Carnosic acid (CA) is a phenolic diterpene characterized by its high antioxidant activity; it is used in industrial, cosmetic, and nutritional applications. We evaluated the radioprotective capacity of CA on cells directly exposed to X-rays and non-irradiated cells that received signals from X-ray treated cells (radiation induced bystander effect, RIBE). The genoprotective capacity was studied by in vivo and in vitro micronucleus assays. Radioprotective capacity was evaluated by clonogenic cell survival, MTT, apoptosis and intracellular glutathione assays comparing radiosensitive cells (human prostate epithelium, PNT2) with radioresistant cells (murine metastatic melanoma, B16F10). CA was found to exhibit a genoprotective capacity in cells exposed to radiation (p < 0.001) and in RIBE (p < 0.01). In PNT2 cells, considered as normal cells in our study, CA achieved 97% cell survival after exposure to 20 Gy of X-rays, eliminating 67% of radiation-induced cell death (p < 0.001), decreasing apoptosis (p < 0.001), and increasing the GSH/GSSH ratio (p < 0.01). However, the administration of CA to B16F10 cells decreased cell survival by 32%, increased cell death by 200% (p < 0.001) compared to irradiated cells, and increased cell death by 100% (p < 0.001) in RIBE bystander cells (p < 0.01). Furthermore, it increased apoptosis (p < 0.001) and decreased the GSH/GSSG ratio (p < 0.01), expressing a paradoxical radiosensitizing effect in these cells. Knowing the potential mechanisms of action of substances such as CA could help to create new applications that would protect healthy cells and exclusively damage neoplastic cells, thus presenting a new desirable strategy for cancer patients in need of radiotherapy.

Carnosic acid (CA) is a phenolic diterpene with high antioxidant activity that supports its radioprotective capacity. This study aims to determine whether the radiosensitizing effect of CA established in B16F10 melanoma cells also occurs in other melanin-producing cells. Cell survival analysis, apoptosis, intracellular glutathione levels, and cell cycle progression were evaluated by comparing radiosensitive cells (PNT2) with radioresistant melanin-producing cells (MELAN A, SK-MEL-1, and B16F10). In PNT2 cells, CA exhibited radioprotective capacity, with 100% cell survival after exposure to 20 Gy of X-rays (p < 0.001), decreasing apoptosis (p < 0.001) and increasing the GSH/GSSG ratio (p < 0.01), without significant modification in cell cycle progression. However, CA administration to irradiated cells failed to exert radioprotection in MELAN A and SK-MEL-1 cells, and even doubled cell death in B16F10 cells (p < 0.001). Specifically, CA did not alter apoptosis or prevent the decrease in GSH/GSSG ratio in MELAN A and SK-MEL-1 cells, while it intensified radiation-induced cell cycle disruptions in all melanin-producing cells. All of these led to a loss of radioprotective capacity in the melanin-producing cells (MELAN A and SK-MEL-1) and even induced a radiosensitizing effect in B16F10 cells. Understanding the mechanisms of action of substances such as CA could promote new applications that protect healthy cells and exclusively damage neoplastic cells when both are present within the same irradiated volume in cancer patients requiring radiotherapy.

There is an urgent need to find and develop radiation countermeasures for both planned and unplanned exposures. However, in recent years, radioprotective substances, such as rosmarinic acid (RA), have been described, presenting contradictory and even paradoxical results. In this paper, we evaluated the genoprotective capacity of 29 substances against chromosomal damage induced by gamma radiation in a comparative study using the same technique, i.e., cytokinesis-block micronucleus (CBMN) assay to evaluate their genoprotective capacities, at the same concentrations and administered before and after exposure to 2 Gy of gamma radiation. We then related the observed effects with their chemical characteristics to appreciate the different mechanisms of action that could explain some apparent contradictions that may emerge. In our study, before exposure to ionizing radiation, RA produced the greatest reduction in the frequency of radiation-induced micronuclei (p < 0.001), presenting the highest magnitude of protection (58%) and a dose reduction factor of 7.1 (p < 0.001); however, it loses this genoprotective capacity when administered after exposure to radiation. These results could be attributed to the different radical-scavenging and antilipoperoxidative activities of each substance tested. Antilipoperoxidant activity was found to be the most important factor in the reduction in radiation-induced chromosomal damage; thus, lipo-antioxidant substances emerged as the most effective in protecting genetic material against oxidative damage.

Carnosic acid (CA) is a phenolic diterpene with high antioxidant activity that supports its radioprotective capacity. This study aims to determine whether the radiosensitizing effect of CA established in B16F10 melanoma cells also occur in other mela-nin-producing cells. Cell survival analysis, apoptosis, intracellular glutathione levels, and cell cycle progression were evaluated by comparing radiosensitive cells (PNT2) with radioresistant melanin-producing cells (MELAN A, SK-MEL-1 and B16F10). In PNT2 cells, CA exhibited radioprotective capacity, with 100% cell survival after expo-sure to 20 Gy of X-rays (p < 0.001), decreasing apoptosis (p < 0.001) and increasing the GSH/GSSH ratio (p < 0.01), without significant modification in cell cycle progression. However, the administration of CA to irradiated cells failed to show radioprotective capacity in MELAN A and SK-MEL-1 cells, it even doubled cell death in B16F10 cells (p < 0.001); did not modify cell apoptosis, nor prevent a decrease in the GSH/GSSG ratio and intensify the modifications in the cell cycle induced by ionizing radiation. All of these led to a loss of radioprotective capacity in the melanin producing cells (MELAN A and SK-MEL-1) and even induced a radiosensitizing effect in B16F10 cells. Understanding the mechanisms of action of substances such as CA could promote new applications that protect healthy cells and exclusively damage neoplastic cells when both are present within the same irradiated volume in cancer patients requiring radiotherapy.

Background: The porcine acellular urinary bladder matrix (AUBM) is a three-dimensional scaffold rich in collagens type I, III, IV, and VI that could be used for guided bone regeneration (GBR). The objective of this study was to compare the physical, mechanical and biological properties of a AUBM with six other collagen membranes of porcine, equine and bovine origin. Methods: Seventy membranes were included ( n = 10 per group). The properties of AUBM membrane were compared with the other animal collagen membranes available: porcine pericardium (PP), equine pericardium (EP), bovine pericaridium (BP), porcine peritoneum (PPE), equine Achilles tendon (EAT), bovine Achilles tendon (BAT). We analysed physical properties (surface morphology, hydrophilic property, degradation ratio and thermal stability), mechanical properties (tensile strength and dry and wet elongation), and biological properties (cell viability, quantification of type I collagen and osteopontin, Alkaline Phosphatase (ALP) activity and calcium deposition). Results: AUBM membranes showed a surface morphology (in smooth and rough surfaces) very similar to those of PP, EP, EAT, and BAT. The most hydrophilic membrane was PPE. The AUBM membranes showed a low degradation ratio and thermal stability similar to the other membranes. AUBM membranes had a tensile strength (dry and wet) and elongation (dry) similar to the other membranes. Their elongation was much higher than the rest when wet. AUBM membrane showed good biological properties. Conclusions: AUBM membrane showed physical and mechanical properties similar to the other six membranes. However, upon wetting they were the membranes with the highest elongation capacity and showed similar properties to PPE membranes in promoting osteogenesis. AUBM could be an ideal collagen source for the manufacture of membranes for GBR, but further clinical studies are needed.

Published cytokinesis-block micronucleus (CBMN) frequencies, normalised to 500 binucleated cells (MN/500 BC), were used to illustrate how the choice of statistical parametrisation affects background-subtracted radioprotection metrics. An illustrative Jeffreys-rule transformation was applied to published normalised frequencies from eight representative experimental groups, drawn from two previously published human-lymphocyte CBMN datasets generated by a single laboratory, within the broader retrospective context of four source studies (2000–2026): an irradiated control, four pre-irradiation radioprotective treatments, one post-irradiation treatment, one radiosensitiser, and an iodine-131 biodosimetry cohort. It was not used as a statistically valid Bayesian inference based on the original experimental counts. Because the original integer micronucleus counts and the exact numbers of binucleated cells scored per condition could not be recovered, the analysis is presented as a descriptive methodological comparison. On the normalised scale, the transformation increased the net MN value when observed frequencies were close to background, with a maximum correction of 2.38 MN/500 BC, and approached the analytically expected asymptotic offset of 0.5 MN/500 BC under the illustrative working parametrisation, as the observed values substantially exceeded the background. Consequently, within the selected groups analysed, the apparent magnitude of protection calculated from the transformed values was lower than the classical estimates for the selected pre-irradiation treatments, showing the largest classical MP values—for example, 79.5% versus 93.8% for rosmarinic acid. The ordering of the selected radioprotective-treatment groups by MP was unchanged. These results illustrate the sensitivity of background-subtracted MN metrics to statistical parametrisation under low-signal conditions. They must not be interpreted as valid experimental uncertainty estimates, as dose estimates, or as clinical decision criteria.