Polymeric Thioxanthones as Potential Anticancer and Radiotherapy Agents

Polysaccharide-based nanocomposites for biomedical applications: a critical review

Polysaccharides (PSA) have taken specific position among biomaterials for advanced applications in medicine. Nevertheless, poor mechanical properties are known as the main drawback of PSA, which highlights the need for PSA modification. Nanocomposites PSA (NPSA) are a class of biomaterials widely used as biomedical platforms, but despite their importance and worldwide use, they have not been reviewed. Herein, we critically reviewed the application of NPSA by categorizing them into generic and advanced application realms. First, the application of NPSA as drug and gene delivery systems, along with their role in the field as an antibacterial platform and hemostasis agent is discussed. Then, applications of NPSA for skin, bone, nerve, and cartilage tissue engineering are highlighted, followed by cell encapsulation and more critically cancer diagnosis and treatment potentials. In particular, three features of investigations are devoted to cancer therapy, i.e., radiotherapy, immunotherapy, and photothermal therapy, are comprehensively reviewed and discussed. Since this field is at an early stage of maturity, some other aspects such as bioimaging and biosensing are reviewed in order to give an idea of potential applications of NPSA for future developments, providing support for clinical applications. It is well-documented that using nanoparticles/nanomaterials above a critical concentration brings about concerns of toxicity; thus, their effect on cellular interactions would become critical. We compared nanoparticles used in the fabrication of NPSA in terms of toxicity mechanism to shed more light on future challenging aspects of NPSA development. Indeed, the neutralization mechanisms underlying the cytotoxicity of nanomaterials, which are expected to be induced by PSA introduction, should be taken into account for future investigations.

An Update on the Anticancer Activity of Xanthone Derivatives: A Review

The annual number of cancer deaths continues increasing every day; thus, it is urgent to search for and find active, selective, and efficient anticancer drugs as soon as possible. Among the available anticancer drugs, almost all of them contain heterocyclic moiety in their chemical structure. Xanthone is a heterocyclic compound with a dibenzo-γ-pyrone framework and well-known to have "privileged structures" for anticancer activities against several cancer cell lines. The wide anticancer activity of xanthones is produced by caspase activation, RNA binding, DNA cross-linking, as well as P-gp, kinase, aromatase, and topoisomerase inhibition. This anticancer activity depends on the type, number, and position of the attached functional groups in the xanthone skeleton. This review discusses the recent advances in the anticancer activity of xanthone derivatives, both from natural products isolation and synthesis methods, as the anticancer agent through in vitro, in vivo, and clinical assays.

The interaction of light-activatable 2-thioxanthone thioacetic acid with ct-DNA and its cytotoxic activity: Novel theranostic agent

In this study, a thioxanthone derivative, 2-Thioxanthone Thioacetic Acid (TXSCH₂COOH) was used to analyze the type of binding to calf thymus DNA in a physiological buffer (Tris-HCl buffer solution, pH:7.0). Several spectroscopic techniques were employed including UV-Vis absorption and fluorescence emission spectroscopy and viscosity measurements were also used to clarify the binding mode of TXSCH₂COOH to ct-DNA. The intrinsic binding constant Kb of TXSCH₂COOH-ct-DNA was found as 2.5 × 10³ M^-1 from the absorption studies. Increasing of fluorescence emission intensity was found approximately 74.4% by adding ct-DNA to the TXSCH₂COOH solution. Fluorescence microscopy was employed to display imaging of the TXSCH₂COOH-ct-DNA solution. Increasing of the iodide quenching effect was observed when TXSCH₂COOH was added to the double stranded DNA and the calculated quenching constants of TXSCH₂COOH and TXSCH₂COOH-ct-DNA were found to be 1.89 × 10³ M^-1 and 1.19 × 10⁴ M^-1, respectively. Additionally, the iodide quenching experiment was conducted with single stranded DNA which led to a high Ksv value. All the experimental results including the viscosity values of ct-DNA with TXSCH₂COOH demonstrated that the binding of TXSCH₂COOH to ct-DNA was most likely groove binding. Furthermore, TXSCH₂COOH was found to be an A-T rich minor groove binder. This was confirmed by the displacement assays with Hoechst 33258 compared to Ethidium Bromide. The in vitro cytotoxic activity measurements were performed by MTT assay on HT29 cell line for 72 h. TXSCH₂COOH exhibited notable cytotoxic activities compared to the standard chemotherapy drugs, fluorouracil (5-FU), cisplatin in tumorigenic HT29 cell line. The 50% growth-inhibitory concentration (IC₅₀) for TXSCH₂COOH was 19,8 μg/mL while 5-FU and cisplatin were 28.9 μg/mL, 20 μg/mL, respectively. The increase in cytotoxic effect when TXSCH₂COOH is activated by light indicates the potential of being theranostic cancer drug candidate.

Development of a fluorometric measurement system used in biological samples upon the determination of iron (II) metal ion

2-thioxanthone thioacetic acid (TXSCH₂COOH, T), which has a fluorometric character, was used for new fluorometric system upon Fe(II) analysis in biological samples as the main target. T-BSA binary complex was firstly consisted with non-covalent interactions between T and BSA at the equilibrium concentration as 1.77 × 10^-4.M. T-BSA binary complex emission was increased at the ratio of 24.40% due to stabilization property of BSA (pH:7), compared with T emission intensity. Fluorescence emission spectroscopy was used for the all measurements because of an economic, a sensitive and a practical method compared with other spectroscopic analysis. T-BSA-Fe(II) triple complex was also obtained by adding Fe(II) ion to T-BSA binary complex solution. Its characterization was performed to be investigated with optimum excitation wavelength, buffer concentration, pH and temperature as 297 nm, 10^-3 M Tris HCl (10^-2M NaCI), pH:7.2 at 25 °C, respectively. The results of Fe(II) analysis in serum showed a certain response in fluorometric T-BSA-Fe(II) triple complex measurement system as 50.42 ± 5.8 µg/dL. The analyses of our fluorometric triple complex system were compared with the reference electrochemiluminescence method and similar results were obtained. Fluorometric measurements of T-BSA-Fe(II) triple complex, its characterization and Fe(II) analysis in this system have not been investigated in literature gives originality to our study.

Evolving role of biomaterials in diagnostic and therapeutic radiation oncology

Radiation therapy to treat cancer has evolved significantly since the discovery of x-rays. Yet, radiation therapy still has room for improvement in reducing side effects and improving control of cancer. Safer and more effective delivery of radiation has led us to novel techniques and use of biomaterials. Biomaterials in combination with radiation and chemotherapy have started to appear in pre-clinical explorations and clinical applications, with many more on the horizon. Biomaterials have revolutionized the field of diagnostic imaging, and now are being cultivated into the field of theranostics, combination therapy, and tissue protection. This review summarizes recent development of biomaterials in radiation therapy in several application areas.

Conventional Type II photoinitiators as activators for photoinduced metal-free atom transfer radical polymerization

A novel methodology for photoinduced metal-free Atom Transfer Radical Polymerization (ATRP) by using conventional Type II photoinitiators such as benzophenone, thioxanthone, isopropyl thioxanthone and camphorquinone as sensitizers is presented.

Bioconjugation and Applications of Amino Functional Fluorescence Polymers

Synthesis and novel applications of biofunctional polymers for diagnosis and therapy are promising area involving various research domains. Herein, three fluorescent polymers, poly(p-phenylene-co-thiophene), poly(p-phenylene), and polythiophene with amino groups (PPT-NH₂ , PPP-NH₂ , and PT-NH₂ , respectively) are synthesized and investigated for cancer cell targeted imaging, drug delivery, and radiotherapy. Polymers are conjugated to anti-HER2 antibody for targeted imaging studies in nontoxic concentrations. Three cell lines (A549, Vero, and HeLa) with different expression levels of HER2 are used. In a model of HER2 expressing cell line (A549), radiotherapy experiments are carried out and results show that all three polymers increase the efficacy of radiotherapy. This effect is even more increased when conjugated to anti-HER2. In the second part of this work, one of the selected polymers (PT-NH₂ ) is conjugated with a drug model; methotrexate via pH responsive hydrazone linkage and a drug carrier property of PT-NH₂ is demonstrated on neuroblastoma (SH-SY5Y) cell model. Our results indicate that, PPT-NH₂ , PPP-NH₂ , and PT-NH₂ have a great potential as biomaterials for various bioapplications in cancer research.