Title:Investigation of Anti-Diabetic Properties of Ceylon Cinnamon Bark Extracts by In-Vitro α-Amylase and α-Glucosidase Inhibition, Molecular Modeling, and Postprandial Blood Glucose Regulation for Potential Nutraceuticals
Volume: 5
Author(s): Chanaka Sandaruwan, Thusitha Kusal, Asitha Siriwardhana*, Wasantha Lankathilake, Kosala Purasinhala, Sahan Gunarathne, Sanjeewa Rodrigo, Manju Gunawardene, Veranja Karunaratne and Gehan A.J. Amaratunga
Affiliation:
- Sri Lanka Institute of Nanotechnology (SLINTEC), Nanotechnology and Science Park, Center for Excellence in Nanotechnology,
Mahenwatte, Pitipana, Homagama, Sri Lanka
- Department of Biochemistry and Molecular Biology, Monash
Biomedicine Discovery Institute, Monash University, Victoria, 3800, Australia
Keywords:
Cinnamon, nutraceuticals, diabetes, extract, α-amylase, α-glucosidase.
Abstract:
Background: Diabetes Mellitus (DM) can appear due to the absence of insulin (DM1-type 1) or poor
response of cells to insulin (DM2-type 2). Even though DM1 cannot be controlled using general treatments, DM2
can be easily controlled or prevented using pharmaceuticals, nutraceuticals, or dietary practices. Ceylon cinnamon
(Cinnamomum zeylanicum) is one such natural remedy that has been consumed against elevated blood glucose
levels in the past. Cinnamon and different types of cinnamon extracts have been scientifically tested for their activities
on the inhibition of α-amylase and α-glucosidase enzymes that are responsible for carbohydrate metabolism
and are effective in blood glucose regulation. However, the combined effect of aqueous and ethanol extracts of
cinnamon bark on blood glucose regulation is still lacking. In this study, Water Extract of Cinnamon (CWE), Ethanol
Extracts of Cinnamon (hot ethanol extract of cinnamon-CHEE, cold ethanol extract of cinnamon-CEE, and 50%
ethanol extract of cinnamon- CEE-50) were studied for their sugar-controlling properties.
Objectives: This study was performed to identify the efficacy of different cinnamon extracts on the inhibition of α-
amylase and α-glucosidase enzymes, followed by animal studies to confirm the use of the extracts in nutraceutical
formulations.
Methods: Water and ethanol-based extraction method was used to prepare cinnamon extracts. These extracts have
been scientifically tested for their activities on the inhibition of α-amylase and α-glucosidase enzymes. Molecular
docking studies were used to identify the binding of the active molecules to the substrate binding sites of α-amylase
and α-glucosidase. In vivo time dependence postprandial blood glucose regulation studies have been performed with
healthy Wistar male rats.
Results: Yields of the CHEE, CEE, and CWE were 14±2%, 12±2%, and 8±1% respectively. According to the LCMS
data, the major component in the CEE was cinnamaldehyde. Both CWE and CEE were subjected to the Total Polyphenol
assay (TPC) and Total Flavonoids (TFC) assays. The TPC of CWE and CEE were 117±1 mg (Gal)/g and
170±10 mg (Gal)/g, while the TFC of CWE and CEE were 359±1 mg (Qc)/g and 254±4 mg (Qc)/g, respectively. In
the α-amylase inhibition assay, Acarbose; a known α-amylase inhibitor, and CEE showed IC50 values of 65.4 ppm
and 2.6 ppm, while CWE failed to show inhibition against α-amylase. In the α-glucosidase inhibition assay, Acarbose;
a known α-amylase inhibitor, CEE, and CWE showed IC50 values of 312 ppm, 4.5 ppm, and 1.3 ppm, respectively.
In vivo time dependence postprandial blood glucose regulation studies that have been performed with healthy
Wistar male rats showed a lowering of blood glucose concentrations by 22%, 11%, and 10% of glucose at 30 min,
60 min, and 90 min compared to the control group.
Conclusion: The CEE contains polyphenols and flavonoids and is effective in inhibiting both α-amylase and α-
glucosidase. The CWE also contains polyphenols and a comparatively higher level of flavonoids and is effective in
inhibiting α-glucosidase while not affecting α-amylase inhibition. Overall, the IC50 data, TPC data, and TFC data
proposed that the inhibition of carbohydrate hydrolyzing enzymes by polyphenols may depend on the polarity of
particular polyphenols. Based on the rat trials, it can be concluded that the 1:1 combination of CWE and CEE may
be useful in formulating postprandial blood glucose level-regulating nutraceuticals.
