Assessment of the antioxidant and nutritive profile of the leaves and berries of Solanum nigrum and Solanum torvum Swart

Abstract

The research focused on analyzing the antioxidant and nutritional properties of Solanum torvum leaves (STL) and berries (STF), as well as Solanum nigrum leaves (SNL) and berries (SNF). The study examined the basic nutritional composition, mineral content, metal presence, total phenolic compounds, and antioxidant capabilities of both plant species. Wild-harvested leaves and unripe berries of S. torvum and S. nigrum were cooked and ground for testing. Statistical analysis included the Student's T-test and calculations of mean ± SEM. Findings revealed that both species of Solanum are sources of dietary fibre, protein, and fats, along with essential minerals like sodium (Na), manganese (Mn), potassium (K), zinc (Zn), and iron (Fe) in different amounts. Notably, the leaves had higher iron content than the berries, indicating their potential superiority in addressing Iron Deficiency Anaemia. Antioxidant activity was highest in STF (61.34±1.05 mg/mL) for water-based extracts and SNL (42.86±1.49 mg/mL) for alcohol-based extracts, highlighting the impact of solvent choice on antioxidant measurement. STL exhibited the greatest phenolic concentration in water extracts, while STF had the highest in alcohol extracts (15.88±0.87 mg/g GAE). Additionally, palmitic acid was identified in SNL and STL, oleic acid (97.03 %, retention time: 10.00 min) in SNB, and Sitosterol (94.93 %, retention time: 26.82 min), a type of phytosterol, in STB. Considering the role of antioxidants in preventing lipid oxidation in food and their contribution to combating degenerative diseases, the study advocates for the potential use of these Solanum species as natural food additives to protect against oxidative damage.