Antioxidant activity of three local leafy vegetables of Western Uganda
Authors: Kinyi Hellen Wambui , Byarugaba Wilson , Vicente‐Crespo Marta 
Published: November 2023

Africa is suffering the double burden of communicable and non‐communicable diseases. Antioxidants have been shown to prevent the development of diabetes, hypertension and cancer as well as slow down the progress of malaria, tuberculosis and HIV. The main dietary sources of antioxidants are fruits and vegetables, both of which are abundant in East Africa. Unfortunately, the natural diversity of the region is not translating into a healthy varied diet for the general population. Traditional vegetable species that used to be frequently consumed are being replaced by the growth of exotic species under the promise of quicker money. These imported vegetables are more expensive and less adapted to the dry/rainy seasons of the region. As a consequence, the average East African consumes little vegetables or none at all during periods of shortages. It is, therefore, key to study the nutritional properties of local products before they are completely lost. Nutritional Biochemists have an important role to play informing the population and policy makers about which species is important to conserve and promote for their nutritional value specially seeing the aggressive (and expensive) government campaigns that have extensively promoted bananas and coffee cultivars, of poor nutritional content, for their economic value.

For this study, three vegetables were chosen due to their availability in local markets of Ishaka municipality in Western Uganda: dodoo (Amaranths), pumpkin leaves (Cucurbits) and eshiwiga (Solanum). They were prepared as is done traditionally and the methanolic extracts of raw, steamed and boiled vegetables were used to analyze the antioxidant activity. Spectrophotometry was used to evaluate reducing power and anti‐hemolytic activity while titration methods were used to determine hydrogen peroxide scavenging activity and vitamin C content. Drosophila melanogaster is currently being used to test the potential of dodoo to protect against oxidative stress. Wild‐type and stress‐sensitive flies are being used as in vivo experimental model. Acute toxicity studies reveal a safe dose of 5mg/ml. The flies will be crushed at 7, 14, 28 and 35 days and the tissue homogenates used to determine the total reducing power, and superoxide dismutase and catalase activities.

Overall, Dodoo has shown the highest activity. The cooking methods had varying effects on the different vegetables across the tests. Cooking the vegetables caused great reduction of the vitamin C content, which was transferred to the water when boiling. The effects of steaming were less destructive than boiling in all tests.

Our results indicate that the local vegetables have the potential to offer antioxidant activity. This capacity can be affected by the traditional cooking methods of which steaming is the most conservative. Dodoo shows the highest antioxidant activity and the advances of the in vivo testing will be presented.

The educational initiative leading to the development of the Drosophila unit in which this work is on‐going is being submitted to the education section of this conference.

Support or Funding Information

The work described was sponsored by a Scholarship from Sayansi Research for Development. We also acknowledge the support of DrosAfrica and Trend.