Astragalus membranaceus is the dried root of the leguminous plant Astragalus membranaceus var. mongholicus or Astragalus membranaceus (A. membranaceus). Its main efficacies include replenishing qi, invigorating the spleen, lifting yang to arrest sinking, benefiting the defensive qi and consolidating the exterior, promoting urination and resolving swelling, and promoting the expulsion of toxins and healing sores. The main chemical components of Astragalus membranaceus include polysaccharides, flavonoids, saponins, amino acids, and a small amount of trace elements. It is a traditional medicinal material widely used in various clinical departments. Modern pharmacological research has shown that Astragalus membranaceus has effects such as protecting the brain, heart, and kidneys, bidirectionally regulating blood pressure, anti-tumor, anti-hypoxia, anti-osteoporosis, anti-oxidation, anti-aging, and regulating immune function. Clinically, it is mainly used in the treatment of cardiovascular diseases, urinary system diseases, ischemia-reperfusion, and so on.

Processing Methods of Astragalus Membranaceus

The processing of traditional Chinese medicines (TCMs) is a unique technique for processing medicinal materials under the guidance of traditional Chinese medicine theory, based on the needs of clinical syndrome differentiation and treatment, the inherent properties of medicinal materials, as well as the different requirements of dispensing and preparation. Proper processing of Astragalus membranaceus can enhance its therapeutic effects and weaken or eliminate its toxic and side effects. There are over 30 processing methods for Astragalus membranaceus, among which honey-fried, wine-fried, salt-fried, stir-fried without any additive, stir-fried with rice, and stir-fried with wheat bran are the most commonly used.

Honey-fried processing is a method that uses refined honey as an auxiliary material, and it is the most widely used method for processing Astragalus membranaceus. The 2015 edition of the Chinese Pharmacopoeia includes two types of prepared slices: Astragalus membranaceus and honey-fried Astragalus membranaceus. Traditional honey-fried processing methods have undergone continuous improvement, and there are currently two main operating methods: the method of mixing honey first and then stir-frying, and the method of stir-frying first and then adding honey. Currently, the method of mixing honey first and then stir-frying is more commonly used. Honey-fried Astragalus membranaceus has the effects of being sweet and warm, nourishing the middle and replenishing qi, moderating medicinal properties, strengthening the spleen and stomach, etc. Compared with raw Astragalus membranaceus, honey-fried Astragalus membranaceus has a milder medicinal property, a better effect of nourishing qi and blood, and an increased effect of warming the lungs and resolving phlegm.

The preparation method of wine-fried Astragalus membranaceus involves adding an appropriate amount of rice wine to Astragalus membranaceus and stir-frying it. For example, 60 mL of rice wine is used for 300g of raw Astragalus membranaceus. Mix well, let it stand for 1 hour, then place it in a hot pan and stir-fry over a gentle fire until dry. Remove and cool for later use. Compared with raw Astragalus membranaceus, wine-fried Astragalus membranaceus can lead the medicine upwards, promote blood circulation and collaterals, and enhance the efficacy of qi flow.

Salt-fried processing, also known as saltwater stir-frying, has two main operating methods. The first is the method of mixing saltwater first and then stir-frying to dryness, where the cleaned medicinal material is mixed with an appropriate amount of saltwater, left to soak and soften until the saltwater is fully absorbed, then placed in a pan and stir-fried over a gentle fire to a certain degree before being removed and cooled. The second is the method of stir-frying the medicinal material first and then adding saltwater, where the cleaned medicinal material is first stir-fried over a gentle fire to a certain degree, then sprayed with saltwater, stir-fried to dryness, and finally removed and cooled. Salt-fried Astragalus membranaceus often adopts the first method, such as mixing 300g of Astragalus membranaceus with saltwater (6g of salt) and stir-frying it over a gentle fire. Salt-fried Astragalus membranaceus can lead the medicine downwards to the kidney meridian, enhancing the effects of nourishing yin and reducing fire, promoting urination, and resolving swelling.

The frying method of processing can be divided into two major categories: plain frying and frying with auxiliary materials. Plain frying can be further subdivided into three types: stir-frying to a yellow color, stir-frying to a charred state, and stir-frying to a carbonized state. When stir-frying Astragalus membranaceus, a gentle fire is required, and the Astragalus membranaceus is stir-fried until its surface turns yellow. The method of plain stir-frying Astragalus membranaceus involves placing the Astragalus membranaceus slices in a pan and stir-frying them over a gentle fire until they turn yellow with scorch marks or a deep yellow color. Remove and cool. Plain stir-fried Astragalus membranaceus can nourish the spleen and replenish qi without causing stagnation, treating spleen deficiency with abdominal distension, poor appetite, and loose stools.

The rice-frying method is one of the frying methods with auxiliary materials. Rice has a long history as a processing auxiliary material. The preparation method of rice-fried Astragalus membranaceus involves placing rice in a pan and stir-frying it until it turns yellow. Then, pour in the cleaned Astragalus membranaceus slices and stir-fry them together until they turn a brownish yellow color. Remove, sieve out the rice, and cool. For every 10kg of Astragalus membranaceus slices, 2kg of rice is used. Rice-fried Astragalus membranaceus helps enhance the spleen-nourishing effect, while also promoting appetite and relieving diarrhea, correcting the inherent beany odor of Astragalus membranaceus.

Clinical Application Research of Astragalus membranaceus

1. Blood-Activating Effects

Ancient medical texts record that Astragalus membranaceus possesses properties such as "dispelling stagnant blood from the five viscera," "promoting blood circulation and blood formation," and "expelling maleficent blood," indicating its blood-activating effects. Modern research has also confirmed that Astragalus membranaceus exhibits antiplatelet aggregation, antithrombotic, and blood volume expansion effects. The modern pharmacological manifestations of its blood-activating effects lie in improving hemorheology and hemodynamics. Changes in hemorheology are one of the key indicators of the blood-activating mechanism. Astragalus membranaceus can reduce platelet adhesion rates, inhibit platelet aggregation, and prevent thrombosis, thereby decreasing whole blood and plasma viscosity. Compared to using Western medicine alone, the combination of Astragalus membranaceus and Bugleweed Decoction (Huangqi Chongteng Yin) with Western medicine in the treatment of patients recovering from qi deficiency and blood stasis-type ischemic stroke not only reduced hemorheological indicators but also lowered levels of inflammatory factors and improved neurological function, demonstrating the "blood-activating and qi-invigorating" effects of Astragalus membranaceus.

Hemodynamics, alongside hemorheology, is another indicator reflecting the pathological manifestations of blood stasis syndrome in the body. Flavonoid compounds in Astragalus membranaceus may promote the expression of erythropoietin by inducing signals mediated by the accumulation of hypoxia-inducible factor-1α (HIF-1α), increasing red blood cell counts, thereby accelerating blood flow and stimulating blood regeneration. Astragaloside IV can reduce left ventricular end-diastolic pressure in rats with heart failure, to some extent elevate left ventricular peak pressure, maximum rates of left ventricular pressure rise and fall, and exhibit cardiotonic effects, improving hemodynamic indicators with an effect comparable to that of captopril. Astragalus membranaceus significantly improves both hemorheology and hemodynamics, and since the primary driving force of blood is derived from the heart, numerous scholars have conducted in-depth research on the role of Astragalus membranaceus in ameliorating cardiovascular diseases. In particular, its effects in protecting against myocardial injury, protecting vascular endothelial cells, strengthening the heart, lowering blood pressure, and dilating blood vessels further emphasize its blood-activating, collaterals-promoting, and blood-dredging actions.

2.Blood Pressure Regulation

Multiple studies have demonstrated that Astragalus membranaceus exerts a bidirectional regulatory effect on blood pressure. Firstly, its vasodilatory effect is attributed to the increased production of nitric oxide (NO), an endogenous vasodilator factor. This NO-mediated dilation enhances local blood flow. Secondly, Astragalus membranaceus promotes diuresis, primarily through mechanisms involving increased excretion of Na+ and Cl- ions and competitive inhibition of Na+, K+-ATPase activity. Lastly, its positive inotropic effect strengthens myocardial contraction by increasing intracellular Ca2+ levels in cardiomyocytes.

3.Treatment of Renal Diseases

The kidney is a primary target organ affected by hypertension and diabetes, and its damage can further exacerbate these conditions. In recent years, domestic and international scholars have conducted extensive research on the pharmacological effects and clinical applications of Astragalus membranaceus and prescriptions containing it in the treatment of renal diseases. Literature shows that Astragalus membranaceus and prescriptions containing it exhibit definitive therapeutic effects in treating renal diseases such as nephrotic syndrome, diabetic nephropathy, hypertensive nephropathy, and renal injury caused by allergic purpura. Numerous clinical studies have demonstrated that combined therapy with Astragalus membranaceus can effectively manage early renal damage in hypertension, effectively controlling blood pressure, reducing urinary protein excretion, and improving renal function, with clinical efficacy superior to that of Western medicine alone.

4.Anti-tumor Effects

Astragalus membranaceus, a traditional Chinese medicine, can promote the expression level of IL-17D in the lungs while upregulating the content of NK cells in the lungs, inhibiting the formation of lung tumor clones. Therefore, Astragalus membranaceus enhances the ability of NK cells to migrate to the lungs by upregulating IL-17D expression, promoting anti-tumor immune effects in the lungs. Scholars have reviewed and evaluated the literature on the treatment of digestive tract tumors with Astragalus membranaceus and its active ingredients, finding that when combined with other anti-tumor drugs, Astragalus membranaceus exhibits anti-tumor, detoxifying, and potentiating effects. Its mechanisms include inducing tumor cell apoptosis, inhibiting tumor invasion, metastasis, and angiogenesis.

In recent years, besides its traditional application in Chinese medicine, Astragalus membranaceus has also demonstrated significant potential for development in Chinese herbal health products. On November 25, 2019, the National Health Commission and the State Administration for Market Regulation jointly issued the "Notice on Conducting a Pilot Program for the Management of Nine Substances, Including Codonopsis pilosula, as Both Traditional Foods and Traditional Chinese Medicinal Materials." Astragalus membranaceus was included in this list, indicating that as it transitions from a traditional Chinese medicinal material to a substance that is both a medicine and a food, it will have broader prospects for development and application in the medical and healthcare sector. This also signifies that Astragalus membranaceus extracts will become even more favored in the market.

References:

[1] Lv Qin, Zhao Wenxiao, Wang Shijun, Teng Jialin, Xin Dan, Li Jinxi, Kong Xianglin. "Research Progress on the Blood-Activating Effects and Modern Pharmacology of Astragalus membranaceus." Chinese Journal of Experimental Traditional Medical Formulae, 2020, 09: 215-224.

[2] Wu Sijun, Peng Lu, Wu Weigang, Li Zheng, Li Wenlong. "Research Progress in the Processing Techniques of Astragalus membranaceus." Chinese Ethnomedicine and Ethnopharmacology, 2019, 22: 74-77.

[3] Sun Jie. "Research Progress on the Clinical Application of Astragalus membranaceus and Its Prescriptions." Chinese Journal of Hospital Pharmacy, 2019, 12: 1311-1314.

About the Author

Xiaonisha, a food technology professional holding a Master's degree in Food Science, is currently employed at a prominent domestic pharmaceutical research and development company. Her primary focus lies in the development and research of nutritional foods, where she contributes her expertise and passion to create innovative products.