Protective effects of phenolic phytochemicals on male fertility: a narrative review.

Infertility is a global health issue and is closely related to oxidative stress, which occurs when high concentrations of free radicals surpass the protective effects of antioxidant molecules and enzymes. Such imbalance causes damage to DNA, as well as cellular proteins and lipids, ultimately leading to the destruction of the blood-testis barrier. This, in turn, hinders spermatogenesis. Various plants and compounds have been employed in an attempt to reverse these damages, such as phenolic compounds. Therefore, this review aims to identify the main phytochemical phenolic compounds and their respective effects when used in the treatment of male infertility. Related information concerning phenolic phytochemical compounds was gathered from studies selected from PubMed, Scopus, and Web of Science databases. The search was conducted using the combination of six terms: "phenolic compounds", "male infertility", "testis", "spermatozoa", "testosterone" and "male fertility". These compounds can raise testosterone levels, reduce lipid peroxidation, and improve tubular histoarchitecture in cases of subfertility associated with diabetes mellitus. They can also mitigate the damage caused by obesity by increasing serum testosterone, antioxidant activity, and sperm motility. When it comes to fertility problems caused by inorganic and organic pollutants, these compounds effectively restore the structure of the seminiferous tubules, increase testosterone levels, and improve sperm quality. Furthermore, phenolic phytochemical compounds have shown beneficial effects in countering the adverse impacts of certain drugs on testicular physiology by reducing apoptosis in testicular tissue, increasing the number of Leydig cells, and promoting spermatocyte production. However, while these compounds may have protective effects on sperm cryopreservation for in vitro fertilization, caution is needed as certain dosages can cause irreversible damage to sperm quality. Overall, plant extracts containing phenolic phytochemical compounds hold promise as a therapeutic avenue for treating infertility and subfertility caused by metabolic disorders and environmental pollutants.