Bitter melon (Momordica charantia; Cucurbitaceae) is native to Asia. The generic name "Momordica" comes from Latin meaning, "to bite", that refers to the seeds with serrated edges which appear as if bitten. The plant lives up to its name "bitter melon" as all parts of the plant including the fruit tastes very bitter. It has been used for centuries in ancient traditional Indian, Chinese, and African pharmacopoeia as anthelminthic, laxative, digestive stimulant and to enhance appetite.

It is grown in tropical areas, including parts of Asia, the Amazon, East Africa, the Caribbean, and throughout South America, where it is used as food as well as medicine. It is an annual, slender, climbing vine with large leaves with long stalks, producing flowers in the leaf axils. The fruits are edible and used for culinary purposes and decoctions of the fruits and leaves in medicine. The bitter melon fruit is oblong in shape (~ 8 to 20 cm) and warty-looking, resembling pickling cucumbers. The young fruits are green and turn to orange-yellow when ripe.

The bright yellow flowers are used to decorate the street drawings (Kolam or rangoli) made out of rice flour or white stone powders, a daily practice in South India during the month of "Margazhi" (December-January). Come the month of Margazhi, it is customary to clean and decorate the frontage of houses to welcome the goddess of wealth (Lakshmi) and visitors with the graceful curves of kolams, on which bright cucurbitaceous flowers are fixed on stands made of cow-dung and placed in the center of the kolams.

Bitter melon fruit is consumed regularly as part of several Asian cuisines. The fruit and/or leaves are cooked alone as a vegetable, stuffed or stir-fried, or with jaggery (molasses) in curry or added in small quantities to beans and soup for a slightly bitter flavor. Sometimes the fruits are parboiled first with a little salt to remove some of the bitter flavoring. The fruits can be dried or pickled for use all through the year. The leaf and fruit extracts are also drunk as juice or tea.

Medicinally, the plant has a long history of uses by the indigenous people of Asia as well as the Amazon and often dispensed in some of the most modern hospitals as part of treatment of diabetes. The fruit juice and/or a leaf tea are also used for sores and wounds, infections, worms and parasites, and for measles, hepatitis, and fevers.

The plant is usually used as a hypoglycemic and antidiabetic agent [1] and many components have been identified from M. charantia which possess hypoglycemic (blood-sugar lowering) properties [2-3]. The hypoglycemic effect of bitter melon is due to Charantin that is more potent than common antidiabetic drugs (eg. Tolbutamide). At least three different groups of constituents in bitter melon have been reported to have hypoglycemic actions of potential benefit in diabetes mellitus- these include a mixture of steroidal saponins known as charantin, insulin-like peptides, and alkaloids. Other medicinal properties associated with bitter melon include antitumour and antimutagenic [4-5] as well as antiviral and antioxidant (6-8) activities.

Bitter melon fruit juice has also been shown to stimulate both glycogen storage by the liver, and insulin secretion by isolated -cells of islets of Langerhans [9-10]. The hypoglycemic activity of the bitter melon fruit has been shown in both spontaneous and chemically induced diabetes mellitus in experimental animals as well as in human patients [9-11]. It has recently been shown that there is a significant increase in the number of cells in the pancreas of streptozotocin (STZ)- induced diabetic rats after 8 weeks of bitter melon fruit juice treatment [12].

REFERENCES

1. Karunanayake & Tennekoon 1993. Search of novel hypoglycaemic agents from medicinal plants. In: A.K. Sharma (Ed.) Diabetes Mellitus and its Complications, An Update, Macmillan India Ltd, New Delhi, India. pp. 192-205.
2. Platel & Srinivasan 1997. Plants foods in the management of diabetes mellitus: vegetables as potential hypoglycemic agents. Nahrung 41:68-74.
3. Raman & Lau 1996. Anti-diabetic properties and phytochemistry of Momordica charantia L (Curcurbitaceae). Phytomed. 2:349-362.
4. Jilka et al. 1983. In vivo antitumor activity of the bitter melon (Momordica charantia). Cancer Res. 43:5151-5155.
5. Guevara et al. 1990. Antimutagens from Momordica charantia. Mutat. Res. 230:121-126.
6. Ng et al. 1992. Proteins with abortifacient, ribosome inactivating, immunomodulatory, antitumor and anti-AIDS activities from Cucurbitaceae plants. Gen. Pharmacol. 23: 579-590.
7. Zhang 1992. Preliminary report on the use of Momordica charantia extract by HIV patients. J Naturopathic Med 3:65-69.
8. Shi et al. 1996. Antioxidant property of fructus momordicae extract. Biochem Molec Biol Int 40:111-121.
9. Welihinda et al. 1982. The insulin releasing activity of the tropical plant Momordica charantia. Acta Biol. Med. Germ. 41:1229-1240.
10. Leatherdale et al. 1981. Improvement in glucose tolerance due to Momordica charantia (Karela). Br. Med. J. 282:1823-1824.
11. Ali et al. 1993. Studies on hypoglycemic in effects of fruit pulp seed and whole plant of Momordia charantia on normal and diabetic model rats. Planta Med. 59:408-412.
12. Ahmed et al. 1998. Effects of Momordica charantia fruit juice on islet morphology in the pancreas of streptozotocin-diabetic rats. Diabetes Res. Clin. Pract. 40:145-151.

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