The researchers prepared extracts from both polished and unpolished Yoom Noon rice and applied them to two well-established colorectal cancer cell lines, HCT116 and HT29. These lines are staples of colon cancer research because they differ in their genetic backgrounds and behavior, giving scientists a way to gauge whether an effect is broad or limited to one tumor type. The team measured cell viability using the MTS assay, a colorimetric technique in which metabolically active cells convert a chemical substrate into a colored product, allowing researchers to quantify how many cells survive after treatment. Trypan blue exclusion, a classic dye-based test that marks dead cells with compromised membranes, provided an independent check on cell survival.

The results revealed a striking difference between the two cancer cell lines. Against HCT116 cells, the polished rice extract achieved a half-maximal inhibitory concentration, or IC50, of 626.74 micrograms per milliliter at 48 hours, while the unpolished extract reached an IC50 of 736.85 micrograms per milliliter. In plain terms, these concentrations were sufficient to cut the viability of HCT116 cells in half within two days. The HT29 line proved more resistant, with both extracts requiring concentrations above 1000 micrograms per milliliter to achieve the same effect. This kind of selectivity between cell lines is common in natural product research and often reflects differences in how tumor cells metabolize compounds or regulate their own survival machinery.

Beyond short-term viability, the investigators probed whether the rice extracts could undermine the long-term proliferative capacity of the cancer cells. They used a clonogenic assay, sometimes called a self-renewal assay, which challenges surviving cells to divide repeatedly and form visible colonies over days to weeks. Cancer cells that retain their ability to seed new colonies are the ones most likely to drive regrowth after treatment. Both polished and unpolished Yoom Noon rice extracts demonstrated a potent anti-proliferative ability against HCT116 and HT29 cells in this assay, indicating that the extracts do not merely slow the cells temporarily but impair their capacity for sustained self-renewal.

Perhaps the most clinically relevant findings concerned metastasis, the process by which cancer cells spread from the original tumor to distant organs and which accounts for the majority of colorectal cancer deaths. The team used wound healing assays, in which a scratch is made across a confluent cell layer and researchers track how quickly cells migrate to close the gap, along with transwell migration assays, in which cells are challenged to move through a porous membrane toward a chemical attractant. At doses that were not cytotoxic, meaning they did not kill the cells outright, the Yoom Noon rice extracts significantly suppressed both the migration and the invasion of HCT116 cells. This distinction matters because it suggests the rice compounds may interfere with the motility machinery of cancer cells at concentrations that would be safer for normal tissue.

To understand the cellular mechanisms driving the suppression of proliferation, the researchers turned to flow cytometry, a technique that passes thousands of individual cells through a laser and quantifies their characteristics one by one. Using Annexin V and propidium iodide staining, they found that treatment with the rice extracts increased apoptotic cell death in both HCT116 and HT29 cells in a dose-dependent manner. Apoptosis is the body’s programmed cell death pathway, a controlled form of cellular suicide that, unlike necrosis, avoids triggering inflammation. Many chemotherapy drugs work by pushing cancer cells into apoptosis, so a food-derived extract that promotes this pathway is of considerable interest for chemoprevention research.

Flow cytometric cell cycle analysis added a second mechanistic layer. The extracts arrested HCT116 cells at the S phase, the stage of the cell cycle during which DNA is replicated. Blocking cells at this checkpoint prevents them from progressing to mitosis and dividing, effectively putting the brakes on tumor growth. The combination of apoptosis induction and S phase arrest suggests the rice extracts act through multiple complementary routes, a pattern often seen with complex botanical mixtures that contain many bioactive compounds working in concert rather than a single isolated molecule.

Just as important as what the extracts did to cancer cells is what they did not do to healthy ones. Using a cytokinesis-blocked micronucleus assay on V79 lung fibroblast cells, the team evaluated genotoxicity, the potential to damage DNA. Micronuclei are small fragments of genetic material that break away from the main nucleus when chromosomes are damaged or missegregated during cell division, and their frequency is a sensitive indicator of DNA harm. The Yoom Noon rice extracts at concentrations of 250 to 750 micrograms per milliliter did not increase the number of micronuclei compared with untreated controls after 24 hours of exposure, indicating the extracts themselves are not genotoxic under these conditions.

The anti-genotoxic results may prove to be the study’s most provocative contribution. When the researchers co-treated the fibroblast cells with the rice extracts and Mitomycin C, a well-known mutagen, they observed a significant reduction in the frequency of micronucleated cells compared with cells exposed to the mutagen alone. In other words, the rice extracts appeared to shield DNA from a known damaging agent. This antimutagenic effect, if it holds up in further studies, would position Yoom Noon rice not only as a possible source of anti-cancer compounds but also as a candidate for chemoprevention, the strategy of using dietary or medicinal agents to stop cancer before it starts.

The authors are careful to frame this as an in vitro study, and the usual caveats apply. Extract concentrations in the hundreds of micrograms per milliliter cannot be directly translated into dietary recommendations, and compounds that survive the digestive system, cross the intestinal barrier, and reach tumor tissue in sufficient quantities remain an open question. Clinical effects would require animal studies and eventually human trials. Nevertheless, the research, supported by the Office of the Royal Development Projects Board of Thailand, establishes a credible first link between a locally significant rice strain and a suite of desirable biological activities: selective inhibition of colorectal cancer cell growth, suppression of migration and invasion, induction of apoptosis, cell cycle arrest, and protection of DNA from mutagenic damage. For a grain developed through a royal agricultural initiative in southern Thailand, Yoom Noon rice has now earned a place in the growing catalogue of natural products under scrutiny for cancer prevention and therapy.

Subject of Research: Anti-cancer and anti-genotoxic effects of Yoom Noon rice extracts on colorectal cancer cells in vitro

Article Title: Anti-cancer and anti- genotoxic potential of Yoom Noon rice: induction of apoptosis, cell cycle arrest, and inhibiting migration and invasion in vitro

Article References: Praphasawat, R., Payuhakrit, W., Surachaijarin, C., Yana, B., & Palipoch, S. (2026). Anti-cancer and anti- genotoxic potential of Yoom Noon rice: induction of apoptosis, cell cycle arrest, and inhibiting migration and invasion in vitro. BMC Complementary Medicine and Therapies. https://doi.org/10.1186/s12906-026-05613-x

Image Credits: AI Generated

DOI: 10.1186/s12906-026-05613-x

Keywords: Yoom Noon rice, colorectal cancer, apoptosis, cell cycle arrest, S phase, micronucleus assay, genotoxicity, antimutagenicity, flavonoids, rice extract, chemoprevention, in vitro

The Lapite site receives a daily mixture of domestic, commercial, medical, agricultural, pharmaceutical and industrial waste, and its leachate flows directly into surrounding water bodies and percolates into the soil, where underground water can become contaminated. Because the dumpsite sits within the city and is worked by cart pushers, truck drivers, food vendors and scavengers who live and earn their living on it, the potential for occupational and residential exposure is substantial. Previous studies had already documented toxic substances in the soil, streams, groundwater and edible crops around the site, but no one had systematically tested the leachate’s effects on living organisms or calculated what its contents might mean for human health.

Chemically, the leachate was alarming. The team measured metals at concentrations ranging from 0.004 to 10.69 milligrams per litre and detected polycyclic aromatic hydrocarbons and phthalate esters at levels between 1.5 times ten to the minus four and 4.32 times ten to the minus two micrograms per litre, all exceeding United States Environmental Protection Agency limits. Alkalinity, chloride, nitrate, sulphate, ammonia, lead, copper, iron, cobalt, arsenic and chromium were all above standards set by Nigerian and international regulators. The leachate contained four phthalates, including bis(2-ethylhexyl) phthalate and di-n-butyl phthalate, both well known as endocrine disruptors, and five PAH congeners flagged as priority pollutants by the USEPA, including benzo(b)fluoranthene and benzo(g,h,i)perylene. A computed Leachate Pollution Index of 7.506, with lead as the largest contributor, exceeded the international benchmark of 7.378 and the value of 5 that signals polluted conditions and a high likelihood of groundwater contamination.

The first biological test used the root tips of the onion Allium cepa, a classic plant model for detecting chromosomal damage. Onion bulbs grown in leachate dilutions from 1 to 40 percent showed a concentration-dependent collapse in root growth, with root length falling to as little as 11.96 percent of controls and a half-maximal effective concentration of just 2.15 percent. The mitotic index, which measures the proportion of cells actively dividing, dropped from 8.33 to 1.25 percent as concentration rose, while the frequency of chromosomal aberrations climbed from 26.73 to 112 percent. Microscopy revealed sticky, vagrant and disoriented chromosomes, anaphase bridges, disturbed spindles and binucleated cells. The pattern of damage pointed the authors toward spindle inhibition rather than direct chromosome breakage: the leachate’s constituents appear to sabotage the machinery that pulls copied chromosomes apart, arresting cell division. Correlation analysis strengthened the case, with the analysed metals and organics showing a strong positive relationship with root growth inhibition and aberration frequency, and a strong negative relationship with the mitotic index.

The aquatic model was the African mud catfish Clarias gariepinus, a commercially important species across West Africa. In a 96-hour acute toxicity test, mortality rose with concentration and reached 100 percent at the 50 and 100 percent dilutions, yielding a median lethal concentration of 17.78 percent. For the longer micronucleus experiment, juvenile fish were exposed to 5 to 25 percent leachate for up to 21 days. Their peripheral red blood cells accumulated micronuclei, small DNA fragments left outside the main nucleus after cell division, along with nuclear buds, binucleated, apoptotic and necrotic cells, all increasing with both concentration and exposure duration. Correlation coefficients between exposure time and nuclear damage ranged from 0.96 to 0.99, indicating an almost linear relationship between how long the fish swam in contaminated water and how badly their genomes fared.

Under the microscope, the fish tissues told a parallel story of systemic injury. Livers showed severe glycogenic and lipid-filled cytoplasm, degeneration of liver cells and fat infiltrating the hepatic tissue, while gills displayed fusion of filaments, inflamed gill arches and haemorrhagic, necrotic lamellae. Gill damage of this kind impairs respiration and ion regulation, and hepatic steatosis reflects a general failure of lipid metabolism under xenobiotic assault. Because fish gills and livers are in direct, continuous contact with the water they inhabit, these lesions offer a realistic preview of what chronic leachate exposure does to aquatic life in streams receiving dumpsite runoff.

The mammalian arm of the study exposed mice to 2.5 to 50 percent leachate in their drinking water for 5, 10 or 20 days. Bone marrow analysis revealed concentration-dependent increases in micronucleated polychromatic and normochromatic erythrocytes, alongside a declining ratio of young to mature red blood cells, a sign that the leachate was accelerating cell turnover and shortening red cell lifespan as bone marrow proliferation was disturbed. Other abnormalities, including Cabot’s rings, teardrop cells, burr cells, helmet cells and oversized or undersized erythrocytes, accumulated with longer exposure, with pooled abnormality counts rising from 89.81 at five days to 114.38 at twenty days. Mouse livers showed necrosis, cytoplasmic vacuolation, portal inflammation, congestion and haemorrhage, with severity generally increasing with concentration. Body weight gain was negatively correlated with leachate exposure, while micronucleus frequencies correlated positively, mirroring the plant and fish results.

The authors attribute the genetic and tissue damage to the leachate’s toxic metals and organic pollutants acting in concert. Metal ions can bind to nuclear proteins and DNA, forming cross-links that alter DNA structure and trigger cell cycle disruption, apoptosis or carcinogenesis, while oxidative stress and reactive oxygen species amplify the injury. PAHs, phthalates and related compounds are established drivers of genomic and epigenetic instability through DNA adduct formation, strand breaks and inhibition of repair pathways. Lead, cadmium and arsenic appear on the World Health Organization’s list of ten chemicals of major public health concern, and the WHO attributes to arsenic circulatory problems, skin destruction and neurotoxic effects, to cadmium kidney damage, bone demineralization and links to neurodegenerative disease, and to lead impaired cognition, anaemia, reduced fertility and risks of stillbirth and miscarriage.

The human health risk assessment used USEPA protocols to estimate exposure through ingestion, dermal contact and inhalation for both adults and children. Hazard quotients followed the order ingestion greater than dermal greater than inhalation, and children registered higher values than adults at every pathway, likely reflecting hand-to-mouth habits that make it easy to consume contaminated soil and water. Hazard indices for individual metals stayed below one, the threshold for non-carcinogenic concern, in both age groups. The cancer picture was far less reassuring. Total lifetime cancer risk values for lead reached 1.63 times ten to the minus four for adults and 1.53 times ten to the minus three for children, both above the 1 times ten to the minus four threshold that defines a high risk of developing cancer, with children again more vulnerable. The authors note that vegetables were being harvested on the dumpsite during sampling, maize was growing on its margins, and goats, dogs and human scavengers foraged across it, all potential routes for biomagnification into the human food chain.

The study has limits the authors acknowledge: because the leachate is a complex mixture, the individual contribution of each chemical cannot be separated due to collinearity, and the precise molecular mechanisms of the damage remain to be worked out. Even so, the convergence of chromosomal damage in plants, micronuclei in fish blood and mouse marrow, and pathological lesions in liver and gill tissue across three kingdoms of life makes a compelling case that uncontrolled dumpsite leachate is not merely an odour problem but an active genotoxic hazard. The team calls for regular monitoring of the site, regulation of raw leachate discharge, and a shift from open dumping toward waste reduction, recovery, recycling and reuse. For the communities living and working around Lapite, and for the millions of people in rapidly urbanising cities across the developing world who live beside similar dumps, the message is stark: the liquid that drains from our waste carries the capacity to reach into the genome itself.

Subject of Research: Cytogenotoxicity and human health risks of municipal solid waste landfill leachate

Article Title: Genetic and systemic disruption by a municipal solid waste leachate in aquatic and terrestrial models, and human cancer risk assessment of the leachate’s metallic constituents

Article References: Bakare, A. A., Balogun, K. B., Ogunbona, M. A., Onyia, E. C., Coker, M. M., Pitso, K. M., Bakare, O. C., Maduna, L. D., Fagbenro, O. S., Magama, S., Taole, M. M., Adeniji, A. O., Phalatsi, M. S., Gbadebo, A. M., Chatanga, P., & Alabi, O. A. (2025). Genetic and systemic disruption by a municipal solid waste leachate in aquatic and terrestrial models, and human cancer risk assessment of the leachate’s metallic constituents. Discover Toxicology, 2(1), Article 22. https://doi.org/10.1007/s44339-025-00044-8

Image Credits: AI Generated

DOI: 10.1007/s44339-025-00044-8

Keywords: landfill leachate, genotoxicity, micronucleus assay, Allium cepa, Clarias gariepinus, heavy metals, polycyclic aromatic hydrocarbons, phthalates, cancer risk assessment, municipal solid waste, Nigeria, histopathology