With reference to previous systematic reviews on male infertility (Li et al., 2022; You et al., 2020), we developed relevant search terms (Table 1). We searched the PubMed, Web of Science, and other databases for relevant studies up to April 2025. Additionally, we reviewed the reference lists of the articles identified through our search strategy and selected relevant literature based on their keywords.

HPG axis plays a central role in regulating male reproductive health by orchestrating the synthesis and release of key hormones, including gonadotropin-releasing hormone (GnRH) from the hypothalamus, luteinizing hormone (LH) and follicle-stimulating hormone (FSH) from the pituitary gland, and T from the testes. This tightly regulated axis governs the proliferation and maturation of germ cells, the maintenance of testicular architecture, and the overall capacity for spermatogenesis (Li et al., 2024). Disturbances in HPG axis function due to aging, chronic diseases, stressors, or exposure to endocrine-disrupting chemicals can impair spermatogenesis and T biosynthesis, leading to male reproductive dysfunction (Selvaraj et al., 2021). LBP, a major bioactive metabolite of Lycii Fructus, has been shown to exert protective effects against various etiologies of male reproductive dysfunction, primarily through modulation of the HPG axis. Experimental studies using 10, 20, and 40 mg/kg doses of LBP demonstrated its effectiveness in reversing diabetes-induced sexual dysfunction and fertility impairment in male mice, primarily through restoring hormonal balance (GnRH, LH, FSH, and T) (Shi et al., 2017b). However, the streptozotocin (STZ) -induced type 1 diabetes model used in this study, which causes complete β-cell destruction, may not accurately reflect human diabetes progression, potentially affecting the interpretation of LBP’s true efficacy (Furman, 2021). Additionally, the study’s failure to examine local testicular factors (e.g., oxidative stress and inflammatory markers) limits comprehensive understanding of LBP’s protective mechanisms and whether its reproductive benefits extend beyond HPG axis regulation. LBP administration (10 mg/kg) effectively restored heat exposure-induced reductions in T, LH and FSH levels while improving oxidative stress markers [increased superoxide dismutase (SOD) activity and decreased malondialdehyde (MDA) content] in the heat stress model. Similar treatment in hemicastrated rats significantly elevated serum T and lowered E2 levels without affecting LH/FSH, indicating potential direct effects on Leydig cells. Both models showed consistent dose-dependent responses with parallel improvements in sexual behavior and sperm quality (Luo et al., 2006). The study’s limitation in assessing key regulatory factors like GnRH, however, precludes definitive mechanistic conclusions. In another heat stress-induced testicular injury model, Hu et al. found that LBP could enhance the expression of Androgen receptor (AR) and Akt phosphorylation in Sertoli cells (Figure 4), stabilize the blood-testis barrier (BTB), and protect spermatogenic function, providing experimental evidence for the clinical prevention and treatment of male reproductive heat stress-induced injuries (Hu et al., 2021a).

In the context of aging-related hypogonadism, Lycii Fructus extract improves serum T levels and upregulates AR expression in testicular tissue, suggesting therapeutic potential in late-onset hypogonadism (LOH) without adversely affecting prostate volume or function (Jeong et al., 2020). In environmental toxicity models, such as juvenile zebrafish exposed to nonylphenol, the study found that LBP could ameliorate testicular damage by stimulating androgen secretion and enhancing antioxidant capacity (Tang et al., 2017). Moreover, LBP has been shown to restore T levels and mitigate androgen decline in animal models subjected to chronic ethanol exposure (Liu et al., 2020), restraint stress (Meng et al., 2022), and diet-induced obesity (Yang et al., 2020), further supporting its role in HPG axis homeostasis.

Oxidative stress plays a pivotal role in testicular injury and male reproductive dysfunction. Excessive generation of reactive oxygen species (ROS) not only damages testicular tissue structure, impairs spermatogenic cells and the BTB, but also induces cell apoptosis and disrupts T synthesis, ultimately leading to decreased fertility (Leisegang et al., 2017). LBP has been extensively reported to exhibit potent antioxidant properties, thereby mitigating testicular injury and reproductive dysfunction caused by various environmental and pathological stressors. In multiple animal models, LBP significantly enhances endogenous antioxidant defenses and reduces oxidative stress, effectively alleviating testicular damage induced by chemotherapeutic agents (e.g., cyclophosphamide and doxorubicin) (Qian and Yu, 2016; Xin et al., 2012), environmental toxins (e.g., bisphenol A and cadmium) (Varoni et al., 2017; Zhang et al., 2013), ionizing radiation (e.g., 60Co-γ irradiation) (Luo et al., 2011), and metabolic disturbances such as diabetes and obesity (Shi et al., 2017a; Yang et al., 2020).

LBP at doses of 0.2, 0.4, and 0.6 g/kg significantly enhanced testicular SOD activity and reduced nitric oxide (NO) levels in a dose-dependent manner, effectively mitigating cyclophosphamide-induced sperm quality deterioration. However, the underlying mechanisms regulating antioxidant enzyme expression by LBP remain to be elucidated LBP (200 mg/kg) effectively reversed doxorubicin-induced elevation of MDA levels and reduction of glutathione peroxidase (GSH-Px) activity, while increasing plasma T levels. This treatment significantly ameliorated doxorubicin-induced testicular weight loss, decreased sperm concentration and motility, and reduced abnormal sperm rates, ultimately attenuating doxorubicin-induced degenerative changes in seminiferous tubules. But the study lacked dose-gradient experiments, and the precise mechanisms underlying its antioxidant effects remain unclear (Xin et al., 2012). LBP at doses of 50, 100, and 200 mg/kg all significantly increased SOD and glutathione GSH-Px activities while reducing MDA content, effectively alleviating bisphenol A (BPA)-induced spermatogenic damage in mouse testes and significantly increasing testicular and epididymal weights. However, these protective effects did not exhibit dose-dependent enhancement. (Zhang et al., 2013). However, Qian & Yu’s study demonstrated that LBP at doses of 0.2, 0.4, and 0.6 g/kg could dose-dependently and significantly enhance testicular SOD activity while reducing nitric oxide (NO) levels, effectively mitigating cyclophosphamide-induced sperm quality deterioration (Qian and Yu, 2016). In the context of radiation-induced injury, LBP significantly antagonizes the deleterious effects of 60Co-γ irradiation on male reproductive function by enhancing antioxidant enzyme activity, reducing DNA damage, maintaining hormonal balance, and improving sexual performance (Luo et al., 2011). Additionally, LBP exhibits therapeutic efficacy in models of metabolic and aging-related testicular injury. In STZ -induced diabetic mice, LBP improves spermatogenesis and preserves testicular architecture by attenuating oxidative stress and inhibiting apoptosis (Shi et al., 2017a). In obesity-induced male infertility, LBP reduces testicular oxidative and endoplasmic reticulum (ER) stress, enhances insulin sensitivity, and restores androgen levels (Yang et al., 2020).

Other metabolites of Lycii Fructus, such as Lycium barbarum seed oil (LBSO) and BET, also display significant antioxidative properties. LBSO alleviates oxidative stress in D-galactose-induced subacute testicular aging and TM4 Sertoli cells by suppressing mitochondrial oxidative stress through the SIRT3/AMPK/PGC-1α signaling pathway (Yang et al., 2021) (Figure 5). BET, a key active component of Lycii Fructus, protects the BTB in diabetic mice by suppressing oxidative stress and modulating the p38 MAPK signaling cascade (Jiang et al., 2019) (Figure 5). Furthermore, in a rat model of testicular torsion-reperfusion injury, Lycii Fructus extract enhance total antioxidant capacity and reduce lipid peroxidation, thus mitigating ischemia-reperfusion-induced testicular damage (Dursun et al., 2015). Collectively, these findings underscore the robust antioxidant capacity of LBP and other Lycii Fructus metabolites in counteracting testicular oxidative damage across a wide spectrum of injury models, highlighting their therapeutic potential in male reproductive disorders. Nevertheless, further research is warranted to elucidate the precise molecular targets and regulatory pathways underlying these protective effects.

Apoptosis, a form of programmed cell death, plays a crucial role in maintaining testicular homeostasis and spermatogenesis (Cao et al., 2025). In the testis, apoptosis facilitates the removal of excess, damaged, or defective germ cells during spermatogenesis, ensuring an optimal balance between germ cell proliferation and maturation (Simões et al., 2013). However, under pathological stimuli—including diabetes, ionizing radiation, chemical or drug toxicity, and chronic psychological stress—the intrinsic (mitochondrial) and extrinsic (death-receptor) apoptotic pathways can become excessively activated, resulting in germ cell depletion, disruption of the seminiferous epithelium, Leydig and Sertoli cell dysfunction, and suppressed T biosynthesis (Yi et al., 2022). Excessive germ cell apoptosis and Sertoli cell injury impair the supportive microenvironment, while Leydig cell apoptosis reduces androgen levels, collectively impairing spermatogenesis and contributing to male infertility. Mitochondria play a central role in this process by releasing pro-apoptotic factors, such as cytochrome c, into the cytoplasm, triggering caspase cascades that lead to DNA fragmentation and cellular demise (Xu et al., 2020). ER-mediated stress pathways also contribute by upregulating CHOP and activating caspase-12, further sensitizing testicular cells to apoptotic signaling (Yang et al., 2020). Thus, regulating testicular apoptosis represents a promising therapeutic target for preserving reproductive function.

LBP has been reported to attenuate apoptosis and oxidative stress in STZ-induced diabetic mice, thereby improving spermatogenic capacity (Lei et al., 2020; Shi et al., 2018; Shi et al., 2017a). The administration of LBP (10 mg/kg) alleviates low-dose ionizing radiation-induced spermatogenic cell apoptosis by upregulating the expression of the anti-apoptotic gene Bcl-2, downregulating the pro-apoptotic gene Bax, and modulating the Bcl-2/Bax ratio. Additionally, it prevents mitochondrial membrane potential depolarization and reduces mitochondrial membrane permeability, thereby mitigating testicular morphological damage (Luo et al., 2014). However, this study failed to establish a dose-response relationship and lacked positive controls (e.g., amifostine) for comparative evaluation of LBP’s relative radioprotective efficacy. In an in vitro cryopreservation study, Yan et al. found that adding LBP to glycerol-egg-yolk-citrate cryopreservation medium increased anti-apoptotic Bcl-2 levels while decreasing pro-apoptotic Bax, cytochrome C, and caspase-3. The modified medium also reduced ROS production. These results suggest LBP protects mitochondrial structure and sperm function by suppressing ROS generation during freeze-thaw cycles, thereby preventing activation of mitochondrial apoptotic pathways (Yan et al., 2020). The study found that consecutive 14-day intraperitoneal administration of BET (200 mg/kg) alleviated testicular damage in male mice subjected to chronic restraint stress (CRS), significantly reducing apoptosis in seminiferous tubules and germ cells without affecting serum testosterone levels. This suggests that BET may exert its testicular protective effects through testosterone-independent pathways, offering a potential dietary intervention strategy for male fertility issues caused by psychological stress (Meng et al., 2022). Additionally, LBP protects Leydig MLTC-1 cells from cisplatin-induced injury by inhibiting ER stress-mediated apoptosis and promotes T production (Yang et al., 2018b) (Figure 4). Collectively, these findings demonstrate that LBP and its related metabolites can modulate both mitochondrial and ER-stress-mediated apoptotic pathways, thereby protecting testicular cells under various pathological insults.

Autophagy is a conserved cellular process that helps remove damaged organelles and misfolded proteins under stress conditions, thus preserving cell survival and homeostasis (Yovitania et al., 2022). In male reproductive disorders, dysregulated autophagy—either insufficient or excessive—has been implicated in impaired spermatogenesis, testicular degeneration, and hormonal imbalance (Chen et al., 2025). Therefore, restoring autophagic balance, rather than simply enhancing or inhibiting it, may help stabilize the testicular microenvironment and improve male fertility. In addition to its anti-apoptotic properties, LBP also exhibits robust autophagy-modulating effects under various pathological conditions.

In in vivo experiments, LBP, 40 mg/kg significantly improved testicular dysfunction in STZ-induced diabetic mice by upregulating the protein expression of phosphorylated PI3K and Akt, and downregulating the protein and mRNA expression of autophagy markers Beclin-1 and LC3I. These results suggest that excessive or maladaptive autophagy may contribute to testicular damage in diabetic conditions, and LBP exerts a protective effect by rebalancing autophagy. However, the study did not establish a causal link between PI3K/Akt activation and autophagy modulation (Shi et al., 2018). Similarly, di(2-ethylhexyl) phthalate (DEHP) promotes the expression of pro-apoptotic proteins such as caspase-3, caspase-8, and Bax, and exacerbates apoptosis by reducing the Bcl-2/Bax ratio, demonstrating dose-dependent toxicity. Lycium barbarum glycopeptide (LBGP), a glyco-conjugate further purified from LBP, is considered one of the most bioactive metabolites of Lycii Fructus (Dai et al., 2023). Zhou et al. found that 100 mg/kg LbGp alleviates testicular injury in mice by reversing DEHP-induced excessive autophagy (downregulation of SIRT1 and upregulation of FoxO3a and LC3), while showing no significant effect on cleaved caspase-3. This suggests that its protective mechanism primarily involves modulating autophagy rather than directly inhibiting apoptosis. Despite these promising results, both studies lack in vitro validation and genetic approaches (e.g., gene knockouts or siRNA), making it difficult to confirm the precise molecular targets involved. Future research should focus on cellular-level investigations to elucidate its molecular mechanisms (Zhou et al., 2022).

Chronic inflammation plays a pivotal role in the pathogenesis of various male reproductive disorders, particularly in pathological conditions such as testicular injury, varicocele, diabetes, and chronic stress-induced reproductive decline. Inflammatory mediators can disrupt the integrity of the BTB (Chojnacka et al., 2016), impair spermatogenesis, exacerbate oxidative stress responses, and promote apoptosis of testicular germ and supporting cells (Figure 5). Macrophages, as key immune cells resident in the testicular microenvironment, have emerged as central regulators of inflammation in male reproductive tissues (Schuppe et al., 2008). Under homeostatic conditions, testicular macrophages contribute to immune privilege and tolerance to autoantigens produced during spermatogenesis (Mosser et al., 2021). However, in response to injury or stress, macrophages become activated and secrete a range of pro-inflammatory mediators, including tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), and interleukin-6 (IL-6), which can impair Sertoli and Leydig cell function, damage seminiferous tubules, and inhibit T synthesis (Shi et al., 2022). Experimental models of male reproductive injury have demonstrated that an imbalance in macrophage polarization—specifically an increase in pro-inflammatory M1 macrophages—is associated with more severe testicular dysfunction and reduced fertility (Balgetir et al., 2024; Li et al., 2023).

Natural metabolites with anti-inflammatory and immunomodulatory properties have garnered increasing attention in the prevention and treatment of male infertility. Studies have shown that BET can significantly improve testicular histoarchitecture and sperm quality in a CRS mouse model, restoring the structural integrity of seminiferous tubules, likely by reducing testicular oxidative stress and levels of pro-inflammatory cytokines (including TNF-α and IL-6) (Meng et al., 2022). In addition, LBP demonstrates potent immunomodulatory activity in a cyclophosphamide-induced male reproductive toxicity model. Research indicates that LBP effectively improves sperm motility, viability, and morphology, while also regulating both systemic and local cytokine levels. It promotes the expression of anti-inflammatory cytokines and inhibits the release of pro-inflammatory mediators (Qian, 2019). These findings suggest that Lycii Fructus–derived metabolites, such as BET and LBP, may help alleviate male reproductive dysfunction by modulating inflammatory responses within the testes. However, current evidence on their specific anti-inflammatory mechanisms remains limited, and further studies are needed to elucidate their immunomodulatory targets, signaling pathways, and therapeutic relevance in inflammation-driven infertility.

Testicular fibrosis is a hallmark feature of chronic testicular injury and a major contributor to irreversible spermatogenic failure. It is characterized by excessive extracellular matrix (ECM) deposition, disruption of seminiferous tubule architecture, and loss of the germ cell microenvironment (Willems et al., 2022). Persistent oxidative stress, inflammation, and apoptosis are known to promote the activation of fibrotic signaling pathways, leading to collagen accumulation and testicular degeneration. Central to this process is the activation of profibrotic cytokines, such as transforming growth factor-beta (TGF-β), as well as the activation of fibroblasts and peritubular myoid cells, which secrete abnormal amounts of collagen types I, III, and IV, along with fibronectin (Xiao et al., 2022). Dysregulated interactions between immune cells (e.g., macrophages, mast cells) and testicular somatic cells further exacerbate ECM accumulation and tissue remodeling, creating a vicious cycle that sustains fibrosis and impairs spermatogenesis (Xu et al., 2024).

Studies have demonstrated that LBP exerts protective effects against ethanol-induced testicular fibrosis and spermatogenic damage. In a chronic low-dose ethanol exposure model in mice, LBP administration significantly improved sperm quality, reduced germ cell apoptosis, and downregulated the expression of fibrosis-related genes such as Col1a1 and Col1a2 (Liu et al., 2020). Similarly, DEHP has been shown to induce abnormal collagen fiber deposition in the testicular interstitium, leading to fibrosis and impaired spermatogenesis. In animal studies, Masson staining revealed marked collagen accumulation following DEHP exposure, while intervention with LbGp significantly alleviated this deposition. Specifically, compared to the control group, the collagen volume fraction (CVF) in the DEHP group increased by 1.90% (P > 0.05), whereas the DEHP + LbGp group showed a 1.86% reduction in CVF compared to the DEHP group (P > 0.05), suggesting a trend toward antifibrotic activity of LbGp, though the changes did not reach statistical significance (Zhou et al., 2022). Moreover, Lycii Fructus appears to exert its antifibrotic effects through multiple mechanisms. First, LBP reduces oxidative stress by upregulating antioxidant enzymes, thereby mitigating ROS-mediated fibroblast activation. Second, LBP suppresses proinflammatory cytokines such as TNF-α and IL-6, both of which are known to promote a fibrotic microenvironment. Third, there is evidence that LbGp may downregulate the TGF-β signaling pathway—a canonical pathway implicated in fibrosis across multiple organs—though this mechanism requires further validation in testicular tissue (Liang et al., 2025).

Wuzi Yanzong Pill is a classical TCM compound formulas for male infertility, composed of five botanical drugs: Lycii Fructus, Cuscuta chinensis, Rubus chingii, Schisandra chinensis, and Plantago asiatica. It is widely used in the treatment of conditions such as oligospermia, asthenospermia, and reduced sexual function. In recent clinical trials of TCM treatments for male infertility, Wuzi Yanzong Pill is frequently used as a control drug, and its safety and efficacy have been well recognized. Basic research has shown that Wuzi Yanzong Pill may exert its effects by regulating testicular oxidative stress, improving mitochondrial function in sperm, and promoting the secretion of reproductive hormones (Hu et al., 2021b; Zeng et al., 2010). A meta-analysis of 11 randomized controlled trials (n = 951) demonstrated that WuZi YanZong formula as an adjuvant therapy significantly improved pregnancy rates (RR 1.68, 95% CI 1.34–2.11) and multiple semen parameters including sperm concentration (+6.87 × 10⁶/mL), total motility (+15.55%), and morphology (−10.38% abnormalities) in men with infertility (Cui et al., 2025). Wuzi Yanzong Pill is generally considered safe and well-tolerated. Most clinical trials either reported no adverse effects or failed to mention them. When reported, side effects were mild and included gastrointestinal discomfort, dizziness, and occasional allergic reactions like skin rash and itching (Cui et al., 2025). These symptoms typically resolved after discontinuing the medication. As shown in Table 3, a randomized controlled trial (n = 80) showed that after 12 weeks of treatment, Yougui Capsules (1.68 g three times daily) demonstrated superior efficacy to Wuzi Yanzong Pills (6 g twice daily) in improving sperm viability (65.7% ± 13.1% vs. 38.1% ± 11.1%) and progressive motility (grade a+b: 47.6% ± 15.8% vs. 24.1% ± 10.9%) in patients with oligoasthenospermia (all P < 0.05), though both treatments showed significant improvements from baseline (He et al., 2012).

Qilin Pill (QLP) is a well-known TCM compound formulas specifically developed for the treatment of male infertility, particularly oligoasthenospermia. Composed of multiple botanical drugs, it has been widely used in clinical practice to improve semen quality and enhance reproductive outcomes (Table 3). Several clinical trials have demonstrated its efficacy and safety in improving sperm parameters and pregnancy rates. A prospective randomized trial (n = 168) demonstrated that 6-month treatment with QLP (6 g tid) significantly improved semen parameters in oligoasthenospermic men compared to placebo, with marked increases in sperm concentration (25.13 vs. 11.62 × 10⁶/mL), total motility (56.33% vs. 26.23%), and pregnancy rates (32.91% vs. 15.85%). However, the study did not report any safety data regarding the medication (Huang et al., 2019). A multicenter randomized double-blind trial (n = 216) demonstrated that 12-week treatment with QLP (6 g tid) significantly improved semen parameters in oligoasthenospermic men compared to Wuzi Yanzong Pills controls, showing time-dependent increases in sperm motility (baseline 21.75%–32.95%), total sperm count (156.27–205.44 × 10⁶/mL), and progressively motile sperm (32.08–61.10 × 10⁶/mL). Safety analysis revealed 10 adverse events in total, with 6 cases (5.56%) in the QLP group (4 cases of mild ALT elevation and 2 cases of mild T-Bil elevation, all leading to treatment discontinuation) and 4 cases (3.74%) in the control group (2 cases of mild ALT elevation, 1 case of abnormal γ-glutamyl transferase requiring treatment cessation, and 1 case of upper respiratory infection that continued medication). The incidence of adverse events showed no statistically significant difference between groups (Mao et al., 2017). A multicenter open-label trial (n = 310 completers) demonstrated that 12-week treatment with QLP (6 g tid) significantly improved semen parameters in oligoasthenospermia patients compared to Wuzi Yanzong Pills controls (6 g bid), with superior increases in sperm concentration, grade a+b motility, and progressive motility (grade a) at all timepoints. While both groups showed improvement from baseline, the QLP group exhibited significantly greater enhancement in all semen parameters. Safety monitoring showed no adverse reactions in the QLP group, while the control group reported 5 cases of mild stomach pain, 2 cases of acid reflux, and 1 case of diarrhea - all of which were mild and did not affect treatment continuation (Shang et al., 2011).

A randomized controlled trial (n = 66) demonstrated that compared to levocarnitine, 12-week treatment with Qixiong Zhongzi Decoction (QZD; 150 mL bid) significantly improved sperm progressive motility (22.7% ± 9.0% vs. 14.1% ± 8.8%) and non-progressive motility (38.7% ± 14.1% vs. 26.2% ± 15.4%) in patients with idiopathic asthenozoospermia (all P < 0.05), while no intergroup differences were observed in semen volume, density, or pregnancy rates. During treatment, two mild adverse events occurred in the QZD group (1 case of cold and 1 case of nausea), and 1 case of headache was reported in the control group, all of which resolved spontaneously without intervention (Wang et al., 2020). A multicenter randomized open-label trial (n = 190 completers) demonstrated that 12-week treatment with Huanshao Capsules (HSC; 3 capsules tid) significantly improved semen parameters in oligoasthenospermia patients with spleen-kidney asthenia compared to Wuzi Yanzong Pills (6 g bid), with time-dependent increases in sperm concentration (baseline 14.78 to 28.78 × 10⁶/mL), progressive motility [grade a: 12.17%–26.97%; Progressively Motile Sperm (PMS): 24.78%–47.67%], and viability (38.64%–60.45%). HSC also achieved higher pregnancy rates (29.17% vs. 18.09%, P < 0.05). Safety monitoring revealed 3 cases of mild and transient dry mouth/throat in the HSC group, which resolved with increased water intake, while the control group reported 4 cases of gastrointestinal discomfort (nausea with/without vomiting) that improved after adjusting medication timing to 30 min post-meal (Yang et al., 2018a).

Overall, although clinical trials exclusively evaluating Lycii Fructus are scarce, current evidence from compound formulas containing Lycii Fructus suggests consistent improvements in semen quality and pregnancy outcomes, with a favorable safety profile. Further rigorously designed trials focusing on Lycii Fructus as a standalone intervention are needed to clarify its specific clinical efficacy.