The Anticancer Effects and Side Effects of Wang Gua Gen (Trichosanthes Root)
Wang Gua, also called Tu Gua, is a perennial herbaceous vine of the genus Trichosanthes in the gourd family (Cucurbitaceae), distributed throughout eastern, central, southern, and southwestern China. Its fruit, seeds, and root can all be used medicinally. As early as the Han dynasty, Zhang Zhongjing used Tu Gua Gen to treat menstrual irregularity in women.
The "Tu Gua Gen San" in the Jingui Yaolue (Essential Prescriptions from the Golden Cabinet) is made from equal parts of Tu Gua Gen (Wang Gua Gen), Shaoyao (Peony), Guizhi (Cinnamon Twig), and Zhe Chong (Eupolyphaga), ground to powder; it treats menstrual irregularity in women due to blood stasis. In modern times this formula is also used for difficult urination caused by benign prostatic hyperplasia in men.
Traditional TCM holds that Wang Gua (the fruit) is bitter and cold, entering the Heart and Kidney meridians; it clears heat, generates fluids, activates blood and resolves stasis, and promotes lactation, mainly treating wasting-thirst (xiaoke), jaundice, dysphagia and regurgitation, amenorrhea, blocked lactation, carbuncles and swellings, and chronic pharyngitis. Wang Gua Gen (the root) is also bitter and cold, but enters the Large Intestine and Stomach meridians; it drains heat and generates fluids, disperses stasis and reduces swelling, mainly treating heat disease with thirst, jaundice, heat-constipation, difficult urination, amenorrhea, insufficient lactation, zheng-jia concretions, and carbuncles and swellings—most of which are various tumor-like diseases. In addition, Wang Gua Zi (the seeds) are also used medicinally, mainly to clear heat, cool blood, and drain dampness, mainly treating lung atrophy with hematemesis and intestinal wind with bleeding.
Cucurbitacin BE (CuBE), isolated from Wang Gua Gen, has been confirmed by modern pharmacological research to have genuine antitumor activity, in a dose-dependent relationship: the higher the concentration, the higher the kill rate against cancer cells. Cucurbitacin BE has a good anticancer effect on human nasopharyngeal carcinoma cells (KB), and at the same time promotes the transformation of normal lymphocytes.
Cucurbitacin BE is found not only in Wang Gua Gen but also in muskmelon stem (Ti Gua Di). Modern pharmaceutical companies have made it into dedicated cucurbitacin tablets for treating nasopharyngeal carcinoma, cervical cancer, oral squamous cell carcinoma, liver cancer, brain tumors, and malignant melanoma. But cucurbitacin tablets also have side effects: after taking them one may experience nausea, vomiting, anemia, abdominal pain, and diarrhea, so patients with gastric and duodenal ulcers and pregnant women cannot take them.
Wang Gua Gen and muskmelon stem can also be ground into a fine powder and administered through the nasal mucosa; some scholars have used this method to treat jaundice hepatitis caused by hepatitis B, with some effect. Whether nasal administration has better efficacy against nasopharyngeal carcinoma requires further study.
Wang Gua Gen has some efficacy for diabetic patients. The Shennong Bencao Jing already records that Wang Gua Gen "governs wasting-thirst with internal bi, blood stasis with amenorrhea, cold-heat and aching, boosts qi and cures deafness," showing that TCM has a long history of using Wang Gua Gen to treat diabetes (xiaoke).
The Shenghui Fang also records that Wang Gua Gen can treat "black ju" (today called gangrene—tissue necrosis that, due to secondary infection by putrefactive bacteria and other factors, turns black, dark green, or other special colors). The usage is: "one jin of raw Tu Gua Gen, pound and extract six ge of juice, take all at once," and it says that after taking it "yellow water should pass in the urine; if it does not, take more."
Wang Gua Gen is used in decoction, generally at 60–90 g fresh or 5–15 g dried; in special cases such as the above gangrene formula, one jin (about 640 g in modern measure) may be used at once. Some materia medica works consider Wang Gua Gen non-toxic, others mildly toxic, but most note that patients with deficiency-cold of the Spleen and Stomach and pregnant women should not take it.