Plant based radioprotectors as an adjunct to radiotherapy: advantages and limitations

Radioprotection and enhanced efficacy by curcumin-loaded chitosan nanoparticles in mitigating radiation-induced liver injury

INTRODUCTION

This study aimed to evaluate the protective effect of curcumin-loaded chitosan nanoparticles (Cur-CsNPs) against radiation-induced liver damage in rats. Curcumin's antioxidant and anti-inflammatory properties, combined with chitosan's drug delivery potential, were leveraged to mitigate the harmful effects of ionizing radiation (IR) on the liver.

METHODS

Cur-CsNPs were characterized using TEM, XRD, DLS, and FTIR. Spectrophotometry assessed drug loading and curcumin release. Cytotoxicity was evaluated using MTT assay on HepG2 cells. The experimental design involved eight groups: a control group, three groups receiving different doses of Cur-CsNPs (25, 50, 100 mg/kg), three groups receiving the same doses plus irradiation (6Gy), and one group receiving irradiation only. H&E and MTC staining were used for histopathological evaluation. The activity of liver enzymes ALT, AST, ALP, and GGT was measured.

RESULTS

In this study, three types of Cur-CsNPs were synthesized using varying ratios of chitosan to TPP ratios, resulting in average sizes of 660 nm, 230 nm, and 120 nm. Cur-CsNPs which exhibited the highest encapsulation efficiency, was selected for further evaluation. TEM confirmed its spherical shape with an average size of 37 nm. Drug release studies demonstrated an 85 % release at pH 5.4 within 70 h. MTT assays indicated low cytotoxicity, with high cell viability maintained across all concentrations and time points. Liver enzyme analysis in rats revealed that Cur-CsNPs, particularly when combined with radiation, mitigated radiation-induced liver damage. Histological examination showed that treatment with Cur-CsNPs reduced liver damage, inflammation, necrosis, and fibrosis in irradiated groups compared to the radiation-only group, which exhibited severe liver damage.

CONCLUSION

The findings of this study show that Cur-CsNPs possess significant potential as a therapeutic agent for protecting against radiation-induced liver injury. The favorable drug release profile, low cytotoxicity, and protective effects observed in enzyme levels and histological assessments highlight the efficacy of Cur-CsNPs. The findings imply that Cur-CsNPs could be an effective strategy for enhancing liver protection in radiation exposure scenarios, warranting further investigation into their mechanisms of action and potential clinical applications.

N-acetyl-L-tryptophan provides radioprotection to mouse and primate models by antagonizing the TRPV1 receptor and substance P inhibition

PURPOSE

The present study was carried out to evaluate the radioprotective activities of N-acetyl-L-tryptophan (L-NAT) using rodent and non-human primate (NHP) models.

MATERIALS AND METHODS

The antagonistic effect of L-NAT on the Transient receptor potential vanilloid-1 (TRPV1) receptor and substance P inhibition was determined using molecular docking and Elisa assays. The in vivo radioprotective activity of L-NAT was evaluated using whole-body survival assays in mice and NHPs. Radioprotective activity of L-NAT was also determined at the systemic level using quantitative histological analysis of bone marrow, jejunum, and seminiferous tubules of irradiated mice.

RESULTS

Molecular docking studies revealed a strong binding of L-NAT with TRPV1 receptor at similar binding pockets to which capsaicin, an agonist of the TRPV1 receptor, binds. Further, capsaicin and gamma radiation were found to induce substance P levels in the intestines and serum of the mice, while L-NAT pretreatment was found to inhibit it. Significant whole-body survival (>80%) was observed in irradiated (9.0 Gy) mice that pretreated with L-NAT (150 mg/kg, b.wt. im) compared to 0% survival in irradiated mice that not pretreated with L-NAT. The quantitative histology of the hematopoietic, gastrointestinal, and male reproductive systems demonstrated significant protection against radiation-induced cellular degeneration. Interestingly, 100% survival was observed with irradiated NHPs (6.5 Gy) that pretreated with L-NAT (37.5 mg/kg, b.wt.im). Significant improvement in the hematology profile was observed after days 10-20 post-treatment periods in irradiated (6.5 Gy) NHPs that were pretreated with L-NAT.

CONCLUSION

L-NAT demonstrated excellent radioprotective activity in the mice and NHP models, probably by antagonizing TRPV1 receptor and subsequently inhibiting substance P expression.

Mitochondria-Targeted Nitronyl Nitroxide Radical Nanoparticles for Protection against Radiation-Induced Damage with Antioxidant Effects

Radiotherapy is a non-invasive method that is widely applied to treat and alleviate cancers. However, radiation-induced effects in the immune system are associated with several side effects via an increase in oxidative stress and the inflammatory response. Therefore, it is imperative to develop effective clinical radiological protection strategies for the radiological protection of the normal organs and immune system in these patients. To explore more effective radioprotective agents with minimal toxicity, a mitochondria-targeted nitronyl nitroxide radical with a triphenylphosphine ion (TPP-NIT) was synthesized and its nanoparticles (NPs-TPP-NIT) were prepared and characterized. The TPP-NIT nanoparticles (NPs-TPP-NIT) were narrow in their size distribution and uniformly distributed; they showed good drug encapsulation efficiency and a low hemolysis rate (<3%). The protective effect of NPs-TPP-NIT against X-ray irradiation-induced oxidative damage was measured in vitro and in vivo. The results show that NPs-TPP-NIT were associated with no obvious cytotoxicity to L-02 cells when the concentration was below 1.5 × 10-2 mmol. NPs-TPP-NIT enhanced the survival rate of L-02 cells significantly under 2, 4, 6, and 8 Gy X-ray radiation exposure; the survival rate of mice was highest after 6 Gy X-ray irradiation. The results also show that NPs-TPP-NIT could increase superoxide dismutase (SOD) activity and decrease malondialdehyde (MDA) levels after the L-02 cells were exposed to 6.0 Gy of X-ray radiation. Moreover, NPs-TPP-NIT could significantly inhibit cell apoptosis. NPs-TPP-NIT significantly increased the mouse survival rate after irradiation. NPs-TPP-NIT displayed a marked ability to reduce the irradiation-induced depletion of red blood cells (RBCs), white blood cells (WBCs), and platelets (PLTs). These results demonstrate the feasibility of using NPs-TPP-NIT to provide protection from radiation-induced damage. In conclusion, this study revealed that NPs-TPP-NIT may be promising radioprotectors and could therefore be applied to protect healthy tissues and organs from radiation during the treatment of cancer with radiotherapy.

Exploring Natural Products as Radioprotective Agents for Cancer Therapy: Mechanisms, Challenges, and Opportunities

Radiotherapy is an important cancer treatment. However, in addition to killing tumor cells, radiotherapy causes damage to the surrounding cells and is toxic to normal tissues. Therefore, an effective radioprotective agent that prevents the deleterious effects of ionizing radiation is required. Numerous synthetic substances have been shown to have clear radioprotective effects. However, most of these have not been translated for use in clinical applications due to their high toxicity and side effects. Many medicinal plants have been shown to exhibit various biological activities, including antioxidant, anti-inflammatory, and anticancer activities. In recent years, new agents obtained from natural products have been investigated by radioprotection researchers, due to their abundance of sources, high efficiency, and low toxicity. In this review, we summarize the mechanisms underlying the radioprotective effects of natural products, including ROS scavenging, promotion of DNA damage repair, anti-inflammatory effects, and the inhibition of cell death signaling pathways. In addition, we systematically review natural products with radioprotective properties, including polyphenols, polysaccharides, alkaloids, and saponins. Specifically, we discuss the polyphenols apigenin, genistein, epigallocatechin gallate, quercetin, resveratrol, and curcumin; the polysaccharides astragalus, schisandra, and Hohenbuehelia serotina; the saponins ginsenosides and acanthopanax senticosus; and the alkaloids matrine, ligustrazine, and β-carboline. However, further optimization through structural modification, improved extraction and purification methods, and clinical trials are needed before clinical translation. With a deeper understanding of the radioprotective mechanisms involved and the development of high-throughput screening methods, natural products could become promising novel radioprotective agents.

Alpha-thiol deoxynucleotide triphosphates (S-dNTPs) as radioprotective agents: A novel approach

In this study, the ability of a mixture of four different alpha-thiol deoxynucleotide triphosphates (S-dNTPs) each at a concentration of 10μM when incorporated into the genomic DNA of proliferating human HL-60 and Mono-Mac-6 (MM-6) cells in vitro to provide protection from 2, 5, and 10 Gy of gamma radiation was investigated. Incorporation of the four different S-dNTPs into nuclear DNA at 10 μM concentration for five days was validated by agarose gel electrophoretic band shift analysis. S-dNTP-treated genomic DNA reacted with BODIPY-iodoacetamide demonstrated a band shift to higher molecular weight to confirm the presence of sulfur moieties in the resultant phosphorothioate DNA backbones. No overt signs of toxicity or obvious morphologic cellular differentiation were noted in the presence of 10 μM S-dNTPs even after 8 days in culture. Significantly reduced radiation-induced persistent DNA damage measured at 24 and 48 h post-exposure by γ-H2AX histone phosphorylation using FACS analysis in S-dNTP incorporated HL-60 and MM6 cells indicated protection against radiation-induced direct and indirect DNA damage. Statistically significant protection by S-dNTPs was noted at the cellular level by CellEvent™ Caspase-3/7 assay, which assess the extent of apoptotic events, and by trypan blue dye exclusion to assed cell viability. The results appear to support an innocuous antioxidant thiol radioprotective effect built into genomic DNA backbones as the last line of defense against ionizing radiation and free radical-induced DNA damage.