Gynostemma pentaphyllum

Description

Jiaogulan belongs to the genus Gynostemma, in the family Cucurbitaceae, which includes cucumbers, gourds, and melons. Its fruit is a small purple inedible gourd. It is a climbing vine, attaching itself to supports using tendrils. The serrated leaflets commonly grow in groups of five (as in G. pentaphyllum) although some species can have groups of three or seven leaflets. The plant is dioecious, meaning each plant exists either as male or female. Therefore, if seeds are desired, both a male and female plant must be grown.

Taxonomy

Gynostemma pentaphyllum is known as Jiaogulan (Chinese: 绞股蓝 "twisting crotched indigo plant") in China. The plant was first described in 1406 CE by Zhu Xiao, who presented a description and sketch in the book Materia Medica for Famine as a survival food rather than a medicinal herb. The earliest record of jiaogulan's use as a drug comes from herbalist Li Shizhen's book Compendium of Materia Medica published in 1578, identifying jiaogulan for treating various ailments such as hematuria, edema in the pharynx and neck, tumors, and trauma. While Li Shi-Zhen had confused jiaogulan with an analogous herb Wulianmei, in 1848 Wu Qi-Jun rectified this confusion in Textual Investigation of Herbal Plants, which also added more information on medicinal usage.

Modern recognition of the plant outside of China originated from research in sugar substitutes. In the 1970s, while analyzing the sweet component of the jiaogulan plant (known as amachazuru in Japan), Masahiro Nagai discovered chemical compounds identical to some of those found in Panax ginseng, an unrelated plant. Afterward, Tsunematsu Takemoto reported that jiaogulan contains four saponins identical to those in Panax ginseng as well as seventeen other similar saponins. Over the next decade 82 saponins (gypenosides) were identified in jiaogulan, compared to the 28 (ginsenosides) found in Panax ginseng.

Distribution and habitat

Over thirty species of Gynostemma are known to grow throughout China, predominantly in the Southwest, although most species exist in at least one other country. The species G. pentaphyllum has the widest distribution outside of China, ranging from India to Southeast Asia to Japan and Korea.

Jiaogulan is a vine hardy to USDA zone 8 in which it may grow as a short lived perennial plant. It can be grown as an annual in most temperate climates, in well-drained soil with full sun. It does not grow well in cold climates with temperatures below freezing.

Toxicity

Jiaogulan does not show toxicity. However, several related plants in the Cucurbitaceae (cucumber) family contain Cucurbitacin compounds, which are responsible for the bitter taste in some edible plants of this family but are highly toxic to mammals.

Use in ethnomedicine

The plant is best known for its use as a herbal medicine. Jiaogulan is most often consumed as an herbal tea, and is also available as an alcohol extract and in capsule or pill form. It has not seen widespread use in traditional Chinese medicine (TCM) because it grows far from central China where TCM evolved; consequently, it was not included in the standard pharmacopoeia of the TCM system. Until recently it was a locally-known herb used primarily in mountainous regions of southern China and in northern Vietnam. It is described by the local inhabitants as the "immortality herb", because people within Guizhou Province, where jiaogulan herbal teas are consumed regularly, are said to have a history of unusual longevity.

In the European Union Jiaogulan is considered Novel Food since a controversial court ruling in 2012, which since then prohibits its sale as food.

Antioxidant

Jiaogulan has been found to increase expression superoxide dismutase (SOD), which is a powerful endogenous cellular antioxidant enzyme. Studies have found that it increases the activities of macrophages, T lymphocytes, and natural killer cells and that it acts as a tumor inhibitor.

Adaptogen

Jiaogulan is known as an adaptogen, which is an herb reputed to help the body to maintain optimal homeostasis. Its chemical constituents include the triterpenoid saponins gypenosides which are closely structurally related to the ginsenosides which are present in ginseng. Most research has been done since the 1960s when the Chinese realized that it might be an inexpensive source of adaptogenic compounds, removing pressure from the ginseng stock. Purported adaptogenic effects include regulating blood pressure and the immune system, improving stamina and endurance. Jiaogulan is also believed to be useful in combination with codonopsis for jet lag and altitude sickness.

Blood pressure

The adaptogenic nature of gypenosides have been found to keep blood pressure in a normal range. In vitro studies indicate that jiaogulan stimulates the release of nitric oxide in isolated heart cells; this is one proposed mechanism by which jiaogulan reduces high blood pressure. In a double-blind study, gypenosides administered to those with Grade II hypertension showed 82% effectiveness in reducing hypertension, compared to 46% for ginseng and 93% for indapamide (a hypertension medication).

Cardiovascular functions

Animal studies as well as clinical testing on humans suggest that jiaogulan, when combined with other herbs, has beneficial effects on cardiovascular system, increasing heart stroke volume, coronary flow, and cardiac output while reducing the heart rate, without affecting arterial pressure.

Cholesterol reduction

Numerous clinical studies in Chinese medical literature have shown that jiagolan lowers serum cholesterol, triglycerides, and LDL (the "bad" cholesterol) while raising HDL ("good" cholesterol) levels, with reported effectiveness rates ranging from 67% to 93% on over 980 patients with hyperlipemia.

Diabetes

Gynostemma pentaphyllum tea has been studied in a randomized controlled trial in type 2 diabetic patients. It may have potential as a hypoglycemic treatment to reduce blood glucose.

Alternate names

Western languages such as English and German commonly refer to the plant as jiaogulan. Other names include: