Usefulness of hexamethylenetetramine as an adjuvant to radiation and cisplatin in the treatment of solid tumors: its independency of p53 status

3DG Functionalized Magnetic Solid Phase Extraction Materials for the Efficient Enrichment of Hexamethylenetetramine in Vermicelli

Solid phase extraction (SPE) is regarded as the most effective purification method for complex matrix samples owing to its simplicity of operator, time-saving, high accuracy, and environmental friendliness. SPE technology is still affected by the high cost of commercial SPE columns and poor adsorption selectivity. Hence, the development of low-cost and highly selective adsorbents is quite challenging and demanding in SPE. In this study, a novel 3DG functionalized magnetic solid phase extraction materials was prepared based on "thiol-ene" click chemistry. The structure, morphology, thermal stability, and magnetic properties of the magnetic composites were studied by Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), thermogravimetric analysis (TGA), and vibrating sample magnetometer (VSM). Then the adsorption performance of composite was determined by static adsorption experiments, which showed fast binding kinetics (100 min) and good adsorption performance (Qe = 65.34 mg/g). Moreover, these magnetic nanoparticles were used as adsorbents for magnetic solid phase extraction (MSPE) and coupled with high-performance liquid chromatography (HPLC) for separation and detection of illegally added hexamethylenetetramine in vermicelli. As for practical application, the recoveries for the spiked samples in the concentration range of 8-40 μg/g were between 83.24-92.69%, and the RSD was between 0.20-2.07%.

Acid-specific formaldehyde donor is a potential, dual targeting cancer chemotherapeutic/chemo preventive drug for FANC/BRCA-mutant cancer

Background

Development of chemotherapeutic/preventive drugs that selectively kill cancer - the Holy Grail of cancer research - is a major challenge. A particular difficulty arises when chemotherapeutics and radiation are found to be rather ineffective against quiescent cancer cells in solid tumors. In the limited oxygen condition within a solid tumor, glycolysis induces an acidic environment. In such an environment the compound hexamethylenetetramine (HMTA) will act as a formaldehyde donor. HMTA has been characterized a non-carcinogen in experimental animals and causes no major adverse side-effects in humans. We previously reported that both a chicken B-lymphocyte cell line transformed with an avian leucosis virus and human colon cancer cells deficient in the FANC/BRCA pathway are hypersensitive to formaldehyde. Thus, we assessed the potential usage of HMTA as a chemotherapeutic agent.

Results

The differential cytotoxicity of HMTA was tested using chicken DT40 cells deficient in DNA repair under neutral and acidic conditions. While HMTA is not efficiently hydrolyzed under neutral conditions, all HR-deficient DT40 cells tested were hypersensitive to HMTA at pH 7.3. In contrast, HMTA clearly increased cell toxicity in FANCD2-, BRCA1- and BRCA2- deficient cells under acidic conditions.

Conclusion

Here we show that in vitro experiments showed that at low pH HMTA causes drastic cytotoxicity specifically in cells deficient in the FANC/BRCA pathway. These results strongly suggest that HMTA may be an attractive, dual-targeting chemotherapeutic/preventive drug for the selective delivery of formaldehyde to solid tumors and causes cell death in FANC/BRCA-deficient cells without major adverse effects.

Methenamine's journey of 160 years: Repurposal of an old urinary antiseptic for treatment and hypoxic radiosensitization of cancers and glioblastoma

Methenamine (hexamethylenetetramine, hexamine, urotropine) is a compound discovered in 1859, which is still currently being used as a urinary antiseptic. Methenamine is highly soluble in water and polar solvents, and its molecular constitution is similar to adamantane compounds with tetrahedral cage like structure. In acidic conditions, methenamine decomposes to formaldehyde and ammonia. Recently, methenamine has gained a renewal of interest due to antibiotic-resistant bacteria urinary tract infections; interestingly, bacteria cannot gain resistance to formaldehyde. In 1968, David and Burkitt reported remarkable regression of four Burkitt Lymphoma patients in eight subjects who were treated with septicemine (a solution containing 6.3 g of methenamine iodomethylate and 1 g of methenamine sodium benzoate in 100 cc distilled water). Unfortunately, these striking observations did not gain interest in the medical community; despite experimental models that showed that methenamine synergized with hyperthermia, radiation, and chemotherapy to block cancer growth. As the hypoxic core of tumours have an acidic pH, it would be plausible to expect that methenamine would selectively target dormant, non-proliferative, and treatment-resistant cancer clones in large tumours. Moreover, previous data suggests that methenamine can be safely used intravenously and for treatment of infections of the central nervous system. It may therefore be an effective adjuvant in treatment of systemic cancers and glioblastoma.

Synthesis, characterisation and in vitro cytotoxicity of mixed ligand Pt(ii) oxadiazoline complexes with hexamethylenetetramine and 7-nitro-1,3,5-triazaadamantane

trans-Platinum(ii) oxadiazoline complexes with 7-nitro-1,3,5-triazaadamantane (NO₂-TAA) or hexamethylenetetramine (hmta) ligands have been synthesised from trans-[PtCl₂(PhCN)₂] via cycloaddition of nitrones to one of the coordinated nitriles, followed by exchange of the other nitrile by NO₂-TAA or hmta. Stoichiometric control allows for the selective synthesis of mono- and dinuclear complexes where 7-NO₂TAA and hmta act as mono- and bidentate ligands, respectively. Precursors and the target complexes trans-[PtCl₂(hmta)(oxadiazoline)], trans-[PtCl₂(NO₂-TAA)(oxadiazoline)] and trans-[{PtCl₂(oxadiazoline)}₂(hmta)] were characterised by elemental analysis, IR and multinuclear (¹H, ¹³C, ¹⁹⁵Pt) NMR spectroscopy. DFT (B3LYP/6-31G*/LANL08) and AIM calculations suggest a stronger bonding of hmta with the [PtCl₂(oxadiazoline)] fragment, in agreement with the experimentally observed reactivity in the ligand exchange (hmta > 7-NO₂TAA). Replacement of the nitrile by hmta is predicted to be more exothermic than that with 7-NO₂-TAA, although the activation barriers are similar. Protonation of the non-coordinated N atoms is anticipated to weaken the Pt-N bond and lower the activation barrier for ligand exchange. This effect might help activate these compounds in a slightly acidic environment such as some tumour tissues. Ten of the new compounds were tested for their in vitro cytotoxicity in the human cancer cell lines HeLa and A549. Some of the mononuclear complexes are more potent than cisplatin, and their activity is still high in A549 where cisplatin shows little effect. The dinuclear complexes are inactive, presumably due to their lipophilicity and reduced solubility in water.

Synthesis of mesoporous titanium oxide for release control and high efficiency drug delivery of vinorelbine bitartrate

Schematic illustration of porous titanium oxide for drug delivery of vinorelbine bitartrate.