Finding new drug target for alpha amylase.

1. Finding new drug targets for alpha amylase
By :- Parisuta Pradhan (1601106008) & Pratik Dash (1601106010)
Introduction:
α-Amylase is an endoamylase and belongs to glycoside hydrolase family 13 (GH 13)
according to the classification of carbohydrateactive enzymes. It initiates starch
hydrolysis into smaller oligomers. α-Amylases are synthesized as part of a multi-gene
family, which is regulated to provide different isozymes in different tissues. There
are two main isoforms in humans, salivary α-amylases and pancreatic α-amylases,
which exhibit different cleavage patterns through amino acid substitutions, some
near their active site regions. Microorganisms, higher plants, and animals produce a
large number of different protein inhibitors of α-amylases in order to regulate the
activity of these enzymes. These inhibitors can be grouped into six classes based on
their tertiary structures: lectin-like, knottin-like, cereal-type, Kunitz-like, γ-
purothionin-like and thaumatin-like inhibitors. Some of these inhibitors act by
directly blocking the active centre of the enzyme at various local sites.
In animals, α-amylase inhibitors reduce the glucose peaks that can occur after a
meal, slowing the speed with which α-amylase can convert starch to simple sugars
until the body can deal with it. This is of particular importance in people with
diabetes, where low insulin levels prevent extracellular glucose from being cleared
quickly from the blood. Therefore, diabetics tend to have low α-amylase levels in
order to keep glucose levels under control, except after taking insulin, which causes a
rise in pancreatic α-amylase.
Plants use α-amylase inhibitors as a defence strategy. These inhibitors impede the
digestive action of α-amylases and proteinases in the insect gut, thereby acting as
insect anti-feedants. As a result, α-amylase inhibitors have potential in various fields,
including crop protection and the treatment of diabetes.
A review about crude extracts and isolated compounds from plant source that have
been tested for α-amylase inhibitory activity has been done. The analysis of the
results shows a variety of crude extracts that present α-
amylase inhibitory activity and some of them had relevant activity when compared
with controls used in the studies. Amongst the phyto-constituents that have been
investigated, flavonoids are one of them that demonstrated the highest inhibitory
activities with the potential of inhibition related to number of hydroxyl groups in the
molecule of the compound.
Methodology:
Research papers of last five years based on alpha amylase inhibition were collected
from various journal sites like NCBI and Researchgate. The papers were then
analysed and methods were devised for calculating the efficiency of various drugs for

2. inhibition of alpha amylase. Mostly the drugs were derived from plants as the drugs
were found to be more effective. Mostly these drugs are phytochemicals, otherwise
known as secondary metabolites of plants. These metabolites include tannins,
saponins and terpenoids. Also various phenolic compounds like flavonoids and its
derivatives along with some oligosaccharides like Acarbose 1 are also used for
inhibition of alpha amylase enzyme. The mechanism of action of these drugs was
then found out.
Results and Discussion:
The various drugs found to inhibit alpha amylase secretion and action are :-
 Acarbose 1 :- Acarbose 1 belongs to the oligosaccharide family of trestatin
that contain the acarviosine moiety and act as the natural inhibitors of alpha
amylase. This drug is used widely for treatment of Diabetes mellitus and is a
competitive inhibitor of α-amylase. The mechanism of inhibition is due to the
unsaturated cyclohexane ring and the glycosidic nitrogen linkage that mimics
the transition state for the enzymatic cleavage of the glycosidic linkages.
 Flavonoids :- Flavonoids are abundant class of natural phenolic compounds
with several biological activities. They share a common structural skeleton
consisting of two aromatic rings (A and B) linked through three carbons
attached to the A-ring, forming an oxygenated heterocycle (ring C)and are
divided in groups. The power of inhibition is correlated with the number of
hydroxyl groups on the B ring of the flavonoid skeleton. The interaction occurs
with the formation of hydrogen bonds between the hydroxyl groups in
position R6 or R7 of the ring A and position R4’ or R5’ of the ring B of the

3. polyphenol ligands and the catalytic residues of the binding site and formation
of a conjugated π -system that stabilizes the interaction with the active site.
Fig. Structure of flavonoids
 Tannins :- Tannins are another heterogeneous polyphenol group widely
distributed in the plant kingdom. They have a relatively high molecular weight
and can be classified into two major classes: hydrolysable tannins and
condensed tannins. Hydrolysable tannins are subdivided into gallotannins,
derived from gallic acid units linked to a sugar moiety), while condensed
tannins are complex polymers, where the building blocks are usually catechins
and flavonoids. Tannins could cause several effects on the biological system
because they are potential metal ion chelators and protein precipitation
agents forming insoluble complexes with proteins, as well as biological
oxidants. As the mechanism involved in this anti-hyperglycemic effect is
unknown, it is possible that tannins can inhibit α-amylase activity in situ.
Fig. Structure of tannic acid
 Terpenoids :- Terpenoids are compounds that comprise various structures
commonly found in nature with several function in plants and animals. They
usually arise from head-to-tail joining of isoprene units and a combination of
two or more isoprene units divide the terpenoids in monoterpene (C10),
sesquiterpene (C15), diterpene (C20), sesterterpene(C25), triterpene (C30)

4. and tetraterpene (C40) . While triterpenoids are widely distributed in plants,
inhibitory α-amylase activities are related only foroleanane, ursane and
lupane types and the mechanism by which this activity occur still unknown.
Fig. Chemical structure of lupeol
Conclusion:-
α-Amylase, a salivary or pancreatic enzyme plays an important role in early
breakdown of complex carbohydrates into simple molecules. Modulation of α-
amylase activity affects the utilization of carbohydrates as an energy source and
stronger is this modulation; more significant is the reduction is the breakdown of
complex carbohydrates. Thus, the various drugs that target the enzyme α-amylase
were reviewed.