Immunoregulatory Effects of Astragalus membranaceus Extracts and Research Progress
Immune function is a vital process through which the body maintains health, defends against foreign pathogens, and repairs tissue damage. Its stability is directly associated with a range of health issues, including infections, tumors, metabolic diseases, and aging. With the rising incidence of immune-related disorders, exploring safe and effective natural immunomodulators has gained significant importance. Astragalus membranaceus, a frequently used traditional Chinese medicinal herb, has drawn considerable attention due to its remarkable immunomodulatory properties. This article reviews the research progress on the immunomodulatory activities of Astragalus membranaceus, explores its clinical application prospects and future development directions, aiming to provide references for in-depth research and application of Astragalus membranaceus in the field of immune health.
Keywords: Astragalus membranaceus; Immunomodulation; Active components; Mechanisms of action; Clinical prospects
1. Introduction
Immune system homeostasis is crucial for maintaining bodily health. It not only identifies and eliminates pathogens, tumor cells, and foreign substances but also plays a central role in preserving internal environmental balance, regulating inflammatory responses, and facilitating tissue repair. Imbalances in the immune system can lead to either immune hypofunction or excessive immune activation, which may further trigger a variety of diseases. In recent years, with the increasing prevalence of chronic diseases and the expanding aging population, immune regulation has emerged as an important strategy for preventing infections, improving health status, and enhancing treatment efficacy. A growing body of experimental and clinical studies has confirmed that Astragalus extracts and their major active components exert immunopotentiating and immune balance-regulating effects through multi-component, multi-target, and multi-pathway mechanisms. These effects not only effectively strengthen the body’s defense against pathogenic invasion but also ameliorate immune hypofunction, aiding in the management of tumors and chronic diseases. For instance, Astragalus can enhance the phagocytic and killing capacities of innate immune cells (such as macrophages and natural killer cells), promote the proliferation and differentiation of adaptive immune cells (including T and B lymphocytes), and regulate the balance between pro-inflammatory and anti-inflammatory cytokines. Additionally, Astragalus exerts regulatory effects on gut microbiota and the mucosal immune system, which is particularly critical for maintaining overall immune homeostasis.
2. Main Active Components of Astragalus Extracts and Their Immunomodulatory Effects
The immunomodulatory effects of Astragalus extracts primarily stem from the synergistic actions of polysaccharides, saponins, and flavonoids. Among these, Astragalus polysaccharides (APS) are recognized as the most pivotal active components. They can enhance the activity of immune cells—for instance, boosting the phagocytic capacity of macrophages, promoting the proliferation and function of T and B lymphocytes, and regulating the secretion of various immune signaling molecules in the body. Experimental studies, for example, have shown that APS can strengthen immune responses in mice, increase serum antibody levels, and upregulate the expression of factors associated with immune activation, thereby enhancing overall immunity. Saponins (such as astragaloside IV) primarily exert their effects in humoral immunity. Research indicates that they can promote the development and differentiation of B cells into antibody-secreting cells, thereby enhancing the body’s ability to recognize and eliminate foreign antigens. Additionally, saponins exhibit certain anti-inflammatory properties: they can inhibit excessive activation of inflammation-related signaling pathways and reduce the release of inflammatory mediators, helping to maintain immune system balance. Flavonoids (e.g., calycosin) possess dual antioxidant and immunomodulatory activities. On one hand, they can scavenge excessive free radicals in the body, mitigating oxidative stress-induced damage to immune cells. On the other hand, they help regulate the balance of immune responses—promoting the secretion of anti-inflammatory substances while inhibiting excessive inflammatory reactions, thus exerting both protective and regulatory effects on the immune system.
3. Analysis of Mechanisms of Action
3.1 Activation and Functional Regulation of Immune Cells
Astragalus extracts can enhance immune cell function through multiple pathways. Its polysaccharide components can significantly improve the phagocytic capacity of macrophages and the release of pro-inflammatory cytokines, and enhance bactericidal effects by activating intracellular signaling pathways. Meanwhile, Astragalus polysaccharides (APS) can regulate the proportion of T lymphocytes, promote the secretion of immunologically active factors, and weaken the function of regulatory T cells, thereby enhancing the overall immune response. Additionally, Astragalus extracts can boost the activity of natural killer (NK) cells, improving the body’s ability to eliminate tumor cells by inducing the secretion of key immune factors.
3.2 Regulation of Signaling Pathways
Astragalus extracts regulate immune responses through multiple signaling pathways. Its polysaccharide and saponin components can inhibit the activation of key pro-inflammatory signals, thereby reducing the production of inflammatory factors and alleviating inflammatory reactions. Flavonoid components can activate antioxidant pathways, promote the expression of endogenous antioxidant enzymes, and mitigate oxidative stress-induced damage to immune cells. Furthermore, Astragalus flavonoids can inhibit the activity of inflammation-related signaling molecules and reduce the release of pro-inflammatory factors, thereby improving the condition of immune-related diseases.
3.3 Regulation of Gut Microbiota
Recent studies have indicated that the immunomodulatory effect of APS is closely associated with its regulation of gut microbiota. Low-molecular-weight polysaccharides can selectively promote the growth of beneficial bacteria such as Bifidobacterium and Lactobacillus, improve the balance of intestinal microecology, and repair the intestinal mucosal barrier function. Through this "gut-immune axis" effect, Astragalus not only enhances local intestinal immunity but also further elevates systemic immune responses while reducing inflammation levels, providing a theoretical basis for its potential application in immunoregulation and health maintenance.
4. Experimental Studies and Clinical Applications
4.1 Validation via Animal Experiments
Animal studies have further verified the immunomodulatory effects of Astragalus extracts. In immunocompromised mouse models, after intervention with Astragalus, indices of spleen and thymus development significantly recovered, and serum immunoglobulin levels returned to the normal range. In tumor models, Astragalus extracts markedly promoted tumor cell apoptosis, while improving the proportion of splenic T cells and macrophage phagocytic function, thereby enhancing anti-tumor immunity. In infection models, Astragalus extracts inhibited viral replication and boosted the body’s immune response, exerting a protective effect against virus-induced diseases. These experimental findings provide robust evidence for the application of Astragalus in enhancing immune function and preventing/treating diseases.
4.2 Progress in Clinical Research
Clinical studies have further supported the immunomodulatory and adjuvant therapeutic effects of Astragalus extracts. In infectious diseases, healthy individuals who took Astragalus extract showed increased serum immunoglobulin levels and a significant reduction in the incidence of colds. In adjuvant cancer therapy, Astragalus polysaccharides activated natural killer cell function, reduced gastric cancer metastases, and repaired T cell function damaged by chemotherapy, thereby strengthening anti-tumor immunity. In metabolic diseases, Astragalus flavonoid extracts effectively lowered serum uric acid levels in patients with hyperuricemia and alleviated renal inflammatory damage by regulating inflammation-related signaling pathways. These findings indicate that Astragalus holds potential applications in infection prevention, adjuvant tumor immunotherapy, and metabolic disease intervention.
5. Safety and Rational Application
5.1 Safety Evaluation
Current clinical and pharmacological studies generally suggest that Astragalus extracts exhibit high safety at conventional doses. When the daily dosage does not exceed 30 grams, most individuals tolerate it well, with only a few reported cases of mild discomfort such as dry mouth and dry nose, which are mostly transient. Animal experiments and clinical observations indicate that long-term or excessive use may impose a certain burden on liver and kidney functions; thus, it is recommended that continuous use should not exceed three months. It is important to note that adulterants (e.g., Astragalus ernestii) exist in the market, which lack sufficient safety and efficacy and may cause adverse reactions. Therefore, strict selection of authentic medicinal materials such as Astragalus mongholicus or Astragalus membranaceus is essential.
5.2 Clinical Medication Recommendations
In clinical practice, the recommended dose of Astragalus polysaccharides as an immunomodulator is 10–50 mg/kg per day, and physicians may adjust the dose based on individual differences and disease conditions. Attention should be paid to interactions with other drugs during administration. For example, concurrent use with immunosuppressants may reduce the efficacy of the latter and is not recommended; when used in combination with anticoagulants, coagulation function should be monitored to prevent bleeding risks. In addition, individuals with constitution prone to yin deficiency with excessive fire or dampness-heat should use it with caution to avoid exacerbating symptoms. Pregnant women and lactating females should use it under the guidance of professional physicians to ensure safety and efficacy.
6. Comparative Advantages Over Other Immunopotentiators
Compared with commonly used Chinese medicinal herbs such as ginseng and Ganoderma lucidum, Astragalus extracts exhibit unique advantages in immunomodulation. It achieves bidirectional regulation: enhancing the defense capacity of individuals with hypoimmunity while inhibiting excessive inflammatory responses, thus making it suitable for various immune imbalance states. The mechanisms of action of Astragalus are diverse—it not only directly activates immune cells but also exerts comprehensive effects by regulating gut microbiota, enhancing antioxidant capacity, and intervening in multiple signaling pathways, whereas ginseng and Ganoderma lucidum primarily act through single components or pathways. Additionally, clinical studies on Astragalus in infection prevention, adjuvant tumor therapy, and metabolic disease intervention are more extensive. Its accessibility and cost-effectiveness also outperform some rare medicinal materials, endowing it with broader prospects for practical application and promotion.
7. Conclusions and Prospects
Astragalus extracts exert immunopotentiating effects at multiple levels—including immune cell activation, signaling pathway regulation, and gut microbiota modulation—through the synergistic actions of components such as polysaccharides, saponins, and flavonoids. Their clinical efficacy in infection prevention, adjuvant tumor therapy, and metabolic diseases has been fully validated, with favorable safety profiles. Future research should further clarify the targeted effects of different active components on specific immune cell subsets (e.g., the balance of regulatory T cells). Meanwhile, exploring novel formulations such as nano-delivery systems to improve bioavailability and achieve targeted therapy is warranted. Furthermore, integrating gut microbiota analysis and immune phenotyping to develop individualized intervention strategies will help optimize therapeutic outcomes. As a natural immunomodulator, the scientific application of Astragalus extracts is expected to provide new strategies for preventing and intervening in immune-related diseases, while advancing the modernization and precision of traditional Chinese medicine.
References
[1] Zhang X, Qu X, Zou Y. The effect of Astragalus on humoral and cellular immune response: a systematic review and meta-analysis of human studies[J]. Complementary medicine research, 2023, 30(6): 535-543.
[2] Wang X Y, Wang R C, Qu Z Y, et al. Advances on immunoregulation effect of astragalus polysaccharides[J]. Frontiers in Natural Products, 2022, 1: 971679.
[3] Li C X, Liu Y, Zhang Y Z, et al. Astragalus polysaccharide: a review of its immunomodulatory effect[J]. Archives of Pharmacal Research, 2022, 45(6): 367-389.
[4] Zhong Y, Liu W, Xiong Y, et al. Astragaloside Ⅳ alleviates ulcerative colitis by regulating the balance of Th17/Treg cells[J]. Phytomedicine, 2022, 104: 154287.
[5] Zheng Y, Ren W, Zhang L, et al. A review of the pharmacological action of Astragalus polysaccharide[J]. Frontiers in pharmacology, 2020, 11: 349.
[6] Li S, Hu X, Liu F, et al. Bioactive components and clinical potential of Astragalus species[J]. Frontiers in Pharmacology, 2025, 16: 1585697.
