The Anti-Cancer Effects and Toxicity of the Chinese Herb Zaoxiu (Chonglou, Paris polyphylla)

The Chinese herb Zaoxiu is the dried rhizome of Paris polyphylla var. chinensis, Paris polyphylla var. yunnanensis, or Paris polyphylla (family Liliaceae); its common names also include Chonglou and Qiyeyizhihua. In different regions it also has many aliases, such as Ziheche, Baiheche, Luosiqi, Dengtaiqi and Hailuosi.

The appearance of Zaoxiu is quite distinctive: no matter where it is produced, a single flower emerges from seven leaves, so in folk use the name Qiyeyizhihua (“seven leaves, one flower”) is more common. In TCM textbooks its common name is Chonglou; in large dictionaries such as the Zhonghua Bencao (Chinese Materia Medica) and the Zhongyao Dacidian (Great Dictionary of Chinese Materia Medica), its standard name is Zaoxiu.

Zaoxiu's use as medicine first appears in the Shennong Bencao Jing, so its history of use is long. The Shennong Bencao Jing classified Zaoxiu as a “lower-grade” herb with toxic side effects—this category of herbs must not be used in large doses or for long periods. Modern animal experiments have also confirmed that Zaoxiu has a certain toxicity; at high doses it kills experimental mice.

When Zaoxiu is decocted for oral use, the usual adult dose is 5–10 g, with children's doses reduced accordingly. Clinical reports put the toxic dose in humans at 60–90 g, with a latency of about 1–3 hours; the main poisoning symptoms are nausea, vomiting, diarrhea, headache and dizziness, and severe cases may develop convulsions.

Research using flow cytometry shows that Zaoxiu can induce tumor-cell apoptosis even at low doses; this is one of its anti-tumor mechanisms. So when treating tumors, there is no need to use Zaoxiu in large doses.

Zaoxiu can also be applied externally. For external use, the root may be pounded into a paste and applied to lesions on the body surface, or the water or alcoholic extract of Zaoxiu may be applied to the affected area. Zaoxiu is mainly used externally to treat boils, furuncles and abscesses, and red, swollen, painful, itchy skin.

Traditional TCM holds that Zaoxiu is bitter in taste and slightly cold in nature, with a small toxicity; it enters the liver meridian, and has the actions of clearing heat and detoxifying, reducing swelling and relieving pain, and cooling the liver and calming convulsions. It is mainly used for welling-abscesses and sores, throat swelling and pain, breast abscess, snake and insect bites, traumatic injuries, and liver-heat convulsions.

Zaoxiu is bitter and cold and injures the stomach, so it is contraindicated in deficiency-cold patterns, external sores of the yin type, and in pregnancy. In addition, modern pharmacological research has found that Zaoxiu kills sperm and inhibits conception, so both partners in a couple trying to conceive should avoid Zaoxiu.

Zaoxiu has anti-cancer effects. Folk medicine commonly uses Zaoxiu together with Xiakucao (Prunella), Shandougen (Sophora tonkinensis), Huangqin (Scutellaria), Baihuasheshecao (Oldenlandia) and Banzhilian (Scutellaria barbata) to treat lung cancer and various other tumors; combined with Sanqi (Panax notoginseng), Mugua (Chaenomeles) and Weilingxian (Clematis), it can be used for brain tumors or brain metastases.

The water extract of Zaoxiu has a good inhibitory effect on the Ehrlich ascites carcinoma (EAC) strain, but is ineffective against HeLa cells. The methanol extract of Zaoxiu is less effective than the water extract against Ehrlich ascites carcinoma, but has a strong inhibitory effect on the mouse fibroblast (L929) strain and on HeLa cells. The total saponins extracted and isolated from the rhizome of Zaoxiu markedly inhibit the growth of mouse hepatoma H22 cells. Zaoxiu extracts inhibit RNA and DNA synthesis in tumors and the spleen.

The Kang'ai Zhiyan Bencao (Anti-Cancer Experienced Materia Medica) records that Zaoxiu can be widely used for many cancers, such as esophageal, laryngeal, colorectal, lung, liver and brain cancer, cervical cancer, and acute leukemia.

Zaoxiu also has antibacterial, anti-asthmatic, hemostatic and diuretic effects. The Diannan Bencao (Materia Medica of Yunnan) records that Zaoxiu “mainly treats all nameless swellings and toxins, attacks all sorts of sores, toxins, welling-abscesses and carbuncles, is best for back carbuncles, and promotes urination.” This shows that Zaoxiu was used long ago to treat various tumors and difficult urination.

Zaoxiu is also an important external herb for treating phlebitis caused during intravenous infusion in cancer patients. Reports say that grinding the rhizome of Zaoxiu into juice with vinegar and applying it to the affected area 3–4 times daily treated 30 cases of phlebitis caused by intravenous injection of anti-cancer drugs; all were cured. Twenty cases were cured within 2 days, 9 within 3 days, and 1 took 7 days.

The patent medicine Chonglou Jiedu Ding (Chonglou Detoxification Tincture) is a spray made from the rhizome of Zaoxiu for external use; it can be used for shingles (herpes zoster), mumps, skin itching and acute tonsillitis, simply sprayed directly on the affected area.

Zaoxiu is relatively expensive; to avoid wasting the medicinal material, patients may also grind Zaoxiu into powder, fill empty capsules with it, and swallow 0.5–2 g each time, two to three times a day.