Abstract:
Background: Nanoencapsulated herbal extracts have gained significant interest in the
management of diabetes mellitus. Determination of polyphenol, flavonoid contents, and alpha
amylase inhibition activity is a substantial approach to screen herbal extracts and to develop
commercially viable nanoencapsulated herbal formulations. The selection of plants was based
on previously proven antidiabetic activity in literature and the novelty of development of
nanoencapsuled nutraceutcials.
Objective: To determine the Total Polyphenol Content (TPC), Total Flavonoid Content (TFC)
and α-amylase inhibition potential in Coccinia grandis L. (Ivy Gourd, Family: Cucurbitaceae),
Aegle marmelos L. (Bael, Family: Rutaceae) and Catharanthus roseus L. (Madagascar
periwinkle, Family: Apocynaceae) extracts with an aim of selecting herbal extracts to develop
nanoformulations with potent α-amylase inhibitory activity.
Method: Dried leaves of C. grandis, C. roseus and dried fruit of A. marmelos were extracted
with aqueous (0.06 mg/mL), 95% ethanol (0.03 mg/mL), 50% ethanol (0.03 mg/mL) and 50%
acetone (0.03 mg/mL) using ultrasonication method (40 °C, 30 min, 40 kHz). The TPC and
TFC were determined using Folin Ciocalteu method and aluminum chloride method
respectively. The results of TPC and TFC were expressed as Gallic Acid Equivalents (GAE)
and Quercertin Equivalents (QE) respectively. The inhibitory potential in α-amylase inhibition
is expressed in terms of IC50. Acarbose was used as the reference compound.
Results: The highest TPC was obtained with 50% ethanol extract of A. marmelos (23.25±0.33
mg GAE/g) and the highest TFC was obtained with 95% ethanol extract of C. roseus
(38.89±0.22 mg QE/g). Aqueous extract of C. grandis obtained the lowest value of both TPC
(1.51±0.01 mg GAE/g) and TFC (0.46±0.03 QE/g). The 50% ethanol extract of C. grandis
gained the highest α-amylase inhibitory activity with an IC50 value of 3.58±1.16 mg/mL.
Conclusion: The ethanol extracts had high TPC and TFC. The 95% and 50% ethanol extracts
of selected medicinal plants were selected for the development of nanoformulations based on
comparatively high TPC, TFCs and high α-amylase inhibitory activity
