Volume 168, 20 June 2015, Pages 229–236
Uncovering potential of Indonesian medicinal plants on glucose uptake enhancement and lipid suppression in 3T3-L1 adipocytes
Abstract
Ethnopharmacological relevance
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.
Aim of the study
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.
Materials and 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.
Abbreviations
- 2DG, 2-deoxyglucose;
- BSA, bovine serum albumin;
- DEX, dexamethasone;
- DMEM, Dulbecco׳s modified Eagle׳s medium;
- DMSO, dimethyl sulfoxide;
- FBS, fetal bovine serum;
- G6PDH, glucose 6-phosphate dehydrogenase;
- IBMX, 3-isobutyl-1-methylxanthine;
- IDF, International Diabetes Federation;
- KRPH, Krebs–Ringer–phosphate–Hepes;
- PBS, phosphate buffered saline;
- TEA, triethanolamine
Keywords
- Diabetes;
- Obesity;
- Eurycoma longifolia Jack;
- Piper nigrum L.;
- Tropical plants
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