About Authors:
Neha Sharma*, Dr. Rajinder Kaur
Dr Y S Parmar University of Horticulture and Forestry, Solan
* nehabtc@gmail.com
Abstract:
Main source of sugar has long been cane sugar with beet sugar contributing a very less percentage. But these sugars alongwith sweetening qualities have been found to contribute calories, which can lead to various chronic diseases. Stevia rebaudiana is one such medicinal plant which have made possible to offer consumers the sweet taste without calories. Stevia alongwith sweetner offers anti-bacterial, anti-fungal, anti-inflammatory, anti-viral, anti-yeast, cardiotonic, diuretic and hypoglycaemic properties. Hence there is need to study this medicinal plant to promote this natural sweetener and create product awareness. Its genetic diversity study provides better knowledge of the herb and hence its production and so that it can be used more and more by the pharmaceutical industries to serve the mankind.
Reference Id: PHARMATUTOR-ART-1320
Introduction:
From ancient times to today plants have been used as a medicine. Today medicinal plants are important to the global economy (1), as an approximately 85% of traditional medicine preparations involve the use of plants or plant extracts (2). In fact, in recent years the medicinal plant has become very important in the treatment of minor ailments and also on account of the raising costs of health maintenance. In the recent past many research activities on stevia chemical and biological properties has been done. In India, its commercial cultivation has started. Stevia rebaudiana is one of the most valuable tropical medicinal plant. It has been used to sweeten tea for centuries dating back to the Guarani Indians of South America. Studies revealed stevia could replace some or all of the sugar (sucrose) in food industry and pharmaceutical industry. The plant is gradually gaining interest all over the world due to presence of zero calorie sweetener compounds such as stevioside (8.0-11.0%) and rebaudioside A & C (2-4%). The plant is commercially grown in China, Japan, South Korea, India, Ukraine, Australia, Canada, Meico, United States of America, UK, Belgium, Spain and many countries of South America. Literature on this crop is very much scattered. Hence the objective of this review is to compile the literature and condense at one place about Stevia rebaudiana- a medicinal herb as a god’s gift. The review provided here will serve to provide as much information like we have gone through an encyclopedia of stevia.
Morphology and Distribution:
Stevia is a semi bushy perennial plant of Asteraceae family originated from Paraguay. It is one of 154 members of the genus stevia, which gives sweet taste. Stevia is cultivated as a cash crop in number of countries. However, in India cultivation of stevia as a crop is still restricted to the research level. But keeping in view, its increasing popularity alongwith its traditional importance all over the world India has also ventured in the same field.
Stevia rebaudiana is known by number of names viz. sweet leaf, sweet herb of Paraguay, Honey leaf and candy leaf suggesting its widespread use. It is likely to become a major source of high potency sweetener for growing natural food market in future. Stevia is shrubby perennial growing upto 65-75 cm tall, with sessile, oppositely arranged lanceolate to oblanceolate leaves, serrated above the middle. Flowers are white and arranged in an irregular cyme and the flowers are very small (7-15mm). Trichome structures on the leaf surface are of two distinct sizes, one large (4-5µm), one small (2.5µm). The seed is an achene with a feathery pappus.
S. rebaudiana is originally a South American wild plant, but it could be found growing in semi-arid habitat ranging from grassland to scrub forest to mountain terrain.
Propagation:
Its medicinal and commercial value led to the urgent demand for large scale production of stevia plants from elite germplasm. The seeds of stevia show very low germination percentage (3) and propagation by seeds doesnot allow the production of homogenous population resulting in variability in sweetener level and composition (4). Poor seed germination due to low viable seeds is one of the factors limiting large scale cultivation. Vegetative propagation by stem cuttings is also limited by low number of individuals that can be obtained simultaneously from single plants. Hence biotechnology supports the cultivation, and production of stevia.
In vitro propagation:
Tissue culture for clonal propagation of the plant offers a viable means for obtaining plants to be cultivated on a commercial scale. Owing to its significance as a medicinal plant and also to meet its demand it needs to be multiplied at a fast rate. Micro-propagation can provide genetically uniform plants in large numbers. Shoot regeneration in Stevia rebaudiana, from callus initiated from leaf explants on MS 1962 (5) medium (for callus MS medium supplemented with 2.0 mg/l of 2,4-D and 1.0 mg/l Kinetin) supplemented with 5.0 mg/l BA with 1.0 mg/l NAA, was reported (6). Profuse rooting was observed upon transferring the in vitro proliferated shoots by placing them on ½ MS medium containing 100 mg/l activated charcoal.
Somatic embryos (7) were also obtained from floral explants cultured on MS medium supplemented with 2,4-D (9.05 and 18.19µM) and Kinetin (0.0 to 9.2µM). On 9.05µM 2,4-D supplemented medium without kinetin maximum embryogenic callus formation occurred.
A multiple shoot culture was induced from nodal segments on MS medium containing half concentration of macroelements, 1%sucrose and supplemented with NAA (0.01 mg/l) (8).
Tissue culture was carried out on Stevia rebaudiana for in vitro multiplication of Stevia rebaudiana using shoot tips and axillary buds. The axillary buds successfully proliferated on MS with 0.5 mg/l IAA, 5.0 mg/l BAP and 10 mg/l GA3 (9).
A long list of medicinal properties of Stevia:
The property of stevia that called attention was the intense sweet of the leaves and aqueous extracts. According to WHO (World Health Organization) findings it regulates blood pressure, fights cavities, induce pancreas to produce more insulin and act as a bactericidal agent (10).
Leaf extract of stevia promotes effects on certain physiological systems such as cardiovascular and renal and influences hypertension and hyperglycemia. (11). Studies have revealed the strong bactericidal property against a number of pathogenic bacteria including certain E. coli strains (12). Stevia is also rich in terpenes and flavanoids. The phytochemicals present are autoinullin, β- carotene, dulcoside , nilacin, rebaudi oxides, riboflavin, steviol, stevioside and tiamin (13) and possess properties of low uric acid treatment, anesthetic, anti-inflammatory, vasodilator cardiotonic and also it is anti-microbial and anti-tumor activity (14).
Stevia aids to the management of diabetes. It contains protein, ash of crude fiber, which are essential for the maintenance of good health and are comparable to commonly used cereals in India. Due to its higher protein content it shows increased water binding capacity and emulsifying property.
Due to its almost negligible calorie contribution, it is useful for over weight, obese and health conscious individuals.
Conclusion:
Stevia offers lot many advantages to mankind but still India is much behind in the commercialization of Stevia rebaudiana. There should be well known techniques for cultivation of stevia and hence the mankind can use it more and more and can have benefit from it. The present review is an attempt to unfold the unknown sides of stevia and hence to uncover its that side that is yet far from the mankind.
References:
1. Srivastava J, Lambert J and Vietmeyer N. 1995. Medicinal Plants: expanding role in development. World Bank technical paper no. 320. Washington DC. World Bank Agriculture and Forestry Systems.
2. Vieira R F and Skorupa L A. 1993. Brazilian medicinal plants gene bank. Acta Horticulture, 330: 51-58.
3. Felippe G M and Lucas N M C. 1971. Estudo da viabilidabe des frutos de Stevia rebaudiana, Hoehnea, 1: 95-105.
4. Nakamura S and Tamura Y. 1985. Variation in the main glycosides of stevia. Jpn J Trop Agric, 29: 109-116.
5. Murashige T and Skoog F. 1962. A revised medium for rapid growth and bioassay with tobacco tissue cultures. Physiol. Plant, 15: 473-479.
6. Sairkar P, Chandravanshi M K, Shukla N P and Mehrotra N N. 2009. Mass production of an economically important medicinal plant Stevia rebaudiana using in vitro propagation techniques.
7. Filho J C B and Hattori K. 1997. Embryogenic callus formation and histological studies from Stevia rebaudiana Bertoni floret explants. R. Bras. Fisiol. Veg, 9(3): 185-188.
8. Nepovim A and Vanek T. 1998. In vitro propagation of Stevia rebaudiana plants using multiple shoot culture. Planta Med, 64: 775-776.
9. Patil V, Ashwini K S, Reddy P C, Purushotham M G, Prasad T G and Kumar M U. 1996. In vitro multiplication of Stevia rebaudiana. Current Science, 70(11): 10.
10. Bhosle S. 2004. Commercial cultivation of Stevia rebaudiana. Agrobios Newslett. 3: 43-45.
11. Tadhani M B, Patel V H and Subhash R. 2007. In vitro anti-oxidant activities of Stevia rebaudiana leaves and callus. J. Food Comp. Anal., 20: 323-329.
12. Yodyingyuad V and Bunyawong S. 1991. effects of stevioside on growth and reproduction. Human Reprod., 6: 158-165.
13. Crammer B and Ikan R. 1986. Sweet glycosides from the stevia plant. Chem Brit. 22: 915-917.
14. Jayaram S K, Manoharan M S and Illanchezian S. 2008. In vitro anti-microbial and Anti tumor activities of Stevia rebaudiana (Asteraceae) leaf extracts. Trop. Jour. Of Pharmaceu. Research., 7(4): 1143-1149.
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