Mulberry Twig (Sangzhi): Antihypertensive, Hypoglycemic, Lipid-Lowering, Antiobesity and Analgesic Effects
The Chinese medicinal Sangzhi is the tender twig of Morus alba (mulberry family), best harvested in the second or third lunar month. It is produced across China, especially in the silk-producing regions of Jiangsu and Zhejiang, because mulberry leaves feed silkworms and these areas grow many mulberry trees. Sangzhi has been used medicinally since early times. Traditional TCM holds it dispels wind-damp, unblocks the channels, and moves water qi; it is indicated for rheumatic joint pain, wind-stroke hemiplegia, edema and beriberi, and wind-type itching of the skin.
Modern pharmacology shows that the total alkaloids in Sangzhi have clear blood-sugar-, lipid-, and blood-pressure-lowering effects; this is the mechanism behind its use for rheumatic pain, wind-stroke hemiplegia (sequelae), and edema-beriberi. The total alkaloids help treat limb pain and numbness due to type 2 diabetes and peripheral vascular disease: they not only lower blood sugar but rapidly reduce blood cholesterol and low-density lipoprotein, improving symptoms by improving atherosclerosis. But the patent medicine Sangzhi Zong Shengwu Jian Pian has notable side effects—patients taking too much for too long may develop abnormal liver and kidney function, which normalizes after stopping. So when taking Sangzhi-alkaloid tablets, liver and kidney function should be rechecked regularly.
Sangzhi’s lipid-lowering action is recorded in ancient TCM texts. Bencao Tujing says prolonged use of Sangzhi “lightens the body,” and Xixi Danfang Xuan records: “To treat the overweight, drink Sangzhi tea long-term; it drives out dampness and makes people thin.” So the ancients already used Sangzhi for weight loss. Sangzhi is an important herb for limb and joint pain; historical texts note it “benefits the joints” (Bencao Beiyao), “dispels wind and nourishes the sinews, treating all kinds of damp impediment of the joints” (Bencao Shu), “dispels wind disorders of the bones and joints, treating aged crane-knee wind” (Lingnan Caiyao Lu), “treats swollen, painful beriberi so one cannot walk” (Puji Fang), and “treats wind-heat arm pain” (Benshi Fang). The joint impediment described is mostly what modern medicine calls peripheral vascular disease—lower-limb atherosclerosis or thrombosis from various causes—but Sangzhi’s benefit in atherosclerosis extends beyond the limbs. It lowers blood cholesterol and LDL to achieve wind-dispersing and pain relief.
Sangzhi is also a common herb for hypertension. The Zhongcaoya Xin Yiliao Falanchao Huibian once recorded a modern empirical antihypertensive formula, “Shuang Sang Jiangya Tang,” made of Sangzhi, mulberry leaf (Sangye), and motherwort fruit (Chongweizi), each 15 g; add 1000 ml of water, decoct to 600 ml, and soak the feet for 30–40 minutes before bed, then sleep. This is a foot-soaking formula, not an oral one. The herbs may also be ground to a very fine powder and steeped in boiling water for foot soaking, which is more convenient.
The ancients also used Sangzhi for hypertension and the various sequelae of cardiovascular and cerebrovascular disease, which TCM classifies as wind-stroke or “partial wind.” Waitai Miyao records: “For partial wind and all wind disorders, take one large sheng of filed Sangzhi with one large dou of water and decoct down to two large sheng. Keep in a well in summer. Drink one cup daily on an empty stomach.” Here only plain Sangzhi is used.
Modern pharmacology also shows Sangzhi decoction enhances immune function. Patients with low lymphocyte transformation rate who take a daily 30 g Sangzhi decoction for a month show markedly increased lymphocyte transformation; tender twigs work best. Sangzhi also significantly inhibits capillary permeability, thereby reducing inflammation and swelling.
Besides these, Sangzhi has a good cough-relieving action. Weisheng Jianyi Fang records: “For chronic upflow cough with much phlegm, wheezing, and unceasing pus and blood in the sputum, file mulberry twigs finely, boil a decoction, and drink.” Sangzhi also treats cataracts: dry mulberry twigs in the sun, burn to white ash, grind fine, steep in boiling water, strain, and wash the eyes with the liquid. It also treats skin diseases such as purpura wind; the ancients burned it to ash, boiled it into a plaster, and applied it to remove black facial moles.