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Document heading
Modulation of adipogenesis and glucose uptake by Curcuma longa
extract in 3T3L1 and L6 cell lines - An in vitro study
A. Prathapan, Mahesh S Krishna, P.C Lekshmi, K.G Raghu, A. Nirmala Menon*
Agroprocessing and Natural Products Division, National Institute for Interdisciplinary Science and Technology (NIIST), CSIR, Trivandrum, Kerala,
India 695019
Asian Pacific Journal of Tropical Disease (2012)S163-S165
Asian Pacific Journal of Tropical Disease
journal homepage:www.elsevier.com/locate/apjtcm
*Corresponding author: A. Nirmala Menon, Agroprocessing and Natural Products
Division, National Institute for Interdisciplinary Science and Technology (NIIST), CSIR,
Trivandrum, Kerala, India 695019.
E-mail: nirmalamenon2000@gmail.com
Foundation project: It is supported by CSIR (SIP 004).
1. Introduction
Metabolic syndrome describes the human condition
characterized by the presence of coexisting traditional risk
factors for cardiovascular disease, such as hypertension,
dyslipidemia, glucose intolerance, and obesity, in addition
to non traditional risk factors, such as inflammatory
processes and abnormalities of the blood coagulation
system[1]. Obesity currently affects over a billion of people. It
is the growing health problem in many of the richest nations
of the world and should now be considered as a chronic
disease that is reaching epidemic proportions[2]. It acts as
a major risk factor for type 2 diabetes and cardiovascular
diseases. Most drugs used for treating type 2 diabetes
causes obesity as a side effects by reducing blood glucose
level and inducing adipogenesis. Traditional medicinal
can serve as an ideal candidate in treating obesity and
type 2 diabetes by acting on adipocytes and can act as a
better alternative for the treatment of metabolic syndromes.
Curcuma longa (Family: Zingiberacea) is reported to possess
many medicinal properties including cardioprotective,
hypolipidemic, antibacterial, anti-HIV, anti-tumour, anti-
carcinogenic and antiarthritic activities[3].
So the present study aims to evaluate the modulatory
effects of Curcuma longa extract against glucose uptake
and adipocyte differenciation in 3T3L1 and L6 cells
2. Materials and methods
2.1. Chemicals
All the chemicals were purchased from Sigma-Aldrich
(Saint Louis, MO, USA) unless or otherwise stated.
2.2. Preparaton of Curcuma longa extract
Fresh turmeric rhizomes were dried at 40-45 曟, ground
into powder and extracted (250 g) successively with hexane,
ethyl acetate, methanol and water at room temperature.
Ethyl acetate fraction contains highest amount of
curcuminoids was further taken to evaluate its biological
ART ICLE INFO ABSTRACT
Article history:
Received 15 June 2012
Received in revised form 27 June 2012
Accepted 18 October 2012
Available online 28 October 2012
Keywords:
Adipocytes
2-NBDG
Flow cytometry
Metabolic syndrome
Objective: To evaluate the effects of ethyl acetate extract of Curcuma longa against modulation
of glucose uptake and adipogenesis in cell line models. Methods: We used 3T3L1 and L6 cells to
investigate cytotoxicity, glucose uptake with 2-NBDG as probe and adipogenesis. All the analysis
was done with flowcytometry. Results: The results showed that the extract did not possess any
significant glucose uptake activity but it exhibited significant adipocyte differentiation potential.
Conclusions: Ethyl acetate extract of Curcuma longa exhibits significant antiadipogenesis and
can be used as an effective drug for the treatment of obesity and other associated complications.
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A. Prathapan et al ./Asian Pacific Journal of Tropical Disease (2012)S163-S165
S164
properties.
2.3. Determination of the subtoxic concentration of Curcuma
longa by MTT assay
Cytotoxicity of the extract was evaluated against L6 and
3T3L1 after 24 h incubation by MTT assay. The method was
carried out as per previously described protocol[4].
2.4. Glucose uptake assay by 2- NBDG
Glucose uptake assay was performed according to the
previous method[5] in L6 rat skeletal muscle cells with
fluorescent analogue of glucose, 2-NBDG (10 毺M) using
flow cytometry (BD FACS Aria II, USA). Insulin (100 U) and
rosiglitazone (100 nM) served as control.
2.5. Adipocyte differentiation assay
Effect of Curcuma longa extract on inhibiting
differentiation of 3T3-L1 preadipocyte to mature adipocyte
was carried out based on reported protocol[6] using flow
cytometry (BD FACS Aria II, USA).
2.5. Statistical analyses
The experimental results were expressed as mean暲
standard deviation (SD) of triplicate measurements. The
data were subjected to one way analysis of variance and the
significance of differences between means were calculated
by Duncan’s multiple range test using SPSS for Windows,
standard version 7.5.1, and the significance accepted at P <
0.05.
3. Results
3.1. MTT assay
To determine the sub toxic concentrations against 3T3L1
and L6 cell lines, Curcuma longa extract was evaluated at
10, 50, 100 and 200 毺g/mL concentrations and cell viability
was determined by MTT assay. Results showed Curcuma
longa extract exhibited toxicity in both the cell lines after a
concentration of 100 毺g/mL.
3.2. Glucose uptake assay
Effect of Curcuma longa on glucose uptake was checked
by 2-NBDG based assay. L6 cells were pre-incubated
with extract at different concentrations from 1-100 毺g/
mL. Results indicated that Curcuma longa was not able
to enhance uptake of 2-NBDG at subtoxic concentrations
(Figure 1). The effect was compared with standard drug
roziglitazone (100 nM), which showed 38.5% increase in probe
uptake. Uptake potential of cells showed a reduction at 100
毺g/mL concentration compared to control. This might be
due to slight toxic effect of extract against L6 cells.
3.3. Antiadipogenic effect of Curcuma longa extract
Around 10 000 events were recorded and analyzed by
flow cytometer based on difference in size and granularity
which gives a separation between undifferentiated cells
and differentiated cells. Results showed that within a
concentration 1 and 5 毺g/mL, the extract seemed to reduce
adipocyte differentiation and lipid droplet content by 22%
(Figure 2).
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Figure 1. Glucose uptake effect of Curcuma longa.
a) Unstained control; b) NBDG control; c) Insulin treated; d) Roziglitazone treated; e-h) Extract treated at 1, 10, 50 and 100 毺g/mL concentration.
A. Prathapan et al ./Asian Pacific Journal of Tropical Disease (2012)S163-S165 S165
4. Discussion
Adipocyte differentiation inhibitors may be effective
in preventing obesity, atherosclerosis, diabetes and
other associated complications. 3T3-L1 cells are known
to differentiate into adipocytes under the appropriate
conditions[2] and have been useful as a model for adipose
cells, which are one of the major sites of lipid and glucose
metabolism. Overweight and obesity are the result of
excessive adipogenesis and therefore inhibition of the
differentiation of 3T3-L1 cells to adipocytes is beneficial
for the prevention of obesity complicated by diabetes and
atherosclerosis[2]. The inhibition potential of Curcuma longa
was found to be dose dependant suggesting that Curcuma
longa may have altered the expression of any genes involved
in the adipocyte expression.
In conclusion, the present study reveals that Curcuma
longa extract didn’t exhibit any significant glucose uptake
activity but it can inhibit adipocyte diffrenciation and can
serve as an ideal candidate for the management of obesity
and associated metabolic syndromes.
Conflict of interest statement
We declare that we have no conflict of interest.
Acknowledgements
Financial support from CSIR (SIP 004) is greatly
acknowledged.
References
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[2] Arumughan M, Vijayan P, Raghu C, Ashok G, Dhanraj SA,
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(Solanaceae) in 3T3 L1. J Compl Int Med 2008; 5(1): 1-9.
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KG. Effect of heat treatment on curcuminoid, color value and total
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[4] Wilson AP, Cytotoxicity and viability assays. In: Masters JRW.
Animal cell culture: A practical approach. 2nd ed. Oxford: Oxford
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[5] Chen QC, Zhang WY, Jin W, Lee IS, Min BS, Jung HJ. Flavonoids
and isoflavonoids from Sophorae Flos improve glucose uptake in
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Figure 2. Change in percentage of differentiated cells upon extract treatment.
a) Untreated control, b) MDI treated cells, c-f) cells treated with different concentration of extract (1-50 毺g/mL).