Inhibitors of alpha-amylase from plants - a possibility to treat diabetes mellitus type II by phytotherapy?

Antidiabetics of plant origin are in common use. A proof of their effectiveness or their mode of action is often missing. The aim of this work was to review the knowledge about inhibitors of alpha-amylase from plants and to comment on the use in anti-diabetic treatment. Herbal alpha-amylase inhibitors are rarely described in the literature, nevertheless they have the ability to lower postprandial blood glucose level and should be used in the supplementary treatment of diabetes. Important constituents for the inhibitory activity against alpha-amylase are mainly polyphenolic compounds. There is a need for further clinical studies to establish a rational therapy with traditional herbal preparations, especially for the leaves from the blueberry, tamarind, lemon balm and rosemary, the hulls from white kidney beans or green tea extract.