In vitro alpha-glucosidase and alpha-amylase enzyme inhibitory effects of Andrographis paniculata extract and andrographolide

There has been an enormous interest in the development of alternative medicines for type 2 diabetes, specifically screening for phytochemicals with the ability to delay or prevent glucose absorption. The goal of the present study was to provide in vitro evidence for potential inhibition of alpha-glucosidase and alpha-amylase enzymes, followed by a confirmatory in vivo study on rats to generate a stronger biochemical rationale for further studies on the ethanolic extract of Andrographis paniculata and andrographolide. The extract showed appreciable alpha-glucosidase inhibitory effect in a concentration-dependent manner (IC(50)=17.2+/-0.15 mg/ml) and a weak alpha-amylase inhibitory activity (IC(50)=50.9+/-0.17 mg/ml). Andrographolide demonstrated a similar (IC(50)=11.0+/-0.28 mg/ml) alpha-glucosidase and alpha-amylase inhibitory activity (IC(50)=11.3+/-0.29 mg/ml). The positive in vitro enzyme inhibition tests paved way for confirmatory in vivo studies. The in vivo studies demonstrated that A. paniculata extract significantly (P<0.05) reduced peak blood glucose and area under curve in diabetic rats when challenged with oral administration of starch and sucrose. Further, andrographolide also caused a significant (P<0.05) reduction in peak blood glucose and area under the curve in diabetic rats. Hence alpha-glucosidase inhibition may possibly be one of the mechanisms for the A. paniculata extract to exert antidiabetic activity and indicates that AP extract can be considered as a potential candidate for the management of type 2 diabetes mellitus.     

A bitter plant with a sweet future? A comprehensive review of an oriental medicinal plant: Andrographis paniculata

Andrographis paniculata (Burm.f) Nees is one of the most popular and important medicinal plant of the Orient, and South East Asia. It finds mention in various forms in Indian, Chinese, Malay, Thai, Unani, and Japanese systems of medicine. The plant exhibits anti-cancer, anti-inflammatory, anti-diabetic, anti-hypertensive, anti-venom, cholestatic, hepatoprotective, anti-thrombotic, anti-retroviral, anti-microbial, anti-pyretic, anti-malarial, anti-oxidant, immunomodulatory, and cardioprotective effects. The major active principles contributing to biological activity are diterpene lactones, but flavonoids, xanthones and caffeic acid derivatives also contribute to anti-oxidant, anti-proliferative, anti-atherosclerotic, and anti-malarial effects. As a result of its wide spectrum of pharmacological activity, almost impeccable safety profile, being a widely cultivated medicinal plant, we have collected and compiled various facets of this plant. Extensive datamining of the phytochemistry and pharmacology of Andrographis paniculata revealed more than 50 diterpene lactones, 30 flavonoids, 8 quinic acid derivatives, and 4 xanthones. This review contains information on around 80 isolated compounds, out of which more than half of the compounds have no reported pharmacological activity. Though there are some good reviews available on Andrographis paniculata, the authors of the earlier reviews focused on one or two aspects of the plant and none have attempted to integrate the available information on this plant. This provided us the much needed impetus, warranting a full-fledged and complete review on Andrographis paniculata, one of the most popular and important Oriental medicinal plant.