The trypsin inhibitor content of 61 wild edible plant foods of Niger.

In the western Sahel and many other regions of sub-Saharan Africa, wild edible plants contribute significantly to human diets, not only during periods when cereal staples are scarce, but also when they are readily available. Although there have been published reports regarding the nutrient contents of these plant foods, little attention has been devoted to their content of antinutrients such as calcium chelators and inhibitors of the pancreas-derived proteases, trypsin and chymotrypsin, which are required for the efficient digestion and absorption of dietary proteins. In this study, aqueous extracts of 61 different leaves, seeds, fruits and flowers of edible plants gathered in the Republic of Niger were analyzed for their content of trypsin inhibitory substances using alpha-N-benzoyl-DL-arginine-p-nitroanilide as the substrate and bovine trypsin as the enzyme source. Twelve of these plant foods contained more antitrypsin activity than soybeans (1.34-8.18 vs. 1.32 microg trypsin inhibited/mg dry weight). Boiling for 3 min did not inactivate the antitrypsin activity in most of the plant extracts. These data confirm that more than half of the wild edible plant foods widely consumed by various populations who inhabit the western Sahel contain significant quantities of heat-stable trypsin inhibitor that could possibly compromise the bioavailability of proteins present in the diets of these populations.

Use of the Trolox assay to estimate the antioxidant content of seventeen edible wild plants of Niger.

Although wild edible plants of the western Sahel and other parts of sub-Saharan Africa are consumed to some extent at all times of the year, greater amounts are consumed when cereal harvests are insufficient to support the populations living in these areas. The purpose of this study was to use a recently reported Trolox-based assay to measure the total antioxidant capacity of aqueous extracts of 17 plants that we gathered from southern Niger. The antioxidant contents of the aqueous extracts were compared to those of spinach and potato. Of the 17 plants, 11 had a greater antioxidant content than spinach and 14 had a greater antioxidant content than potato. The leaves of Tapinanthus globiferus had the greatest antioxidant content, and the fruit of Parinari macrophylla had the lowest. In general, leaves contained more antioxidants than either fruits or seeds. The total antioxidant capacity of the aqueous extracts was relatively high, indicating that the wild plants of the western Sahel may contain substantial amounts of water-soluble flavonoid glycosides, which are potent antioxidants and have been shown to have anticancer properties.

Nutrient content of the edible leaves of seven wild plants from Niger.

Wild plants play an important role in the diet of the inhabitants of Niger. These plants tend to be drought-resistant and are gathered both in times of plenty as well as times of need. Used in everyday cooking, famine foods may be an important source of nutrients. The goal of this study was to investigate the nutritional role of wild plants in the nigérien diet. To this end, leaves of seven plants species were analyzed for their mineral, amino acid and fatty acid contents: Ximenia americana, Amaranthus viridus, Corchorus tridens, Hibiscus sabdarifa, Maerua crassifolia, Moringa oleifera, and Leptadenia hastata. Ximenia americana contained large amounts of calcium. Large quantities of iron were present in Amaranthus viridus. All seven plants contained significant amounts of selenium and phosphorus. Corchorus tridens contained the most protein (19-25% dry weight), and its composition compared favorably to the World Health Organization's standard for essential amino acids. Moringa oleifera contained 17% protein and compared favorably with the WHO standard. Corchorus tridens contained the largest amounts of the two essential fatty acids linoleic and alpha-linolenic acids. These results reinforce the growing awareness that wild edible plants of the Western Sahel can contribute useful amounts of essential nutrients, including amino acids, fatty acids and trace minerals, to human diets.