title: Uncovering potential of Indonesian medicinal plants on glucose uptake enhancement and lipid suppression in 3T3-L1 adipocytes.
abstract: BACKGROUND
  As obesity is a key factor in the development of type 2 diabetes, lowering lipid accumulation in adipose tissues is as important as increasing insulin sensitivity in diabetic patients. The selected plant extracts used in this screen have been traditionally used in Indonesian medicine for the treatment of diabetes and its complications.
  
  
  OBJECTIVE
  To investigate the ability of the selected plants to both increase insulin sensitivity through the enhancement of glucose uptake after insulin induction in adipocytes and suppress lipid production in the same target cells.
  
  
  METHODS
  Dried Indonesian medicinal plants were extracted with 50% (v/v) aq. methanol. The extracts were dissolved in 50% DMSO when tested in 3T3-L1 adipocytes. The screening platform consists of insulin-induced glucose uptake, lipid accumulation, and cell viability. Initially, an enzymatic fluorescence assay was designed to demonstrate the enhancement of 2-deoxyglucose (2-DG) uptake after insulin induction. Different concentrations of the extracts that enhanced glucose uptake were subjected to lipid accumulation assay using Oil Red O staining. Potential extracts based on lipid suppression were subsequently assessed by CCK-8 cell viability assay to distinguish lipid reduction activity from cytotoxicity.
  
  
  RESULTS
  Out of 59 plants, 13 plants demonstrated their ability to increase glucose uptake in 3T3-L1 adipocytes after insulin induction, and 4 of these plants' extracts suppressed lipid production of the cells. The CCK-8 assay results of those 4 plant extracts suggest that the lipid inhibition activity of Eurycoma longifolia Jack (root) and Piper nigrum L. (fruits) extracts is not attributed to their cytotoxicity in the adipose cells. Both of the plant extracts increased glucose uptake by more than 200% at 50 μg/mL and suppressed lipid accumulation in a concentration-dependent manner.
  
  
  CONCLUSIONS
  Screening of selected Indonesian medicinal plants has uncovered the potentials of E. longifolia Jack (root) and P. nigrum L. (fruits) with dual active functions, increasing insulin sensitivity through the enhancement of glucose uptake and reducing lipid accumulation in adipose cells. These findings suggest that the ability of both plants to suppress lipid production would provide additional benefits in the treatment of diabetes.
authors: Laboratory of Food Biochemistry, Division of Applied Bioscience, Graduate School of Agriculture, Hokkaido University, Kita-ku, Sapporo 060-8589, Japan.
authors: Lucy
authors: L
authors: Lahrita
authors: Laboratory of Food Biochemistry, Division of Applied Bioscience, Graduate School of Agriculture, Hokkaido University, Kita-ku, Sapporo 060-8589, Japan. Electronic address: eikato@chem.agr.hokudai.ac.jp.
authors: Eisuke
authors: E
authors: Kato
authors: Laboratory of Food Biochemistry, Division of Applied Bioscience, Graduate School of Agriculture, Hokkaido University, Kita-ku, Sapporo 060-8589, Japan.
authors: Jun
authors: J
authors: Kawabata
mesh_terms: D041721:3T3-L1 Cells; D017667:Adipocytes / Q000187:drug effects / Q000378:metabolism; D000818:Animals; D035701:Eurycoma; D005638:Fruit; D005947:Glucose / Q000378:metabolism*; D007214:Indonesia; D007328:Insulin / Q000494:pharmacology; D050356:Lipid Metabolism / Q000187:drug effects; D051379:Mice; D029222:Piper nigrum; D010936:Plant Extracts / Q000494:pharmacology*; D018517:Plant Roots; D010946:Plants, Medicinal
chemical_list: D007328:Insulin; D010936:Plant Extracts; D005947:Glucose
keywords: Diabetes; Eurycoma longifolia Jack; Obesity; Piper nigrum L.; Tropical plants