In vitro inhibitory activity of some lichen extracts against α-amylase enzyme

Noninsulin-dependent diabetes mellitus (NIDDM) is a metabolic disorder that is characterized by hyperglycemia and can be controlled by inhibition of enzymes which are responsible for breakdown of starch and increase the amount of blood sugar, α-amylase is one of these enzymes. Herbal alpha-amylase inhibitors are rarely described in the literatures, despite their important constituents for the inhibitory activity of this enzyme and also less toxicity and side effects compared to currently used chemical drug to control hyperglycemia. Lichens are great source of natural compounds with different biological activities and various enzyme inhibitory activitites. In the present study, four different lichens extracts obtained from Ramalina sinensis, Heterodermia leucomelos, herpothallon sp. and Parmatorema reticulatum were evaluated at different concentrations to observe the α-amylase inhibitory activity. Amongst the four, H. leucomelos showed highest inhibition with 95% and highest IC50 with 27.6 mg/ml. R. sinensis had least activity among all extracts in 15mg/ml concentration with 80% inhibition and 3.31 mg/ml of IC50 value. The results of the all extracts from 10 to 15-mg/ml concentrations clearly indicate the potential of these extracts to manage hyperglycemia by inhibiting the activity of α-amylase enzyme.