Cytotoxicity and radiosensitising activity of synthesized dinitrophenyl derivatives of 5-fluorouracil

Apoptosis Induced by Ziziphora tenuior Essential Oil in Human Colorectal Cancer Cells

Ziziphora (Cacotti in Persian) belongs to the Lamiaceae family (mint group) and is vastly found in Iran and Asia. This traditional medicinal plant is normally used as analgesic and for treatment of particular gastrointestinal diseases. Since colorectal cancer is one of the most common causes of death in the world and the second leading cause of cancer death among adults, there is a pressing need to inhibit this malignancy by using methods with minimal side effects. One of these methods is the use of natural resources such as medical plants. This study is aimed at investigating the expression of apoptosis-related genes in the adjacent culture of colorectal cancer epithelial cells (HT-29) with Ziziphora essential oil (ZEO). The essential oil was extracted from Ziziphora leaves, and its compounds were determined and then added to the HT-29 culture medium at different concentrations. After 24 hours, the HT-29 cells were harvested from the medium and cytotoxicity was analyzed by MTT assay. After MTT assay and determination of the percentage of apoptosis by flow cytometry, RNA extraction was performed and the expression levels of Bax, Bcl-2, caspase 3 (C3), and caspase 9 (C9) were analyzed using newly designed primers by reverse transcription (RT) qPCR method and GeniX6 software. Also, specific antibodies were used for western blot analyses of those molecules. GC analysis revealed 42 different compounds in the ZEO, including pulegone (26.65%), menthone (5.74%), thymol (5.51%), and menthol (1.02%). MTT assay showed that the concentration of 200 μg/ml of ZEO had the highest HT-29 cell death during 24 hours. After incubation with the concentration of 50 μg/ml of ZEO for 24 and 48 hours, caspase 3 and 9 gene expressions in the treated group increased compared to those in the control group (P < 0.001), while the Bcl-2 expression decreased. The results showed that having anticancer compounds, ZEO can increase C3 and C9 and decrease Bcl-2 expressions, causing apoptosis in HT-29 cells in vitro. This can lead to the use of ZEO as a factor for colorectal cancer treatment.

The paradox role of caspase cascade in ionizing radiation therapy

Radiotherapy alone or in combination with chemotherapy/surgery is widely used for treatment of cancers. It reduces tumor growth and prevents metastasis. While ionizing radiation activates caspase cascade resulted in apoptosis in cancer cells, it also stimulates tumor cell re-population that leads to reduce the effectiveness of the radiation therapy. This review describes the mechanisms for paradox role of caspase cascade in cancer therapy and discusses the logical and practical strategies for improvement the therapeutic index of radiotherapy through enhancement of radiosensitivity and decreasing the rate of tumor recurrence.

Bioreductive deprotection of 4-nitrobenzyl group on thymine base in oligonucleotides for the activation of duplex formation

Oligonucleotides containing 4-O-(4-NO2-benzyl)thymine residues were synthesized to assess potential prodrug-type action against hypoxic cells. These modified oligonucleotides were incapable of stable duplex formation under non-hypoxic conditions. However, following deprotection of the thymine residues under bioreductive conditions, the deprotected oligonucleotides were able to form stable duplexes with target oligonucleotides.

In vitro and in vivo toxicological evaluations of methyl ferulate, methyl p-coumarate, and pulegone 1,2-epoxide

CONTEXT

Toxicological screening of natural compounds for medicinal purposes.

OBJECTIVES

The objective of this study is to evaluate the toxicity of methyl ferulate (MF), methyl p-coumarate (MpC), and pulegone 1,2-epoxide (PE) with in vitro and in vivo assays.

MATERIALS AND METHODS

The in vitro toxicity of MF, MpC, and PE was assessed at a concentration of 10 mg/ml with the Ames assay using two strains of Salmonella typhimurium TA98 and TA100. Human red blood cells (RBC) were used to determine the hemolytic activity of these compounds. The cytotoxicity of above compounds was determined with brine shrimp lethality bioassay (BSLB) at the concentrations of 0.1-20 mg/ml. While dermal and ocular irritation studies were conducted on healthy rabbits (n = 8) for 96 and 12 h post-topical application of test compounds, respectively.

RESULTS

PE produced 6-8% hemolysis of RBCs at all the tested concentrations while MF and MpC produced 10-5% hemolysis up to 20 mg/ml, and 50-85% hemolysis at concentrations of 40 and 80 mg/ml, respectively. The Ames assay indicated that MF, MpC, and PE were non-mutagenic as the test values were not significantly higher as compared with background values of the assay. BSLB suggested the lethal concentration (LC50) values of MF, MpC, and PE as 4.38, 6.74, and 25.91 mg/ml, respectively. In vivo ocular and dermal irritation scores of MF, MpC, and PE were comparable with ethanol (control) in rabbits indicating the non-irritant nature of these natural compounds.

CONCLUSION

The present studies suggest that these compounds are non-toxic/non-irritant and might be used for medicinal purposes.

Synthesis, in vitro aerobic and hypoxic cytotoxicity and radiosensitizing activity of novel metronidazole tethered 5-fluorouracil

Background and the purpose of the study

Several 2, 4-dinitrophenyl and 2,4-dinitrophenylamine tethered 5-FU (5-fluorouracil) compared to their components have shown minimal or no cytotoxicity to HT-29 cell line under aerobic conditions but high cytotoxicity and radiosensitizing effects under hypoxic conditions. In the present study the cytotoxicity and radiation potentiation of three novel analogues of these compounds by replacing 2,4-dinitrophenyl moiety with 2-methyl-5-nitroimidazole, a known radiosensitizer and cytotoxic agent was investigated.

Methods

Tethered compounds 7–9 were prepared by the reaction of 1-(t-butoxycarbonyl)-5-fluorouracil 6 with metronidazole esters 2–4 followed by removal of the t-butoxycarbonyl protecting group. Cytotoxicity of compounds in HT-29 cells with or without radiation were determined by 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT), propidium iodide (PI)-digitonin and clonogenic assays.

Results

Tethered compounds 7–9 induced time-and concentration–dependent cytotoxicity under hypoxia but had no significant effect under aerobic conditions. These compounds also showed selective and concentration- dependent radiosensitization effects under hypoxic conditions.

Conclusion

Tethered compounds 7–9 compared to 5-FU 5 showed minimal cytotoxicities under aerobic and selective radiosensitizing activities under hypoxic conditions. Also effects of these compounds were higher than those of metronidazole 1 which is a known cytotoxin and radiosensitizer under hypoxic conditions.