Sweet Fruit Used as Sugar Substitute and Medicinal Herb
by Subhuti Dharmananda, Ph.D., Director, Institute for Traditional Medicine, Portland, Oregon
Luo Han Guo (luohanguo) refers to the fruit of Siraitia grosvenori, formerly called Momordica grosvenori, a member of the Curcubitaceae (1).
The fruit is well-known for its sweet taste; this plant family (Gourd family) has other members that contain remarkable sweet components, including additional species of the genus Siraitia (e.g., S. siamensis, S. silomaradjae, S. sikkimensis, S. africana, S. borneensis, and S. taiwaniana 2) and the popular herb jiaogulan (Gynostemma pentaphyllum).
The latter herb, which has both sweet and bitter tasting triterpene glycosides in its leaves, is now sold worldwide as a tea and made into an extract for use in numerous health-care products (3).
Luohanguo has been used as a medicinal herb for treating cough and sore throat (4) and is popularly considered, in southern China, to be a longevity aid (5). These are the same uses as listed for jiaogulan. Luohanguo has more recently been developed into a non-caloric sweetener to compete with other herbal sweeteners such stevioside from the unrelated Stevia leaf. (6).
Luohanguo(羅漢果) is primarily grown in southern China, mainly in Guangxi Province, with most of the product from the mountains of Guilin. The steep mountains provide shade and they are frequently surrounded by mists that further protect against excessive sun, yet the temperature in this southern province is warm.
The wild plant is rare, thus luohanguo has been cultivated in the region for many years. There are descriptions of its cultivation in the area dating back to 1813 (5). Guilin now has a 4,000-acre luohanguo growing area that produces 10,000 pieces of fruit annually (7).
Most of these fields are in Yongfu and Lingui Counties, which are recognized in China as sites having an unusually high number of residents living to an age 100 years or more (8, 9), which some attribute to the consumption of luohanguo, as well as the pristine environment. However, the local residents mainly proclaim the benefits of tranquil lifestyle, simple diet, and regular exercise.
Longjiang Town (Dragon River) of Yongfu County was named "Home of Chinese luohanguo Fruits." Several factories have been established in this region to produce luohanguo extracts and finished products, the oldest being the Yongfu Pharmaceuticals Factory.
A carefully prepared visual presentation of luohanguo cultivation and its environs is offered by the Dragon River Company, a New York based international company that set-up manufacturing in the town of Dragon River
Luohanguo(羅漢果) is collected as a round green fruit that turns brown upon drying. The sweet taste of luohanguo comes primarily from mogrosides, a group of terpene glycosides, present at the level of about 1% of the fleshy part of the fruit (10).
Both the fresh and dried fruits are extracted to yield a powder that is 80% or more mogrosides. The mogrosides have been numbered, 1-5, and the main component is called mogroside-5, previously known as esgoside (see chemical structure diagram below).
Other, similar compounds from luohanguo have been labeled siamenoside and neomogroside. The mixed mogrosides are estimated to be about 300 times as sweet as sugar by weight, so that the 80% extracts are nearly 250 times sweeter than sugar; pure mogrosides 4 and 5 may be 400 times as sweet as sugar by weight.
Recent work on luohanguo includes investigation of the antioxidant activity of the mogrosides (13) and their potential use as cancer prevention compounds (14).
This suggested effect is based on the understanding that antioxidants can produce significant reversal or suppression of the early stage of cancer development, which has been an area of particular interest for tea drinking (15).
Further, luohanguo and its sweetening component are often mentioned in relation to diabetes and obesity, because it can substitute for caloric sugars normally consumed in the diet.
REFERENCES
Ling Yeouruenn, A New Compendium of Materia Medica, 1995 Science Press, Beijing.
Dawson GE, et al., Process and composition for sweet juice from Cucurbitaceae fruit, U.S. patent 5,411,755, May 2, 1995.
Blumert M and Liu Jialiu, Jiaogulan: China's Immortality Herb, 1999 Torchlight Pub., Badger, CA.
Dai Yinfang and Liu Chengjun, Fruit as Medicine, 1986 The Ram's Skull Press, Kuranda, Australia.
Dragon River Health Products, http://www.dragonriver.net/eng/home.html
Kinghorn AD and Soejarto DD, Discovery of terpenoid and phenolic sweeteners from plants, Pure Applied Chemistry 2002; 74(7): 1169-1179.
Guangxi Science and Technology Information Network, http://www.gxsti.net.cn/esti/2resourse.htm
People's Daily Online, Culture: Guilin has more centenarians, November 26, 1999; http://fpeng.peopledaily.com.cn/199911/26/eng19991126R107.html
Strait's Times, Village of longevity gets onto tourist map, http://straitstimes.asia1.com.sg/mnt/html/webspecial/gallery/livelong/story.html
Hsu HY, et al., Oriental Materia Medica, 1986 Oriental Healing Arts Institute, Long Beach, CA
Croom, EM Jr., Luo Han Guo: A literature review, http://www.hort.purdue.edu/newcrop/articles/momordica%20croom.html
Lee CH., Intense sweetener from Lo Han Kuo, Experientia 1975, 31(5): 533-534.
Shi H, et al., Antioxidant property of fructus momordicae extract, 1996 Biochemistry and Molecular Biology International 1996; 40 (6): 1111-1121.
Konoshima T and Takasaki M, Cancer-chemopreventive effects of natural sweeteners and related compounds, Pure Applied Chemistry 2002; 74(7): 1309-1316.
Katiyar SK and Mukhtar H, Tea antioxidants in cancer chemoprevention, Journal of Cellular Biochemistry, Supplement 1997; 27: 59-67.
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