.014 µM compared to celecoxib as reference drug with IC50 value of 0.05 µM. Altogether, these results indicate that these derivatives can be effective anti-inflammatory agents.     

Inhibition of microtubule assembly in vitro by TN-16, a synthetic antitumor drug

An antitumor drug, 3-(1-anilinoethylidene)-5-benzylpyrrolidine-2,4-dione (TN-16) inhibited the assembly of porcine brain microtubules in vitro. The assembly induced by taxol was also suppressed by the drug. However, the latter required much higher concentration of TN-16 than the former. Binding studies by means of the fluorometric method and the spun-column procedure indicate that the inhibition was caused by the reversible binding of the drug to the colchicine-sensitive site of tubulin. The affinity of TN-16 to tubulin was almost equal to that of nocodazole.     

Effect of combined administration of a synthetic low-toxicity lipid A derivative,DT-5461a,and indomethacin in various experimental tumor models of colon 26 carcinoma in mice

We investigated the antitumor effects of a synthetic lipid A derivative, DT-5461a, in combination with indomethacin in three experimental tumor models (peritoneal carcinomatosis, liver tumor, and lung tumor models) of transplanted colon 26 carcinoma in mice. This carcinoma produces the immunosuppressive prostaglandin E₂ (PGE₂). Intravenous administration of DT-5461a alone resulted in little or no prolongation of survival time [increase in life span (ILS): –2%–22%]. When indomethacin was given in drinking water a slight or moderate increase in survival time was seen (ILS: 4%–45%). In contrast, the combination of DT-5461a and indomethacin induced an additive increase in life span (ILS: 16% to more than 193%). The strongest antitumor effect of this combined therapy was seen in the peritoneal carcinomatosis model; in this model, plasma PGE₂ concentrations were considerably higher than in normal mice, and concentrations were further but transiently increased by DT-5461a administration. Following oral indomethacin administration, these elevated PGE₂ concentrations were reduced to the level in untreated normal mice. Furthermore, intratumoral tumor necrosis factor (TNF) activity in the group receiving the combined therapy was significantly higher than that in the DT-5461a-treated group. No TNF production was induced by the administration of indomethacin alone. These results suggest that the antitumor effect of DT-5461a can be enhanced by combination with indomethacin, and that the inhibition of PGE₂ production may have a role in this antitumor effect.This study is dedicated to the memory of the late Dr. Yasuaki Osada, in acknowledgement of his encouragement and support     

New benzimidazothiazole derivatives as anti-inflammatory,antitumor active agents: Synthesis,in-vitro and in-vivo screening and molecular modeling studies

A new series of benzimidazothiazole derivatives has been synthesized. The structure of the products was confirmed by spectroscopic techniques such as IR, NMR and mass spectroscopy. The tested compounds were evaluated for their anti-inflammatory activity either in vitro through the COX enzyme inhibition assay, or in vivo through carrageenan paw edema technique. Results revealed that compound 25 and 29 represented the most active ones among the entire series with % inhibition 72.19, 72.07 for COX-1, and 87.46, 87.38 for COX-2, respectively. Interestingly, all synthesized compounds exhibited IC₅₀ values less than both reference drugs celecoxib and naproxen, indicating their superior potency. For compound 25, it showed about 340 and 198 times more potent than celecoxib and naproxen respectively as COX-1 inhibitor (IC₅₀ value 0.044 vs. 15.000 and 8.700 µM), and 10 and 115 times more potent than the same drugs as COX-2 inhibitor (IC₅₀ value 4.52 vs. 40.00 and 520.00 nM). The antitumor activity of the products was also evaluated and the results obtained are consistent with those obtained by the anti-inflammatory screening where compounds 25 and 29 proved to be the most active ones among the other compounds with %GI ranging from 31.5 to 62.5% and they exhibited the lowest IC₅₀ values as well. The ADMET analysis of the tested compounds was also performed in addition to the molecular modeling studies that included flexible alignment, surface and electrostatic maps in addition to the Lipinisk's rule of five.     

Characterization of the exogenous interleukin-2 requirements for the generation of enhanced antitumor cytotoxicity by thymocytes from low-dose melphalan-treated MOPC-315 tumor bearers

We have shown previously that thymocytes from MOPC-315-tumor-bearing mice treated with low-dose melphalan (l-phenylalanine mustard) (l-PAM TuB mice) are superior to thymocytes from untreated MOPC-315-tumor-bearing mice or thymocytes from untreated normal mice or normal mice treated with low-dose melphalan in their ability to generate an antitumor cytotoxic response following 5-day in vitro stimulation with MOPC-315 tumor cells in the presence of a low concentration of recombinant interleukin-2 (rIL-2) [Mokyr MB, Bartik MM, Ahn M-C (1989) Cancer Res 49; 870]. Here we characterize the rIL-2 requirements for the generation of enhanced antitumor cytotoxicity byl-PAM TuB thymocytes relative to normal thymocytes upon in vitro stimulation with MOPC-315 tumor cells. Specifically, we show that delaying the addition of a low concentration of rIL-2 to 5-day in vitro stimulation cultures of thymocytes resulted in a progressive decline in the generation of antitumor cytotoxicity by both normal andl-PAM TuB thymocytes. However, even when rIL-2 was added on day 2 after culture initiation, thymocytes froml-PAM TuB mice generated a more potent antitumor cytotoxicity than did thymocytes from normal mice. In addition, when rIL-2 was added at the time of culture initiation, replacement of the conditioned medium with fresh medium lacking rIL-2 on day 3 of the 5-day in vitro stimulation culture period eliminated the ability of normal thymocytes, and reduced (but did not eliminate) the ability ofl-PAM TuB thymocytes, to generate a significant level of antitumor cytotoxicity. A low concentration of fresh rIL-2 was sufficient to restore completely the generation of antitumor cytotoxicity by normal orl-PAM TuB thymocytes when added to the stimulation cultures immediately after the removal of the rIL-2-containing conditioned medium. The same low concentration of rIL-2 was also sufficient for restoring the generation of antitumor cytotoxicity by cultures ofl-PAM TuB thymocytes, but not normal thymocytes, from which the rIL-2-containing medium was removed 1 day earlier. At the same time, conditioned medium from stimulation cultures ofl-PAM TuB thymocytes was not superior to conditioned medium from stimulation cultures of normal thymocytes in supporting the generation of antitumor cytotoxicity by either normal orl-PAM TuB thymocytes. Thus, the enhanced lytic activity generated byl-PAM TuB thymocytes, relative to normal thymocytes, upon stimulation with MOPC-315 tumor cells and a low concentration of rIL-2, does not appear to be the result of enhanced production of helper-like factors byl-PAM TuB thymocytes.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-01350 from the National Cancer Institute     

Effect of the orthoquinone moiety in 9,10-phenanthrenequinone on its ability to induce apoptosis in HCT-116 and HL-60 cells

9,10-Phenanthrenequinone (9,10-PQ) is one of the most abundant quinones among diesel exhaust particulates. Recent data have suggested that quinones induce apoptosis in immune, epithelial and tumor cells, leading to respirator illness; however, the mechanisms by which quinones induce apoptosis and the structure required for this remain unknown. We studied the antitumor activity of 9,10-PQ analogs against two human tumor cell lines, HCT-116 colon tumor cells and HL-60 promyelocytic leukemia cells. The loss of the cis-orthoquinone unit in 9,10-PQ abrogated its ability to induce apoptosis in the two tumor cell lines, and the LC₅₀ values of these analogs were indicated over 10 μM. An analog of 9,10-PQ in which the biaryl unit had been deleted displayed a reduced ability to induce tumor cell apoptosis, while the analogs 1,10-phenanthroline-5,6-dione (9) and pyrene-4,5-dione (10), which also had modified biaryl units, exhibited increased tumor cell apoptotic activity. The cis-orthoquinone unit in 9,10-PQ was identified as essential for its ability to induce apoptosis in tumor cells, and its biaryl unit is also considered to influence orthoquinone-mediated apoptotic activity.