Obesidad

PHCOG REV.

REVIEW ARTICLE

α-glucosidase inhibitors from plants: A natural
approach to treat diabetes
Sunil Kumar, Smita Narwal, Vipin Kumar, Om Prakash
Institute of Pharmaceutical Sciences, Kurukshetra University, Kurukshetra - 136 119, Haryana, India
Submitted: 15-05-2010

Revised: ?????

Published: ???????

ABSTRACT
Diabetes is a common metabolic disease characterized byabnormally high plasma glucose levels, leading to major
complications, such as diabetic neuropathy, retinopathy, and cardiovascular diseases. One of the effective managements of
diabetes mellitus, in particular, non–insulin-dependent diabetes mellitus (NIDDM) to decrease postprandial hyperglycemia, is
to retard the absorption of glucose by inhibition of carbohydrate hydrolyzing enzymes, such asα-glucosidase and α-amylase,
in the digestive organs. α-Glucosidase is the key enzyme catalyzing the final step in the digestive process of carbohydrates.
Hence, α-glucosidase inhibitors can retard the liberation of d-glucose from dietary complex carbohydrates and delay glucose
absorption, resulting in reduced postprandial plasma glucose levels and suppression of postprandial hyperglycemia. Inrecent years, many efforts have been made to identify effective α-glucosidase inhibitors from natural sources in order to
develop a physiologic functional food or lead compounds for use against diabetes. Many α-glucosidase inhibitors that are
phytoconstituents, such as flavonoids, alkaloids, terpenoids,anthocyanins, glycosides, phenolic compounds, and so on,
have been isolated from plants. In thepresent review, we focus on the constituents isolated from different plants having
α-glucosidase inhibitory potency along with IC50 values.
Key words: Alkaloids, anthocyanins, diabetes, flavonoids, α-glucosidase, glycosides, terpenoids

INTRODUCTION
Diabetes mellitus is the most serious, chronic metabolic disorder
and is characterized by high blood glucose levels. One therapeutic
approach totreat diabetes is to retard the absorption of glucose
via inhibition of enzymes, such as α-glucosidase, in the digestive
organs.[1,2] α-Glucosidase (α-d-glucoside glucohydrolase) is an
exo-type carbohydrase distributed widely in microorganisms,
plants, and animal tissues,[3] which catalyzes the liberation of
α-glucose from the non reducing end of the substrate. Inhibiting
this enzyme slowsthe elevation of blood sugar following a
carbohydrate meal.[4] It is a membrane bound enzyme present in
Address for correspondence:
Prof. Vipin Kumar,
Institute of Pharmaceutical Sciences, Kurukshetra University,
Kurukshetra -136 119, Haryana, India.
E-mail: vipbhardwaj@rediffmail.com
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the epithelium of thesmall intestine, which works to facilitate
the absorption of glucose by the small intestine by catalyzing
the hydrolytic cleavage of oligosaccharides into absorbable
[Figure 1] monosaccharides.[5]
By the inhibition of α-glucosidase in the intestine, the rate of
hydrolytic cleavage of oligosaccharide is decreased and the
process of carbohydrate digestion spreads to the lower part of
smallintestine. This spreading of digestion process delays the
overall absorption rate of glucose into the blood. This has proved
to be one of the best strategies to decrease the postprandial rise
in blood glucose and in turn help avoiding the onset of late
diabetic complications.[5]
There are reports of the presence of α-glucosidase inhibitors,
such as acarbose[6,7] andvoglibose,[8] in microorganisms,and
nojirimycin[9-11] and 1-deoxynojirimycin[11] in plants, as well as
the effects of α-glucosidase inhibitor in wheat kernels on blood
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DOI:
10.4103/0973-7847.79096

Pharmacognosy Reviews | January-June 2011 | Vol 5 | Issue 9

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Figure 1: Conversion of oligosaccharide to glucose
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