Use of the Single Cell Gel Electrophoresis Assay for the Detection of DNA-protective Dietary Factors: Results of Human Intervention Studies

Plant-based diet and oxidative stress-induced DNA damage in post-surgery colorectal cancer patients: Results from a randomized controlled trial

Oxidative stress-induced DNA damage may impact long-term outcomes in colorectal cancer (CRC) patients. While bioactive compounds in plant foods have been linked to DNA protection, evidence among patients in remission remains limited. The present study aimed to investigate the effect of a one-year personalized intensive dietary intervention on DNA damage in post-surgery, non-metastatic CRC patients. Participants were enrolled 2-9 months after surgery in the ongoing randomized controlled trial, Norwegian dietary guidelines and colorectal cancer survival (CRC-NORDIET). Eligible participants (aged 50-80 years, primary stage I-III CRC) were randomized to either a plant-based dietary intervention targeting oxidative stress and inflammation, or to a control group that received standard dietary advice as a part of routine cancer care. As a secondary analysis, this study included 156 participants (78 in the intervention group and 78 in the control group) from the total 503 patients enrolled in CRC-NORDIET study. DNA damage in peripheral mononuclear blood cells (PBMCs) was assessed using the enzyme-modified comet assay during a 12-month follow-up period. A significant intervention effect on DNA base oxidation from baseline to 12 months was observed (P = 0.04), representing a 32 % reduction in the intervention group compared to the control group. No significant effect on DNA strand breaks was found. In conclusion, adherence to a plant-based dietary pattern may reduce DNA base oxidation in post-surgery CRC patients. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT01570010.

Elucidation of Potential Genotoxicity of MXenes Using a DNA Comet Assay

MXenes are among the most diverse and prominent 2D materials. They are being explored in almost every field of science and technology, including biomedicine. In particular, they are being investigated for photothermal therapy, drug delivery, medical imaging, biosensing, tissue engineering, blood dialysis, and antibacterial coatings. Despite their proven biocompatibility and low cytotoxicity, their genotoxicity has not been addressed. To investigate whether MXenes interfere with DNA integrity in cultured cells, we loaded the cells with MXenes and examined the fragmentation of their chromosomal DNA by a DNA comet assay. The presence of both Ti3C2Tx and Nb4C3Tx MXenes generated DNA comets, suggesting a strong genotoxic effect in murine melanoma and human fibroblast cells. However, no corresponding cytotoxicity was observed, confirming that MXenes were well tolerated by the cells. The lateral size of the MXene flakes was critical for developing the DNA comets; submicrometer flakes induced the DNA comets, while larger flakes did not. MXenes did not induce DNA comets in dead cells. Moreover, the extraction of the chromosomal DNA from the MXene-loaded cells or mixing the purified DNA with MXenes showed no signs of DNA fragmentation. Unconstrained living MXene-loaded cells did not show cleavage of the DNA with MXenes under electrophoresis conditions. Thus, the DNA comet assay showed the ability of submicrometer MXene particles to penetrate living cells and induce DNA fragmentation under the applied field. The most probable mechanism of DNA comet formation is the rotation and movement of submicrometer MXene flakes inside cells in an electric field, leading to cleavage and DNA shredding by MXene's razor-sharp edges. Under all other conditions of interest, titanium- and niobium-carbide-based MXenes showed excellent biocompatibility and no signs of cytotoxicity or genotoxicity. These findings may contribute to the development of strategies for cancer therapy.

Multiomics: Functional Molecular Biomarkers of Micronutrients for Public Health Application

Adequate micronutrient intake and status are global public health goals. Vitamin and mineral deficiencies are widespread and known to impair health and survival across the life stages. However, knowledge of molecular effects, metabolic pathways, biological responses to variation in micronutrient nutriture, and abilities to assess populations for micronutrient deficiencies and their pathology remain lacking. Rapidly evolving methodological capabilities in genomics, epigenomics, proteomics, and metabolomics offer unparalleled opportunities for the nutrition research community to link micronutrient exposure to cellular health; discover new, arguably essential micronutrients of microbial origin; and integrate methods of molecular biology, epidemiology, and intervention trials to develop novel approaches to assess and prevent micronutrient deficiencies in populations. In this review article, we offer new terminology to specify nutritional application of multiomic approaches and encourage collaboration across the basic to public health sciences to advance micronutrient deficiency prevention.

Effects of Different Combinations of Phytochemical-Rich Fruits and Vegetables on Chronic Disease Risk Markers and Gene Expression Changes: Insights from the MiBLEND Study, a Randomized Trial

Adequate fruit and vegetable (F and V) intake, as recommended by the World Health Organization (over 400 g/day), is linked to reduced chronic disease risk. However, human intervention trials, especially with whole F and V and in complex combinations, are lacking. The MiBlend Study explored the effects of various phytochemical-rich F and V combinations on chronic disease risk markers, phytochemical absorption, and gene expression in blood. This randomized cross-over study involved participants consuming two of seven different F and V blends for 2 weeks (450 g/day), following a 2-week low F and V intake period (50 g/day). Each blend represented major phytochemical classes (flavonoids, anthocyanins, carotenoids, and glucosinolates) or combinations thereof. Markers of chronic disease risk, including DNA damage, oxidative stress, and retinal microvasculature, were measured. Increasing F and V intake significantly improved plasma antioxidant capacity, DNA damage protection, and retinal arteriolar dilation. Flavonoid-rich, carotenoid-rich, and complex blends notably reduced DNA damage susceptibility. Anthocyanin-rich and carotenoid-rich interventions were most effective in boosting antioxidant capacity, while blends high in flavonoids, especially combined with anthocyanins, significantly improved retinal microvasculature. Gene expression analysis revealed changes in DNA repair, signal transduction, and transcription processes, indicating mechanisms for these health benefits. The study suggests specific F and V blends can provide targeted health improvements, emphasizing the importance of both overall F and V intake and the specific phytochemical composition for personalized preventive strategies.

Effect of a personalized intensive dietary intervention on base excision repair (BER) in colorectal cancer patients: Results from a randomized controlled trial

DNA repair is essential to maintain genomic integrity and may affect colorectal cancer (CRC) patients' risk of secondary cancers, treatment efficiency, and susceptibility to various comorbidities. Bioactive compounds identified in plant foods have the potential to modulate DNA repair mechanisms, but there is limited evidence of how dietary factors may affect DNA repair activity in CRC patients in remission after surgery. The aim of this study was to investigate the effect of a 6-month personalized intensive dietary intervention on DNA repair activity in post-surgery CRC patients (stage I-III). The present study included patients from the randomized controlled trial CRC-NORDIET, enrolled 2-9 months after surgery. The intervention group received an intensive dietary intervention emphasizing a prudent diet with specific plant-based foods suggested to dampen inflammation and oxidative stress, while the control group received only standard care advice. The comet-based in vitro repair assay was applied to assess DNA repair activity, specifically base excision repair (BER), in peripheral blood mononuclear cells (PBMCs). Statistical analyses were conducted using gamma generalized linear mixed models (Gamma GLMM). A total of 138 CRC patients were included, 72 from the intervention group and 66 from the control group. The BER activity in the intervention group did not change significantly compared to the control group. Our findings revealed a substantial range in both inter- and intra-individual levels of BER. In conclusion, the results do not support an effect of dietary intervention on BER activity in post-surgery CRC patients during a 6-month intervention period.

An updated review of functional ingredients of Manuka honey and their value-added innovations

Manuka honey (MH) is a highly prized natural product from the nectar of Leptospermum scoparium flowers. Increased competition on the global market drives MH product innovations. This review updates comparative and non-comparative studies to highlight nutritional, therapeutic, bioengineering, and cosmetic values of MH. MH is a good source of phenolics and unique chemical compounds, such as methylglyoxal, dihydroxyacetone, leptosperin glyoxal, methylsyringate and leptosin. Based on the evidence from in vitro, in vivo and clinical studies, multifunctional bioactive compounds of MH have exhibited anti-oxidative, anti-inflammatory, immunomodulatory, anti-microbial, and anti-cancer activities. There are controversial topics related to MH, such as MH grading, safety/efficacy, implied benefits, and maximum levels of contaminants concerned. Artificial intelligence can optimize MH studies related to chemical analysis, toxicity prediction, multi-functional mechanism exploration and product innovation.

Understanding mechanisms of antioxidant action in health and disease

Several different reactive oxygen species (ROS) are generated in vivo. They have roles in the development of certain human diseases whilst also performing physiological functions. ROS are counterbalanced by an antioxidant defence network, which functions to modulate ROS levels to allow their physiological roles whilst minimizing the oxidative damage they cause that can contribute to disease development. This Review describes the mechanisms of action of antioxidants synthesized in vivo, antioxidants derived from the human diet and synthetic antioxidants developed as therapeutic agents, with a focus on the gaps in our current knowledge and the approaches needed to close them. The Review also explores the reasons behind the successes and failures of antioxidants in treating or preventing human disease. Antioxidants may have special roles in the gastrointestinal tract, and many lifestyle features known to promote health (especially diet, exercise and the control of blood glucose and cholesterol levels) may be acting, at least in part, by antioxidant mechanisms. Certain reactive sulfur species may be important antioxidants but more accurate determinations of their concentrations in vivo are needed to help assess their contributions.

The Comet Assay in Drosophila: A Tool to Study Interactions between DNA Repair Systems in DNA Damage Responses In Vivo and Ex Vivo

The comet assay in Drosophila has been used in the last few years to study DNA damage responses (DDR) in different repair-mutant strains and to compare them to analyze DNA repair. We have used this approach to study interactions between DNA repair pathways in vivo. Additionally, we have implemented an ex vivo comet assay, in which nucleoids from treated and untreated cells were incubated ex vivo with cell-free protein extracts from individuals with distinct repair capacities. Four strains were used: wild-type OregonK (OK), nucleotide excision repair mutant mus201, dmPolQ protein mutant mus308, and the double mutant mus201;mus308. Methyl methanesulfonate (MMS) was used as a genotoxic agent. Both approaches were performed with neuroblasts from third-instar larvae; they detected the effects of the NER and dmPolQ pathways on the DDR to MMS and that they act additively in this response. Additionally, the ex vivo approach quantified that mus201, mus308, and the double mutant mus201;mus308 strains presented, respectively, 21.5%, 52.9%, and 14.8% of OK strain activity over MMS-induced damage. Considering the homology between mammals and Drosophila in repair pathways, the detected additive effect might be extrapolated even to humans, demonstrating that Drosophila might be an excellent model to study interactions between repair pathways.