Therapeutic Potential of Carica papaya (L.) Extract on NRF2/KEAP1 and Apoptotic Pathways in Asbestos-Induced Lung Toxicity

Our plain-English summary of Therapeutic Potential of Carica papaya (L.) Extract on NRF2/KEAP1 and Apoptotic Pathways in Asbestos-Induced Lung Toxicity, by U. Haider, M. Ahmad, W. Nasir, et al (Food Science & Nutrition, 2026).

The study

• Authors: U. Haider, M. Ahmad, W. Nasir, N.U. Khan, M.S. Tariq, B. Aslam, S.U. Rehman, J. Sun
• Journal: Food Science & Nutrition
• Published: 2026;14(7):e71984
• Read it: PubMed · Publisher · Free full text

Abstract

Plant derived natural products and medicinal herbs have recently gain more attention as therapeutic agents to treat various ailments. The current study aims to explore the potential role of C. papaya's natural intervention in reducing the asbestos-induced pulmonary damage. A total of 32 male albino rats were grouped into NC, PC, STD (Montelukast Sodium 10 mg/kg), and C.P (500 mg/kg) groups, having eight animals in each group. Experimental units from the PC were exposed to asbestos fibers in a glass chamber for 2-3 h daily. Biological tissues for histopathology were preserved in formalin, lung tissue for qRT-PCR was immersed in TRIzol, broncho-alveolar lavage fluid (BALF) was collected for protein analysis, and serum was separated for oxidative biomarkers. Data was analyzed by the ANOVA and Tukey's test, and GraphPad Prism (v 8.0) was used for graphical representation. Results of the study revealed that after treatment, serum antioxidant markers were significantly enhanced in the C.P group (p ≤ 0.05), whereas oxidative markers were reduced significantly in the C.P group (p ≤ 0.05). Markers of protein analysis from BALF and wet-to-dry ratio increased in the PC group, but a significant decline was seen in the C.P group (p ≤ 0.05). Results of qRT-PCR showed upregulation of oxidative response pathway molecules and apoptotic markers in PC such as NRF1, DUOX, DUOXA1, DUOXA2, BAX, BID, CASP9, CYT-C, and NFE-2 L2. Parallel to this, an elevated response from antioxidant markers and calcium homeostasis regulators was seen in the C.P-treated group. Microscopic insights revealed normal parenchyma of the lung and trachea in the NC group, which was worsened with thickened airways, fibrotic alveolar walls, and lodged fibers of asbestos seen in the tissue samples of the PC group. Treatment with C. papaya revealed a restored histopathological profile with better alveolar architecture and mitigated effects of asbestos fibers. The results of this study suggest that C. papaya exhibits strong antioxidant potential to mitigate oxidative stress caused by inorganic source.

© 2026 The Author(s). Food Science & Nutrition published by Wiley Periodicals LLC.

In plain English

This was an experiment in rats, not people. The authors split 32 male albino rats into four groups of eight: normal controls (NC), asbestos-exposed (PC), montelukast sodium 10 mg/kg (STD), and papaya (Carica papaya) leaf extract 500 mg/kg (C.P). The PC group was exposed to asbestos fibers in a glass chamber for 2 to 3 hours a day. The study design section of the supplied text is garbled, and the readable text does not name the asbestos type or dose. The asbestos-exposed rats had lower levels of the antioxidant enzymes SOD and catalase and raised nitric oxide. They also had more protein in fluid washed from the lungs and a higher wet-to-dry lung ratio, which is a sign of fluid in the lungs. Their lungs showed thickened airways, fibrotic alveolar walls and lodged asbestos fibers. In the papaya group, these measures and several genes linked to oxidative stress and calcium signaling moved significantly in the opposite direction, and the lung tissue looked more normal. The authors concluded that papaya has strong antioxidant potential against this damage. They cautioned that their short rat model may not reflect chronic human asbestos disease.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: Animal experiment (laboratory study in rats comparing four groups)
• Who was studied: 32 male albino rats in four groups of eight: normal control (NC), asbestos-exposed (PC), montelukast sodium 10 mg/kg (STD), and C. papaya leaf extract 500 mg/kg (C.P). The papaya leaves came from the botanical garden of the University of Agriculture Faisalabad, Pakistan. The study dates are not given in the readable text.
• Exposure: Asbestos fibers, given by exposure in a glass chamber for 2 to 3 hours daily. The readable text does not give the fiber type, the concentration or the number of exposure days. The Study Design section, where these details might appear, is garbled in the supplied text. The treatment was a 70% ethanol extract of C. papaya leaves.
• Main results:
  • SOD and catalase were decreased in the asbestos-exposed (PC) group and significantly increased in the papaya (C.P) group (p less than or equal to 0.05).
  • Serum MDA, a marker of lipid damage, was significantly higher in the PC group than in the C.P group (p less than or equal to 0.05).
  • Nitric oxide was significantly elevated in the PC group (p less than or equal to 0.05).
  • Protein markers in lung lavage fluid (BALF) and the lung wet-to-dry ratio increased in the PC group and declined significantly in the C.P group (p less than or equal to 0.05).
  • Expression of the NFE2L2 (NRF2) gene was significantly lower in the PC group than in the NC group (p less than or equal to 0.05). It was significantly higher in both the STD and C.P groups.
  • The calcium-signaling genes GRK-2, CALM-2 and PIAS-2 were significantly upregulated in the PC group compared with the NC group. They were significantly downregulated in the STD and C.P groups (p less than or equal to 0.05).
  • Under the microscope, NC lungs were normal. PC lungs showed thickened airways, fibrotic alveolar walls and lodged asbestos fibers. C.P lungs showed a restored profile with better alveolar architecture.
  • The papaya leaf extract had a total phenolic content of 540 plus or minus 2.8868 mg gallic acid per gram.
• The authors' conclusion: The authors concluded that C. papaya shows strong antioxidant potential to reduce oxidative stress caused by an inorganic source (asbestos) in this rat model. They also stated that it may modulate calcium signaling, NRF2-related antioxidant pathways and apoptosis-related signaling in lung damage.
• Limitations the authors state:
  • The exposure regimen was designed to cause sub-chronic injury without deaths. It may therefore not fully replicate chronic, progressive human asbestos-related lung disease.
  • Differences between rats and humans in drug metabolism, immune response and tissue repair call for caution in applying the findings to humans.

Topics

Medical terms in this study, explained in our Lexicon: Histopathology, Biomarker, Parenchyma, Oxidative Stress.

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