Hibiscus sabdariffa (Roselle) is in high demand worldwide due to its beneficial health properties owing to the polyphenols content, mainly in the flower calyx. The objective of this study was to find the best conditions (time and liquid: solid ratio) to extract polyphenols from Roselle using Ultrasound-Assisted Extraction (UAE) (40 kHz, 180 W), with ethanol how solvent; as well as determine the yield of phenols, anthocyanin, flavonoids, tannins, antioxidant activity (DPPH) and antigenotoxic effect (comet assay). A traditional solid-liquid extraction was applied as a reference. Extraction times of 40 and 60 min resulted in the highest polyphenols (13.019 mg GAE/g dry weight (dw)), flavonoids (4.981 CE/g dw), anthocyanins (1.855 mg Cya3GE/g dw), and tannins (0.745 CE/g dw) recoveries and an antioxidant activity (DPPH) of 74.58%. Extracts from white calyces contained similar amounts of phenols and flavonoids, but very little condensed tannins (0.049 CE/g dw) and practically no anthocyanins. Extracts from red and white calyces, showed antigenotoxic activity and repaired capacity of damage caused by mutagens in human lymphocytes.

There is considerable controversy with regard to the genotoxicity of glyphosate, with some reports stating that this compound is non-toxic for fish, birds and mammals. In this work, we used the comet assay to examine the genotoxicity of glyphosate isopropylamine (0.7, 7, 70 and 700 µM) in human lymphocytes, erythrocytes of Oreochromis niloticus and staminal nuclei of Tradescantia (4430) in vitro and in vivo. Cells, nuclei and fish that had and had not been exposed to 5 mM N-nitrosodiethylamine (NDEA) were used as positive and negative controls, respectively. Significant (p < 0.01) genetic damage was observed in vivo and in vitro in all cell types and organisms tested. Human lymphocytes and Tradescantia hairs showed lower genetic damage in vivo compared to in vitro, possibly because of efficient metabolization of the herbicide. In O. niloticus erythrocytes, significant (p < 0.001) genotoxicity was observed at > 7 µM, whereas in vitro, glyphosphate was genotoxic in human lymphocytes and Tradescantia hairs at > 0.7 µM. These results indicate that glyphosate is genotoxic in the cells and organisms studied at concentrations of 0.7-7 µM.

Glyphosate is noted for being non-toxic in fishes, birds and mammals (including humans). Nevertheless, the degree of genotoxicity is seriously controversial. In this work, various concentrations of a glyphosate isopropylamine salt were tested using two methods of genotoxicity assaying, viz., the pink mutation assay with Tradescantia (4430) and the comet assay with nuclei from staminal cells of the same plant. Staminal nuclei were studied in two different forms, namely nuclei from exposed plants, and nuclei exposed directly. Using the pink mutation assay, isopropylamine induced a total or partial loss of color in staminal cells, a fundamental criterion utilized in this test. Consequently, its use is not recommended when studying genotoxicity with agents that produce pallid staminal cells. The comet assay system detected statistically significant (p < 0.01) genotoxic activity by isopropylamine, when compared to the negative control in both the nuclei of treated plants and directly treated nuclei, but only the treated nuclei showed a dose-dependent increase. Average migration in the nuclei of treated plants increased, when compared to that in treated nuclei. This was probably due, either to the permanence of isopropylamine in inflorescences, or to the presence of secondary metabolites. In conclusion, isopropylamine possesses strong genotoxic activity, but its detection can vary depending on the test systems used.

There is considerable controversy regarding the genotoxicity of glyphosate (N-(phosphonomethyl) glycine). It has been suggested that the genotoxicity of this herbicide is increased by the adjuvants added to commercial formulations based on glyphosate. The effect of various concentrations of glyphosate and three commercial glyphosate-based herbicides (GBH) on human lymphocytes was evaluated. Human blood cells were exposed to glyphosates of 0.1, 1, 10 and 50 mM as well as to equivalent concentrations of glyphosate on commercial formulations. Genetic damage (p < 0.05) was observed in all concentrations with glyphosate and with FAENA and TACKLE formulations. These two commercial formulations showed genotoxicity that was concentration-dependent but in a higher proportion compared to pure glyphosate only. Higher glyphosate concentrations increased the frequency and range of tail lengths of some migration groups, and the same was observed for FAENA and TACKLE, while in CENTELLA the migration range decreased but the frequency of migration groups increased. We show that pure glyphosate and commercial GBH (FAENA, TACKLE and CENTELLA) gave signals of genotoxicity in human blood samples in the comet assay. The genotoxicity increased in the formulations, indicating genotoxic activity also in the added adjuvants present in these products. The use of the MG parameter allowed us to detect a certain type of genetic damage associated with different formulations.

To assess the genotoxic activity of N-nitroso diethylamine (NDEA), maleic hydrazide (MH), and ethyl methane sulfonate (EMS) using two systems: the comet assay on nuclei from Tradescantia, and the pink mutation test on Tradescantia staminal hairs (clone 4430). Tradescantia cups was obtained from Laboratorio de Citogenética y Mutagénesis del Centro de Ciencias de la Atmósfera de la Universidad Nacional Autónoma de México and treated with: N-nitroso diethylamine (NDEA) at 1, 5, 10 mM, maleic hydrazide (MH) at 1, 5, 10 mM and ethyl methane sulfonate (EMS) at 15, 30 and 45 mM; and used in both pink mutation assay and comet assay using cellular nuclei from Tradescantia staminal hairs. The observation of staminal hair was realized along eight days (6-14) after treatment), flowers produced day 14 after treatment were utilized done according to Underbrink. In previous reports on plants, were comet assay was used, breaking cellular wall and separating by centrifugation gradient are necessary. Here, nuclei from staminal hairs were obtained by squashing the cells (is not necessary to utilize to break special procedure cellular wall), collected using a nylon mesh of 80 Mm and next the comet assay was applied. Student's T test was the statistical test used for analyzing the comet assay data. Both assays showed a great sensitivity to the studied mutagens. A relationship between the dose-pink event and the dose-tail length was evident. Even though the Tradescantia mutation assay is a sensitive test with MH and EMS, low doses of NDEA were not able to induce a significant increase in the pink event frequencies; however, the comet assay was able to detect the mutagenic effect of NDEA at the same dose. Thus, it is clear that the comet assay is highly sensitive to the lowest dose of chemical mutagens. The comet assay on nuclei from Tradescantia staminal hairs is a useful tool to monitor genotoxic agents; it is simple, highly sensitive, and faster than the pink mutation test.

Glyphosate is a controversial herbicide. Its genotoxicity and presence in various ecosystems have been reported. The use of ascorbic acid and resveratrol could protect different organisms from glyphosate-induced genetic damage. In the present study, specific genetic damage induced by glyphosate was evaluated in erythrocytes of Oreochromis niloticus, Ambystoma mexicanum and human lymphocytes. Simultaneously, the antigenotoxic capacity of various concentrations of ascorbic acid and resveratrol was evaluated by means of pretreatment and simultaneous treatment protocols. The 0.03, 0.05 and 0.07 mM concentrations of glyphosate induced significant genotoxic activity (p < 0.05) in human lymphocytes and in erythrocytes of the species studied, and could cause genomic instability in these populations. The reduction in genetic damage observed in human lymphocytes exposed to high concentrations of glyphosate is only apparent: excessive genetic damage was associated with undetectable excessive tail migration length. A significant (p < 0.05) antigenotoxic effect of ascorbic acid and resveratrol was observed in all concentrations, organisms and protocols used. Both ascorbic acid and resveratrol play an important role in maintaining the integrity of DNA. Ascorbic acid in Oreochromis niloticus, Ambystoma mexicanum reduced glyphosate-induced genetic damage to a basal level. Therefore, our data indicate that these antioxidants could help preserve the integrity of the DNA of organisms exposed to glyphosate. The consumption of antioxidants is a useful tool against the genotoxicity of glyphosate.