High-Resolution
α‑Amylase Assay Combined
with High-Performance Liquid Chromatography–Solid-Phase Extraction–Nuclear
Magnetic Resonance Spectroscopy for Expedited Identification of α‑Amylase
Inhibitors: Proof of Concept and α‑Amylase Inhibitor
in Cinnamon
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Abstract
Type 2 diabetes affects millions
of people worldwide, and new improved
drugs or functional foods containing selective α-amylase inhibitors
are needed for improved management of blood glucose. In this article
the development of a microplate-based high-resolution α-amylase
inhibition assay with direct photometric measurement of α-amylase
activity is described. The inhibition assay is based on porcine pancreatic
α-amylase with 2-chloro-4-nitrophenyl-α-d-maltotriose
as substrate, which this gives a stable, sensitive, and cheap inhibition
assay as requested for high-resolution purposes. In combination with
HPLC–HRMS–SPE–NMR, this
provides an analytical platform that allows simultaneous chemical
and biological profiling of α-amylase inhibitors in plant extracts.
Proof-of-concept with an artificial mixture of six compoundsof
which three are known α-amylase inhibitorsshowed that
the high-resolution α-amylase inhibition profiles allowed detection
of sub-microgram amounts of the α-amylase inhibitors. Furthermore,
the high-resolution α-amylase inhibition assay/HPLC–HRMS–SPE–NMR
platform allowed identification of cinnamaldehyde as the α-amylase
inhibitor in cinnamon (<i>Cinnamomum verum</i> Presl.)