In vitro and in vivo antioxidative and radioprotective capacities of polysaccharide isolated from Mesona Blumes gum

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.

Cell damage repair mechanism in a desert green algae Chlorella sp. against UV-B radiation

The protective ozone layer is continually depleting owing to an increase in the levels of solar UV-B radiation, which has harmful effects on organisms. Algae in desert soil can resist UV-B radiation, but most research on the radiation resistance of desert algae has focused on cyanobacteria. In this study, we found that desert green algae, Chlorella sp., could maintain high photosynthetic activity under UV-B stress. To examine the tolerance mechanism of the desert green algae photosystem, we observed the physiological and transcriptome-level responses of Chlorella sp. to high doses of UV-B radiation. The results showed that the reactive oxygen species (ROS) content first increased and then decreased, while the malondialdehyde (MDA) content revealed no notable lipid peroxidation during the UV-B exposure period. These results suggested that Chlorella sp. may have strong system characteristics for scavenging ROS. The antioxidant enzyme system showed efficient alternate coordination, which exhibited a protective effect against enhanced UV-B radiation. DNA damage and the chlorophyll and soluble protein contents had no significant changes in the early irradiation stage; UV-B radiation did not induce extracellular polysaccharides (EPS) synthesis. Transcriptomic data revealed that a strong photosynthetic system, efficient DNA repair, and changes in the expression of genes encoding ribosomal protein (which aid in protein synthesis and improve resistance) are responsible for the high UV-B tolerance characteristics of Chlorella sp. In contrast, EPS synthesis was not the main pathway for UV-B resistance. Our results revealed the potential cell damage repair mechanisms within Chlorella sp. that were associated with high intensity UV-B stress, thereby providing insights into the underlying regulatory adaptations of desert green algae.

Effects of electron beam irradiation on proteins and exopolysaccharide production and changes in Microcystis aeruginosa

Purpose: Microcystis aeruginosa often threaten human health and safety for the toxin and unpleasant odor and removal difficulties during water treatment process. In order to remove it, a novel method high energy was studied in this research.Materials and methods: The electron beam generated by an accelerator was applied to irradiate M. aeruginosa at various doses of 1, 2, 3, 4 and 5 kGy. The effects of irradiation on M. aeruginosa characteristics and mechanism have been researched through surveying the changes in pH and conductivity, changes of algae cell community structure and respiration rate, and changes of protein and exopolysaccharides production were also detected.Result: The data showed that exposure to 2-5 kGy radiation could make pH decrease. Microcystis aeruginosa increased through its own photosynthesis and physiological regulation. The increasing damage to algal cells led to the exosmosis of the contents, which increased the electrical conductivity of algae liquid and decreased the area of algae cells colony. 2-5 kGy irradiation decreased protein content and destroy the antioxidant system and thus reduced the secretion of extracellular polysaccharidesConclusions: 2-5 kGy radiation could control the algae growth and produced obvious effect. The respiration rate decreased obviously that made M. aeruginosa lose activity in a short time. The results proved that irradiation could change the algae growth and affect its life characteristic efficiently in a short time.