Phytochemical Study and Evaluation of the Nutritional Potential of Glyphaea brevis Leaves from the Flora of Togo

Abstract

Glyphaea brevis is a food plant used in traditional medicine to treat hypertension and a number of infectious diseases. It has been the subject of very few studies and there is little data on its nutritional value. The aim of the present study is therefore to exploit the leaves of Glyphaea brevis from Togolese flora. Aqueous and hydroethanolic extracts were obtained by maceration of leaf powder. Phytochemical tests and polyphenol and flavonoid assays were carried out using colorimetric methods. Antioxidant activity was assessed in vitro using the DPPH radical scavenging test and the FRAP test. The nutritional value of Glyphaea brevis leaves was assessed using standard AOAC methods, and toxicity was assessed using an acute toxicity test in wistar rats. Phytochemical screening revealed the presence of flavonoids, saponosides, tannins, gallic tannins, terpenoids and mucilages in the aqueous extract. In addition to these compounds, anthocyanins and terpenes were found in the hydroethanol extract. The determination of polyphenols and flavonoids in the considered extracts showed that the hydroethanolic extract of the leaves contained the highest levels of these phenolic compounds: 200.893 ± 4.805 mgEAG/gE for polyphenols and 74.034 ± 2.815 mgEQ/gE for flavonoids respectively. The IC50 for antiradical compounds (DPPH●) were 1271.136 ± 3.204 μg/mL for the hydroethanolic extract and 1535 ± 2.310 μg/mL for the aqueous extract and the antioxidant activity with the FRAP test was 914.333 ± 2.205 μmol/L and 440.966 ± 1.105 μmol/L respectively. The levels of biochemical compounds were 64.99% for digestible carbohydrates, 12.14% for fibre, 19.03% for protein and 3.84% for fats. The energy value was 393.85 Kcal/100g DM. Spectrophotometer assays revealed the presence of minerals such as Na, Ca, Mg, K and Fe at significant levels, with a Na/K ˂ 1 ratio. The acute toxicity test did not reveal any signs of toxicity. All the results obtained in this study therefore justify the therapeutic and dietary use of Glyphaea brevis leaves.