Radix Astragali is the dried root of perennial herbs, Astragalus membranaceus (Fisch.) Bunge and Astragalus mongholicus Bunge (Fabaceae) (1, 2); family Leguminosae.[1]

It is mainly produced in inner Mongolia, Shanxi, Gansu and Heilongjiang provinces of China.[1]

It is sweet, slightly warm in nature and manifests its therapeutic actions in the spleen and lung meridians[1]

Primarily, the active constituents of Radix Astragali consist of polysaccharides and flavonoids.[2] The polysaccharides of Radix Astragali include two glucans, AG-1 (astragalus glucan-1) and AG-2 (astragalus glucan-2), and two heteroglycans, AH-1 (astragalus heteroglycan-1 and AH-2 (astragalus heteroglycan-2). There are other astragalus polysaccharide groups which contain D-glucose, D-galactose, and L-araban. The flavonoid-containing compounds include 7,3-dimercapto-4, 1-methoxyisoflavone, 3-dimercapto-7, 4,1-methoxyisoflavone, catycosin, kumatakenin and fomononetin. Radix Astragali also contains numerous amino acids, trace elements and various other components, such as astragalus saponin I-II, astragalosides I-IV and soyasapogenoside. Identified amino acids include daucosterol, choline, betaine, folic acid, nicotinamide, and linoleic acid. Beta-sterol, lupeol, hexanol, palmitic acid, 6-o-beta-D-pyranoglucose, 3-o-beta-D-xylopyranose and carotenol can also be extracted from Astragalus membranaceus (Fisch.) Bge.[26-33]

Radix Astragali invigorates qi (vital energy) and ascends the yang-qi. It also benefits protective qi and consolidates the exterior of the body. Other uses include promoting diuresis ,relieving edema (generalized swelling of the body), supporting qi to promote skin wound/ulcer healing and promoting tissue/ muscle regeneration. [1] It is used to treat the syndromes due to various qi deficiencies: 1. Treatment of spleen and stomach qi deficiency: Radix Astragali is particularly good at invigorating the qi of the middle burner. It is suitable for people with a spleen qi deficiency, which manifests with symptoms of fatigue, eating small amounts and wet and soft stools.     2. Treatment of middle qi collapse: The spleen rules the ascention of clear yang. Upward movement of qi is mainly governed by spleen yang as body yang qi normally tends to ascend. The upward movement of yang qi is important fors upporting the organs and maintaining them in normal organ position inside the body. When the spleen yang is deficient, there is an inadequate ascending power. This condition is known as the collapse of middle qi. Middle qi refers to the qi of the middle burner, which is located around the spleen and the stomach. As a result, the collapse of middle qi will lead to organs sagging downwards. For example, in some cases of chronic diarrhea, the continuous exhaustion of qi that occurs in this condition will lead to the collapse of middle qi and cause a prolapsed rectum. Radix Astragali is good at invigorating the middle qi and ascending the clear yang. By resuming the ascending power, the correct placement of the organs can be resumed.     3. Treatment of lung qi deficiency and spontaneous sweating caused by a deficiency of protective qi deficiency; prevention of exogenous evil invasion due to a qi deficiency: The lungs rule the protective qi, which circulates in the body's exterior regions like the skin, mucosa and muscles. Protective qi is mainly responsible for defense against the invasion of exogenous evils. If the lungs are healthy, the protective qi will be abundant to assure the body's ressistance to invading pathogens. Protective qi circulating at the skin level also consolidates the secretion of sweat and regulates it. If a lung deficiency is present, the protective qi will be inadequate, leading to the loss of protective qi's consolidation and protection functions. As a result, sweat will be "leaked" out, causing spontaneous sweating. Spontaneous sweating is a specific indicator of asthenia syndrome of superficies. Due to the lack of protective qi, individuals with spontaneous sweating are easily prone to attack from external evils making them at risk for developing problems such as coughs, colds and influenza. Radix Astragali invigorates lung qi, which in turn benefits protective qi. By resuming the abundance of protective qi, the body's exterior can be consolidated and spontaneous sweating resolved. Therefore, this herb is often applied by individuals with spontaneous sweating who are vulnerable to influenza, coughs or colds. It is also used for the treatment of a lung qi deficiency with accompanying symptoms of cough and shortness of breath.     4. Treatment urinary difficulty and edema due to inadequate transformation of dampness from qi: Chinese medicine believes that normal water flows only when the qi flows properly as well. When the body's qi is deficient, it will affect the distribution of the body fluids throughout the body and results in edema (an excess water accumulation in the tissues that causes generalized body swelling). Radix Astragli invigorates qi and promotes diuresis, thereby relieving edema. When used in combination with herbs that support the spleen and kidneys, it is beneficial in the treatment of proteinuria and edema of chronic nephritis patients.     5. Treatment of both qi and blood deficiencies associated with an unruptured abscess (skin ulcer with pus) or an unhealed but ruptured abscess (skin ulcer with pus): Radix Astragali supports qi to promote skin wound/ulcer healing. It helps drain the pus and promote tissue/ muscle regeneration.     6. Treatment of a blood exhaustion caused by a qi deficiency: Qi is the commander of blood and thus promotes the production of blood. When Radix Astragali is used with other herbs that invigorate the blood, the combination helps to produce blood and treats the problems like a sallow complexion (skin appears dull yellow), tired spirit and deficient pulse.     7. Treatment of blood in the stool and metrorrhagia due to a qi deficiency: One of the functions of qi is to "consolidate" the flow of blood. It means the blood will normally flow inside the blood vessels when there is sufficient qi to provide good consolidation. If qi is deficient, the blood flow will become abnormal and no longer be kept inside the blood vessels. Bleeding then occurs in qi deficient areas which in turn can lead to blood in the stool and metrorrhagia. By invigorating qi, Radix Astragali can treat the bleeding caused by the qi deficiency.     8. Treatment of stagnant blood flow caused by a qi deficiency: Qi is the commander of blood which means the blood flow is regulated by qi. When there is qi deficiency that leads to severe blood stagnation, symptoms like pain, numbness and paralysis of one side of the body (hemiplegia) can develop. By combining with herbs that promote qi production or blood flow, Radix Astragali invigorates qi to "move" the blood which benefits blood circulation. Therefore the blood stagnation can be relieved.     9. Treatment of a body fluid deficiency resulting from a qi deficiency: Qi can be transformed to produce body fluid. Therefore, Radix Astragali can invigorate qi to produce body fluid and treat the frequent thirst symptom caused by an underlying qi deficiency.

This herb's Chinese name 'Huang qi' is actually comprised of two Chinese words. The first word "Huang" (黃) means "yellow". Yellow is the color of the herb. Yellow is also the color of the "middle", the "earth" and the "spleen". The second word "Qi" (耆) means "superior" or "senior". The Chinese name of the herb suggests that the herb was considered to be a superior herb used for tonification functions.[4] 1. According to the summary in the Bencao Congxin (New Compilation of Materia Medica): "Radix Astragali is sweet in taste with a warm property. The raw herb can be used to consolidate the exterior of the body. If there is an absence of sweating, it can restore normal sweating, and if there is excessive sweating, it can regulate it to a normal degree. It warms the muscles and strengthens the striae as well as invigorates qi."   The striae are the places where protective qi flows. Protective qi is responsible for protecting the body against the attack of exogenous evils. It can also warm the skin and muscles and regulate the sweating functions. Chinese Medicine places high emphasis on observation of sweating control. Normal sweating control reflects the abundance and good functioning of protective qi. When protective qi is sufficient, sweating will then be under firm and normal control, and the exterior which is the skin and muscles will be considered to be "consolidated". Protective qi is actually governed by the lungs as lungs rule the exterior. Therefore by supporting the lung and protective qi, Radix Astragali can provide good protection against the influence of exogenous evils.   2. Radix Astragali can alleviate heat in the muscles resulting from a qi (vital energy) deficiency.[3] When qi is deficient, the consolidation of the exterior becomes inadequate; and this lets the body's yang-qi wander over the exterior creating heat in the muscles. This is the type of heat manifestation caused by a qi deficiency that Radix Astragali can remove. 3. When the herb is pretreated by broiling, it can invigorate the middle (which is the spleen and stomach) to benefit primordial qi, warm the triple burner and strengthen the spleen and stomach. It can promote the production of blood and muscle growth or regeneration.[3] Qi produces blood. When the blood is sufficient, muscle and tissue can grow or regenerate. 4. Radix Astragali helps drain pus and provide internal (qi) support. It is considered the "sage" herb for abscesses and skin ulcers.[3] Chinese medicine believes that for good healing of abscesses, the toxic qi contained in the abscesses need to be transformed into pus in order to facilitate their evacuation. This process needs internal qi support in order to for this transformation to occur. 5. Radix Astragali can also be used in the treatment of chicken pox or other diseases that manifest with the development of vesicular-papules without adequate"dispersing of the evils."[3] In Chinese Medicine, chicken pox or other diseases that manifest as the development of vesicular-papules are caused by an attack of external evils. For healing chicken pox, the evils need to be “dispersed” through the exterior of the body. This process will lead to further even distribution of the vesicular-papules. This manifestation is considered normal for healing chicken pox. If the vesicular-papules do not develop, it is usually caused by a qi deficiency, and the evils inside the vesicular-papules are considered to be suppressed and trapped inside without proper dispersing. Although symptoms of chicken pox disappear in the end, evils still trapped inside the body can launch an attack in the future when the body is weak. Since Radix Astragali is good at invigorating qi, it supports the normal eruption of vesicular-papules, which assists the healing process for eruptive skin diseases. It is important to note that Radix Astragali is only suitable for the above conditions, such as abscess, ulcers and skin eruptions, when there is a yang deficiency or qi deficiency without heat symptoms.[3]

1. Effects on Immune System   Both in vitro and in vivo investigations show Astragalus membranaceus possess immune enhancing effects. [5-16] Cell culture and Animal studies Using a local xenogenic graft-versus-host reaction (XGVHR) three crude extracts of Astragalus membranaceus were tested on mononuclear cells (MNC's) derived from healthy normal donors and 13 cancer patients. Both groups showed that Astragalus membranaceus extracts had significant immuno-potentiating activity.[7] Another study of an Astragalus membranaceus extract combined with low dose recombinant interleukin- 2 (rIL2) (100u/ml) generated an 80% lymphokine-activated killer (LAK) cell activity similar to the 76% of LAK cell activity generated by a high dose rIL2 (1000u/ml). This study suggests that a decreased dose of rIl2 could be used in combination with this herb to reduce toxicity associated with high dose rIL2. Reversal of cyclophosphamide-induced immuno-suppression in rats was also attributed to polysaccharide fractions of this herb. [8-11] Phagocytic activity of the reticuloendothelial system was increased in mice fed with a gastric gavage daily or on alternate days for one to two weeks of an Astragalus membranaceus decoction. Even when the rehabilitation of the mouse reticuloendothelial system was disrupted by injection of carbon particles before administration of the Astragalus membranaceus extract, the phagocytic index was enhanced [5-6]. Induction of an antibody response to a T-cell-dependent antigen was noted with intravenous administration of a crude Astragalus membranaceus extract to normal mice, or mice immuno-suppressed by cyclophosphamide, radiation treatment, or ageing. The response is associated with an increase in T-helper cell activity in both normal and immuno-suppressed mice[12]. Another in vivo study performed on cyclophosphamide-immuno-suppressed mice has suggested that Astragalus membranaceus extracts may modulate the immune system through activation of macrophages and splenic lymphocytes[13]. Polysaccharide fractions from Astragalus membranaceus root extracts are thought to be responsible for the herb's immunostimulant activity[5,12,14] Clinical studies Administration of an aqueous Astragalus membranaceus extract orally or intra-nasally to 1000 human subjects was found to decrease the incidence and shorten the course of the common cold. Two months of oral administration of Astragalus membranaceus in people susceptible to the common cold increased IgA and IgG levels in their nasal secretions.[5] Increase in serum IgM, IgE, and cAMP concentrations were found in adults treated with an oral dose of Astragalus root (15.6g / person / day, for 20 days).[15] Astragalus membranaceus extracts have also been reported to stimulate the production of interferon in response to viral infections.[14-16]   2. Diuresis       Animal studies   When rats were given subcutaneous injection of 0.5g/kg Radix Astragali and anaesthetized dogs were given i.v. injection of 0.5g/kg Radix Astragali, prominent diuretic effects were observed. The diuretic potency of Radix Astragali (subcutaneous injection at 0.5g/kg) in rats was shown to be comparable to that of 0.05g/kg aminophylline and 0.2mg/kg dihydrochlorothiazide. The effect was most prominent one to 1.5 hours after administration.[17]   3. Effects on Cardiovascular System       Animal studies   Blood pressure lowering effects: When 0.5g/kg of Radix Astragali decoction was injected i.v. to anaesthetized dogs, blood pressure was reduced, the effect of which lasted for 0.5 to1 hour. However, following secondary administration, this hypotensive effect was less pronounced, indicating that Radix Astragali may be a rapidly tolerated herb. When 0.5g/kg of Radix Astragali decoction was given by gavage instead, blood pressure was also notably reduced, but to a lesser extent.[17] Radix Astragali was shown to be able to control the increase of blood pressure in a spontaneous hypertension rat model. When rats were given a 0.5g/ml Radix Astragali water decoction at a dose of 2ml daily by gavage, the degree of blood pressure increase in the treatment group of the spontaneous hypertensive rat model was shown to be less than that of control group. The average blood pressure increase in the treatment group was 3.22±3.03 kPa (24.2±22.8 mmHg) as compared to 6.22±2.81 kPa (46.8±21.1 mmHg) in the control group. The results suggest Radix Astragali may be able to control an increase in blood pressure in a spontaneous hypertensive rat model.[19] In vitro studies Cardiovascular activity: Both the contractility and contraction amplitude of isolated frog or toad hearts was enhanced with alcohol extracts of Radix Astragali. [5] Dogs given an intraperitoneal (i.p.) injection of Radix Astragali did not produce any immediate effects on heart rate, but three to four hours after administration demonstrated inverted and biphasic T waves and prolonged S-T intervals.[5] Furthermore, a positive inotropic effect on isolated rat hearts was reported from use of saponins isolated from Radix Astragali. The resting potential of cultured rat myocardial cells also decreased with use of saponins, suggesting that they may exert an inotropic effect through modulation of Na+/K+ exchanging ATPase.[20]   4. Anti-inflammatory effects       Animal studies   When rats were given 50mg/kg astragalus saponin I by gavage, and 5mg/kg astragalus saponin I by i.v. injection, the increase in capillary permeability induced by histamine and by 5-hydroxytyptamine was antagonized. When 25-100mg/kg of saponin I was given by gavage, it significantly suppressed carrageenin-induced edema in the rat hind paw. The inhibitory rate within the dose range of 25-50mg/kg showed linear correlation.[19-21]   5. Hematological effects       Cell culture studies   When 0.2g/ml of Radix Astragali decoction was added to in vitro pathological red blood cells isolated from patients with systemic lupus erythematosus (SLE), it was shown to protect the deformability of red blood cells treated with glutaraldehyde, and reduce the degree of cell damage. Hence it was suggested that Radix Astragali's ability to invigorate qi may help maintain the deformability of red blood cells.[23]   6. Anti-stress effects       Animal studies   When 50g/kg of Radix Astragali decoction was given to mice by gavage, the level of hydroxyproline in skin tissues was elevated, whilst the weight of the adrenal glands were increased so that the mice became more tolerant to hypoxic conditions. Stress was induced in mice when they had to swim while carrying weights. Radix Astragali decoction was shown to possess anti-stress effects when the swimming durations of mice were prolonged following administration of Radix Astragali.[24-25]   7. Toxicity[17]       Animal studies   Acute toxicity: When mice were gavage fed with 0.4-0.7ml Radix Astragali decoction (equivalent to 7.5g/kg raw herb), no abnormality was observed within 48 hours and LD50 could not be detected. When Radix Astragali was injected i.p. into mice, the LD50 was found to be 40 ± 5g/kg. Difficulty in breathing and loss of sensation in limbs in the animals were observed, followed by death. Chronic toxicity: When rats were injected i.p. with 0.9-1.3 ml Radix Astragali (equivalent to 0.5g/kg raw herb) for 30 days, no toxic side effects or death were reported.

A decoction is typically made with 10-15g of Radix Astragali and three to four cups of boiling water until the volume is reduced by half.[1] For a high dose, 30-60g would be used. A decoction is usually taken orally and split into two doses, but this dose may taken all at once or escalated depending on the person's condition and recommendation by the Chinese medicine practitioner.

Astragalus root is contraindicated in individuals with exterior syndromes, yin vacuity leading to internal heat, or digestive problem due to food retention. It is also not suitable for skin sores or abscess conditions with significant swelling, pain and redness.

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