Curcumin shields rat livers from hydrogen peroxide damage in rat study

A daily oral dose of curcumin-rich turmeric extract substantially blunted severe liver injury in rats that drank water spiked with hydrogen peroxide for 50 days, according to a new study published in the Egyptian Liver Journal. The damage was dramatic to begin with: the liver enzyme ALT surged from 44 to 1190 units per liter, AST climbed from 180 to 1300 units per liter, alkaline phosphatase rose from 60 to 340 units per liter, and total bilirubin jumped from 0.7 to 5.0 milligrams per deciliter. Under the microscope, the livers of untreated animals showed severe hepatocellular necrosis, steatotic changes, apoptosis-like cellular alterations, and infiltration by mixed inflammatory cells. When the animals also received the extract by gavage once daily, those biochemical and structural markers moved back toward normal, with the strongest overall protection measured at the highest dose tested, 200 milligrams per kilogram of body weight.

The experiment, conducted at the College of Pharmacy, University of Mosul in Iraq, was designed to test whether a Curcuma longa extract could defend the liver against a controlled oxidative assault. Twenty-four healthy Wistar albino rats weighing 170 to 210 grams were randomly divided into six groups of four animals each. One group served as the negative control and received distilled water. A second group drank only 5 percent hydrogen peroxide in water for 50 days to induce oxidative stress and hepatic injury. A third group received the extract alone at 100 milligrams per kilogram as a safety control. The remaining three groups drank the hydrogen peroxide solution while being treated with the extract at 50, 100, or 200 milligrams per kilogram. Because individual water consumption was not recorded, the researchers could not calculate the exact daily hydrogen peroxide dose in milligrams per kilogram and reported exposure only as the concentration in drinking water.

The extract itself was prepared from turmeric rhizomes purchased at a local market, washed, air-dried, milled, and extracted in a Soxhlet apparatus with 70 percent aqueous ethanol for roughly four to six hours. After the ethanol was removed under reduced pressure at 40 to 50 degrees Celsius, the dried residue was suspended in 0.9 percent sterile saline and mixed immediately before each administration, since the extract was not completely water-soluble. Notably, the extract was not chemically standardized, and its curcumin and total-curcuminoid contents were never quantified, a limitation the authors themselves flag. That means the observed effects cannot be attributed exclusively to curcumin; other constituents of the extract may have contributed to the biological response.

At the end of the 50-day period, the animals were anesthetized with pentobarbital sodium and euthanized, and blood was drawn from the vena cava. Serum was analyzed on a Reflotron Plus analyzer for alanine aminotransferase, aspartate aminotransferase, alkaline phosphatase, and total bilirubin, the standard quartet of markers that rises when hepatocyte membranes rupture and intracellular enzymes leak into the circulation. Liver tissue was fixed in formalin, embedded in paraffin, sectioned at approximately 5 micrometers, stained with hematoxylin and eosin, and examined by a qualified pathologist. A separate portion of each liver was homogenized under ice-cold conditions for molecular work, where RNA was extracted, reverse-transcribed, and quantified by quantitative real-time PCR on a QuantStudio 5 system, with expression normalized to the housekeeping genes GAPDH and beta-actin using the 2-delta-delta-Ct method.

The histological story unfolded in a clear dose gradient. Livers from the normal control and from the extract-only safety group showed normal hepatic architecture, with hepatocytes arranged in cords radiating from the central vein and no fatty change, inflammation, or necrosis, indicating that the extract alone at 100 milligrams per kilogram produced no detectable hepatic injury. The hydrogen-peroxide-only group, by contrast, displayed widespread apoptosis-like alterations, severe necrosis, pronounced steatosis, and mixed inflammatory-cell infiltration. Treatment reversed this picture stepwise: at 50 milligrams per kilogram the livers still showed moderate necrosis, apoptosis-like changes, notable fatty deposits, and inflammatory infiltration; at 100 milligrams per kilogram only mild necrosis and apoptosis-like alterations remained, with moderate fatty deposits and sparse inflammatory cells; and at 200 milligrams per kilogram the architecture was the most preserved of all treated groups, with no evident necrosis or apoptosis-like changes, no fatty deposits, and only minimal scattered inflammatory-cell infiltration.

The biochemical data tracked the histology. At 50 milligrams per kilogram, ALT and AST remained high at 1110 and 1160 units per liter respectively, a modest improvement. At 100 milligrams per kilogram, ALT fell to 605 and AST to 840 units per liter. The 200-milligram-per-kilogram dose produced the largest overall improvement, lowering ALT to 520, AST to 550, and alkaline phosphatase to 120 units per liter, while total bilirubin dropped to 2.0 milligrams per deciliter from the 5.0 seen in the injured group. Even so, the authors emphasize that these markers generally remained above the negative-control values, so the findings indicate partial biochemical recovery rather than complete restoration of normal liver function. The extract-only group showed liver enzymes and bilirubin comparable to the negative control, with ALT of 68 and AST of 154.3 units per liter and bilirubin of 0.9 milligrams per deciliter.

Lipid measurements told a quieter story. Cholesterol and triglyceride levels varied only slightly across the treated groups, with cholesterol at 180, 192.7, and 218 milligrams per deciliter and triglycerides at 382, 290, and 304 milligrams per deciliter at the 50, 100, and 200 milligram-per-kilogram doses, compared with 205 and 420 milligrams per deciliter in the hydrogen-peroxide-only group. None of these differences reached statistical significance against the positive control, indicating that the extract did not markedly influence lipid-profile parameters during the experimental period.

The molecular readouts added nuance. The antioxidant gene SOD was sharply suppressed by hydrogen peroxide, falling to 0.11-fold of the negative-control level, and the extract partially restored it to 0.58-, 0.61-, and 0.67-fold at the 50, 100, and 200 milligram-per-kilogram doses, a gradual but incomplete recovery. The pro-inflammatory cytokine IL-6, which had soared to 13.9-fold, dropped to 1.10-, 2.64-, and 4.00-fold across the same doses, and the proto-oncogene MYC, also elevated to 13.9-fold, fell to 1.15-, 2.00-, and 3.48-fold. Intriguingly, the greatest reductions in both IL-6 and MYC occurred at the lowest dose, and the response did not follow a linear dose-dependent pattern, a nonlinear behavior the authors suggest may reflect differences in biological regulation, extract composition, absorption, or inter-animal variation, though these possibilities were not directly investigated. Caspase-3, by contrast, behaved in a cleanly dose-dependent fashion, declining from 5.50-fold in the injured group to 4.10-, 2.70-, and 1.90-fold at the three escalating doses, with the strongest reduction at 200 milligrams per kilogram.

Several caveats temper the enthusiasm. Each group contained only four animals, which limits statistical power and amplifies biological variation. All four genes were measured at the messenger RNA level only, without protein confirmation by Western blotting, ELISA, immunohistochemistry, or enzyme-activity assays, so the results do not directly establish changes in Caspase-3 protein abundance, cleavage, or enzymatic activity. The apoptosis-like histological findings were likewise not confirmed by TUNEL staining or detection of cleaved Caspase-3 protein. The extract was not standardized by chromatographic analysis, and the precise daily hydrogen peroxide exposure could not be calculated because water intake was not monitored. The authors call for future work with larger sample sizes, formal sample-size calculation, standardized extract characterization, monitoring of hydrogen peroxide intake, and protein-level and functional validation of the molecular findings.

Within those limits, the study delivers a coherent signal: an ethanolic turmeric extract, delivered orally throughout a 50-day oxidative challenge, reduced liver enzyme leakage, lowered bilirubin, preserved hepatic architecture, partially restored antioxidant gene expression, suppressed inflammatory signaling, and drove a dose-dependent decline in Caspase-3 messenger RNA, with the strongest overall biochemical and histological protection at 200 milligrams per kilogram. Because the work was performed in a small rat model with an unstandardized extract and a nonphysiological oxidative insult, it establishes proof of concept rather than a clinical recommendation, and the authors note that the overall hepatoprotective response, while strongest at the highest dose, was not uniformly dose dependent across all measured molecular markers.

Subject of Research: Hepatoprotective effects of curcumin-rich Curcuma longa extract against hydrogen peroxide-induced oxidative liver injury in rats

Article Title: Hepatoprotective effects of curcumin against hydrogen peroxide–induced oxidative liver injury in rats

Article References: Barsoom, S. H. (2026). Hepatoprotective effects of curcumin against hydrogen peroxide–induced oxidative liver injury in rats. Egyptian Liver Journal, 16(1), Article 63. https://doi.org/10.1186/s43066-026-00550-3

Image Credits: AI Generated

DOI: 10.1186/s43066-026-00550-3

Keywords: curcumin, turmeric extract, liver injury, oxidative stress, hydrogen peroxide, rats, hepatoprotection, ALT, Caspase-3, IL-6, SOD, gene expression