Xerophyta stenophylla is a Promisor Functional Plant from Angola

Xerophyta stenophylla (Velloziaceae) is a medicinal plant from Muxima region (Luanda, Angola) known as Iona, widely used by the local population in preparations (decoctions) for the treatment of various diseases, mainly for symptom relief and treatment of schistosomiasis. In Angola it grows abundantly in the municipality of Quibala, province of Kwanza Sul and the rest of the southern region of the country (Namibe)1. The scientific literature presents few studies with this species and the contributions related to its chemical, pharmacological and functional properties may validate its millenary use by Angolan populations. In this sense and meeting a demand from the scientific bases on the traditional use of Angolan plants, the present study aimed at a preliminary chemical study of species X. stenophylla seeking to identify its possible functional properties and potential valorization as source of bioactive compounds. Samples (7g, leaves and stems) were subjected to decoction with 300 mL of distilled water in triplicate. Aqueous filtrates were freeze-dried and stored at 4°C until analysis. For determination of the chemical parameters, the extracts were reconstituted with distilled water. Total soluble phenolics of extracts were determined with Folin–Ciocalteu reagent according to the method of Vinha et al.2 with minor modifications. The amount of total phenolic compounds was calculated from the analytical curve of gallic acid (covering the concentration range between 5 and 300 µg/mL) and expressed as mg of gallic acid equivalents (GAE) per 100g of dry weight (dw). Total flavonoids were determined according to Costa et al.3 with some modifications and calculated from the analytical curve prepared with catechin and expressed as mg of catechin equivalents (CAE) per 100g of dw of the plant material. The anti-radical ability (DPPH radical scavenging assay) of the extracts was evaluated according to Costa et al.3 with minor modifications. An analytical curve was prepared with Trolox (linearity range: 2.5–100 µg/mL, R2 > 0.996) and the antioxidant capacity expressed as µmol Trolox equivalents per 100g of plant material on dw. The FRAP assay was carried out according to Costa et al.3 The standard curve was constructed using ferrous sulphate (linearity range: 150–2000 µM, R2 > 0.996) and the results were expressed as ferrous sulphate (FSE) equivalents per gram of dw. Iona tea presented very promising results (Table 1) regarding the bioactive content as well as its antioxidant properties being this work the first preliminary chemical study carried out with this species. Further chemical and pharmacological evaluations will be carried out to contribute to the knowledge of the functional and pharmacological properties of this species.