||This article needs more medical references for verification or relies too heavily on primary sources. (November 2012)|
Tripterygium wilfordii, or léi gōng téng (Mandarin) (Chinese:雷公藤, Japanese: raikōtō), sometimes called thunder god vine but more properly translated thunder duke vine, is a vine used in traditional Chinese medicine for treatment of fever, chills, edema, and carbuncles.
Tripterygium wilfordii recently has been investigated as a treatment for a variety of disorders including rheumatoid arthritis, cancer, chronic hepatitis, chronic nephritis, ankylosing spondylitis, polycystic kidney disease, and obesity, as well as several skin disorders. It is also under investigation for its apparent antifertility effects, which, it is speculated, may provide a basis for a male oral contraceptive.
Triptolide, a diterpene triepoxide, is a major active component of extracts derived from Tripterygium wilfordii. Triptolide has multiple pharmacological activities including anti-inflammatory, immune modulation, antiproliferative, and proapoptotic activity.
Reduction of male fertility
The plant contains many active compounds, at least six of which have male antifertility effect: (triptolide, tripdiolide, triptolidenol, tripchlorolide, 16-hydroxytriplide, and a compound known as T7/19, whose structure is unpublished). The mechanism by which they affect fertility is not yet understood. What is known is that daily doses of these compounds reduce sperm counts and also severely affect the formation and maturation of sperm, causing them to be immotile.
Scientific research into medical effects
Certain extracts from T. wilfordii, as well as from T. hypoglaucum (now considered identical to T. regelii) and T. regelli, were discovered in the 1980s to have temporary antifertility effects, which has led to research on its potential as a contraceptive.
"Tripterygium wilfordii Hook.f., known as Leigongteng (Thunder God Vine) in traditional Chinese medicine, has attracted much attention for its applications in relieving autoimmune disorders such as rheumatoid arthritis and systemic lupus erythematosus, and for treating cancer. Molecular analyses of the ITS and 5S rDNA sequences indicate that T. hypoglaucum and T. doianum are not distinct from T. wilfordii, while T. regelii should be recognized as a separate species. The results also demonstrate potential value of rDNA sequence data in forensic detection of adulterants derived from Celastrus angulatus in commercial samples of Leigongteng."
Not enough is known about T. wilfordii to actually test it as a contraceptive. Research thus far has dealt with establishing the mechanism by which the plant affects fertility, and investigating toxicity and side effects. What has been learned is encouraging, however: in both animals and humans, low doses of various Tripterygium extracts[clarification needed] can produce significantly lowered sperm density and motility indices without major side effects. When the treatment was ended in the various trials, all indices returned to normal within months.
T. wilfordii could be an effective pharmaceutical alternative to contraceptives based on hormonal manipulation.
A small molecule triptolide derived from T. wilfordii has been shown to disrupt mitochondrial function in cells and is under investigation as an antitumor agent or to suppress autoimmune disorders.
In China, T. wilfordii has an established history of use in the treatment of rheumatoid arthritis. The herb shows immunosuppressive, cartilage protective, and anti-inflammatory effects. The National Center for Complementary and Integrative Health has noted that one systematic review of the literature found that T. wilfordii may improve some RA symptoms, though another systematic review has stated that the serious side effects occur frequently enough to make the risks of taking this herbal supplement too high for the possible benefits. A 2014 clinical trial with 207 RA patients compared the efficacy and safety of T. wilfordii (TwHF) with methotrexate (MTX) in the treatment of active rheumatoid arthritis (RA). This study concluded that "TwHF monotherapy was not inferior to, and MTX+TwHF was better than, MTX monotherapy in controlling disease activity in patients with active RA."
Drugs derived from the plant also show potential for reduction and elimination of pancreatic tumors in mice. Clinical trials may soon begin for the development of a drug for use in humans.
At medicinal doses, T. wilfordii extract does have significant side effects, including immunosuppression. However, this may not apply to contraceptive use. Many of the side effects are caused by the other active compounds found in the plant, and do not appear when a pure extraction of its compounds with antifertility effect is used. In addition, the dose required to lower fertility is significantly lower than the standard medicinal dose.
In August 2011, the UK Medicines and Healthcare Products Regulatory Agency published a drug safety bulletin advising consumers not to use medicines containing lei gong teng. This was due to concerns over potentially serious side effects. 
However, a recent review stated that although T. wilfordii has toxic potential, careful extraction gives an acceptable frequency of adverse reactions, which are largely related to the gastrointestinal tract and amenorrhea. The review found that T. wilfordii extract is useful remedy for postmenopausal rheumatoid arthritis.
The Beijing TV series of China Medicine has shown people being treated successfully with the herb in a formula for rheumatoid arthritis, and outlined some practice to alleviate problems of using the herb. As often the case of TCM, formulations need to be adjusted for individual's physiology for best result.
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- Harvard study: Could Chinese ‘thunder god vine’ plant be cure-all for obesity? http://www.washingtonpost.com/news/to-your-health/wp/2015/05/22/harvard-study-could-chinese-thunder-god-vine-plant-be-cure-all-for-weight-loss/
-  Drug Safety Update: Traditional Chinese medicines containing lei gong teng (tripterygium wilfordii)
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