Minor Diterpene Glycosides from Commercial Extracts of Stevia rebaudiana

Stevia rebaudiana Bertoni (Asteraceae) is a plant well known to produce a mixture of high-potency sweet compounds that have been in the market since the 1970's as low-calorie sweeteners. Stevia rebaudiana is a perennial shrub indigenous to the mountainous regions of Paraguay and Brazil. The native cultures of Paraguay and Brazil have safely used teas made from stevia leaves for sweetening for centuries. Cultivars of Stevia rebaudiana have been selected for enhanced production of select glycosides and are now grown commercially in China, Japan, Korea, India and elsewhere. The Joint FAO/WHO Expert Committee on Food Additives (JECFA) has established a monograph for Steviol Glycosides, the latest issued in 2010. The United States Food and Drug Administration granted GRAS regulatory acceptance of rebaudioside A in 2008 and steviol glycosides in 2010. The European Union approved steviol glycosides for marketing in November 2011. In 2008, a leading market research company reported that the global market for stevia sweetener had reached 500 million dollars and could reach 10 billion dollars in just a few years. The world demand for Stevia leaves is expected to exceed 6 – 8 million metric tonnes in the next 10 years. Stevioside and Rebaudioside A, also known as Rebiana, are the major glycoside sweeteners from S. rebaudiana which have been commercialized for human consumption throughout Asia, Europe, North and South America. S. rebaudiana and its cultivars have been reported to produce as many as 35 glycosides containing the same aglycone, steviol. Examination of both crude and partially processed commercial extracts of Stevia shows the presence of numerous minor metabolites which are very similar in chemical and physical properties and are often present as low level impurities in commercial grade Rebaudioside A and Stevioside. The structure similarities between these metabolites and the commercially available stevioside sweeteners which possess a high safety margin for use in foods, suggest the newly recognized minor metabolites should be isolated, characterized and made available for biological evaluation including especially examination for their organoleptic properties. A significant goal of the present effort is to prepare these minor components in sufficient quantities to make them available for extensive biological evaluation.