• Journal of the Korean Society of Food Science and Nutrition
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• v.39 no.2
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• pp.313-318
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• 2010

This study was carried out to evaluate the antioxidant activity of stevia extracts from Stevia rebaudiana Bertoni leaves. Stevia extracts were prepared by three different methods including hot water extraction (HWE) at $120^{\circ}C$ for 4 hr, vacuum extraction (VE) at $65^{\circ}C$ for 4 hr under 0.08 MPa, and fermentation of hot water extract (FHWE) using Lactobacillus buchneri. The antioxidant activities measured by radical scavenging activity, ferric-reducing antioxidant potential ability, and thiobarbituric acid reactive substance showed the highest values in vacuum extract. Also, the antioxidant activities of all extracts were higher than those of stevioside and rebaudioside at the same concentrations, known as the major active components in stevia. To define the antioxidative compound in stevia extracts, the total phenol content was measured, and it was shown that the highest contents of total phenolic compounds were in vacuum extract. These results suggest that the antioxidant activity of stevia extract was due to the phenolic compound components. In addition, vacuum extraction was the proper method to prepare stevia extract with higher antioxidant activity.

• Korean Journal of Food Science and Technology
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• v.42 no.5
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• pp.586-592
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• 2010

This study investigated the effects of Stevia rebaudian bertoni leaf extract on lipid profiles in C57BL/6J mice, as compared to stevioside. Fourty mice were divided into four groups: NC (normal diet and DW), HC (high fat diet and DW), HLSV (high fat diet and stevia leaf extract, 1 mL/kg/day), and HSS (high fat diet and stevioside, 1 mL/kg/day). Serum triglyceride concentrations were significantly lower in the HLSV and HSS groups than in the HC group. Epididymal fat pad weights were significantly lower in the HLSV and HSS groups than in the HC group. We also evaluated the serum and liver carnitine levels (NEC, AIAC, ASAC, TCNE) of all the groups. These results were supported by the mRNA expression of enzymes related to lipid metabolism (ACC, PPAR${\alpha}$, ACS, CPT-I) assessed by RT-PCR. Overall, the results show the antiobesity effects of stevia leaf extract as compared to stevioside in high fat diet induced obese mice.

• Korean Journal of Food Science and Technology
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• v.14 no.2
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• pp.179-183
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• 1982

This experiment was carried out to clarify the optimal concentrations of growth regulators for callus induction and the condition of callus culture of leaf tissue taken from Stevia rebaudiana Bertoni. The content of stevioside, sweetening component, in leaf-derived callus of stevia was also investigated. It was shown that the optimal concentrations of benzyladenine (BA) and ${\alpha}-naphthalene$acetic acid (NAA) for callus induction were $10^{-6}M$ and $10^{-5}M$, respectively. Reculture of these calli in media (Linsmaier and Skoog) supplemented with BA $10^{-6}M$ and NAA $10^{-5}M$ resulted in profuse calli 15 to 20 days after incubation. When sweetening components produced by callus were extracted and identified by TLC, stevioside appeared to have Rf value 0.50 in TLC which was exactly same as standard stevioside. Stevioside content obtained by TLC-FID analyzer was 260mg per 100g on the basis of dry weight.

• Journal of Life Science
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• v.18 no.2
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• pp.228-233
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• 2008

Antimicrobial activities of ethanol extracts of about 60 endemic Korean herbs and medicinal plants were investigated. When compared to the group treated with phenoxyethanol as a positive control, the growth of Pseudomonas aeruginosa was inhibited by Styrax japonica, Stevia rebaudiana, Morus Leaf, Coptis chinensis and Slavia miltorrhiza Bunge, the latter showing the strongest inhibition (97%). The growth of Staphylococcus aureus was inhibited by Acorus calamus, Pinus densiflora, Ginkgo biloba, Dryopteris crassirhizoma, Chrysanthemum zawadskii, Slavia miltorrhiza Bunge and Coptis chinensis, the latter showing the strongest inhibition (99%). The growth of yeast type fungi Candida albicans was inhibited to about 35% by Scutellaria baicalensis Geogr and about 33% by Coptis chinensis as determined by paper disk method. The growth of bacterium Malassezia furfur was inhibited by Paeonia lactiflora, Rosa multiflora, Coptis chinensis, Citrus aurantium L. subsp, Paeonia suffruticosa Andrews, and Galla rhois, the latter showing the strongest inhibition (57%). The growth of Propionibacterium acnes was inhibited by Galla rhois, Paeonia lactiflora, Morus bombycis, Cucumis sativus, Stevia rebaudiana, Coptis chinensis and Slavia miltorrhiza Bunge. Interestingly, Coptis chinensis and Slavia miltorrhiza Bunge showed the strongest inhibition (99%) similar to that in postive control. The possible components and their action modes were suggested and discussed.