The inhibitory effect of the crude extract of Centella asiatica on α-amylase activity

Abstract

Inhibition of α-amylase activity can reduce the postprandial blood glucose level which can be achieved by drugs and medicinal plants (such as Castanospermum austral or black bean). Tannins in black bean have potential inhibitory effect on α-amylase activity [1]. Tannin is also found in Centella asiatica (L.) Urban. [2]. Therefore, the effect of ethanolic extract from Centella asiatica on α-amylase activity was investigated in vitro. The edible parts of Centella asiatica was extracted by 80% ethanolic solution. The total phenolic compound of sample extract was measured [3]. The α-amylase inhibition assay was applied [4]. To determine the effect of the Centella asiatica extract on the α-amylase activity, 10 to 50mg/ml of extracts and 10mg/ml of acarbose (α-amylase inhibitory drug), and active compounds found in Centella asiatica (tannin, rutin, and quercetin) were prepared. The results showed that the extract of Centella asiatica contained total phenolic compound equivalent to 97.45mg of gallic acid/g dry weight. Acarbose and tannin could inhibit α-amylase activity (97.6% and 37.9%, respectively). Whereas, quercetin and rutin did not inhibit α-amylase activity which was similar to the study of Jo et al. [5]. Moreover, the extract of Centella asiatica had α-amylase inhibitory activity (11.4%) at the final concentration of 30mg/ml while other concentrations of this extract had no inhibition. Although, the percentage of inhibition by Centella asiatica extract was less than acarbose, Centella asiatica extract could be a benefit candidate for treatment of diabetes mellitus. However, further in vivo studies are needed to be investigated.