Comparison of Antioxidant, Flavonoid and Polyphenol Content of Three Selected Solanaceae Genera from Kigezi, Southwest Uganda

Solanaceae is family of plants widely used in food, sauce and herbal medicine because its members are rich in carbohydrates, proteins, fats, vitamins, mineral salts and other trace and essential nutrients like phenols and flavonoids that retard degenerative diseases and stress. Knowledge on purposeful use of solanaceae in food and medicine in Uganda is low. Aqueous extracts of dry leaves of three selected solanum genera growing in Kabale were compared for their polyphenol and flavonoid contents and antioxidant properties. Total polyphenol (TPC) and total flavonoid (TFC) contents were determined by the Folin-Ciocalteu and aluminium chloride colorimetric methods respectively. Antioxidant properties and radical scavenging were determined using DPPH, hydrogen peroxide, thiocyanate-iron (III) complex and iron (II)/(III)-linoleic acid systems. The polyphenol content of dry leaves of S. anguivi was 1750 ± 0.70, that for S. macrocarpon was 104 ± 0.45 and S. nigrum was 97.80 ± 0.15 GAE/g yet the flavonoid content was 7.40 ± 0.30, 35.00 ± 0.60 and 16.40 ± 0.40 mg/QE/g for S. anguivi, S. macrocarpon and S. nigrum respectively. The DPPH scavenging at IC50 were 7.80 ± 0.25; 45.60 ± 0.30 and 42.90 ± 0.20 respectively yet hydrogen peroxide scavenging at IC50 stood at 6.89 ± 0.15; 27.00 ± 0.35 and 17 .90 ± 0.20 μg/mL in the respective order for S. anguivi, S. macrocarpon and S. nigrum. The available data suggests the plants are very good food supplements of high nutritive and chemotherapeutic values. However, there is need to perform in vivo and vitro experiments to deduce their efficacy on mammals.