Phytochemical profiling and soluble sugars of African ginger (Siphonochilus aethiopicus) from different growing regions in South Africa

Abstract

African ginger (Siphonochilus aethiopicus) is distributed in different regions of South Africa and contains bioactive constituents that provide health benefits. However, there is limited information describing the phytochemical and soluble sugars in different parts of the plant from different regions. Phytochemical profiling was evaluated by 2,2-diphenyl-1-picrylhydrazyl free radical scavenging activity and ferric reducing power. In addition, colourimetric methods assessed total phenolics and flavonoids, and soluble sugars using liquid chromatography assisted by the refractive-index detector, respectively. The highest total phenolics were observed in the root extracts from Mbombela and Tzaneen (54.5 ± 2.0 and 56.6 ± 6.9 mg gallic acid equivalents g⁻¹, respectively). Mbombela recorded the highest flavonoids in the root (14.8 ± 0.0 µg quercetin equivalents [QE] g⁻¹) followed by Empangeni in the leaf (12.7 ± 1.1 µg QE g⁻¹) and rhizome extracts (14.2 ± 1.9 µg QE g⁻¹). The results showed the highest concentration of sucrose, glucose and fructose in the leaf and rhizome from Brits and Empangeni areas. In both methods, the leaf showed higher antioxidant activity compared with that of the root and rhizome. Plant parts, especially the leaves, could be used as a potential source of antioxidants and provide the basis for further applications in different industries, such as the food and pharmaceutical sectors.