Journal of Medicinal Plants Research Vol. 4(14), pp. 1502-1507, 18 July, 2010 Available online at http://www.academicjournals.org/JMPR DOI: 10.5897/JMPR09.090 ISSN 1996-0875 ©2010 Academic Journals Full Length Research Paper Screening of African traditional vegetables for their alpha-amylase inhibitory effect Bharti Odhav 1 *, Thangaraj Kandasamy 1,2 , Nonhlanhla Khumalo 1 and Himansu Baijnath 1 1 Department of Biotechnology and Food Technology, Durban University of Technology, Durban 4000, South Africa. 2 Centre for Plant Breeding and Genetics, Tamil Nadu Agricultural University, Coimbatore – 641 003, India. Accepted 6 July, 2010 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 of Amaranthus 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) and C. 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. INTRODUCTION Many developing countries around the world use tra- ditional medicine, in particular herbal medicine, because it is sometimes the only affordable source for healthcare (Bhattarai, 1993; Manandhar, 1995). As for the dev- eloped countries, the use of herbal medicine for chronic diseases is encouraged because there is concern about the adverse effects of chemical drugs and treatment using medicines of natural origin appears to offer more gentle means of managing such diseases (WHO, 2002). Herbal drugs are prescribed widely because of their effectiveness, fewer side effects and are relatively low in cost. Diabetes mellitus is the most common endocrine *Corresponding author. E-mail: odhavb@dut.ac.za. Tel: +27- 31-3735330. Fax: +27-31-3735351. disease worldwide and about 173 million people suffer world wide. Diabetes causes about 5% of all deaths globally each year and 80% of the people with diabetes live in low and middle income countries. Diabetes deaths are likely to increase by more than 50% in the next 10 years unless urgent action is taken (WHO, 2008). Most prevalent form of diabetes is non-insulin dependent diabetes mellitus (NIDDM / Type II). Many and diverse therapeutic strategies for the treatment of Type II diabetes are known. Conventional treatments include the reduction of the demand for insulin, stimulation of endogenous insulin secretion, enhancement of the action of insulin at the target tissues and the inhibition of degradation of oligo- and disaccharides (Groop et al., 1997, Perfetti et al., 1998). The α-glucosidase enzymes such as α-amylase are responsible for the breakdown of oligo and/or disaccharides to monosaccharides. The inhibition of these enzymes leads to a decrease of blood