Abstract:
Andrographis paniculata is an important medicinal plant reported for its efficacy in the
treatment and management of various medical conditions in different parts of the world. This
study evaluates the α-amylase inhibitory and antioxidant activities of the crude extracts, solvent
fractions and isolated compounds from aerial parts of A. paniculata. Chromatographic
fractionation of the aqueous methanol fraction led to isolation of 14-deoxyandrographolide (1)
and andrographolide (2). The isolated compounds were characterized by set of spectroscopic
techniques such as nuclear magnetic resonance (NMR), infrared (IR) spectroscopy, mass
spectrometry (MS) and their structures were confirmed by x-ray crystallography and by
comparison of data with literature. The extract, fractions and isolated compounds were evaluated
for anti-diabetic and antioxidant activities. Aqueous methanol fraction displayed the highest
amount of total phenolic (TPC) and flavonoid content (TFC) of 9.42 ± 0.95 mg gallic acid
equivalent/g (mg GAE/g) and 40.08 ± 17.93 mg quercetin equivalent/g (mg QUE/g) respectively
amongst the extract and fractions. The aqueous methanol fraction, crude methanol extract and nhexane fraction exhibited better α-amylase inhibitory activity with an inhibitory concentration
(IC50) of 0.057 ± 0.012, 0.0610 ± 0.035 and 0.080 ± 0.021 mg/mL respectively than acarbose, a
standard reference drug with an IC50 value of 0.127 ± 0.013 mg/mL. Compound 1 and 2 exhibited a
lower inhibitory activity with an (IC50) values of 0.637 ± 0.003 and 0.761 ± 0.013 mg/mL
respectively. The results of these study on A. paniculata may justify its traditional use in the
management of diabetes mellitus.
