Screening of African traditional vegetables for their alpha-amylase inhibitory effect.

Abstract

Diabetes is a syndrome of disordered metabolism resulting in abnormally high blood sugar levels (hyperglycemia). The one possibility of lowering postprandial glucose levels is by the inhibition of α-amylase activity. In this study, aqueous extracts from leaves, fruits and flowers, stems and roots of twenty African traditional vegetable plants were tested for their inhibitory effect on α-amylase. The results showed that leaves of Centella asiatica (3 and 5 mg/ml) and Ceratotheca triloba (5 mg/ml), roots of Cleome monophylla (5 mg/ml), fruits and flowers ofAmaranthus hybridus (3 mg/ml), Justicia flava (3 mg/ml) and Chenopodium album(3 mg/ml), stem parts of J. flava (3 mg/ml), Portulaca oleracea (3 mg/ml) andCleome monophylla (3 mg/ml) showed significant (more than 70%) reduction in α-amylase activity. Though results from this study showed significant α-amylase inhibition at higher concentrations (3 and 5 mg/ml), traditionally used anti-diabetic medicinal plants are found to have α-amylase inhibition at very low concentrations, mostly less than 1 mg/ml. These traditional plant species regularly consumed as vegetables by rural people, will not only give dietary nutritional benefits, but also play vital role in inhibiting α-amylase activity, thereby reducing the blood glucose level and benefiting diabetic patients.   Key words: African leafy vegetables, anti-diabetic, α-amylase, inhibitory effects.