The protective effect of allantoin in yam on cyclophosphamide induced premature ovarian failure
Premature ovarian failure (POF) is a common disease of the gynecological endocrine system. In recent years, the incidence rate of POF in women of childbearing age has increased, and the decline of ovarian function has seriously affected the quality of life of patients, and significantly increased the risk of cardiovascular disease, osteoporosis, metabolic disorders and other related diseases. In cancer and systemic lupus erythematosus patients, the clinical application of POF and cyclophosphamide (CP) is closely related. CP can interfere with ovarian function through oxidative stress, hormone secretion, and inflammation. Finding a safe and effective ovarian function protector is the key to subsequent clinical drug development.
Yam, as one of the traditional Chinese medicinal materials with the same origin of medicine and food, contains rich active ingredients such as steroidal saponins, polysaccharides, allantoin, flavonoids, and phenolic glycosides. The diversity of its chemical composition gives it various pharmacological effects, such as antioxidant, anti-inflammatory, immune regulation, uric acid lowering, anti-tumor, and therapeutic effects on kidney disease. Research has shown that the development and utilization of Chinese medicinal materials and natural products that share the same origin as food and medicine are of great significance in protecting the ovaries. Allantoin (ALL) is the main active ingredient in yam, which has functions such as anti stress, anti-inflammatory, regulating intestinal microbiota, and promoting cell growth. In previous studies, the research team found that yam and ALL have estrogen like effects through the expression of estrogen receptor alpha and G protein coupled estrogen receptors in uterine tissue. Natural plant estrogens have a positive effect on the development of ovarian follicles in rats. Therefore, this study used a CP induced premature ovarian failure rat model to explore how ALL improves hormone levels, follicle development, and maturation levels in POF rats, and explored its mechanism of improving POF from the perspective of oxidative stress, providing reference for the development and utilization of yam and its active ingredient ALL in female reproductive protection.

 

Cyclophosphamide (CP) is a chemotherapy drug widely used to treat malignant tumors and autoimmune diseases, but its toxic side effects are strong and can cause permanent damage to the ovaries. In the past few decades, the protection of reproductive ability and the recovery of ovarian function have become very important in cancer treatment, as this treatment regimen can improve the quality of life of female cancer patients. In addition, CP can also affect major organs such as the heart and kidneys by activating oxidative stress markers and overconsumption of antioxidant defense mechanisms. Therefore, improving CP’s damage to organs by regulating oxidative stress is one of the focuses of this study.

The toxicity of CP is related to the production of one of its metabolites, acrolein. After CP treatment, cancer patients show a significant decrease in glutathione (GSH), which may be the result of the binding of acrolein. GSH is a tripeptide and an important antioxidant and free radical scavenger in the body. At the same time, CP also alters the activity of other endogenous antioxidants in healthy ovarian tissue, such as SOD, promoting intracellular free radical damage in ovarian cells. In this study, ALL significantly protected rat ovaries from oxidative stress caused by CP. ALL is a metabolite produced by purine degradation, which exists in the bodies of animals and plants. It can promote skin cell growth and wound healing, stimulate fibroblast growth, and has estrogen like effects. Therefore, while exploring its protective effects against organ damage, this study also focuses on its antioxidant effects and pathways of action. In this study, 70mg/kg and 140mg/kg of allantoin were found to maintain ovarian GSH Px and SOD activity, and significantly inhibit MDA, protecting rat ovaries from CP induced oxidative stress induced ovarian damage.

The nuclear transcription factor Nrf2 belongs to the CNC leucine zipper transcription activator family, which protects protein coding genes by inducing antioxidant activity and regulates oxidative deoxygenation reactions in the intracellular environment. Nrf2 activates downstream antioxidant proteins and enzymes by binding to antioxidant response elements (ARE), and protects against oxidative stress. In this study, we found a decrease in Nrf2 expression and an increase in oxidative stress in the ovaries of POF rats; ALL regulates the level of Nrf2 at a certain dose. Research has shown that the expression of downstream target genes (HO-1, NQO1, etc.) is consistent with Nrf2 nuclear translocation, which not only confirms the involvement of the Kelch like as social protein 1 (Keap1) – Nrf2 ARE pathway, but also suggests that HO-1 and NQO1 play a critical role in maintaining redox homeostasis. HO-1 is a subtype of heme oxygenase that is easily stimulated and induced, playing an indirect antioxidant role. NQO1 can clear superoxide anion radicals and alleviate the excessive accumulation of reactive oxygen species (ROS) upregulated by oxidative stress. In our study, the POF rat model did not show significant expression of NQO1 in its ovaries. However, after continuous administration for 14 days, the positive drug EV and ALL significantly increased the expression level of NQO1 at a dose of 70mg/kg, suggesting that they may also play a positive role in ovarian injury stress. This result may be related to the stability, dual active sites, and non enzymatic activity of NQO1. It is possible that CP stimulation did not activate NQO1, while ALL can bind to the active site at a certain dose. Therefore, further research and exploration are needed. The POF rat model significantly reduced the expression of HO-1 in the ovaries, while the positive drug EV and ALL showed a significant improvement in HO-1 expression at a dose of 140mg/kg. HO-1 is a stress responsive protein that catalyzes the degradation and conversion of heme proteins into bilirubin. The products of its breakdown metabolism have antioxidant, anti apoptotic, and immunomodulatory effects. Therefore, HO-1 can play a protective role under stress, suggesting that ALL may improve ovarian injury in POF rats by regulating HO-1 to exert antioxidant stress effects. Further research is needed to investigate the impact of oxidative stress on the NQO1 pathway in this study.

ALL increased the expression of HO-1 and Nrf2 in the ovarian tissue of POF rats, alleviated oxidative stress, regulated hormone levels, and improved ovarian dysfunction in POF rats. This study provides a reference for the development and utilization of yam and its active ingredient ALL.