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Journal of Thai Traditional & Alternative Medicine Vol. 8 No. 2 May-August (Supplement) 2010 Ùı

PP-2

The Screening of Lipase Inhibitors from Indigenous Vegetables and Herbs in

Northeastern of Thailand

Somjintana Taveepanich

Department of Chemistry, Faculty of Science, Ubon Ratchathani University, Warinchamrap, UbonRatchathani, Thailand
34190

Rationale: Agents that inhibit fat digestion are of theoretical benefit in the treatment of obesity. Orlistat,
a hydrogenated derivative of lipstatin which is a natural product from the bacteria Streptomyces toxytricini,
inhibits the absorption of 30% of dietary fat, and this has been shown to reduce body weight in patients with
obesity. Extracts of vegetables and medicinal plants were screened in pursuit of new sources of pancreatic
lipase inhibitors. These sources could represent a starting point for further investigation in developing func-
tional food and isolation of active compounds.
Objective: To determine the potential of various indigenous vegetables and herbs in Northeastern of
Thailand that have been used for antiobesity purposes.
Methodology: Forty-five indigenous vegetables and herbs were selected and collected from Northeastern
of Thailand. Their edible parts were extracted by 95% methanol. The extracts were tested for antilipase activity
determination. A solution (5 mg/mL) was prepared from type II crude porcine pancreatic lipase. Then a 3.3 mM
solution of p-nitrophenylpalmitate (PNP) in acetonitrile and ethanol (1:2) was prepared. The composition of the
reaction mixture was: 10 μL of 3.3 mM PNP, 162 μL of 75 mM Tris-HCl buffer (pH = 8.5), 16 μL of extract and
o
12 μL of enzyme solution. The mixture was incubated at 37 C for 25 min before the substrate was added. In the
positive control, the extract was replaced with the same volume of methanol:water mixture (1:1). Orlistat were
used as standard references. The antilipase activity was performed by the observation of decreasing of enzyme
antilipase activity. The absorbance was measured in Ultraviolet-visible spectrophotometer at 405 nm. The
activity was calculated and plotted against concentrations of the extracts. The concentrations which showed
50% antilipase activity (IC ) were determined. IC values were compared. The experiment was done in
50 50
triplicate.
Results: A majority of extracts exhibited inhibitory activity. Thrity-seven extracts that showed at least
some inhibitory activity (below 50%) and four extracts that showed moderate inhibitory activity (50-70%). Over
70% inhibitory activity exhibited by five extracts, Cissampelos pareira L., Sesbania grandiflora (L.) Desv. Averrhoa
carambloa L., Sauropus androgynus (L.) Mert., Senna siamea (Lam.) Irwin & Barneby. The highest antilipase
activity was found in the methanol extract of Senna siamea (Lam.) Irwin & Barneby with an IC value of 0.11
50
mg/mL, meanwhile orlistat showed IC value 0.01 μg/mL ). For other plants, the IC values were in the range
50 50
of 0.13 to 0.47 mg/ml. The inhibitory potency of the crude extract was weaker than that of orlistat. Since a crude
extract includes not only active substances but also non-active components, the activity of the extract could be
lower than that of the active compound which would be contained in a plant. The pancreatic lipase inhibitory
phytochemicals contained in plants or isolated from plants have been reported to be saponins and polyphenols.
Some reports on lipase inhibitory activity has been documented for plants belonging to Fabaceae. The extracts
of Senna siamea (Lam.) Irwin & Barneby were found to be good candidates for further studies to isolate
pancreatic lipase inhibitors.
Conclusion: In this study it was shown that extracts from Senna siamea (Lam.) Irwin & Barneby are of
value as a starting point for the further isolation and identification of active inhibitory compounds or for
developing antiobesity functional food.