Leukemia remains a major cause of cancer-related illness and death worldwide, and while treatments have improved substantially, current therapies - particularly chemotherapy - carry significant toxicity and are often too aggressive to use in older patients. This reality has fueled interest in natural compounds that might fight leukemia with fewer side effects.
Urolithins are natural compounds produced in the human gut when bacteria metabolize ellagitannins and ellagic acid, which are polyphenols found in pomegranates, walnuts, and berries. Rather than ellagic acid itself being the active compound, it is the urolithins - particularly urolithin A and urolithin B - that are actually bioavailable and responsible for many of the health benefits attributed to pomegranate consumption.
Prior studies had shown urolithins have anti-cancer effects in prostate cancer, colon cancer, and breast cancer cell lines. However, their potential against leukemia and the specific metabolic mechanisms through which they act had not been investigated systematically. This study specifically examined the effects of urolithin A and B on two leukemia cell lines: Jurkat (a T-cell leukemia line) and K562 (a chronic myelogenous leukemia line).
Using a powerful technique called metabolomics - the comprehensive measurement of all small-molecule metabolites inside a cell - the researchers aimed to map exactly how urolithins rewire leukemia cell metabolism and whether these metabolic changes drive the cancer cells toward programmed death (apoptosis).
The first finding was straightforward: both urolithin A and urolithin B significantly inhibited the proliferation of Jurkat and K562 leukemia cells in a dose-dependent manner. Cells treated with 25 micromol/mL of either compound for 48 hours showed a pronounced reduction in viability compared to untreated controls.
Microscopic examination of treated cells revealed characteristic signs of apoptosis (programmed cell death): chromatin condensation - where DNA inside the nucleus compresses into dense, irregular masses - and a reduction in cells with normal nuclear morphology. This morphological change is one of the hallmarks of cells undergoing programmed death.
Urolithin A showed somewhat stronger antiproliferative capability than urolithin B across both cell lines. The IC50 values - the concentration required to reduce cell viability by 50% - confirmed that urolithin A was more potent, though both compounds were effective. This difference may relate to their slightly different chemical structures, as urolithin A has an additional hydroxyl group compared to urolithin B.
These growth inhibitory effects were observed in two biologically distinct leukemia cell lines - Jurkat (T-cell origin) and K562 (CML origin) - suggesting that urolithins may have broad activity across different leukemia subtypes rather than being specific to a single cancer biology.
Using LC-MS/MS metabolomics (liquid chromatography coupled with mass spectrometry), the researchers measured hundreds of intracellular metabolites in both treated and untreated leukemia cells. This untargeted approach revealed a broad metabolic landscape shift affecting multiple pathways simultaneously.
One of the most significant metabolic changes was a shift in how leukemia cells generate energy. Cancer cells typically rely heavily on glycolysis (converting glucose to lactate) even when oxygen is available - a phenomenon called the Warburg effect. Urolithin treatment increased levels of glucose, succinic acid, and acetolactate, along with butyrl-carnitine and other TCA cycle intermediates, indicating that cells were switching from the Warburg-style glycolytic metabolism toward oxidative phosphorylation (OXPHOS).
Carnitine is a molecule essential for fatty acid oxidation, the process by which cells burn fat for energy. Urolithin treatment induced elevated carnitine levels in treated cells, fueling the TCA (tricarboxylic acid) cycle through beta-oxidation. This metabolic reprogramming - from glycolysis toward fat oxidation and mitochondrial respiration - is associated with slower cancer cell growth and greater vulnerability to apoptosis.
The pathway enrichment analysis identified significant alterations in carbohydrate metabolism, glutamate metabolism, glutathione metabolism, the TCA cycle, and sphingolipid metabolism as the top pathways affected by urolithin treatment, highlighting that these compounds do not act through a single metabolic enzyme but rather reshape the entire metabolic network of leukemia cells.
Cancer cells have an unusually high demand for glutamine, using this amino acid not just to build proteins but as a critical carbon and nitrogen source for biosynthesis, energy production, and protection against oxidative stress. Urolithin treatment was shown to reduce glutamine and 2-hydroxyglutarate levels in treated leukemia cells.
Glutamine normally contributes to the synthesis of glutathione, the cell's primary antioxidant defense. By disrupting glutamine metabolism, urolithins may reduce the ability of leukemia cells to neutralize reactive oxygen species (ROS), creating a state of oxidative stress that contributes to cell death. Additionally, treatment increased glucosamine accumulation, which feeds into the hexosamine pathway and may further modulate cell survival signals.
Urolithins also altered one-carbon metabolism, a network of reactions centered around the amino acid methionine that controls DNA methylation, RNA methylation, and histone methylation - collectively known as epigenetic regulation. Treatment increased levels of SAM (S-adenosylmethionine) and spermine, suggesting that urolithins alter the methylation landscape of leukemia cells. This epigenetic disruption could affect the expression of many cancer-associated genes simultaneously.
The one-carbon metabolic changes are particularly intriguing because DNA and histone methylation patterns are known to be dysregulated in leukemia, and drugs that target epigenetic enzymes are already approved for treating some leukemia subtypes. Urolithins appear to modulate similar pathways through metabolic rather than direct enzymatic effects.
Lipid metabolism is deeply intertwined with cell survival and death decisions. Certain fatty acid species can directly activate caspases - the enzymes that execute programmed cell death. Urolithin treatment caused accumulation of three specific lipid species in leukemia cells: LysoPC (lysophosphatidylcholine), prostaglandin F1a, and palmitoleic acid, all of which are established markers of cells entering apoptosis.
These lipids act as apoptosis signals by activating caspase cascades. For example, lysophosphatidylcholine can activate caspase-1, while fatty acid derivatives trigger apoptosis via caspases 2, 3, 6, 7, 8, and 9 simultaneously. The accumulation of these pro-apoptotic lipid metabolites suggests that urolithins push leukemia cells toward cell death through lipid signaling, not just through direct cytotoxicity.
To confirm that apoptosis was actually occurring, the researchers used Annexin V/7-AAD flow cytometry, a standard assay that distinguishes live cells, early apoptotic cells, and late apoptotic/dead cells. The results showed that urolithin A and B treatment induced approximately 50% apoptosis in K562 cells and 60-70% apoptosis in Jurkat cells, confirming that the metabolic changes observed are indeed linked to cell death.
Urolithins also increased levels of methyl-guanine, a metabolite associated with oxidative DNA damage, in treated cells. DNA damage is another potent trigger of apoptosis, suggesting that urolithins kill leukemia cells through multiple convergent pathways - metabolic reprogramming, oxidative stress, lipid signaling, and DNA damage - rather than through a single mechanism.
The overall picture that emerges from this study is that urolithins act as broad metabolic disruptors in leukemia cells. Unlike targeted drugs that block a single enzyme or receptor, urolithins simultaneously alter energy metabolism, glutamine utilization, one-carbon metabolism, lipid signaling, and antioxidant defense. This multi-target action may be both a strength (harder for cancer cells to develop resistance) and a challenge (harder to optimize dosing for a specific target).
The switch from Warburg-effect glycolysis toward oxidative phosphorylation is particularly noteworthy. This metabolic shift has been associated with reduced cancer stemness and proliferation in other cancer types, and drugs that force this transition are an active area of anti-cancer drug development. Urolithins appear to achieve this shift naturally through their effects on carnitine levels and fatty acid oxidation.
The authors propose that urolithins could be developed as components of combination therapies for leukemia, potentially being paired with conventional chemotherapy agents or targeted drugs. Because urolithins are naturally derived gut metabolites with favorable safety profiles, they may be able to sensitize leukemia cells to other treatments without adding substantially to toxicity.
However, the study was conducted entirely in cell culture models, and the concentrations used (25 micromol/mL) may not be easily achievable in human blood through dietary pomegranate consumption alone. Clinical translation will require formulation development to achieve adequate bioavailability, as well as studies in animal models and eventually clinical trials to confirm safety and efficacy in leukemia patients.