Ratio-dependent effects of photoactivated hypericin and manumycin A on their genotoxic and mutagenic potential.

Natural compounds originated from plants and microorganisms and their combinations are currently being investigated as a possible treatment for several diseases including cancer. Hypericin (photodynamically-active pigment from Hypericum perforatum L.) and manumycin A (inhibitor of farnesyltransferase from Streptomyces parvulus) belong to the chemicals potentially applicable in clinical practice. In this study we evaluated potential cytotoxic (via trypan blue exclusion test), genotoxic (via DNA-topology and comet assays), and mutagenic effects (via bacterial reverse mutation test) of these compounds and their combinations considering the molecular mechanism of their action in cell-free and cellular systems. Our results did not reveal neither cytotoxic nor mutagenic activities of tested compounds and their combinations. Regarding the genotoxic potential, no damage of plasmid DNA in cell-free system was detected. On the other hand, photoactivated hypericin and manumycin A were able to induce primary DNA damage in human lymphocytes analyzed by comet assay. The possible antagonistic interactions between these two metabolites were estimated using SynergyFinder software analysis and experimental data obtained from comet assay. Our findings indicate that not only the presence of substances, but also their ratio plays an important role in resulting effects of the combined treatment in cellular system.

Comparison of Cytotoxic, Genotoxic, and DNA-Protective Effects of Skyrin on Cancerous vs. Non-Cancerous Human Cells.

Secondary metabolites as a potential source of anticancer therapeutics have been the subject of many studies. Since hypericin, a metabolite isolated from Hypericum perforatum L., shows several biomedical properties applicable in oncology, the aim of our study was to investigate its potential precursor skyrin in terms of genotoxic and DNA-protective effects. These skyrin effects were analyzed by cell-free methods, and cytotoxicity was estimated by an MTT assay and by a trypan blue exclusion test, while the genotoxic/antigenotoxic potential was examined by comet assay using non-cancerous human lymphocytes and the HepG2 cancer cell line. Skyrin did not show DNA-damaging effects but rather exhibited DNA-protectivity using a DNA-topology assay. However, we observed only weak antioxidant and chelating skyrin properties in other cell-free methods. Regarding the cytotoxic activity of skyrin, HepG2 cells were more prone to skyrin-induced death in comparison to human lymphocytes. Skyrin in non-cytotoxic concentrations did not exhibit elevated genotoxicity in both cell types. On the other hand, skyrin displayed moderate DNA-protective effects that were more noticeable in the case of non-cancerous human lymphocytes. The potential genotoxic effects of skyrin were not observed, and its DNA-protective capacity was more prominent in non-cancerous cells. Therefore, skyrin might be a promising agent used in anticancer therapy.

Genotoxic potential of bisphenol A: A review.

Bisphenol A (BPA), as a major component of some plastic products, is abundant environmental pollutant. Due to its ability to bind to several types of estrogen receptors, it can trigger multiple cellular responses, which can contribute to various manifestations at the organism level. The most studied effect of BPA is endocrine disruption, but recently its prooxidative potential has been confirmed. BPA ability to induce oxidative stress through increased ROS production, altered activity of antioxidant enzymes, or accumulation of oxidation products of biomacromolecules is observed in a wide range of organisms - estrogen receptor-positive and -negative. Subsequently, increased intracellular oxidation can lead to DNA damage induction, represented by oxidative damage, single- and double-strand DNA breaks. Importantly, BPA shows several mechanisms of action and can trigger adverse effects on all organisms inhabiting a wide variety of ecosystem types. Therefore, the main aim of this review is to summarize the genotoxic effects of BPA on organisms across all taxa.

Physiological Responses of Young Pea and Barley Seedlings to Plasma-Activated Water.

This study demonstrates the indirect effects of non-thermal ambient air plasmas (NTP) on seed germination and plant growth. It investigates the effect of plasma-activated water (PAW) on 3-day-old seedlings of two important farm plants-barley and pea. Applying different types of PAW on pea seedlings exhibited stimulation of amylase activity and had no inhibition of seed germination, total protein concentration or protease activity. Moreover, PAW caused no or only moderate oxidative stress that was in most cases effectively alleviated by antioxidant enzymes and proved by in situ visualization of H2O2 and ˙O2-. In pea seedlings, we observed a faster turn-over from anaerobic to aerobic metabolism proved by inhibition of alcohol dehydrogenase (ADH) activity. Additionally, reactive oxygen/nitrogen species contained in PAW did not affect the DNA integrity. On the other hand, the high level of DNA damage in barley together with the reduced root and shoot length and amylase activity was attributed to the oxidative stress caused by PAW, which was exhibited by the enhanced activity of guaiacol peroxidase or ADH. Our results show the glow discharge PAW at 1 min activation time as the most promising for pea. However, determining the beneficial type of PAW for barley requires further investigation.

The Effect of Non-Thermal Plasma on the Structural and Functional Characteristics of Human Spermatozoa.

Significant antibacterial properties of non-thermal plasma (NTP) have converted this technology into a promising alternative to the widespread use of antibiotics in assisted reproduction. As substantial data available on the specific in vitro effects of NTP on male reproductive cells are currently missing, this study was designed to investigate selected quality parameters of human spermatozoa (n = 51) exposed to diffuse coplanar surface barrier discharge NTP for 0 s, 15 s, 30 s, 60 s and 90 s. Sperm motility characteristics, membrane integrity, mitochondrial activity, production of reactive oxygen species (ROS), DNA fragmentation and lipid peroxidation (LPO) were investigated immediately following exposure to NTP and 2 h post-NTP treatment. Exposure to NTP with a power input of 40 W for 15 s or 30 s was found to have no negative effects on the sperm structure or function. However, a prolonged NTP treatment impaired all the sperm quality markers in a time- and dose-dependent manner. The most likely mechanism of action of high NTP doses may be connected to ROS overproduction, leading to plasma membrane destabilization, LPO, mitochondrial failure and a subsequent loss of motility as well as DNA integrity. As such, our findings indicate that appropriate plasma exposure conditions need to be carefully selected in order to preserve the sperm vitality, should NTP be used in the practical management of bacteriospermia in the future.

The Effects of Cold Atmospheric Pressure Plasma on Germination Parameters, Enzyme Activities and Induction of DNA Damage in Barley.

Climate change, environmental pollution and pathogen resistance to available chemical agents are part of the problems that the food industry has to face in order to ensure healthy food for people and livestock. One of the promising solutions to these problems is the use of cold atmospheric pressure plasma (CAPP). Plasma is suitable for efficient surface decontamination of seeds and food products, germination enhancement and obtaining higher yields in agricultural production. However, the plasma effects vary due to plasma source, treatment conditions and seed type. In our study, we tried to find the proper conditions for treatment of barley grains by diffuse coplanar surface barrier discharge, in which positive effects of CAPP, such as enhanced germination or decontamination effects, would be maximized and harmful effects, such as oxidation and genotoxic potential, minimized. Besides germination parameters, we evaluated DNA damage and activities of various germination and antioxidant enzymes in barley seedlings. Plasma exposure resulted in changes in germination parameters and enzyme activities. Longer exposures had also genotoxic effects. As such, our findings indicate that appropriate plasma exposure conditions need to be carefully optimized in order to preserve germination, oxidation balance and genome stability, should CAPP be used in agricultural practice.

Non-Thermal Plasma-A New Green Priming Agent for Plants?

Since the earliest agricultural attempts, humankind has been trying to improve crop quality and yields, as well as protect them from adverse conditions. Strategies to meet these goals include breeding, the use of fertilisers, and the genetic manipulation of crops, but also an interesting phenomenon called priming or adaptive response. Priming is based on an application of mild stress to prime a plant for another, mostly stronger stress. There are many priming techniques, such as osmopriming, halopriming, or using physical agents. Non-thermal plasma (NTP) represents a physical agent that contains a mixture of charged, neutral, and radical (mostly reactive oxygen and nitrogen species) particles, and can cause oxidative stress or even the death of cells or organisms upon interaction. However, under certain conditions, NTP can have the opposite effect, which has been previously documented for many plant species. Seed surface sterilization and growth enhancement are the most-reported positive effects of NTP on plants. Moreover, some studies suggest the role of NTP as a promising priming agent. This review deals with the effects of NTP treatment on plants from interaction with seed and cell surface, influence on cellular molecular processes, up to the adaptive response caused by NTP.

Hyperforin Exhibits Antigenotoxic Activity on Human and Bacterial Cells.

Hyperforin (HF), a substance that accumulates in the leaves and flowers of Hypericum perforatum L. (St. John's wort), consists of a phloroglucinol skeleton with lipophilic isoprene chains. HF exhibits several medicinal properties and is mainly used as an antidepressant. So far, the antigenotoxicity of HF has not been investigated at the level of primary genetic damage, gene mutations, and chromosome aberrations, simultaneously. The present work is designed to investigate the potential antigenotoxic effects of HF using three different experimental test systems. The antigenotoxic effect of HF leading to the decrease of primary/transient promutagenic genetic changes was detected by the alkaline comet assay on human lymphocytes. The HF antimutagenic effect leading to the reduction of gene mutations was assessed using the Ames test on the standard Salmonella typhimurium (TA97, TA98, and TA100) bacterial strains, and the anticlastogenic effect of HF leading to the reduction of chromosome aberrations was evaluated by the in vitro mammalian chromosome aberration test on the human tumor cell line HepG2 and the non-carcinogenic cell line VH10. Our findings provided evidence that HF showed antigenotoxic effects towards oxidative mutagen zeocin in the comet assay and diagnostic mutagen (4-nitroquinoline-1-oxide) in the Ames test. Moreover, HF exhibited an anticlastogenic effect towards benzo(a)pyrene and cisplatin in the chromosome aberration test.

Photoactivated hypericin is not genotoxic.

The study was designed to test the potential photogenotoxicity of hypericin (HYP) at three different levels: primary DNA damages, gene mutations and chromosome aberrations. Primary genetic changes were detected using the comet assay. The potential mutagenic activity of HYP was assessed using the Ames/Salmonella typhimurium assay. Finally, the ability of photoactivated HYP to induce chromosome aberrations was evaluated by the in vitro mammalian chromosome aberration test and compared to that of non-photoactivated HYP. The results have shown that photoactivated HYP can only induce primary DNA damages (single-strand DNA breaks), acting in a dose-response manner. This activity depended both on HYP concentrations and an intensity of the light energy needed for its photoactivation. However, mutagenic effect of photoactivated HYP evaluated in the Ames assay using three bacterial strains S. typhimurium (TA97, TA98 and TA100) was not confirmed. Moreover, photoactivated HYP in the range of concentrations (0.005-0.01 µg/ml) was not found to be clastogenic against HepG2 cells. Our findings from both the Ames assay and the chromosome aberrations test provide evidence that photoactivated HYP is not genotoxic, which might be of great importance mainly in terms of its use in the photodynamic therapy.