Title page for ETD etd-10202009-094300

Type of Document Master's Thesis
Author Koh, Gar Yee
Author's Email Address gkoh3@tigers.lsu.edu
URN etd-10202009-094300
Title Preparation of the Chinese Sweet Leaf Tea Extract and Its Anti-obesity Effect in Rodents
Degree Master of Science (M.S.)
Department Renewable Natural Resources
Advisory Committee
Advisor Name Title
Liu, Zhijun Committee Chair
Martin, Roy Committee Member
Xu, Zhimin Committee Member
  • Rubus suavissimus
  • Chinese sweet leaf tea
  • Crude Extraction
  • Purification
  • Alcohol Precipitation
  • Anti-obesity
Date of Defense 2009-09-30
Availability unrestricted
The aqueous leaf extract of Rubus suavissimus (Chinese sweet leaf tea) was active in inhibiting angiogenesis, which could be used to suppress adipogenesis and cause weight loss. Following this revelation and approach, the anti-obesity effect was thoroughly investigated in normal and obese rat models.

The investigations began with the preparation of quality-controlled extract. First, the crude extraction methods were examined leading to the characterization of the chemical composition. Second, the impure components were removed by alcohol precipitation and column chromatography, resulting in a standardized sweet leaf tea extract (RUS). Third, three bioavailable compounds identified from the urine analyses were re-constituted to form the purified sweet leaf tea extract (GER), which accounted for 27% by weight of the RUS. These standardized and purified sweet leaf tea extracts were then evaluated for their anti-obesity effect in normal and obese-prone rats.

Both RUS and GER reduced body weight gain by 7% (p =0.999) in normal rodents but statistical analyses failed to show any significance due to small sample size. Amazingly, it was discovered that the use of the tri-compounds combination (GER) produced the same anti-obesity effect as the standardized extract (RUS). Consequently, new experiments were focused on the GER using obese-prone rats as the study model. GER showed a significant anti-obesity effect by reducing 22% (pí▄ 0.001) weight gain compared to the high-fat diet control group. Total abdominal fat was reduced significantly by 48%, indicating that the lost body mass was mainly due to the loss of body fat. Other benefits of the Chinese sweet leaf tea extract included lowered blood glucose, cholesterol, and triglycerides. Food intake was not affected. No adverse effects were observed.

This research provides exciting insights about the novel use of the Chinese sweet leaf tea as a safe and effective anti-obesity agent beyond its historic use as a natural sweetener. Human clinical investigations are strongly warranted to determine the effective doses and long-term use safety in combating obesity or managing body weight.

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