Biological effects of stevioside on the survival of Escherichia colistrains and plasmid DNA

Simultaneous quantification of stevioside and rebaudioside A in different stevia samples collected from the Indian subcontinent

Background:

A high performance thin layer chromatographic (HPTLC) method was developed for simultaneous estimation of stevioside and rebaudioside A in Stevia rebaudiana samples collected from different regions of Indian subcontinent.

Materials and Methods:

The separation was achieved by using acetone: ethyl acetate: water (5:4:1, v/v/v) as the solvent system on precoated silica gel 60 F₂₅₄ TLC plates. The densitometric quantification of stevia glycosides was carried out at wavelength 360 nm in absorption mode after spraying with anisaldehyde sulphuric acid as detecting reagent.

Results:

The well resolved peaks for stevioside and rebaudioside A were observed at R_f values 0.31± 0.02 and 0.21± 0.02 respectively. The calibration curves were found linear with a wide range of concentration 100 - 2000 ng spot^-1 with good correlation coefficient 0.996 and 0.991 for stevioside and rebaudioside A, respectively.

Conclusions:

The proposed method was validated as per the ICH (International Conferences on Harmonization) guidelines and found simple, sensitive, economic, reproducible, robust and accurate for quantitative analysis of stevia glycosides, which can be applied for quality control of stevia as well as to check.

Steviol glycosides from Stevia: biosynthesis pathway review and their application in foods and medicine

Stevia rebaudiana, a perennial herb from the Asteraceae family, is known to the scientific world for its sweetness and steviol glycosides (SGs). SGs are the secondary metabolites responsible for the sweetness of Stevia. They are synthesized by SG biosynthesis pathway operating in the leaves. Most of the genes encoding the enzymes of this pathway have been cloned and characterized from Stevia. Out of various SGs, stevioside and rebaudioside A are the major metabolites. SGs including stevioside have also been synthesized by enzymes and microbial agents. These are non-mutagenic, non-toxic, antimicrobial, and do not show any remarkable side-effects upon consumption. Stevioside has many medical applications and its role against diabetes is most important. SGs have made Stevia an important part of the medicinal world as well as the food and beverage industry. This article presents an overview on Stevia and the importance of SGs.

Stevioside and related compounds: therapeutic benefits beyond sweetness

Stevioside, an abundant component of Stevia rebaudiana leaf, has become well-known for its intense sweetness (250-300 times sweeter than sucrose) and is used as a non-caloric sweetener in several countries. A number of studies have suggested that, beside sweetness, stevioside along with related compounds, which include rebaudioside A (second most abundant component of S. rebaudiana leaf), steviol and isosteviol (metabolic components of stevioside) may also offer therapeutic benefits, as they have anti-hyperglycemic, anti-hypertensive, anti-inflammatory, anti-tumor, anti-diarrheal, diuretic, and immunomodulatory actions. It is of interest to note that their effects on plasma glucose level and blood pressure are only observed when these parameters are higher than normal. As steviol can interact with drug transporters, its role as a drug modulator is proposed. This review summarizes the current knowledge of the pharmacological actions, therapeutic applications, pharmacokinetics and safety of stevioside and related compounds. Although much progress has been made concerning their biological and pharmacological effects, questions regarding chemical purity and safety remain unsolved. These issues are discussed to help guide future research directions.