Polyphenolic and nutritional composition and antioxidant potential of calyx extracts from the R72-1 variety of Hibiscus sabdariffa cultivated on soils rehabilitated by half-moons

Abstract

The low soil fertility limits the cultivation of the R72-1 variety of Hibiscus sabdariffa in the Bassitenga province. This study evaluated the effect of half-moon structures on the polyphenolic composition and the nutritional and antioxidant potentials of calyces from the R72-1 variety. Soils from amended and control plots were analyzed according to the BUNASOLS manual. Extracts prepared with acetone/water/acetic acid, methanol-HCl, and distilled water were characterized using spectrophotometric methods, Kjeldahl, phenol-sulfuric acid, DPPH, ABTS, FRAP, and HPTLC. Rehabilitated soils showed increased fertility (rating 25.75 to 38.25). Calyces from these soils exhibited higher levels of total phenolics (58.42±2.05 mg GAE/g), flavonoids (24.27±2.82 mg QE/g), anthocyanins (14.84±2.25 mg ECy/g), proteins (0.726±0.042%), sugars (32.25±1.26 mg GE/g), and strong antioxidant activity (AAI = 1.24). Anthocyanin profiles remained identical to those of the control. Chromatographic analysis revealed the presence of six anthocyanin compounds with different Rf values. These results therefore confirm a quantitative effect of half-moons on anthocyanin compounds.