Stevia, The Sweet Herb

December 29, 2005

Stevia – The Sweet Herb Stevia rebaudiana is popularly known as Sweet Herb. It is native to North Eastern Paraguay where it is used in folk medicine. Dr.Moises Santiago Bertoni (1887) reported about new species of stevia. He named Stevia rebaudiana in the honor of Paraguay chemist Rebaudi. In 1908, it was Rasenack who reported to the scientific community about presence of sweeteners in the plant. In 1931, Briedel and Lavieille continued the work of Rasenack and succeeded in isolating Stevioside.

 
In 1970, use of chemical sweeteners was prohibited in Japan. Stevia ahs been used as sweetener in Japan for over 25 years. It is estimated that 50 tones of Steviosides are consumed annually in Japan. Further stevia holds 50% of the sweeteners market in Japan. China is not lagging behind. Her stevia is widely used in food stuffs, beverages and pickles.
 
Food and Drug Administration (FDA) in late eighties banned stevia for it use as dietary supplement or sweetener. In 1991 after so much argument, FDA lifted ban on stevia and allowed the import and sale in United Stats of America. Today stevia and Steviosides are sold as dietary supplements. Experts are of the view that status of stevia as dietary supplement is appropriate and more scientific studies are required to give it status of a drug
 
In 1908 crop of stevia was raised for the first time. In 1918, a botanist (name not confirmed) from America introduced the people with amazing properties of the stevia. In 1932 G.S. Brady, American Trade Commissioner discussed the commercial viability of the plant. It can be said with certainty that stevia was brought in the limelight by work of Bertoni. During World War II, stevia was grown in England as a sugar substitute.
 
Stevia rebaudiana is member of Compositae. Stevia rebaudiana is a tender perennial plant. Stem is weak and leaves are arranged alternately. Flowers are small and white and arranged in indeterminate heads. Seeds are minute. As far as traditional medicinal use of Stevia is concerned, it is has been used in Brazil and Paraguay. The Guarani community used stevia for imparting sweetness to teas.
 
In addition, Stevia was used for cardiac edema, obesity, high blood pressure and gastritis. Herbalists in Brazil describe stevia as hypoglycemic, antihypertensive, diuretic and cardiac tonic. They use the plant for the treatment of obesity, fatigue, dental caries and high blood pressure

Importance of Medicinal plants

December 29, 2005
The medicinal plants find application in pharmaceutical, cosmetic, agricultural and food industry. The use of the medicinal herbs for curing disease has been documented in history of all civilizations. Man in the pre-historic era was probably not aware about the health hazards associated with irrational therapy. With the onset of research in medicine, it was concluded that plants contain active principles, which are responsible, for curative action of the herbs.
Before onset of synthetic era, man was completely dependent on medicinal herbs for prevention and treatment of diseases. With introduction of scientific procedures the researchers, were able to understand about toxic principles present in the green flora. The scientists isolated active constituents of the medicinal herbs and after testing some were found to be therapeutically active. Aconitine, Atisine, Lobeline, Nicotine, Strychnine, Digoxin, Atropine, Morphine are some common examples.
The efficacy of some herbal products is beyond doubt, the most recent examples being Silybum marianum (silymarin), Artemisia annua (artemesinin) and Taxus baccata (taxol). On the other hand, randomized, controlled trials have proved the efficacy of some established remedies, for instance, Ginkgo biloba for tinnitus, Hypericum perforatum is a reputed remedy for depression. In Hypericum some researchers are of the view that hypericin is the active principle of the herb and some believe that hyperforin is responsible for antidepressant action of the herb.
Recently research has supported biological activities of some medicinal herbs. Cancer is such a segment where researchers are expecting new molecules from herbs that can provide us with tools for fighting this dreaded disease. Allamanda cathratica [allamandin], Elephatopus elatus [elephantpoin], Helenium autmnale [helenalin] Vernonia hymenlepis, Heliotropium indicum [Indicine-N-oxide], Daphne mezereum (mezerien) and Stereospermum suaveolans [laphacol] are medicinal plants that have shown significant tumor inhibiting effect.
Diabetes mellitus is another area where a lot of research is going on. Ajuga reptens (the active principle is said to potentiate effects of insulin), Galagea officinalis (galagine), Bougainvillea spectabilis (pinitol), Momordica charantia (chirantin), Gymnema sylvestre (gymnemic acid) are some medicinal herbs that have shown effectiveness in non-insulin dependent diabetes. Recently extract of Tecoma stans has shown potent anti diabetic activity. Alkaloid tecomonine is considered to be active principle of the herb.
Arthritis is another potential disease where no satisfactory answer is present in modern medicine. Commiphora mukul (guggulsterones), Boswellia serrata [boswellic acid], Withania somnifera (withanolides), Ruscus acueleatus (ruscogenin), Harpagophytum procumbens (harpagoside) are prominent plants with anti- arthritic activity. Harpagoside is a precious constituent as it has anti rheumatoid activity. Rest of all natural products has anti-inflammatory activity.
Chrysanthemum parthenium traditionally known as feverfew has shown promising results in migraine, a disease that has eluded the researchers from centuries. The herb contains sesquiterpenes lactones called parthenolides, which are the active principles of the herb. Hepatoprotective action of certain botanicals deserves attention. Sedum sarmentosum [sarmentosin], Schisandra chinensis [waweizichun and schisantherin] have shown their ability to lower raised liver enzymes in viral hepatitis.
Croton sublyratus [plaunotol] has potent and wide spectrum anti peptic ulcer action. A number of plant derivatives have shown anti-Aids activity. Ancistrocladus korupensis [michellamine-b], Caulophyllum langigerum [calanolide-a], Caulophyllum teymani [costatolide-a], Homalanthus nutans [prostratin], Conospermum sp [concurvone] are the medicinal herbs from African countries that are being employed in research for finding a suitable cure for Aids.
The concept of antioxidants is fastly catching up and latest research has shown that a number of herbal derivatives have excellent antioxidant action. Bacopa monnieri contains bacosides A and B and bacoside A is a strong antioxidant, which reduces several steps of free radical damage. Coleus forskohlii [forskolin], Grape seed [proanthocyanidins], Camellia sinensis [polyphenols], Huperzia serrata [huperzine], Pinus maritima [Pycnogenol], Borago officinalis [gamma linoleic acid] and Vinca minor [Vinpocetine] are potential antioxidants.
The plant is a biosynthetic laboratory, not only for chemical compounds, but also a multitude of compounds like glycosides, alkaloids etc. These exert physiological and therapeutic effect. The compounds that are responsible for medicinal property of the drug are usually secondary metabolites. A systematic study of a crude drug embraces through consideration of primary and secondary metabolites derived as a result of plant metabolism. The plant material is subjected to phytochemical screening for the detection of various plant constituents.
With onset of scientific research in herbals, it is becoming clearer that the medicinal herbs have a potential in today’s synthetic era, as numbers of medicines are becoming resistant. According to one estimate only 20% of the plant flora has been studied and 60%of synthetic medicines owe their origin to plants. Ancient knowledge coupled with scientific principles can come to the forefront and provide us with powerful remedies to eradicate the diseases.
References:
1. Phytotherapy Research (United Kingdom), 1996, 10/SUPPL. 1 (S25-S26) Properties and medical use of flavonolignans (Silymarin) from Silybum marianum. .
2. Martinez and Staba 1988; Fulzele et al. 1991; Whipkey et al. 1992; Ferreira and Janick 1996. Artemisinin distribution in Artemisia annua.
3. Kersey RG, Vance NC, Taxol and cephaomanine from Taxus baccata needles. In :JNP59[2]:117-123.1996.
4. Dfeudis FV , Ginkgo bloba extract (Egb 761): Pharmacological activities and clinical applications .In : Elsevier Editions Scientifiques.1991.
5. Kleijinen J, Kniposchild P, (1992B) Ginkgo biloba. Lancet, 1136-1139.
6. Muruganandam, A. V., S. Ghosal, et al. (2000). The role of xanthones in the antidepressant activity of Hypericum perforatum involving dopaminergic and serotonergic systems. Biogenic Amines. [print] 15(5): 553-567.
7. Sun, W., X. F. Shi, et al. (2000). Preliminary determination of hypericin in Hypericum perforatum extract by HPLC. Zhongguo Yiyao Gongye Zazhi. [print] April 31(4): 172-173.
8. Vormfelde, S. V. and W. Poser (2000). Hyperforin in extracts of St John’s wort (Hypericum perforatum) for depression. Archives of Internal Medicine. [print] September 160(16): 2548-2549.
9. Kupchan SM, Baxter RL. Mezerein: antileukemic principle isolated from Daphne mezereum L. Arzneimittelforschung 1991 Oct; 41(10): 1072-6
10. Camps F et al., (1985) An Quim 81c (1): 74-85.
11. Barthel a, Reuter G,PA 23:26.1968.
12. Sarah H. Bates 3, Robert B. Jones2 and Clifford J. Bailey*, J Asian Nat Prod Res 2000; 2(4): 321-327.
13. Raza H, et.al., Modulation of xenobiotic metabolism and oxidative stress in chronic streptozotocin-induced diabetic rats fed with Momordica charantia fruit extract. J Biochem Mol Toxicol. 2000; 14(3):131-9.
14. Ahmad N, et.al., Effect of Momordica charantia (Karolla) extracts on fasting and postprandial serum glucose levels in NIDDM patients. Bangladesh Med Res Counc Bull. 1999 Apr; 25(1):11-3.

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December 29, 2005

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