Cytotoxicity of iodine-131 radiopharmaceutical in tumor and non-tumor human cells and radioprotection by integral juices of Vitis labrusca L.

Iodine-131 (I-131) radioisotope it causes the formation of free radicals, which lead to the formation of cell lesions and the reduction of cell viability. Thus, the use of radioprotectors, especially those from natural sources, which reduce the effects of radiation to healthy tissues, while maintaining the sensitivity of tumor cells, stands out. The objective of the present study was to evaluate the cytoprotective/radioprotective effects of whole grape juices manufactured from the conventional or organic production systems, whether or not exposed to ultraviolet (UV-C) light irradiation. The results showed that I-131 presented a cytotoxic effect on human hepatocellular cells (HepG2/C3A) at concentrations above 1.85 MBq/mL, after 24 and 48 hours of treatment, though all concentrations (0.0037 to 7.40 MBq/mL) were cytotoxic to non-tumor human lung fibroblast (MCR-5) cells, after 48 hours. However, grape juices (10 and 20 µL/mL) did not interfere with the cytotoxic effect of the therapeutic dose of I-131 on tumor cells within 48 hours of treatment, while protecting the non-tumor cells, probably due to its high antioxidant activity. In accordance with their nutraceutical potential, antioxidant and radioprotective activity, these data stimulate in vivo studies on the use of natural products as radioprotectants, such as grape juice, in order to confirm the positive beneficial potential in living organisms.

Antimutagenic and radioprotective activities of beta-carotene against the biological effects of iodine-131 radiopharmaceutical in Wistar rats.

Radioactive iodine-131 (131I) is used in the treatment and diagnosis of thyroid gland injuries. However, because it emits ionizing radiation, it causes harmful effects to cells. Given that beta-carotene (BC) has antioxidant and antigenotoxic properties, this study aimed to investigate its radioprotective and antimutagenic activity in relation to 131I at the dose that is used to treat hyperthyroidism using a test system of bone marrow cells from Wistar rats (Rattus norvegicus). The doses were 0.2 mL of 8 mg BC/mL corn oil and 25 µCi 131I per 100 g body weight, and they were given via gavage in acute and subchronic treatments. Treatment groups included simultaneous, pre-treatment, post-treatment, and continuous treatment types. In all antimutagenic acute treatments, BC had a significant antimutagenic/radioprotective activity in relation to 131I. In subchronic antimutagenic treatments, BC reduced the damage that was caused by the radioisotope; however, this reduction was not statistically significant because of the relatively low percentage of chromosomal abnormalities that were observed with only 131I compared to the acute treatment. These results demonstrate the radioprotective and antimutagenic activity of BC, indicating its use by the population, which inevitably is exposed to mutagenic agents, as a means of health protection.

Cytotoxic and mutagenic effects of iodine-131 and radioprotection of acerola (Malpighia glabra L.) and beta-carotene in vitro.

The radioisotope iodine-131 [(131)I] can damage DNA. One way to prevent this is to increase the amount of antioxidants via dietary consumption. The goal of this study was to evaluate the radioprotective effect of fresh acerola pulp and synthetic beta-carotene in Rattus norvegicus hepatoma cells (HTC) in response to [(131)I] exposure in vitro. Cellular DNA damage was subsequently assessed using a cytokinesis block micronucleus assay. The mutagenic and cytotoxic activities of doses of [(131)I] (0.1, 0.5, 1, 5, and 10 µCi), acerola (0.025, 0.125, and 0.25 g acerola pulp/mL), and beta-carotene (0.2, 1, and 2 µM) were evaluated. Radioprotective tests were performed by simultaneous treatment with acerola (0.25 g/mL) plus [(131)I] (10 µCi) and beta-carotene (0.2 µM) plus [(131)I] (10 µCi). Acerola, beta-carotene, and low concentrations of [(131)I] did not induce micronucleus formation in HTC cells; in contrast, high concentrations of [(131)I] (10 µCi) were mutagenic and induced DNA damage. Moreover, neither acerola nor beta-carotene treatment was cytotoxic. However, acerola reduced the percentage of [(131)I]-induced damage, although beta-carotene did not show a similar effect. Thus, our results suggest that acerola diet supplementation may benefit patients who are exposed to [(131)I] during thyroid diagnostics and therapy.